开云体育

There's a possibility I'll be in Pittsburgh for a few days. I won't have much in the way of spare time, but I'd like to know if there are any electronic surplus places worth checking out.

Primary interests: Test gear and pre-divestiture Bell System phone equipment. Some small interest in computer components (not a priority, though).

Thanks much.


-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies --
kyrrin (at) bluefeathertech do/t c=o=m
"Quid Malmborg in Plano..."

Hi

Try this site for addresses etc for surplus stores in USA etc. Has lots of interesting items.



KW

Google 'surplus electronics pittsburgh'


?
HankC, Boston
WA1HOS



________________________________
From: "TekScopes@..." <TekScopes@...>
To: TekScopes@...
Sent: Sunday, June 30, 2013 5:36 PM
Subject: [TekScopes] Digest Number 7897



All about classic Tektronix CRT o'scopes

All about classic Tektronix CRT o'scopes Group
15 New Messages
Digest #7897

1a
Re: One idea for cleaning wafer switches, using Scotch Brite by "Don & Karen Patterson" sufnish
1b
Re: One idea for cleaning wafer switches, using Scotch Brite by "HankC" hankc918
1c
Re: One idea for cleaning wafer switches, using Scotch Brite by "HankC" hankc918
1d
Re: One idea for cleaning wafer switches, using Scotch Brite by "Jerry Barr" kj6ntl
2a
Re: 7904 transistors by "Tom Miller" tmillermdems
2b
Re: 7904 transistors by "Glenn Little WB4UIV" glittle_29445
2c
Re: 7904 transistors by "Tom Miller" tmillermdems
2d
Re: 7904 transistors by "Christopher Hilton-Johnson" crippo2
2e
Re: 7904 transistors by "G?ran Krusell" gorankrusell
3a
Re: Can you run a 7k mainframe upside down? by "Stefan Trethan" stefan_trethan
3b
Re: Can you run a 7k mainframe upside down? by "HankC" hankc918
4a
Re: 2252 'scope with Counter Timer issue - resolved by "raymonddompfrank" raymonddompfrank
5a
Re: Tek 7613 Desoldering Large P/S Capacitors by "HankC" hankc918
6.1
Re: HV Multiplier defective in 7603? - resolved, sort of by "raymonddompfrank" raymonddompfrank
7a
Re: Electronic goodies, Pittsburgh by "kiloowatt" kiloowatt
Messages
1a
Re: One idea for cleaning wafer switches, using Scotch Brite
Sun Jun?30,?2013 11:23?am (PDT) . Posted by:
"Don & Karen Patterson" sufnish
I have used this GC burnisher for relays in the past. It might work for switches as well. Amazon's price looks high compared to other listings YAHOO found. I used this one for illustration because it worked best to cut and paste.

Quantity:
$16.99 + $5.90 shipping
In Stock. Sold byADVENTURER&# 39;S BAG

or
Sign in to turn on 1-Click ordering.

More Buying Choices
Have one to sell? Sell yours here
Share

Share your own customer images
GC Electronics Fine Grade Burnishing Tool Excellent For Removing Oxidation 3 Inch Long
by GC Electronics
Be the first to review this item
List Price: $24.19
Price: $16.99
You Save: $7.20 (30%)
Only 4 left in stock.
Ships from and sold by ADVENTURER&# 39;S BAG.
This burnishing tool is ultra fine grade making it excellent for removing oxidation from switches & relay contacts.
Width: 0.12. Thickness: 0.012.

Take care,
Don Patterson

On Jun 30, 2013, at 9:53 AM, Jerry Barr wrote:

they do have a good size group of burnishers but ure is definitely cheaper /tho the set is 36.00/but the holder is quality and the size of a pen/and the burnishers are diff sizes shapes etc. and are flexible

Jerry KJ6NTL
From: keithostertag <keitho@strucktower. com>
To: TekScopes@yahoogrou ps.com
Sent: Sunday, June 30, 2013 3:41 AM
Subject: [TekScopes] Re: One idea for cleaning wafer switches, using Scotch Brite

Hey thanks Mike, I never would have thought of using "burnisher&quo t; as a search term for these! I'll give them a try sometime.

Until then, I believe my homemade tool has several advantages:

Far less likely to cause accidental damage.
Being essentially a deep soft pad, it can reach places the burnisher can't (the other side of raised sections/protuberan ce).
It is always immediately available.

Some company probably makes a similar tool that uses a soft pad, but I haven't yet found it...

Keith

--- In mailto:TekScopes% 40yahoogroups. com, "Mike Czuhajewski" <wa8mcq@. ..> wrote:

...back in the old days of rotating tv tuners we used to purchase a
small metal abt 3/16x1.5 inches abrasive contact cleaning strip....

I remember those well from my USAF days, a very long time ago. Mouser
carries them, made by OK Industries. Search on "burnisher&quo t;.

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1b
Re: One idea for cleaning wafer switches, using Scotch Brite
Sun Jun?30,?2013 1:39?pm (PDT) . Posted by:
"HankC" hankc918
You can also use pipe cleaners.
There are some which have stiffer bristles in them.
They will clean the wafer part if you keep switching it back & forth.
Try a smoke shop.

?
HankC, Boston
WA1HOS

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1c
Re: One idea for cleaning wafer switches, using Scotch Brite
Sun Jun?30,?2013 1:48?pm (PDT) . Posted by:
"HankC" hankc918
You could cut the matchbook striker into a narrow strip & insert it into an X-acto knife handle in place of the blade.

?
HankC, Boston
WA1HOS

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1d
Re: One idea for cleaning wafer switches, using Scotch Brite
Sun Jun?30,?2013 2:26?pm (PDT) . Posted by:
"Jerry Barr" kj6ntl
I like that idea/ gud one

Jerry KJ6NTL


____________ _________ _________ __
From: HankC <hankc918@yahoo. com>
To: "TekScopes@yahoogrou ps.com" <TekScopes@yahoogrou ps.com>
Sent: Sunday, June 30, 2013 1:48 PM
Subject: [TekScopes] Re: One idea for cleaning wafer switches, using Scotch Brite

?

