Re: Tektronix 2440 bad power supply?
Hi,
May be trivial, but this has happened to me. Check all the ribbon
cable connections between the boards. I had one that got pulled out
partially when I folded out the board, and was causing all kinds of
weird symptoms. Check that all all firmly seated in their connectors.
If it never completed self cal, there may be garbage in the nvram, so
once you get the scope running, I recommend to do a Cold Start to
clear it, otherwise it may get very much confused.
Also, check the ripple on the power lines, that may be out of spec.
While I'm no fan of the common Internet wisdom of 'recapping cures
everything', I had 3 24xx DSO, and all of them had bad/marginal caps
in the PSU, so I guess one can safely assume that those caps need
replacing. Don't forget about C244 in the control power supply.
Szabolcs
RichR via Groups.Io <choicetrans1@...> ezt ¨ªrta
(id?pont: 2018. j¨²n. 27., Sze, 23:53):
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I recently purchased a 2440 with a 4000 code, battery weak. Everything else appeared to be working. That was the only fault code. I replaced the two ram modules with new. The original were obsolete (DS1235BWL-120) so I purchased DS1230-100+. When I first turned on the scope everything powered up and there were plenty of fault codes so I started a self calibration. It never completed the self calibration. The scope went blank. I was able to power it up only occasionally until it stopped completely. It no longer tries to test when it is powered on the only lights on are the three GPIB lights. The screen will start with some erroneous dots and then go blank. I have tested the low power board and have some readings that do not match the schematics The voltage reading according to the power supply overcurrent check page 478 of the manual do not match. The voltages on the side board are correct so I am not sure where to proceed. I have attached a - of the readings I got from the power supply. Any help is greatly appreciated. Thank you, Rich
/g/TekScopes/files/015-0282-00/TEK%202440%20Power%20supply%20test/TEK2440%20Curret%20test20180627_12351992.pdf
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Re: OT: Film of Phillips plant in the 1930s
Now we're talkin'! I love this old technology. I have some old hand blown vacuum tubes and amps from the early days. A couple older than me and I am a wwII vj era baby! I just bought a 50's Phillips HF 10 amp, 100% factory original, right down to 90% test Phillips tubes. It was advertised on Mexico's equivalent of ebay as a "dryer". The owner thought the metal perforated cage covering the trannies and heat generating tubes was to "dry" things on. I'm glad that I rescued it before he used it to dry chilis or make jerky on.? Thx for this link! On Wednesday, June 27, 2018, Fabio Trevisan <fabio.tr3visan@...> wrote: Wow!
There were guys blowing glass bulbs dressed on waistcoats!
Those were definitely more civilized days!
And for a film that seemed to be sort of institutional... what great
takes! I wonder who was the photographer.
Nice video.
Rgrds,
Fabio
On Wed, Jun 27, 2018 at 01:54 pm, Albert LaFrance wrote:
Including production-line hand blowing of tube envelopes:
<> &t=405s
Albert
-- Good judgement comes from experience; experience comes from bad judgement. 99 times out of 10 a blown fuse is not due to a bad fuse.....
|
I mentioned that I read this in an earlier post, Jeff. It makes sense to
see why the 55v is out of range. I somehow suspect more than one thing
wrong. And after watching the video Vincent referenced, it looks like it
wont be super easy r&r ing many of the components. I do have pretty good
soldering gear, so wish me luck, and thanks for your posts.
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On Wednesday, June 27, 2018, Jeff Urban <JURB6006@...> wrote: Sorry. that should read "NONE of them can short it out"
The sources are only using the 55 volts for reference, it does not feed
them. If all of them are out, it is unlikely that they all just got that
way and that the problem is with the 55 volts.
You should see some of my other typos.
--
Good judgement comes from experience; experience comes from bad judgement.
99 times out of 10 a blown fuse is not due to a bad fuse.....
|
This REALLY helps as it is the only detailed repair dealing with almost exactly my issues. I do also realize that I'm not going to have much in the way of parts, other than resistors and some electrolytic caps to replace the bad tantalums i might encounter. I might be able to find some of the filters here in Mexico, but if I do they will likely be both old and expensive. I got sidetracked today with Mexico playing a World Cup game and my friends and students wouldnt accept no for an answer. So I will attempt to fit in Fabio's suggestions and see if I can do a little sleuthing based on the video. I'm already looking forward to part 2....3?....4? That is an interesting you tube channel. Thanks Vincent! On Wednesday, June 27, 2018, Vincent Trouilliez < vincent.trouilliez@...> wrote: Hi Musicamex,
You might find this video helpful, from the YT channel "the Radio Shop",
posted just 4 days ago.
