Re: Looking for Power Cord for 400-series Scope
Okay, Jim. I took a second look and the power entry section is just a small part of the back panel so that would be a fairly easy replacement.
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Barry" <n4buq@...>
To: [email protected]
Sent: Tuesday, July 24, 2018 11:14:21 PM
Subject: Re: [TekScopes] Looking for Power Cord for 400-series Scope
Okay - I'll take a look again at that. Perhaps it isn't as much trouble as I
was thinking it was.
Thanks,
Barry - N4BUQ
----- Original Message -----
From: "Jim Olson" <v_12eng@...>
To: [email protected]
Sent: Tuesday, July 24, 2018 10:51:07 PM
Subject: Re: [TekScopes] Looking for Power Cord for 400-series Scope
The panel is easy to get off it is held on just two flat head phillips
screws
and the fuse cover box it lifts off with the cord attached you just need to
take off the wires the ground is bolted to the frame right at the cord in
and the white neutral wire is soldered to the fuse box and the power is
attached to a blue piece on the main board soldered too.
Jim
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Re: All TekScopes email sent to Spam
The mail isn't coming from yahoo any more guys, we moved to the groups.io server.
Dave
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of John Griessen Sent: 25 July 2018 21:18 To: [email protected]Subject: Re: [TekScopes] All TekScopes email sent to Spam On 07/25/2018 02:36 PM, Harvey White wrote: It's possible
that the classification of the yahoo email has changed somehow,
causing your email program to put it elsewhere. Right. various yahoo.com servers may have been downgraded in their trustworthiness and then the settings of your junk sensing flag it as junk. If you change settings to allow from yahoo it will probably come through. That's called whitelisting. No problem here using thunderbird email reader. I also run my own mail server and it is not using the real time blacklisting rankings of yahoo to reject mail from yahoo. Yahoo is still deemed trustworthy by them as far as I can tell.
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Re: All TekScopes email sent to Spam
On Wed, Jul 25, 2018 at 11:35 AM, Carl Hallberg wrote:
Help,
Now all my TekScopes email is sent to spam folder. Is this a Yahoo problem?
Carl Hallberg (W9CJH)
Same issue here. Marked them as not spam and all is fine now.
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Re: Tek 495P A54 Memory Board Repair
Chipquick is definitely very useful when the project calls for it.
JK
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of stefan_trethan Sent: Wednesday, July 25, 2018 4:36 PM To: [email protected]Subject: Re: [TekScopes] Tek 495P A54 Memory Board Repair If anyone is having trouble with replacing components, maybe try Chipquick low temperature alloy. Recently I came into an obscene hoard of that stuff, and found that it works rather well. I don't really use it, I have the tools and practice to replace anything I work with (the other day I exchanged a transformer over 50 times on the same board!), but that low melting alloy makes it really easy, even without any special tools. I would still recommend that you get the tools and skills to do this the old fashioned way, but if you are worried about damaging some expensive piece of kit then this Chipquick stuff might just steady your hand. A colleague has even used gallium to swap parts without any soldering at all. Not so useful for repairs, but it was a pretty neat trick as long as you didn't jostle the board. Funny metal, that, especially if you put some on aluminium. ST
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Re: WTB: v9.7 EPROMs for 495P memory board
On Wed, 25 Jul 2018, Rick Boswell wrote: Want to buy 495P v9.7 EPROMs which are installed on the A54 memory board.
P/Ns 160-8316-00 and 160-8315-00. There are 9 EPROMs in v9.7 firmware in 494AP that should be the same as you have. They are part numbers 160-8315-00 to 160-8323-00. First 2 are on that memory board, rest is on GPIB board. I have all firmware images and can send 'em to you so you would be able to program your own chips. There is another thing -- it is _NOT_ just those switches that tell the firmware what instrument it runs on. There is also another MCU on the front panel that runs its own firmware. Main instrument firmware asks the front panel MCU about hardware version and that is taken into consideration when deciding what hardware it runs on. For example, 494AP and 2756P have EXACTLY SAME switches configuration and main firmware decides what it runs on based on what front panel controller told. 494AP and 2756P are identical inside just case and front panel is different. 2756P has full-blown 494AP chassis inside sans front panel and its own front panel. Part of the case not occupied by 494AP chassis is simply empty. If you remove that chassis and install a 494AP front panel on it the thing will tell you it is 494AP and will happily run as 494AP without flipping a single switch. And BTW, did you replace _ALL_ electrolytic caps in the power supply except those 2 big ones protruding through its cover? If you didn't start with this first -- it is almost 100% probability that most (if not all) of those capacitors are dead and your instrument just acts erratically. There is absolutely no reason to even start doing anything on any part of the instrument until you have the power supply refurbished. You should also make sure the fan is working properly -- unlike some other instruments in 49x it is CRITICAL. If it doesn't work your PS will overheat in almost no time. --- * * KSI@home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * *
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Re: All TekScopes email sent to Spam
Uh, aren't we on groups.io now rather than yahoo?? Yahoo is out of the picture.
Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: John Griessen <john@...> Date: 7/25/18 1:17 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] All TekScopes email sent to Spam On 07/25/2018 02:36 PM, Harvey White wrote: ?? It's possible
that the classification of the yahoo email has changed somehow,
causing your email program to put it elsewhere. Right.? various yahoo.com servers may have been downgraded in their trustworthiness and then the settings of your junk sensing flag it as junk.? If you change settings to allow from yahoo it will probably come through.? That's called whitelisting. No problem here using thunderbird email reader. I also run my own mail server and it is not using the real time blacklisting rankings of yahoo to reject mail from yahoo.? Yahoo is still deemed trustworthy by them as far as I can tell.
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Re: All TekScopes email sent to Spam
I thought our group was using "groups.io" not Yahoo.? Yahoo should not be involved unless they are your email client.? I use Yahoo email client and web based email.? That Yahoo client dumped all of my messages to SPAM one day last week.? But I marked them as "Not Spam" and everything has be good since then.
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On ?Wednesday?, ?July? ?25?, ?2018? ?03?:?18?:?04? ?PM? ?CDT, John Griessen <john@...> wrote: On 07/25/2018 02:36 PM, Harvey White wrote: ? It's possible
that the classification of the yahoo email has changed somehow,
causing your email program to put it elsewhere. Right.? various yahoo.com servers may have been downgraded in their trustworthiness and then the settings of your junk sensing flag it as junk.? If you change settings to allow from yahoo it will probably come through.? That's called whitelisting. No problem here using thunderbird email reader. I also run my own mail server and it is not using the real time blacklisting rankings of yahoo to reject mail from yahoo.? Yahoo is still deemed trustworthy by them as far as I can tell.
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Re: Tek 495P A54 Memory Board Repair
If anyone is having trouble with replacing components, maybe try
Chipquick low temperature alloy.
Recently I came into an obscene hoard of that stuff, and found that it
works rather well.
I don't really use it, I have the tools and practice to replace
anything I work with (the other day I exchanged a transformer over 50
times on the same board!), but that low melting alloy makes it really
easy, even without any special tools.
I would still recommend that you get the tools and skills to do this
the old fashioned way, but if you are worried about damaging some
expensive piece of kit then this Chipquick stuff might just steady
your hand.
A colleague has even used gallium to swap parts without any soldering
at all. Not so useful for repairs, but it was a pretty neat trick as
long as you didn't jostle the board. Funny metal, that, especially if
you put some on aluminium.
ST
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Re: All TekScopes email sent to Spam
On 07/25/2018 02:36 PM, Harvey White wrote: It's possible
that the classification of the yahoo email has changed somehow,
causing your email program to put it elsewhere. Right. various yahoo.com servers may have been downgraded in their trustworthiness and then the settings of your junk sensing flag it as junk. If you change settings to allow from yahoo it will probably come through. That's called whitelisting. No problem here using thunderbird email reader. I also run my own mail server and it is not using the real time blacklisting rankings of yahoo to reject mail from yahoo. Yahoo is still deemed trustworthy by them as far as I can tell.
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Re: Tek 495P A54 Memory Board Repair
Grayhill makes some DIP switches that are sealed with epoxy on each pin, and I've seen them with a clear layer of tape that is to be removed after a board is cleaned. They are the types with recessed actuators.
I have some old stock of Grayhill 76RSB04. The datasheet specifies adding a 's' suffix to have them shipped with the tape. The RSB part of the stock number is for the recessed rocker.
Microdyne used these, and I never saw any bad ones.
<>
Michael A. Terrell
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-----Original Message----- From: Harvey White <madyn@...>
Sent: Jul 25, 2018 3:38 PM
To: [email protected]
Subject: Re: [TekScopes] Tek 495P A54 Memory Board Repair
On Wed, 25 Jul 2018 17:10:29 +0100, you wrote:
Pretty clear you're not helpless!