You could cut the matchbook striker into a narrow strip & insert it into an X-acto knife handle in place of the blade.

HankC, BostonWA1HOS


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2a
Re: 7904 transistors
Sun Jun?30,?2013 11:28?am (PDT) . Posted by:
"Tom Miller" tmillermdems

Tucker has them for $5 each. Eight in stock. Tucker is a good, reliable vendor.

ts.com/Search. aspx?Mfg= TEK&Page= 14

Best regards,
Tom

----- Original Message -----
From: atonizzo
To: TekScopes@yahoogrou ps.com
Sent: Sunday, June 30, 2013 2:14 PM
Subject: [TekScopes] 7904 transistors

Hi:

I am fixing a 7904 that has a busted power supply.
Both inverter transistors (Q1234 and Q1241) are busted
due to a connection to 240V while setup for 115V.

The transistors are Motorola 151-03-6800 and I will be
looking around for a replacement of the same kind, but
I was also wondering if anybody has has any success
trying more modern replacements for these parts.

Any suggestion about similar parts would be appreciated.

Regards
Tony


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2b
Re: 7904 transistors
Sun Jun?30,?2013 11:54?am (PDT) . Posted by:
"Glenn Little WB4UIV" glittle_29445
Transistor 151-0368-00 is a 2N6300.
This is a Tektronix part number.
Motorola may have been the only supplier.
This transistor appears to be available from:

northern. com/TekParts/ Tek151Page. php

for $1.62 each.

Hope this helps. This was located by my friend Google.

73
Glenn
WB4UIV

At 02:14 PM 6/30/2013, you wrote:

Hi:

I am fixing a 7904 that has a busted power supply.
Both inverter transistors (Q1234 and Q1241) are busted
due to a connection to 240V while setup for 115V.

The transistors are Motorola 151-03-6800 and I will be
looking around for a replacement of the same kind, but
I was also wondering if anybody has has any success
trying more modern replacements for these parts.

Any suggestion about similar parts would be appreciated.

Regards
Tony



-------- --------- --------- --------- -

Yahoo! Groups Links

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2c
Re: 7904 transistors
Sun Jun?30,?2013 12:23?pm (PDT) . Posted by:
"Tom Miller" tmillermdems
Hi Glenn,

The 2N6300 shows up as a NPN Darlington in a TO-66 package.

So I am not sure VeroniaNorthern has the equivalent part number right. They do carry original Tek parts though and most likely it will be the right part.

The service manual for the early 7904 calls out an RCA 61577 as a replacement. In any case, the schematic shows a NPN transistor in the circuit, not a darlington.

Regards,
Tom

----- Original Message -----
From: Glenn Little WB4UIV
To: TekScopes@yahoogrou ps.com
Sent: Sunday, June 30, 2013 2:54 PM
Subject: Re: [TekScopes] 7904 transistors

Transistor 151-0368-00 is a 2N6300.
This is a Tektronix part number.
Motorola may have been the only supplier.
This transistor appears to be available from:

northern. com/TekParts/ Tek151Page. php

for $1.62 each.

Hope this helps. This was located by my friend Google.

73
Glenn
WB4UIV

At 02:14 PM 6/30/2013, you wrote:

Hi:

I am fixing a 7904 that has a busted power supply.
Both inverter transistors (Q1234 and Q1241) are busted
due to a connection to 240V while setup for 115V.

The transistors are Motorola 151-03-6800 and I will be
looking around for a replacement of the same kind, but
I was also wondering if anybody has has any success
trying more modern replacements for these parts.

Any suggestion about similar parts would be appreciated.

Regards
Tony



-------- --------- --------- --------- -

Yahoo! Groups Links

Reply to sender . Reply to group . Reply via Web Post . All Messages (6) . Top ^
2d
Re: 7904 transistors
Sun Jun?30,?2013 1:37?pm (PDT) . Posted by:
"Christopher Hilton-Johnson" crippo2
Tony
151-0368-00 are commonly used in the 'hi-efficiency& #39; 7K series PSU. This
translates to the 2N6300, recently available from Ebay (china source).
In some mainframes, where higher power is required, (eg 7844) Tek
'selected&# 39; the 2N6300 and called it a 151-0386-01. Sphere lists the -01
version as MJ13015. There are 3 available on Ebay now for $19+ (& same
vendor has more from time to time).
In my experience the China parts are iffy, the MJ13015 works fine.

Chris HJ

On 30/06/2013 19:14, atonizzo wrote:

Hi:

I am fixing a 7904 that has a busted power supply.
Both inverter transistors (Q1234 and Q1241) are busted
due to a connection to 240V while setup for 115V.

The transistors are Motorola 151-03-6800 and I will be
looking around for a replacement of the same kind, but
I was also wondering if anybody has has any success
trying more modern replacements for these parts.

Any suggestion about similar parts would be appreciated.

Regards
Tony

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2e
Re: 7904 transistors
Sun Jun?30,?2013 2:10?pm (PDT) . Posted by:
"G?ran Krusell" gorankrusell
Hi Tony,
I used the BU208A from ST with good result.

G?ran

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3a
Re: Can you run a 7k mainframe upside down?
Sun Jun?30,?2013 11:40?am (PDT) . Posted by:
"Stefan Trethan" stefan_trethan
Yes, you can run them upside down, but only with the trace inverted,
and be prepared to go back in time (no heavy meals beforehand).

When turning over any old piece of equipment listen carefully for any
loose parts and do a visual inspection. They may cause shorts and most
equipment contains a few loose screws by design (The ones you are
always left with when putting something back together).

You'd really have to flip the CRT or deflection pins to make this
work, and everything else will still be backwards.
For heaven's sake get a few rackmounts.

ST

On Sun, Jun 30, 2013 at 7:35 PM, cheater00 . <cheater00@gmail. com> wrote:

Returning to the original post... any ideas? :)

D.

