Re: Power supply problem with Tek 2220
Hi Tan,
This morning I remembered about an interesting 2235 repair that was done by
a very crafty person by the name of Irwin Zosa during 2007 and 2008.
Irwin lives in your part of the world in the Philippines where it is almost
as hot as in Singapore. His basic problem was the same as yours, the 2235
would shut itself down with a thermal problem.
There was not much interest in his 2235 problem on Tekscopes at that time,
so the email exchanges we had went off group as he worked his way through
the problem. Once he had the problem solved, he posted a nice summary of his
findings to the Tekscopes group.
Irwin's repair summary is in message number 36518 and it was posted on Jan
6, 2009.
He found a number of problems as he went along, but his final discovery
might amaze you.
It sure amazed me because I would have never found it!
tom jobe...
PS I will paste in Irwin's 2235 repair summary below to save you the trouble
of getting it from the Tekscopes Message archive.
Hello to all: Way back in the first quarter of 2007, I had this
problem of my 2235 shutting down after a few minutes from switching
it ON. After a lot of interaction from forum members I finally
nailed down the problem. Here is a brief summary of this process:
First, I checked all the voltages according to the service manual and
they were OK. I also checked the ESR of the capacitors and they read
good but the unit being about twenty years old or so, I decided to
replace the secondary caps (C960, C961, C962, C963, C968, C970) with
ultra-low ESR, 105-degree C Nichicons. I could not find 840uF units
so I used 1000uF. The problem still did not go away although the
length of time-to-shutdown increased. I also replaced the FET
switcher Q9070 (IRF710)with a higher rated device (IRF840). I then
replaced Q946 and Q947 with TIP41 units. At every change that I
made, slight improvements were observed. I also replaced R912 (357
Ohms)with a 390 Ohm part to increase the shutdown threshold of this
2235. Then I replaced the secondary rectifiers CR954, CR955 (MR814),
CR956, CR957 (MR812), CR960, CR961, CR962, CR963 (MR812). The
replacements that I used were the MUR160 ultra-fast rectifiers. All
of these were not done "shotgun" style and in the exact order as
described but rather, followed logical steps of checking one section
at a time. I even thought of thermal runaway because T944, T948, and
Q9070 would heat up so much (really hot!). I also noticed early on
that the frequency of the pre-regulator section (U930) was about
72KHz and in the service manual it is listed as about 60KHz. It
suddenly dawned on me to try to reduce the operating frequency of
this section so I replaced R919 and now it is running at 60KHz. The
excessive heat has gone and no more shutdown. I tried to run the
scope for about half a day and still no shutdown. This 2235 has all
of the power supply improvements already installed from the factory
(but why was the pre-regulator section running at 70KHz ?). I would
like to thank the forum members who gave their insights. Special
thanks goes to Tom Jobe, who stayed with me all the way in this
repair project. He took the time to take measurement readings for
me, gave his analyses, and even offered parts that I may need for
free. At some point I was considering another brand of oscilloscope
but I held on to this (even keeping it in storage for almost a year
because of this problem) because from my research, these TEK scopes,
during their time, were among the best. I think they still are.
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Tek W Plugin 7000 & up serial.
Greetings to the group.
I found a copy a later W manual with the FET mod. If there is a need I will scan and post it online. Its listed in the change section and is 13 pages (schematic and pictures).
Let me know.
Regards,
Jerry
W2JI
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Sold: Tek 067-1039-01 TM500 Pattern Generator
The unit has been sold.
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On 1/22/2012 1:04 PM, Oz-in-DFW wrote: Unknown, untested, looks to be in decent shape.
High Res pics at
$50 or best offer +$15 shipping in US. International shipping is
available, but you'll coverall costs, fees, and tariffs.
--
mailto:oz@...
Oz
POB 93167
Southlake, TX 76092 (Near DFW Airport)
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TAS485 quirks and known issues
I have recently?acquired?a TAS485 and I was wondering if anyone knows what are the usual quirks or known issues with this series of scopes.
Is there a blue shield for this series of scopes, because I like blue.
Thanks.
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Re: Tekscopes at the Computer History Museum
Tom, in 82 we redesigned/copied the SWTPC Computer on EURO-cards (100x160mm) and sold it here in germany. Last year, by chance i found one of our constructed/manufactured computers in a dumster ;-) Now it's in my store for the next 100 years ;-) Peter ============================ The next microprocessor I had was the SWTPC 6800. I really liked doing assembly with the Motorola instruction set.