For what it's worth, I find pulling a SOIC is simple with basic tools, I
use solder wick along all the pins first then 'ping' each pin in turn by
using a scalpel point - No 3 handle with 11 blade - inserted between the
pin and the next and applying a *very* slight twist behind the pin as I
heat it, to lift it clear of the pad and then work my way along. I find
this works and leaves the PCB clean, tidy and ready for the replacement
and the removed part totally reusable in the event that it was ok after
all .....not that that ever happens of course...!
Sometimes a bit of flux before you start is worthwhile, depends on the
solder/solder wick condition. Yep, have to agree with this opinion, wonder why? <grin>
Also FWIW, I concur with the comments re DIP switches, don't know why
they were so unreliable (PCB washing perhaps?) but I've had to replace a
significant number of the GPIB address selector switches on both TEK and
HP gear, had them failed open and closed but mostly open.
Contaminants from the cleaning process, and that most are not sealed
by any stretch of the imagination. Bet you.
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Re: Tek 495P A54 Memory Board Repair
On Wed, 25 Jul 2018 17:10:29 +0100, you wrote: Pretty clear you're not helpless!
For what it's worth, I find pulling a SOIC is simple with basic tools, I
use solder wick along all the pins first then 'ping' each pin in turn by
using a scalpel point - No 3 handle with 11 blade - inserted between the
pin and the next and applying a *very* slight twist behind the pin as I
heat it, to lift it clear of the pad and then work my way along. I find
this works and leaves the PCB clean, tidy and ready for the replacement
and the removed part totally reusable in the event that it was ok after
all .....not that that ever happens of course...!
Sometimes a bit of flux before you start is worthwhile, depends on the
solder/solder wick condition. Yep, have to agree with this opinion, wonder why? <grin>
Also FWIW, I concur with the comments re DIP switches, don't know why
they were so unreliable (PCB washing perhaps?) but I've had to replace a
significant number of the GPIB address selector switches on both TEK and
HP gear, had them failed open and closed but mostly open.
Contaminants from the cleaning process, and that most are not sealed by any stretch of the imagination. Bet you. Harvey
Adrian
On 7/25/2018 4:31 PM, Rick Boswell wrote:
I am on a mission to demonstrate that I am not helpless. Ordered the 74LS244 tri-state buffer and Grayhill DIP switches from DigiKey this AM. For less than $10 I got a lifetime supply of both. Will be a bit more complicated than I thought as the buffer is in an SO style surface mount package, not a DIP. We'll see. If I screw it up, I'll send it to you to bail me out!
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Re: All TekScopes email sent to Spam
On Wed, 25 Jul 2018 18:35:50 +0000 (UTC), you wrote: Help,
Now all my TekScopes email is sent to spam folder. Is this a Yahoo problem? All email is directed by your email program, not yahoo. It's possible that the classification of the yahoo email has changed somehow, causing your email program to put it elsewhere. You might want to check watch filters (or kill filters), the terminology likely will change program to program. Harvey Carl Hallberg (W9CJH)
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On Wed, Jul 25, 2018 at 12:38 AM, satbeginner wrote: the recommended IRF730 has a input capacity of 620pF
The ordered replacement IPA60R280E6 has a typical input capacity of 950pF.