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3b
Re: Can you run a 7k mainframe upside down?
Sun Jun?30,?2013 1:35?pm (PDT) . Posted by:
"HankC" hankc918
That raises another "Why" question.

?
HankC, Boston
WA1HOS

____________ _________ _________ __
From: "TekScopes@yahoogrou ps.com" <TekScopes@yahoogrou ps.com>
To: TekScopes@yahoogrou ps.com
Sent: Saturday, June 29, 2013 3:06 PM
Subject: [TekScopes] Digest Number 7894


All about classic Tektronix CRT o'scopes

All about classic Tektronix CRT o'scopes Group
15 New Messages
Digest #7894


7d
Re: Can you run a 7k mainframe upside down? by "cheater00 ." cheatercheater00@ rocketmail. com

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4a
Re: 2252 'scope with Counter Timer issue - resolved
Sun Jun?30,?2013 11:58?am (PDT) . Posted by:
"raymonddompfrank" raymonddompfrank

Writing this on my iPhone, having dinner out (21:00h here).
David, your paragraph "it seems that..." is correct in its entirety.
In my 2252 the phase detector out (pin ... of the logic chip), controlling the VCO was stuck at 4V, no matter what I did with the VCO (control voltage). I did indeed put in a DIL OCXO (made by Micro Crystal of Switzerland) . I have a few of those from Ebay.
In my 2252, the 10 MHz oscillator is one transistor + xtal. No extra buffering. Small load already detuned to below 10 MHz.
Jittered signal to VCO is stil added.

Raymond
--- In TekScopes@yahoogrou ps.com, David <davidwhess@ ...> wrote:

I am going by the 2247A schematics but I doubt the 2252 is different.

It seems like he replaced the original 10 MHz crystal oscillator with
an OCXO (?) and the original integrated phase detector with an XOR
phase detector. I think he kept the original 200 MHz VCO.

I am not sure why he had problems sampling the 10 MHz signal. There
is an emitter follower used as a buffer to drive the integrated phase
detector. Maybe the buffer was bad and not the phase detector? Maybe
he could have connected the 10 MHz OCXO to the external reference in.

Note that the integrated phase detector does a lot more than just
detect phase. The 10 MHz crystal oscillator or external reference is
divided down to 1 MHz (so the external reference can be 10 MHz, 5 MHz,
or 1 MHz) and then multiplied up to 200 MHz. The phase detector
includes pseudo random noise generator clocked at 125 kHz (1 MHz
divided by 8) which dithers the VCO when time intervals are measured
(including rise and fall times) which prevents phase coherence between
the test signal and the oscillator which would produce marginal
measurements.

On Sun, 30 Jun 2013 10:13:05 -0700 (PDT), Jerry Barr
<kj6ntl@. ..> wrote:

hi just curious what freq is the counter up to/100 MHz or? 500/ I have a 500mhz counter that needs? a similar fix / cud I get the schematic of ure circuit/wud appreciate

Jerry KJ6NTL


________ _________ _________ ______
From: raymonddompfrank <r.domp.frank@ ...>
To: TekScopes@yahoogrou ps.com
Sent: Sunday, June 30, 2013 8:19 AM
Subject: [TekScopes] Re: 2252 'scope with Counter Timer issue - resolved

?

It has turned out that the PLL output was in fact defective. I have replaced it with a simple XOR-based phase detector. Since it proved difficult to bring out the 10MHz X-tal signal without increasing load too much (it made tuning as high as 10MHz difficult), I decided to put a small OCXTO (!) on the same PCB as the new PLL circuitry. Extremely simple, extremely successful and always accurate to within less than 1 LSD count...

Thanks all for your responses and help!

Raymond

--- In mailto:TekScopes% 40yahoogroups. com, "raymonddompfr ank" <r.domp.frank@ > wrote:

Hi all,
May I please ask your help with the following:

My recently acquired 2252 'scope has an issue with its counter timebase. Its display jitters somewhat (3 LS Digits) and indicates frequencies about 2 % low. X-tal oscillator (10 MHz) around Q1901 is OK.
- Signal at pin 58 (TC) on U1905 (Fast Counter Logic) is around 200 MHz, jitters as well.
- Signal at pin 23 (PFC) U1902 (Slow Counter Logic) is steady at around 4V. It should be pulsing when PLL in lock according to service doc.
Obviously, anode of varactor CR1903 is at almost 4V, mostly steady. It should be at about 2V with PLL in lock. (FM) noise coming from U1902 pin 22 is visible though.
C1913 and C1914 are not visible on the PCB, nor are places to put them, possibly only parasitic capacitance used.
I haven't yet checked VCO input on U1902 (pin 26).
Here's (another) part of what I don't understand: Displayed frequency being low would indicate timebase too fast, which would indicate varactor capacitance low, which would indicate its control voltage too high. Then why doesn't PFC pulse low? PFC defective? My error in thinking?
I will try and measure TC on U1905, next offer an external 200 MHz signal and see what happens. Also try and measure VCO on U1902. Can anyone give me some guidance in how to proceed apart from these actions?

Raymond

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5a
Re: Tek 7613 Desoldering Large P/S Capacitors
Sun Jun?30,?2013 1:27?pm (PDT) . Posted by:
"HankC" hankc918
Ken,

You raise some good points that the open cap could someday short out.
I had intended to remove it but never got around to it.
So far, so good. :<)? Three yrs & counting.

?
HankC, Boston
WA1HOS

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6.1
Re: HV Multiplier defective in 7603? - resolved, sort of
Sun Jun?30,?2013 1:37?pm (PDT) . Posted by:
"raymonddompfrank" raymonddompfrank
In the sentence below: "The on-screen "image" was too small, so PDA voltage probably too low, UNLESS:..." , image was too *large*, obviously. Thanks for noting it, Albert!