--
Empfehlen Sie GMX DSL Ihren Freunden und Bekannten und wir
belohnen Sie mit bis zu 50,- Euro! https://freundschaftswerbung.gmx.de
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Re: Tekscopes at the Computer History Museum
I also think he is right about the 8080. I do remember the 4004 and for a
short time the 8008 chip sets. We were looking at them to use in an IFF
transponder.
?
In '84, I bought an 8080 chip for $200. That was a lot of money then. Also,
a 1702 EPROM. Just 256 bytes.
?
And 2102 static ram chips with 1x1k bits ( I think).
?
The next microprocessor I had was the SWTPC 6800. I really liked doing
assembly with the Motorola instruction set.
?
I know Tek used a lot of the Mot CPUs in many different products.
?
?
Fun, fun, fun! :)
?
?
Tom
?
?
?
?
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----- Original Message -----
Sent: Sunday, January 22, 2012 11:55
PM
Subject: RE: [TekScopes] Re: Tekscopes at
the Computer History Museum
?
These dates sound correct: I remember reading the introductory data
sheet
for the 4004 in 1971 or 1972. It made no sense at all. I couldn't
figure out
what it was. I was used to logic gates and this was alien to me.
1974 sounds right for the 8080. I missed the introduction of that chip
but I
was building a Z80 system 3 years
later.
Dennis
-----Original Message-----
From: Brad Thompson,
Sunday, January 22, 2012 5:34 PM
Hello, Tom and the
group--
IIRC, the 8080 was introduced in 1974; the 4004 was introduced
in 1971.
In the early 1960s, I worked as a co-op student at a company
that
manufactured magnetic-core logic (nonvolatile, radiation-resistant,
very low
power consumption). Four bits per cubic
inch.
73--
Brad AA1IP
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Resent due to a mailer error. * BEGIN FORWARDED MESSAGE * On 22-Jan-12 at 17:46 Bruce Lane <kyrrin@...> wrote: Fellow Tekkies,
I've just acquired a PG508 from That Evil Auction Site. Would anyone
happen to have an original manual for sale?
Let me know... Thanks!
Bruce Lane, Owner & Head Hardware Heavy, Blue Feather Technologies -- kyrrin (at) bluefeathertech do/t c=o=m "Quid Malmborg in Plano..."
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Re: Tekscopes at the Computer History Museum
These dates sound correct: I remember reading the introductory data sheet
for the 4004 in 1971 or 1972. It made no sense at all. I couldn't figure out
what it was. I was used to logic gates and this was alien to me.
1974 sounds right for the 8080. I missed the introduction of that chip but I
was building a Z80 system 3 years later.
Dennis
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-----Original Message-----
From: Brad Thompson, Sunday, January 22, 2012 5:34 PM
Hello, Tom and the group--
IIRC, the 8080 was introduced in 1974; the 4004 was introduced in 1971.
In the early 1960s, I worked as a co-op student at a company that
manufactured magnetic-core logic (nonvolatile, radiation-resistant, very low
power consumption). Four bits per cubic inch.
73--
Brad AA1IP
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Tektronix 2712/2710/27XX 300Hz Filter F.S.
Hello All: ? I currently have a Tektronix 300Hz filter for the 27XX series Spectrum Analyzer's for sale. If interested please contact me off the reflector. ? 73
Rich, AJ3G
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David, More for you below. Hope it helps:
Could also be C866 is shorted, but that would be extemely rare.
To eliminate that, pull one side up temporalialy, and power up and
re-measure R860 volts.
+69V with ref to ground.
I think you measured the "high" side of R860(the 130V supply line). Maybe I should have said measure the collector of Q860; this is the same as the base of Q869 and the low side of R860; or should be if connections are OK. Again, this would be with one end of C866 lifted.
I must thank you for your persistent help so far Jimmy, very explicit
instructions that are very easy to follow!
Thanks.
re cap ripple testing, do I put scope probes only on the cap pins of
each individual cap to test each cap?