For what it's worth: the broken FET I found in my scope when I got is was a
IRF710 (400V 200pF...) I am no expert on driving power FETs, however I think the biggest concern is the gate charge rather than Gate/Source capacitance ? There is a good deal of correlation between the two of course, but they aren't 1:1 related. In datasheet, on the first page of any MOSFET, the key parameter they specify to brag about how good their FET is (running cool and going fast), is RDson, and gate charge. BTW I got carried away in a previous post... the RDson of the modern replacement I used is 280mohoms not 28mohoms, of course, so "only" an order of magnitude better than the old part, not 2 orders. Still, quite impressive.... Gate charge tells you exactly just how many electrons/energy you need to shove into the gate to turn the FET on. Up to your gate driver to supply this many electrons in as short a time as it possibly can, to make the transition as fast as possible, to waste as little energy as possible and make the FET run as cool as possible. It's more to do with the "rise time". I feel gate/source capacitance is more of a limiting factor when you are trying to drive the FET as fast as possible. Like in the hundreds of kHz. But in the 22XX Tek scopes, the regulator runs at only 40kHz or so. So I think we are in the case of slow signal but with fast edges, aren't we. I looked at the datasheet of all the FETs you mentioned, plus the one I bought to fix my 2215 the other day. One can see that there is no linear relationship between input capacitance, and gate charge. Here goes : IRF 730 700pF 38nC IRF 710 170pF 17nC IRF 820 400pF 19nC IPA60R280E6 950pF 43nC IPP60R280P7 760pF 18nC So for example take the old IRF820 I pulled from 2215. My replacement IPP60R280P7, has twice the input capacitance (Rated 100V higher than the IRF820), BUT..... the gate charge is virtually the same, even a tad lower if anything, at 18nC versus 19nC. And if you compare it to the IPA60R280E6, though a very similar FET made by the same manufacturer, in the same vein... has more than double the gate charge (but only a bit more input capacitance). Waiting to the expert to chime in, but as for me, unless I am demonstrated otherwise, I will continue to worry more about (total) gate charge than input capacitance. At least for the old Tek scopes that are driven very slowly at only a few tens of kHz. So IOW, Leo... the FET you bought, with more than twice the gate charge of the old FET well.... might "work", kinda, but as for efficiency/power dissipation and long term reliability, that would need more investigation... Depends how much headroom was designed in the driver circuitry. I am not competent enough to analyze/quantify the operation of this circuitry. At least you in your scope, the FET is mounted a heat sink, with some air around it (might have a fan also ??), so you have some margin there... unlike my 2215 which has no heatsink and zero air around it... :-/ Anyway, keep us posted on you progress ! ^^ Vincent Trouilliez
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Re: All TekScopes email sent to Spam
Same here. Any ideas?
www.cwgsy.net/private/mandoline "Error 008472. Horrible bug encountered. $Deity knows what happened."
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On Wednesday, 25 July 2018, 19:36:02 GMT+1, Carl Hallberg via Groups.Io <n9ess@...> wrote:
Help,
Now all my TekScopes email is sent to spam folder.? Is this a Yahoo problem??
Carl Hallberg? (W9CJH)
|
All TekScopes email sent to Spam
Help,
Now all my TekScopes email is sent to spam folder. Is this a Yahoo problem?
Carl Hallberg (W9CJH)
|
Re: Weird serial number on 7L14
This is interesting! I have a 3L5 with serial number J22. Would that also be a prototype?
Bob Krassa AC?JL
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Re: Homemade tunnel diodes
Thanks for the documents. It indeed seems a good subject for tinkering and having fun building samplers. On Jul 25, 2018 9:46 AM, "Bruce Griffiths" <bruce.griffiths@...> wrote:
1N4007's have been used in high voltage discrete NLTLs.
Anritsu use NLTLs in theire VNA samplers:
Even Ceramic capacitors have been tried:
.
18.50.18/doc/06085283.pdf?languagebutton=pt-BR
Bruce
On 25 July 2018 at 13:56 Mark Kahrs <mark.kahrs@...> wrote:
I hate to disagree with Jose, but there have been a fair number of papers
on constructing NLTLs --- some even using discrete diodes.
If you'd like to read a review of the patents, may I refer you to this
short paper? I know the author personally.
Patents and Microwave Measurements-Nonlinear Transmission Lines [TCC
Tidbits] <>
<>IEEE Microwave Magazine
<>
Year: 2016, Volume: 17, Issue: 7
<>
Pages: 78 - 81
On Tue, Jul 24, 2018 at 1:00 PM, Craig Sawyers <
c.sawyers@...> wrote:
FWIW non-linear optical methods are used to compress the length of laser
light pulses. Somewhat
analogous to NLTL's, but at 10^14Hz.
Craig
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Ed
Breya via Groups.Io
Sent: 24 July 2018 17:32
To: [email protected]
Subject: Re: [TekScopes] Homemade tunnel diodes
Jose said:
"Not many people seem to have made DIY NLTL, let alone samplers
based on
it."
This is probably true, because NLTLs usually have lots of stages, so
can
get very big and
complicated
before you get remarkable compression. For simplicity and
effectiveness,
a single SRD/varactor of
the
right type, in the right circuit environment, is pretty hard to beat
for
straight up impulse
generation or
frequency multiplication. A whole bunch of them cascaded can form a NLTL, with its edge-
enhancement and wide BW. As always, it depends on the particulars of
the
application.
I don't think there's a need for a "modern" replacement for the
SRD/varactor. It's a common RF
part -
not at all an obsolete technology. Nowadays there are alternatives
for
many applications, by using
fast
active devices capable of appropriate edge speeds.