Chap is fixing a 465 with similar LV issues.
You might have to skip the first 20 minutes to get to the start of his
repair.
IIRC he had bad filter caps (the cans), then bad pass/power transistor,
then bad small signal transistor, the one that's between the op-amp and the
pass transistor.
Hope this helps,
Vincent Trouilliez
-- Good judgement comes from experience; experience comes from bad judgement. 99 times out of 10 a blown fuse is not due to a bad fuse.....
|
Re: 2465DMM repair and a $1000 US fine or one year year in prison?
How do these feet look?
Friend of mine recently got a Rubber capable 3d printer...
Tam
---
With best regards
Tam HANNA (emailing on a BlackBerry PRIV)
Enjoy electronics? Join 11k other followers by visiting the Crazy Electronics Lab at
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Re: Anybody need some Tek 369-0031-00 Fan Turbines?
Hi Walter. I wish I lived closer. I have several Tek and Fluke
instruments used in a free school I run in Mexico. I do have a shipping
address in California and possibly a fellow musician that summers in BC
might be able to help if you have a few things that would "fit". Would it
be best to contact you through the email addresses provided.?
Thanks, Russ
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On Wednesday, June 27, 2018, walter shawlee <walter2@...> wrote: Doing more clean up at Sphere, I found a factory bag full of the 2.5 inch
black fan turbine blade assemblies used in many Tek scopes (465, 475, 2465,
etc.). sorry, no fan motors to go with them, but if you have a damaged fan
assembly, I can help with that! i think they are too fragile to send in a
padded bag, probably needs a box to ship safely. There's 4 new turbines in
the bag, US$5 each if anybody can use them.
Lots of over-stocked Tek, HP and Fluke bits to clean out, if you will be
up this way (Kelowna, BC, Canada) please stop by, we can load you up with
cheap and free stuff, and tons of factory manuals. Just WAY too much stuff
here. There's not another stuff day scheduled for the rest of this year,
but we have extra stuff all the time, so visitors are welcome!
All the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.
--
Good judgement comes from experience; experience comes from bad judgement.
99 times out of 10 a blown fuse is not due to a bad fuse.....
|
Re: Tektronix 2440 bad power supply?
Same as mine, when I said boot I should have said screen dead. I had the three leds above the screen flashing a code. The code is in the service manual but I cant tell you exactly where. I did have a lighted screen just nothing but a lit screen. Sent from Mail for Windows 10 From: RichR via Groups.Io Sent: Wednesday, June 27, 2018 8:22 PM To: [email protected]Subject: Re: [TekScopes] Tektronix 2440 bad power supply? I have no screen at all. The scope does not do a self test so I cannot get to an initial calibration. I did not copy the calibration constants and when I first powered the scope it ran a self test as normal and came up with the expected fail codes. When I tried to do an auto set, it started and then the screen went blank. I have no screen now when I power up. The fan works so I have some power. I will try to find the current sense resistors. Thank you for the replies, Rich On Wednesday, June 27, 2018, 6:20:09 PM EDT, Dewey Wyatt <kn4wddewey@...> wrote: U664 is where the calibration constants are stored did you copy them to the new ram? If not you will need to do a complete recalibration. I went through a 2430a recently and bought a chip reader and writer to be able to save and copy the constants from one to the other. U360 holds stored waveforms and isn¡¯t as important as the u664. Hope this helps. Mine wouldn¡¯t boot either without writing the calibration constants to the new dallas chip. Even with auto setup it wouldn¡¯t boot after I copied the chips data all went well. Sent from Mail for Windows 10 From: RichR via Groups.Io Sent: Wednesday, June 27, 2018 5:53 PM To: [email protected]Subject: [TekScopes] Tektronix 2440 bad power supply? I recently purchased a 2440 with a 4000 code, battery weak. Everything else appeared to be working. That was the only fault code. I replaced the two ram modules with new. The original were obsolete (DS1235BWL-120) so I purchased DS1230-100+. When I first turned on the scope everything powered up and there were plenty of fault codes so I started a self calibration. It never completed the self calibration. The scope went blank. I was able to power it up only occasionally until it stopped completely. It no longer tries to test when it is powered on the only lights on are the three GPIB lights. The screen will start with some erroneous dots and then go blank. I have tested the low power board and have some readings that do not match the schematics The voltage reading according to the power supply overcurrent check page 478 of the manual do not match. The voltages on the side board are correct so I am not sure where to proceed. I have attached a - of the readings I got from the power supply. Any help is greatly appreciated. Thank you, Rich /g/TekScopes/files/015-0282-00/TEK%202440%20Power%20supply%20test/TEK2440%20Curret%20test20180627_12351992.pdf--- This email has been checked for viruses by AVG.