First, did you see my earlier posting about measuring ripple with an old analog meter that has an "OUTPUT" terminal? Anyway... Here's how I would check for excessive ripple using another (test) scope. This will work for all of the big filter caps that have one terminal connected to chassis ground. DO NOT use this method for the filter cap (C806) in the 130V supply because neither one of its terminals is connected to chassis ground: <<<<<<Be carefully around the AC input/mains power!!!>>>> 1. Ground a 10X probe hooked to the test scope to chassis of problem scope. Use a good-quality clip lead to extend the probe's ground lead if the length of the ground lead is not enough for easy measurements, AND INSULATE the 2 alligators' connection with some black electrical tape so this won't short something out if it accidentally touches anything. 2. Set test scope channel to 50V/div. (Use 5V/div if you've got a scope that does not auto-sense probe attenuation). Be sure to use a 10X probe. 3. Set test scope channel to AC coupling and vertically center the sweep. (You can initially use DC coupling if you want to see the DC component also.) 4. Set test scope for Line trigger, and about 10mS/div. Adjust trigger for a steady sweep (flat line when probe tip is not connected to anything). 5. Carefully probe the "hot" side of each big filter cap. For most, the "hot" side is the "+" terminal. However, for some like C808 (1800 uF) for the -50V supply, it would be the "-" terminal. If the cap is good, you should see a sweep that's still nearly flat. I'm thinking no peak-to-peak waveform on a filter cap should be more than about 3V. If necessary, increase vertical sensitivity to 5V/div, or less, so V peak-to-peak can be more accurately measured. You DON'T won't to overdrive the test scope's channel amp by using too much sensitivity (As a general rule, don't let the waveform go vertically too much off the top/bottom of the screen.) It is good to return the test scope's channel to the 50V/div before going on to the next cap!!!!! To check filter cap C806 in the 130V supply use two 10X probes, two scope channels of the test scope, set one channel for "Invert" and use the "Add" vertical function. Make sure both channels have equal V/div settings, and they are adjusted for equal gain. This is basically a differential measurement. To verify test scope's settings (equal gains, etc.), probe a common signal point with both probes and make sure there's no (or very little) signal/ripple. It will be good to post your ripple measurements. Regards, Jimmy
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Re: Power supply problem with Tek 2220
Hi Francis,
You are spot on. ?There is no stupid
question.
?
After I downloaded the 2230 (as directed
by Tom) and compared with the 2220/2230.
Immediately, I notice the
difference.? The 2220/2230 has a thermal shutdown board which is not
present in the 2235.
So, for my 2220 it is an indication that
the thermal shutdown is working.?
I believe it is at working at the correct
temperature because shutdown always happen when the chassis is burning hot (can
hold for a 4 to 5 sec before it burns)
I will try to do a test to disconnect the
shutdown and see it the shutdown happens again, just to locate the cause.
?
Comparison between 2220 and 2235 PS
????????????????????????????
??2220???????????????????????
2235?????????????????
Comments
-5V supply ??????????????Yes????????????
????????????No
R907?????????????????????
??549
ohm?????????????????
357 ohm??? ????????Current
rating on +43V for 2220 is about 30% higher
Thermal shutdown?? ??Yes???????????????????????
No?
?
Rgds,
Chor Ming
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From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Francis
Sent: Monday, January 23, 2012
4:41 AM
To: TekScopes@...
Subject: [TekScopes] Re: Power
supply problem with Tek 2220
?
?
Hi,
I downloaded the 2230 manual (thanks Tom...) to see how the PS was
made, and then came to my mind a stupid question: is there a thermal
shutdown board on your scope, and did you check it?
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Re: Tekscopes at the Computer History Museum
On 1/22/2012 8:29 PM, Thomas Miller wrote: I worked at Bendix Communications Division from '66 to '71. Even had my
own 545 Tek scope. They were the days. DTL had just arrived and a lot of
military systems were just being converted to the pure digital domain.
It was around 1971 that the 8080 came out and the world was about to
really change. Hello, Tom and the group-- IIRC, the 8080 was introduced in 1974; the 4004 was introduced in 1971. In the early 1960s, I worked as a co-op student at a company that manufactured magnetic-core logic (nonvolatile, radiation-resistant, very low power consumption). Four bits per cubic inch. 73-- Brad AA1IP
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Re: Tekscopes at the Computer History Museum
I worked at Bendix Communications Division from '66 to '71. Even had my own
545 Tek scope. They were the days. DTL had just arrived and a lot of military
systems were just being converted to the pure digital domain. It was around 1971
that the 8080 came out and the world was about to really change.
?
Regards.
Tom
?
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----- Original Message -----
Sent: Sunday, January 22, 2012 7:35
PM
Subject: RE: [TekScopes] Re: Tekscopes at
the Computer History Museum
?
In 1967 I worked at Bendix Aerospace and saw this F4 autopilot on the
floor
of one of the factories. I believe Bendix designed it. It is indeed
an
electromechanical monster. I always wondered how they figured it out it.
It
must have been a nightmare with all those layers of rods, gears,
actuators,
and servos.
All the autopilots I worked on at Bendix were
analog computers. Fortunately
when I started there all the new designs use
the new uA709 IC OpAmps. That
was a revolutionary leap in technology. But
before I could fully appreciate
the beauty of OpAmps everything changed
again.