Raymond

--- In TekScopes@yahoogrou ps.com, "raymonddompfr ank" <r.domp.frank@ ...> wrote:

This issue has been resolved but has left me wondering.
After I came to the conclusion that the HV multiplier must be defective, I removed it and made some measurements in the -2975 V circuits. Reason: The circuit stabilized at a voltage near -4 KV... I measured the high-ohm voltage divider R's (R1245A and -B), all active components like CR1244 (curve tracer) and voltages, all other R's and C's in the focus and grid bias etc. areas and all checked out OK. Unfortunately, I could't do HV (leakage) measurements on components. Although the HV divider R's (ratios) all showed the correct resistances, the circuit stabilized at almost -4 KV. I measured the (very small) current through R1201 and it was ok. The one explanation that I can give is leakage on the PCB's surface but I cleaned it thoroughly both with water-soluble soap and organic solvent (no acetone...) although it had looked very clean already.
In the end, I decided to put a resistor in series with R1245A to reduce the HV. This worked ok.
To add (or not) to the confusion:
I assembled a HV multiplier from discrete components, which worked ok. After an initial test I potted them in polyurethane. The whole thing is the same size as the original, BUT:
The on-screen "image" was too small, so PDA voltage probably too low, UNLESS:
I increased HV by removing the series resistor that I had added...
I think it was David who suggested that HV may have been at -4KV before, finally causing the HV multiplier to fail and he may be right.
Since adjusting vertical and horizontal gain did not allow enough reduction of the image size to fully correct the increased size, I decided to accept an increase of HV to almost -3.3 KV (from the intended -2975V) by permanently installing a resistor as mentioned before. Its value is 68K. Not the most elegant solution but it allows adjusting hor. and vert. gain with some reserve.
The 'scope has been operating flawlessly, with a very sharp and stable image for a few weeks now.

Thanks all for your input, suggestions and help!

Raymond



--- In TekScopes@yahoogrou ps.com, "raymonddompfr ank" <r.domp.frank@ > wrote:

Hi all,
My recently restored and very nice early Heerenveen (NL-) made 7603 has developed a problem:
After working OK for a few days, suddenly brightness and focus deteriorated, came back again, deteriorated again and finally the screen became completely dark, all this within 5 minutes. After I opened the case, it immediately became apparent that the HV cage was quite hot, I guess around 50C. Most likely, that's because of Q1216 and Q1218 heating up. No burning smell.

Looking for the fault, being careful and full of respect for HV, I did the following:

1. Disconnected HV cage and measured all LV voltages (-50V, -15V, +5V, +15V, +5-V, +130V), using a 'scope with DVM). All ok, ripple very low.

2. Reconnected HV cage. LV's remain ok, HV Test point (should be -2975V)reaches ca -1.8KV, next goes further negative, something like -2.5KV, then back to around -1.8KV etc. with a period of 1 or 2 seconds. Sort of tick mode below -1.8KV. LV's remain OK, so the 'scope isn't in tick mode. PDA voltage sort of follows change of HV (used P6015). No brightness.

3. Unplugged and discharged post deflection anode. 'Scope behaved as in 2.

4. Disconnected HV Multiplier (U1230) at its input. HV test point reaches almost -4KV and remains steady.

To me, this looks like a HV breakdown in the multiplier.
It seems that these multipliers are rather expensive at Qservice etc. so I'm considering buying one second hand locally or building one myself. Apart from obvious things like HV isolation (air), >10KV C's and >7KV(?) diodes, would there be any special things to consider when building a multiplier myself?

Any thoughts at all on this?

Thanks!

Raymond

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7a
Re: Electronic goodies, Pittsburgh
Sun Jun?30,?2013 2:36?pm (PDT) . Posted by:
"kiloowatt" kiloowatt
Hi

Try this site for addresses etc for surplus stores in USA etc. Has lots of interesting items.

. com/surplus/ surpcats. html

KW

--- In TekScopes@yahoogrou ps.com, Daniel Koller <kaboomdk@ ...> wrote:

Hi folks,

?? ??I am going to "second" this question. ?? I too will be in PGH over the July 4th weekend and am curious if anyone has any suggestions on where to find good surplus and used equipment.

?? ??However, I'm going to guess that there is not much chance of a good surplus store based on my observations. ??Back in 1994, when I went to a meeting in Pittsburgh, I was walking down the Strip near the downtown end and there were still a bunch of old hardware stores doing ironmongery - selling machine tools and parts, scrap metal, and I remember cheap drill press vices that impressed me at the time as being from China. ??

?? Since then I've married a woman who is from Pittsburgh and we go there often to visit family, and my last walk down the Strip was more like a visit to the shopping mall - lots of eateries, trinket stores (selling clearly Chinese goods), florists.... not the sorts of places where you'd expect to find instruments. ??

?? ??My point is it's not just the Strip that has undergone major changes in the past decades. ??I suspect the whole region is cleaned up. ??Westinghouse long ago shrunk down though they are now growing again. ?? All the steel and heavy industry was gone DECADES ago. ??There is not much industry left.

?? ??I did notice a bunch of industrial buildings and warehouses off I376 on the way to the airport and I have yet to check out what's there, so perhaps there is some hope in the outskirts of town. ??If anyone has some specific Ideas of stores to check, I'm happy to go.

?? ??Now on the other hand, if anyone wants to know where to get plant fossils....( OT!)

?? ??Dan



____________ _________ _________ __
From: Bruce Lane <kyrrin@. ..>
To: milsurplus@. ..
Cc: voip@...; tekscopes@yahoogrou ps.com
Sent: Saturday, June 29, 2013 10:55 PM
Subject: [TekScopes] Electronic goodies, Pittsburgh



??
There's a possibility I'll be in Pittsburgh for a few days. I won't have much in the way of spare time, but I'd like to know if there are any electronic surplus places worth checking out.

Primary interests: Test gear and pre-divestiture Bell System phone equipment. Some small interest in computer components (not a priority, though).

Thanks much.

-=-=-=-=-=-= -=-=-=-=- =-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- hertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"Quid Malmborg in Plano..."