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Re: Tektronix 2440 bad power supply?
I have no screen at all. The scope does not do a self test so I cannot get to an initial calibration. I did not copy the calibration constants and when I first powered the scope it ran a self test as normal and came up with the expected fail codes. When I tried to do an auto set, it started and then the screen went blank. I have no screen now when I power up. The fan works so I have some power. I will try to find the current sense resistors. Thank you for the replies, Rich
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Show quoted text
On Wednesday, June 27, 2018, 6:20:09 PM EDT, Dewey Wyatt <kn4wddewey@...> wrote: U664 is where the calibration constants are stored did you copy them to the new ram? If not you will need to do a complete recalibration. I went through a 2430a recently and bought a chip reader and writer to be able to save and copy the constants from one to the other. U360 holds stored waveforms and isn¡¯t as important as the u664. Hope this helps. Mine wouldn¡¯t boot either without writing the calibration constants to the new dallas chip. Even with auto setup it wouldn¡¯t boot after I copied the chips data all went well. Sent from Mail for Windows 10 From: RichR via Groups.Io Sent: Wednesday, June 27, 2018 5:53 PM To: [email protected]Subject: [TekScopes] Tektronix 2440 bad power supply? I recently purchased a 2440 with a 4000 code, battery weak. Everything else appeared to be working. That was the only fault code. I replaced the two ram modules with new. The original were obsolete (DS1235BWL-120) so I purchased DS1230-100+. When I first turned on the scope everything powered up and there were plenty of fault codes so I started a self calibration. It never completed the self calibration. The scope went blank. I was able to power it up only occasionally until it stopped completely. It no longer tries to test when it is powered on the only lights on are the three GPIB lights. The screen will start with some erroneous dots and then go blank. I have tested the low power board and have some readings that do not match the schematics The voltage reading according to the power supply overcurrent check page 478 of the manual do not match. The voltages on the side board are correct so I am not sure where to proceed. I have attached a - of the readings I got from the power supply. Any help is greatly appreciated. Thank you, Rich /g/TekScopes/files/015-0282-00/TEK%202440%20Power%20supply%20test/TEK2440%20Curret%20test20180627_12351992.pdf--- This email has been checked for viruses by AVG.
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Re: OT: Film of Phillips plant in the 1930s
Wow!
There were guys blowing glass bulbs dressed on waistcoats!
Those were definitely more civilized days!
And for a film that seemed to be sort of institutional... what great takes! I wonder who was the photographer.
Nice video.
Rgrds,
Fabio
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Show quoted text
On Wed, Jun 27, 2018 at 01:54 pm, Albert LaFrance wrote:
Including production-line hand blowing of tube envelopes:
<> &t=405s
Albert
|
Re: 2465DMM repair and a $1000 US fine or one year year in prison?
Leo,
Undoubtedly you should go to prison... not for removing the label... but for that steal you scored.
Lucky guy! Just a stuck beam finder button!
Rgrds,
Fabio
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On Wed, Jun 27, 2018 at 05:26 am, satbeginner wrote:
Hi all,
I couldn't help myself and got (another) 2465 on "the Bay"
This time it was a 2465DMM, shown with the beamfinder button pressed (while
nobody was pressing it :-)
Still, shipping from the States to Europe is not cheap, but they accepted my
offer, and I am happy with what I paid.