2 years later autopilots were being designed with digital
logic. The
Concorde autopilot used DTL.
Then they started building
B52 subsystems with ROM lookup tables. I used to
have to blow out diodes in
those tiny ROM packages one bit at a time.
They were exciting times to
be in electronics.
Dennis
-----Original Message-----
From:
phorphile, Sunday, January 22, 2012 9:22 AM
In the Navy in '65 I was
treated to a visit inside an F4 Phantom simulator
trailor. That was one big
analog electromechanical maise on wheels. Analog
computers laid the ground
work for digital to take off from.
> ......They have heard of analog
computers, sort of, but they're treated
like the redheaded stepchild.
.......
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Re: Tek 7k plug-in prices rising...
China has finally re-valued its currency!
From: Aaron To: TekScopes@... Sent: Sunday, January 22, 2012 4:44 PM Subject: [TekScopes] Re: Tek 7k plug-in
prices rising...
?
> > Have you seen the BIN price for this?
> > Item 270788500453
> Perhaps that's in HK $ ??
They just forgot to put the decimal point in when typing the price. If you check the sales history, they sold one unit for almost exactly 1/100 of the price in that listing.
I wonder what the listing fee was for that ad...
Aaron
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Re: Tekscopes at the Computer History Museum
I defer to your superior knowledge of the history of computers, Steve, but I think you contradicted yourself. During the Civil war the new battefield howitzers didn't have the help of digital computers to aim them. What was learned and the mathematics developed for ever more complex artillery aiming schemes, as an example, laid the groundwork for which digital technology later took over and refined the job. Sir Isacc Newton didn't have an Apple ;-)
Arden
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While analog computers made some amazing advances for their day, I disagree with the comment that they laid the groundwork for modern digital computers. The early designs of digital computers did not leverage anything from analog computers, and took totally independent paths. Probably the only connection is that one of the early digital computers ¨C ENIAC, was designed for the purpose of computing trajectory tables for large field artillery ¨C a similar task the Nike flight path computer performed. The latter provided correction information in real time, while ENIAC actually computed tables of numbers that were published in field manuals.
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Anyone know where I can download a manual for the 5L4N? Thanks, AL
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Re: Need Manual for Type W, SN 4560 & 5336
Bernd and Egge,
I was aware of the change from Nuvistors to FETs in the 1A1, but didn't know a similar thing had happened to the Type W.
If you are able to find the mod kit, would you mind scanning the modified schematic? I'm a complete beginner to electronics and chase enough dead ends even when I have a full manual in front of me. With incomplete schematics I find myself second-guessing everything. :-(
I checked eBay and Dave's(ArtekMedia) site but didn't see any manuals for SN >7000, although I sent an inquiry to the eBay listings that didn't show a part number or SN range for the manual.
What does PWB stand for, as mentioned in Egge's post below this?
Aaron
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--- In TekScopes@..., "Egge Siert" <eggeja@...> wrote: It seems that you have two Type W's with the FET-Frontend and the PWB for these. With SN 7000 and above this was standard. For this late versions a new Manual was printed. FET-Frontends (less drift) were used in late Type 1A1's (I don't for sure also 1A2's) and the 1A7A (which has the same circuit as the later 7A22).
Egge Siert
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Re: Total beginner with newly acquired 475 with issues
Hi "newbarrie"'
There is far more expertise on this forum than mine but here are some points to get started with, but not specific to the 475:
Scopes (and all electronics) that have been sitting around unused for a long time develop not only visible "verdigris" but invisible oxidation and corrosion effects. Wherever two metals are mechanically opposed to pass an electric current is where you will find problems. Apply an electrical contact cleaner that contains a lubricating protectant (I recommend MG Chemicals Super Contact Cleaner) to all connectors, unseat and reseat them at least a couple of times. Plug-in intgrated circuits can also be a problem but leave them to a later level of diagnostics. With switches be a little more careful where you apply the contact cleaner, keep it only to the contacts as well as you can. You can apply cleaner with an artist's brush in tight spaces. Rotate switches several times to restore functioning. Check for loose hardware, tight screws and nuts are required at some points to insure good grounding. You may be surprised at the results you get by performing this procedure. Next, before attempting to do further diagnositics, get a service manual and make it a reading project until you have a good sense of what the scope is all about electronically and how to perform diagnostics and calibration. When you are ready to dig into the cause of particular failures here's the place to get help.
Arden
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......I also have acquired through the ubiquitous Ebay a half dead Tek 475 scope to play with. ......