Reply to sender . Reply to group . Reply via Web Post . All Messages (3) . Top ^
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Howdy,

? Thanks for the reply. ? I was hoping someone in this group actually knows of a specific place that is a good resource. ? One piece of advice from one of the very experienced members of the group is better than a thousand Google searches, which turns up a lot of junk that needs to be sorted through. ?And I don't have the time to call, let alone drive by each of the "hits" returned.

? That said, I did do a Google search and turned up one promising possibility: ?? ? I just wonder if they will sell to you if you walk off the street or not. ?But University surplus departments were once a great source of equipment, till they discovered you could auction off the stuff on ebay and make a lot more money that way.

? There is also this list:


?
? But it hasn't been updated in 4 years. ?Nothing in Pittsburgh.

Dan


________________________________
From: HankC <hankc918@...>
To: "TekScopes@..." <TekScopes@...>
Sent: Monday, July 1, 2013 9:40 AM
Subject: [TekScopes] Re: Electronic goodies, Pittsburgh



?
Google 'surplus electronics pittsburgh'

?
HankC, Boston
WA1HOS



________________________________
From: "TekScopes@..." <TekScopes@...>
To: TekScopes@...
Sent: Sunday, June 30, 2013 5:36 PM
Subject: [TekScopes] Digest Number 7897



All about classic Tektronix CRT o'scopes

All about classic Tektronix CRT o'scopes Group
15 New Messages
Digest #7897

1a
Re: One idea for cleaning wafer switches, using Scotch Brite by "Don & Karen Patterson" sufnish
1b
Re: One idea for cleaning wafer switches, using Scotch Brite by "HankC" hankc918
1c
Re: One idea for cleaning wafer switches, using Scotch Brite by "HankC" hankc918
1d
Re: One idea for cleaning wafer switches, using Scotch Brite by "Jerry Barr" kj6ntl
2a
Re: 7904 transistors by "Tom Miller" tmillermdems
2b
Re: 7904 transistors by "Glenn Little WB4UIV" glittle_29445
2c
Re: 7904 transistors by "Tom Miller" tmillermdems
2d
Re: 7904 transistors by "Christopher Hilton-Johnson" crippo2
2e
Re: 7904 transistors by "G?ran Krusell" gorankrusell
3a
Re: Can you run a 7k mainframe upside down? by "Stefan Trethan" stefan_trethan
3b
Re: Can you run a 7k mainframe upside down? by "HankC" hankc918
4a
Re: 2252 'scope with Counter Timer issue - resolved by "raymonddompfrank" raymonddompfrank
5a
Re: Tek 7613 Desoldering Large P/S Capacitors by "HankC" hankc918
6.1
Re: HV Multiplier defective in 7603? - resolved, sort of by "raymonddompfrank" raymonddompfrank
7a
Re: Electronic goodies, Pittsburgh by "kiloowatt" kiloowatt
Messages
1a
Re: One idea for cleaning wafer switches, using Scotch Brite
Sun Jun?30,?2013 11:23?am (PDT) . Posted by:
"Don & Karen Patterson" sufnish
I have used this GC burnisher for relays in the past. It might work for switches as well. Amazon's price looks high compared to other listings YAHOO found. I used this one for illustration because it worked best to cut and paste.

Quantity:
$16.99 + $5.90 shipping
In Stock. Sold byADVENTURER&# 39;S BAG

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GC Electronics Fine Grade Burnishing Tool Excellent For Removing Oxidation 3 Inch Long
by GC Electronics
Be the first to review this item
List Price: $24.19
Price: $16.99
You Save: $7.20 (30%)
Only 4 left in stock.
Ships from and sold by ADVENTURER&# 39;S BAG.
This burnishing tool is ultra fine grade making it excellent for removing oxidation from switches & relay contacts.
Width: 0.12. Thickness: 0.012.

Take care,
Don Patterson

On Jun 30, 2013, at 9:53 AM, Jerry Barr wrote:

they do have a good size group of burnishers but ure is definitely cheaper /tho the set is 36.00/but the holder is quality and the size of a pen/and the burnishers are diff sizes shapes etc. and are flexible

Jerry KJ6NTL
From: keithostertag <keitho@strucktower. com>
To: TekScopes@yahoogrou ps.com
Sent: Sunday, June 30, 2013 3:41 AM
Subject: [TekScopes] Re: One idea for cleaning wafer switches, using Scotch Brite

Hey thanks Mike, I never would have thought of using "burnisher&quo t; as a search term for these! I'll give them a try sometime.

Until then, I believe my homemade tool has several advantages:

Far less likely to cause accidental damage.
Being essentially a deep soft pad, it can reach places the burnisher can't (the other side of raised sections/protuberan ce).
It is always immediately available.

Some company probably makes a similar tool that uses a soft pad, but I haven't yet found it...

Keith

--- In mailto:TekScopes% 40yahoogroups. com, "Mike Czuhajewski" <wa8mcq@. ..> wrote:

...back in the old days of rotating tv tuners we used to purchase a
small metal abt 3/16x1.5 inches abrasive contact cleaning strip....

I remember those well from my USAF days, a very long time ago. Mouser
carries them, made by OK Industries. Search on "burnisher&quo t;.

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1b
Re: One idea for cleaning wafer switches, using Scotch Brite
Sun Jun?30,?2013 1:39?pm (PDT) . Posted by:
"HankC" hankc918
You can also use pipe cleaners.
There are some which have stiffer bristles in them.
They will clean the wafer part if you keep switching it back & forth.
Try a smoke shop.

?
HankC, Boston
WA1HOS

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1c
Re: One idea for cleaning wafer switches, using Scotch Brite
Sun Jun?30,?2013 1:48?pm (PDT) . Posted by:
"HankC" hankc918
You could cut the matchbook striker into a narrow strip & insert it into an X-acto knife handle in place of the blade.