Ed
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WTB: v9.7 EPROMs for 495P memory board
Want to buy 495P v9.7 EPROMs which are installed on the A54 memory board. P/Ns 160-8316-00 and 160-8315-00. Or, complete working A54 board with these EPROMs installed.
RIck
K8EZB
|
Re: Tek 495P A54 Memory Board Repair
When you want to align and solder a new SOC IC, I apply a little solder to one corner pin, then position the new IC on the pads. Then I heat the pin over the pad with the solder. If it looks good, IO solder the opposite corner, then go down one side, then the other. Look for solder bridges, then it's ready to power up. If there are solder bridges, my method is to tilt the board with the row of pins running vertically. Then I apply a drop of liquid RMA rosin flux along the row of pis. Apply a drop of fresh solder on the tip of the iron, then run it down the row. It will remove solder bridges, and remove any excess solder. I used to do this to ICs with .015" center to center spacing. QA couldn't tell my rework from that done by our new automated Heller reflow oven. I recommend buying a half pound spool of Multicore .015" 63/37 solder for rework. It makes soldering these parts much easier, and a half pound will last you for years. I used it with a special .015" tip from Plato, along with a collet for an Ungar Loner soldering iron. A stereo microscope is a big help if you have bad eyes.
I saw a fair number of bad 74LS244 ICs on new boards at our production facility so I could almost replace them in my sleep. I also found them in the wrong position, or installed backwards when they came out of production.
Multicore-63-37-CRYSL-502-3-015DIA-28SWG-Henkel-LOCTITE
Michael A. Terrell
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-----Original Message----- From: Adrian <Adrian@...>
Sent: Jul 25, 2018 12:10 PM
To: [email protected]
Subject: Re: [TekScopes] Tek 495P A54 Memory Board Repair
Pretty clear you're not helpless!
For what it's worth, I find pulling a SOIC is simple with basic tools, I
use solder wick along all the pins first then 'ping' each pin in turn by
using a scalpel point - No 3 handle with 11 blade - inserted between the
pin and the next and applying a *very* slight twist behind the pin as I
heat it, to lift it clear of the pad and then work my way along. I find
this works and leaves the PCB clean, tidy and ready for the replacement
and the removed part totally reusable in the event that it was ok after
all .....not that that ever happens of course...!
Sometimes a bit of flux before you start is worthwhile, depends on the
solder/solder wick condition.
Also FWIW, I concur with the comments re DIP switches, don't know why
they were so unreliable (PCB washing perhaps?) but I've had to replace a
significant number of the GPIB address selector switches on both TEK and
HP gear, had them failed open and closed but mostly open.
Adrian
On 7/25/2018 4:31 PM, Rick Boswell wrote:
I am on a mission to demonstrate that I am not helpless. Ordered the 74LS244 tri-state buffer and Grayhill DIP switches from DigiKey this AM. For less than $10 I got a lifetime supply of both. Will be a bit more complicated than I thought as the buffer is in an SO style surface mount package, not a DIP. We'll see. If I screw it up, I'll send it to you to bail me out!
|
Re: Tek 495P A54 Memory Board Repair
Pretty clear you're not helpless!
For what it's worth, I find pulling a SOIC is simple with basic tools, I use solder wick along all the pins first then 'ping' each pin in turn by using a scalpel point - No 3 handle with 11 blade - inserted between the pin and the next and applying a *very* slight twist behind the pin as I heat it, to lift it clear of the pad and then work my way along. I find this works and leaves the PCB clean, tidy and ready for the replacement and the removed part totally reusable in the event that it was ok after all .....not that that ever happens of course...!
Sometimes a bit of flux before you start is worthwhile, depends on the solder/solder wick condition.
Also FWIW, I concur with the comments re DIP switches, don't know why they were so unreliable (PCB washing perhaps?) but I've had to replace a significant number of the GPIB address selector switches on both TEK and HP gear, had them failed open and closed but mostly open.
Adrian
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Show quoted text
On 7/25/2018 4:31 PM, Rick Boswell wrote: I am on a mission to demonstrate that I am not helpless. Ordered the 74LS244 tri-state buffer and Grayhill DIP switches from DigiKey this AM. For less than $10 I got a lifetime supply of both. Will be a bit more complicated than I thought as the buffer is in an SO style surface mount package, not a DIP. We'll see. If I screw it up, I'll send it to you to bail me out!
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David C. Partridge
Sergey Kubushyn
Michael A. Terrell
Vince
Jose Luu