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Re: Force DSA-602 to proceed past 11A34-induced POST error?
It looks like David and Javier were right and this plugin was just missing some sort of calibration constant, fixed by running EA on a good DSA 602 mainframe.
I have now been using it for one week, in various 11k mainframes, with no trouble at all.
Thanks again guys!
Aaron
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--- In TekScopes@..., David <davidwhess@...> wrote:
This sounds familiar so maybe your sanity is safe. I remember reading
about this series of oscilloscopes and something about using a newer
model to refresh the calibration or initialization or something data
in a plug-in so that it would work with an older oscilloscope.
On Sun, 15 Jan 2012 13:53:15 -0000, "Aaron"
<ataylor@...> wrote:
Javier,
When I tried telling it to exit diagnostics before, it wouldn't do it, but it is 5am here, so I probably did something stupid, like bumping the touchscreen enable/disable button. Thank you for letting me know that it should work and I will definitely give that another try next time. Unfortunately, I can't test it at the moment(see below).
Now I'm really questioning my sanity. The mainframe I was using has very old firmware on it. Thinking that perhaps a newer firmware version would let me exit the diagnostics and continue on, I tried my second mainframe. In this mainframe, the plugin works fine and throws out zero errors. To make things even more odd, when I try it in the original mainframe, it now exhibits zero errors. So now the plugin works in both mainframes, with no errors, and all four channels take good measurements.
In another 15 minutes I will know if it will pass EA, although it already passed the partial EA that the newer mainframe insists on running every time the configuration changes.
I guess it is an intermittent problem.
Aaron
I've around a 11A34 with a failure in channel 4, and I've put it on a
DSA-602. It fails (as expected), but in the POST screen that appears,
when selecting "Exit Diagnostics" the DSA starts, and enables you to use
the other channels in the failing 11A34 (of course, it also throws
errors during EA). I am trying to capture four channels simultaneously with my DSA-602,
which requires three plugins. Unfortunately, my third 11A34 is
misbehaving. When it is inserted, the mainframe fails POST with errors
about there being zero gain in channel four of the plugin.
...
wondering if anyone knows a way to force the mainframe to ignore the
errors so I can use channels 1-3?
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Re: Tek 7k plug-in prices rising... 7L13/7L14
If the only thing wrong with the 7L13 is a broken knob, then I think $1k
is a reasonable price. Microwave spectrum analyzers are always
expensive. Though a 7L13 or 7L14 is on the low-end of the frequency
range, it might be OK for many people, without the $3k . . $5k . . .
expense of getting something with a higher frequency range.
One potential advantage of the 7L13/14 is that the schematics are
available and there is no power supply or display electronics to worry
about. I think more modern or similar vintage but more capable spectrum
analyzers which are not 7000 series plugins would have a lot more
electronics to go wrong, including power supplies, firmware-based
microprocessor stuff, CRT displays etc.
I recently bought a 7L14, in the 2.5GHz version (without a 1.8GHz LPF
and input limiter) for $650 or so. I knew it had problems, and I fixed
some of them - multiple dead tantalum capacitors. I now suspect its
input mixer needs its diodes replacing, since its sensitivity was very
low, and there needs to be quite a lot of work to make the displayed
frequency match what the device was actually responding to. At present
it is not responding to any signal. Now I know more about these
devices, I realize I need the 1.8GHz LPF, but fortunately MiniCircuits
make one which should work OK - and the cost is under $50.
I have now acquired three of John Griessen's <john@...>
excellent 7000 series extender kits:
so I will be able to work on this beast. Its not for everyone, but I
liken this introduction to microwave electronics to buying my first
vehicle - a clapped out 1961 VW Kombi van - and the years of learning
experiences as I rebuilt various engines, always imperfectly, and
successfully refurbished the gearbox and many other parts.
It can't be ruled out that I am crazy too, but I only bid this because
someone else was ready to bid a little lower. One fellow in Western
Australia has a 7L14 (1.8GHz version) with the TR502 tracking generator
- bought on the understanding it was fully working for ~$1.5k. That
seems reasonable to me, but it turns out that it is lacking sensitivity
and so probably in need of diode replacement in the input mixer, plus
potentially other faults.
- Robin
Magnus wrote:
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The winning bid for this one leaves me stunning. It comes with no
warranty and has a broken knob as per the item description...
I have no disbelief in the 7L13 spectrum analyser's quality and
capabilities. And I am aware that these are offered rarely - but...
The buyer was willing to pay _1 grand _USD as you US chaps might put it.
|
Bruce Lane
KB6NAX