?
HankC, Boston
WA1HOS

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1d
Re: One idea for cleaning wafer switches, using Scotch Brite
Sun Jun?30,?2013 2:26?pm (PDT) . Posted by:
"Jerry Barr" kj6ntl
I like that idea/ gud one

Jerry KJ6NTL


____________ _________ _________ __
From: HankC <hankc918@yahoo. com>
To: "TekScopes@yahoogrou ps.com" <TekScopes@yahoogrou ps.com>
Sent: Sunday, June 30, 2013 1:48 PM
Subject: [TekScopes] Re: One idea for cleaning wafer switches, using Scotch Brite

?

You could cut the matchbook striker into a narrow strip & insert it into an X-acto knife handle in place of the blade.

HankC, BostonWA1HOS


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2a
Re: 7904 transistors
Sun Jun?30,?2013 11:28?am (PDT) . Posted by:
"Tom Miller" tmillermdems

Tucker has them for $5 each. Eight in stock. Tucker is a good, reliable vendor.

ts.com/Search. aspx?Mfg= TEK&Page= 14

Best regards,
Tom

----- Original Message -----
From: atonizzo
To: TekScopes@yahoogrou ps.com
Sent: Sunday, June 30, 2013 2:14 PM
Subject: [TekScopes] 7904 transistors

Hi:

I am fixing a 7904 that has a busted power supply.
Both inverter transistors (Q1234 and Q1241) are busted
due to a connection to 240V while setup for 115V.

The transistors are Motorola 151-03-6800 and I will be
looking around for a replacement of the same kind, but
I was also wondering if anybody has has any success
trying more modern replacements for these parts.

Any suggestion about similar parts would be appreciated.

Regards
Tony


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2b
Re: 7904 transistors
Sun Jun?30,?2013 11:54?am (PDT) . Posted by:
"Glenn Little WB4UIV" glittle_29445
Transistor 151-0368-00 is a 2N6300.
This is a Tektronix part number.
Motorola may have been the only supplier.
This transistor appears to be available from:

northern. com/TekParts/ Tek151Page. php

for $1.62 each.

Hope this helps. This was located by my friend Google.

73
Glenn
WB4UIV

At 02:14 PM 6/30/2013, you wrote:

Hi:

I am fixing a 7904 that has a busted power supply.
Both inverter transistors (Q1234 and Q1241) are busted
due to a connection to 240V while setup for 115V.

The transistors are Motorola 151-03-6800 and I will be
looking around for a replacement of the same kind, but
I was also wondering if anybody has has any success
trying more modern replacements for these parts.

Any suggestion about similar parts would be appreciated.

Regards
Tony



-------- --------- --------- --------- -

Yahoo! Groups Links

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2c
Re: 7904 transistors
Sun Jun?30,?2013 12:23?pm (PDT) . Posted by:
"Tom Miller" tmillermdems
Hi Glenn,

The 2N6300 shows up as a NPN Darlington in a TO-66 package.

So I am not sure VeroniaNorthern has the equivalent part number right. They do carry original Tek parts though and most likely it will be the right part.

The service manual for the early 7904 calls out an RCA 61577 as a replacement. In any case, the schematic shows a NPN transistor in the circuit, not a darlington.

Regards,
Tom

----- Original Message -----
From: Glenn Little WB4UIV
To: TekScopes@yahoogrou ps.com
Sent: Sunday, June 30, 2013 2:54 PM
Subject: Re: [TekScopes] 7904 transistors

Transistor 151-0368-00 is a 2N6300.
This is a Tektronix part number.
Motorola may have been the only supplier.
This transistor appears to be available from:

northern. com/TekParts/ Tek151Page. php

for $1.62 each.

Hope this helps. This was located by my friend Google.

73
Glenn
WB4UIV

At 02:14 PM 6/30/2013, you wrote:

Hi:

I am fixing a 7904 that has a busted power supply.
Both inverter transistors (Q1234 and Q1241) are busted
due to a connection to 240V while setup for 115V.

The transistors are Motorola 151-03-6800 and I will be
looking around for a replacement of the same kind, but
I was also wondering if anybody has has any success
trying more modern replacements for these parts.

Any suggestion about similar parts would be appreciated.

Regards
Tony



-------- --------- --------- --------- -

Yahoo! Groups Links

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2d
Re: 7904 transistors
Sun Jun?30,?2013 1:37?pm (PDT) . Posted by:
"Christopher Hilton-Johnson" crippo2
Tony
151-0368-00 are commonly used in the 'hi-efficiency& #39; 7K series PSU. This
translates to the 2N6300, recently available from Ebay (china source).
In some mainframes, where higher power is required, (eg 7844) Tek
'selected&# 39; the 2N6300 and called it a 151-0386-01. Sphere lists the -01
version as MJ13015. There are 3 available on Ebay now for $19+ (& same
vendor has more from time to time).
In my experience the China parts are iffy, the MJ13015 works fine.

Chris HJ

On 30/06/2013 19:14, atonizzo wrote:

Hi:

I am fixing a 7904 that has a busted power supply.
Both inverter transistors (Q1234 and Q1241) are busted
due to a connection to 240V while setup for 115V.

The transistors are Motorola 151-03-6800 and I will be
looking around for a replacement of the same kind, but
I was also wondering if anybody has has any success
trying more modern replacements for these parts.

Any suggestion about similar parts would be appreciated.

Regards
Tony

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2e
Re: 7904 transistors
Sun Jun?30,?2013 2:10?pm (PDT) . Posted by:
"G?ran Krusell" gorankrusell
Hi Tony,
I used the BU208A from ST with good result.

G?ran

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3a
Re: Can you run a 7k mainframe upside down?
Sun Jun?30,?2013 11:40?am (PDT) . Posted by:
"Stefan Trethan" stefan_trethan
Yes, you can run them upside down, but only with the trace inverted,
and be prepared to go back in time (no heavy meals beforehand).

When turning over any old piece of equipment listen carefully for any
loose parts and do a visual inspection. They may cause shorts and most
equipment contains a few loose screws by design (The ones you are
always left with when putting something back together).

You'd really have to flip the CRT or deflection pins to make this
work, and everything else will still be backwards.
For heaven's sake get a few rackmounts.

ST

On Sun, Jun 30, 2013 at 7:35 PM, cheater00 . <cheater00@gmail. com> wrote:

Returning to the original post... any ideas? :)

D.

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3b
Re: Can you run a 7k mainframe upside down?
Sun Jun?30,?2013 1:35?pm (PDT) . Posted by:
"HankC" hankc918
That raises another "Why" question.

?
HankC, Boston
WA1HOS

____________ _________ _________ __
From: "TekScopes@yahoogrou ps.com" <TekScopes@yahoogrou ps.com>
To: TekScopes@yahoogrou ps.com
Sent: Saturday, June 29, 2013 3:06 PM
Subject: [TekScopes] Digest Number 7894


All about classic Tektronix CRT o'scopes

All about classic Tektronix CRT o'scopes Group
15 New Messages
Digest #7894


7d
Re: Can you run a 7k mainframe upside down? by "cheater00 ." cheatercheater00@ rocketmail. com

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4a
Re: 2252 'scope with Counter Timer issue - resolved
Sun Jun?30,?2013 11:58?am (PDT) . Posted by:
"raymonddompfrank" raymonddompfrank

Writing this on my iPhone, having dinner out (21:00h here).
David, your paragraph "it seems that..." is correct in its entirety.
In my 2252 the phase detector out (pin ... of the logic chip), controlling the VCO was stuck at 4V, no matter what I did with the VCO (control voltage). I did indeed put in a DIL OCXO (made by Micro Crystal of Switzerland) . I have a few of those from Ebay.
In my 2252, the 10 MHz oscillator is one transistor + xtal. No extra buffering. Small load already detuned to below 10 MHz.
Jittered signal to VCO is stil added.

Raymond
--- In TekScopes@yahoogrou ps.com, David <davidwhess@ ...> wrote:

I am going by the 2247A schematics but I doubt the 2252 is different.

It seems like he replaced the original 10 MHz crystal oscillator with
an OCXO (?) and the original integrated phase detector with an XOR
phase detector. I think he kept the original 200 MHz VCO.

I am not sure why he had problems sampling the 10 MHz signal. There
is an emitter follower used as a buffer to drive the integrated phase
detector. Maybe the buffer was bad and not the phase detector? Maybe
he could have connected the 10 MHz OCXO to the external reference in.

Note that the integrated phase detector does a lot more than just
detect phase. The 10 MHz crystal oscillator or external reference is
divided down to 1 MHz (so the external reference can be 10 MHz, 5 MHz,
or 1 MHz) and then multiplied up to 200 MHz. The phase detector
includes pseudo random noise generator clocked at 125 kHz (1 MHz
divided by 8) which dithers the VCO when time intervals are measured
(including rise and fall times) which prevents phase coherence between
the test signal and the oscillator which would produce marginal
measurements.

On Sun, 30 Jun 2013 10:13:05 -0700 (PDT), Jerry Barr
<kj6ntl@. ..> wrote:

hi just curious what freq is the counter up to/100 MHz or? 500/ I have a 500mhz counter that needs? a similar fix / cud I get the schematic of ure circuit/wud appreciate

Jerry KJ6NTL


________ _________ _________ ______
From: raymonddompfrank <r.domp.frank@ ...>
To: TekScopes@yahoogrou ps.com
Sent: Sunday, June 30, 2013 8:19 AM
Subject: [TekScopes] Re: 2252 'scope with Counter Timer issue - resolved

?

It has turned out that the PLL output was in fact defective. I have replaced it with a simple XOR-based phase detector. Since it proved difficult to bring out the 10MHz X-tal signal without increasing load too much (it made tuning as high as 10MHz difficult), I decided to put a small OCXTO (!) on the same PCB as the new PLL circuitry. Extremely simple, extremely successful and always accurate to within less than 1 LSD count...

Thanks all for your responses and help!

Raymond

--- In mailto:TekScopes% 40yahoogroups. com, "raymonddompfr ank" <r.domp.frank@ > wrote:

Hi all,
May I please ask your help with the following:

My recently acquired 2252 'scope has an issue with its counter timebase. Its display jitters somewhat (3 LS Digits) and indicates frequencies about 2 % low. X-tal oscillator (10 MHz) around Q1901 is OK.
- Signal at pin 58 (TC) on U1905 (Fast Counter Logic) is around 200 MHz, jitters as well.
- Signal at pin 23 (PFC) U1902 (Slow Counter Logic) is steady at around 4V. It should be pulsing when PLL in lock according to service doc.
Obviously, anode of varactor CR1903 is at almost 4V, mostly steady. It should be at about 2V with PLL in lock. (FM) noise coming from U1902 pin 22 is visible though.
C1913 and C1914 are not visible on the PCB, nor are places to put them, possibly only parasitic capacitance used.
I haven't yet checked VCO input on U1902 (pin 26).
Here's (another) part of what I don't understand: Displayed frequency being low would indicate timebase too fast, which would indicate varactor capacitance low, which would indicate its control voltage too high. Then why doesn't PFC pulse low? PFC defective? My error in thinking?
I will try and measure TC on U1905, next offer an external 200 MHz signal and see what happens. Also try and measure VCO on U1902. Can anyone give me some guidance in how to proceed apart from these actions?

Raymond

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5a
Re: Tek 7613 Desoldering Large P/S Capacitors
Sun Jun?30,?2013 1:27?pm (PDT) . Posted by:
"HankC" hankc918
Ken,

You raise some good points that the open cap could someday short out.
I had intended to remove it but never got around to it.
So far, so good. :<)? Three yrs & counting.

?
HankC, Boston
WA1HOS

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6.1
Re: HV Multiplier defective in 7603? - resolved, sort of
Sun Jun?30,?2013 1:37?pm (PDT) . Posted by:
"raymonddompfrank" raymonddompfrank
In the sentence below: "The on-screen "image" was too small, so PDA voltage probably too low, UNLESS:..." , image was too *large*, obviously. Thanks for noting it, Albert!

Raymond

--- In TekScopes@yahoogrou ps.com, "raymonddompfr ank" <r.domp.frank@ ...> wrote:

This issue has been resolved but has left me wondering.
After I came to the conclusion that the HV multiplier must be defective, I removed it and made some measurements in the -2975 V circuits. Reason: The circuit stabilized at a voltage near -4 KV... I measured the high-ohm voltage divider R's (R1245A and -B), all active components like CR1244 (curve tracer) and voltages, all other R's and C's in the focus and grid bias etc. areas and all checked out OK. Unfortunately, I could't do HV (leakage) measurements on components. Although the HV divider R's (ratios) all showed the correct resistances, the circuit stabilized at almost -4 KV. I measured the (very small) current through R1201 and it was ok. The one explanation that I can give is leakage on the PCB's surface but I cleaned it thoroughly both with water-soluble soap and organic solvent (no acetone...) although it had looked very clean already.
In the end, I decided to put a resistor in series with R1245A to reduce the HV. This worked ok.
To add (or not) to the confusion:
I assembled a HV multiplier from discrete components, which worked ok. After an initial test I potted them in polyurethane. The whole thing is the same size as the original, BUT:
The on-screen "image" was too small, so PDA voltage probably too low, UNLESS:
I increased HV by removing the series resistor that I had added...
I think it was David who suggested that HV may have been at -4KV before, finally causing the HV multiplier to fail and he may be right.
Since adjusting vertical and horizontal gain did not allow enough reduction of the image size to fully correct the increased size, I decided to accept an increase of HV to almost -3.3 KV (from the intended -2975V) by permanently installing a resistor as mentioned before. Its value is 68K. Not the most elegant solution but it allows adjusting hor. and vert. gain with some reserve.
The 'scope has been operating flawlessly, with a very sharp and stable image for a few weeks now.

Thanks all for your input, suggestions and help!

Raymond



--- In TekScopes@yahoogrou ps.com, "raymonddompfr ank" <r.domp.frank@ > wrote:

Hi all,
My recently restored and very nice early Heerenveen (NL-) made 7603 has developed a problem:
After working OK for a few days, suddenly brightness and focus deteriorated, came back again, deteriorated again and finally the screen became completely dark, all this within 5 minutes. After I opened the case, it immediately became apparent that the HV cage was quite hot, I guess around 50C. Most likely, that's because of Q1216 and Q1218 heating up. No burning smell.

Looking for the fault, being careful and full of respect for HV, I did the following:

1. Disconnected HV cage and measured all LV voltages (-50V, -15V, +5V, +15V, +5-V, +130V), using a 'scope with DVM). All ok, ripple very low.

2. Reconnected HV cage. LV's remain ok, HV Test point (should be -2975V)reaches ca -1.8KV, next goes further negative, something like -2.5KV, then back to around -1.8KV etc. with a period of 1 or 2 seconds. Sort of tick mode below -1.8KV. LV's remain OK, so the 'scope isn't in tick mode. PDA voltage sort of follows change of HV (used P6015). No brightness.

3. Unplugged and discharged post deflection anode. 'Scope behaved as in 2.

4. Disconnected HV Multiplier (U1230) at its input. HV test point reaches almost -4KV and remains steady.

To me, this looks like a HV breakdown in the multiplier.
It seems that these multipliers are rather expensive at Qservice etc. so I'm considering buying one second hand locally or building one myself. Apart from obvious things like HV isolation (air), >10KV C's and >7KV(?) diodes, would there be any special things to consider when building a multiplier myself?

Any thoughts at all on this?

Thanks!

Raymond

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7a
Re: Electronic goodies, Pittsburgh
Sun Jun?30,?2013 2:36?pm (PDT) . Posted by:
"kiloowatt" kiloowatt
Hi

Try this site for addresses etc for surplus stores in USA etc. Has lots of interesting items.

. com/surplus/ surpcats. html

KW

--- In TekScopes@yahoogrou ps.com, Daniel Koller <kaboomdk@ ...> wrote:

Hi folks,

?? ??I am going to "second" this question. ?? I too will be in PGH over the July 4th weekend and am curious if anyone has any suggestions on where to find good surplus and used equipment.

?? ??However, I'm going to guess that there is not much chance of a good surplus store based on my observations. ??Back in 1994, when I went to a meeting in Pittsburgh, I was walking down the Strip near the downtown end and there were still a bunch of old hardware stores doing ironmongery - selling machine tools and parts, scrap metal, and I remember cheap drill press vices that impressed me at the time as being from China. ??

?? Since then I've married a woman who is from Pittsburgh and we go there often to visit family, and my last walk down the Strip was more like a visit to the shopping mall - lots of eateries, trinket stores (selling clearly Chinese goods), florists.... not the sorts of places where you'd expect to find instruments. ??

?? ??My point is it's not just the Strip that has undergone major changes in the past decades. ??I suspect the whole region is cleaned up. ??Westinghouse long ago shrunk down though they are now growing again. ?? All the steel and heavy industry was gone DECADES ago. ??There is not much industry left.

?? ??I did notice a bunch of industrial buildings and warehouses off I376 on the way to the airport and I have yet to check out what's there, so perhaps there is some hope in the outskirts of town. ??If anyone has some specific Ideas of stores to check, I'm happy to go.

?? ??Now on the other hand, if anyone wants to know where to get plant fossils....( OT!)

?? ??Dan



____________ _________ _________ __
From: Bruce Lane <kyrrin@. ..>
To: milsurplus@. ..
Cc: voip@...; tekscopes@yahoogrou ps.com
Sent: Saturday, June 29, 2013 10:55 PM
Subject: [TekScopes] Electronic goodies, Pittsburgh



??
There's a possibility I'll be in Pittsburgh for a few days. I won't have much in the way of spare time, but I'd like to know if there are any electronic surplus places worth checking out.

Primary interests: Test gear and pre-divestiture Bell System phone equipment. Some small interest in computer components (not a priority, though).

Thanks much.

-=-=-=-=-=-= -=-=-=-=- =-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- hertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"Quid Malmborg in Plano..."

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