Long story short: unpacking cost more time than the actual repair: Contact
cleaner on the beamfinder switch and it was good to go :-)
When the time comes I will re-cap the PS and calibrate the scope, but for now
I am happy (again).
Nice touch: I could be fined 1000$ US or be sentenced to one year jail time
because I unauthorized removed a label :-) :-)
Pictures can be found here: /g/TekScopes/album?id=61275
Un saludo,
Leo
P.S. I could use the rear rubber feet for this DMM scope.
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Re: Tektronix 2440 bad power supply?
U664 is where the calibration constants are stored did you copy them to the new ram? If not you will need to do a complete recalibration. I went through a 2430a recently and bought a chip reader and writer to be able to save and copy the constants from one to the other. U360 holds stored waveforms and isn¡¯t as important as the u664. Hope this helps. Mine wouldn¡¯t boot either without writing the calibration constants to the new dallas chip. Even with auto setup it wouldn¡¯t boot after I copied the chips data all went well. Sent from Mail for Windows 10 From: RichR via Groups.Io Sent: Wednesday, June 27, 2018 5:53 PM To: [email protected]Subject: [TekScopes] Tektronix 2440 bad power supply? I recently purchased a 2440 with a 4000 code, battery weak. Everything else appeared to be working. That was the only fault code. I replaced the two ram modules with new. The original were obsolete (DS1235BWL-120) so I purchased DS1230-100+. When I first turned on the scope everything powered up and there were plenty of fault codes so I started a self calibration. It never completed the self calibration. The scope went blank. I was able to power it up only occasionally until it stopped completely. It no longer tries to test when it is powered on the only lights on are the three GPIB lights. The screen will start with some erroneous dots and then go blank. I have tested the low power board and have some readings that do not match the schematics The voltage reading according to the power supply overcurrent check page 478 of the manual do not match. The voltages on the side board are correct so I am not sure where to proceed. I have attached a - of the readings I got from the power supply. Any help is greatly appreciated. Thank you, Rich /g/TekScopes/files/015-0282-00/TEK%202440%20Power%20supply%20test/TEK2440%20Curret%20test20180627_12351992.pdf--- This email has been checked for viruses by AVG.
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Re: Tektronix 2440 bad power supply?
Hi Rich:
I don¡¯t have the manual here in front of me, but I did a lot of troubleshooting and calibration of the 2440 series. What you describe, reminds me of the current sense resistors going out of tolerance. If I recall these are very low value resistors, with tight tolerances. If they drift the PSU will start acting very similar to what you describe.
Hopefully, someone can tell you which resistors these are.
Rich Miller
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On Jun 27, 2018, at 1:03 PM, RichR via Groups.Io <choicetrans1@...> wrote:
I recently purchased a 2440 with a 4000 code, battery weak. Everything else appeared to be working. That was the only fault code. I replaced the two ram modules with new. The original were obsolete (DS1235BWL-120) so I purchased DS1230-100+. When I first turned on the scope everything powered up and there were plenty of fault codes so I started a self calibration. It never completed the self calibration. The scope went blank. I was able to power it up only occasionally until it stopped completely. It no longer tries to test when it is powered on the only lights on are the three GPIB lights. The screen will start with some erroneous dots and then go blank. I have tested the low power board and have some readings that do not match the schematics The voltage reading according to the power supply overcurrent check page 478 of the manual do not match. The voltages on the side board are correct so I am not sure where to proceed. I have attached a - of the readings I got from the power supply. Any help is greatly appreciated. Thank you, Rich
/g/TekScopes/files/015-0282-00/TEK%202440%20Power%20supply%20test/TEK2440%20Curret%20test20180627_12351992.pdf
|
Tektronix 2440 bad power supply?
I recently purchased a 2440 with a 4000 code, battery weak. Everything else appeared to be working. That was the only fault code. I replaced the two ram modules with new. The original were obsolete (DS1235BWL-120) so I purchased DS1230-100+. When I first turned on the scope everything powered up and there were plenty of fault codes so I started a self calibration. It never completed the self calibration. The scope went blank. I was able to power it up only occasionally until it stopped completely. It no longer tries to test when it is powered on the only lights on are the three GPIB lights. The screen will start with some erroneous dots and then go blank. I have tested the low power board and have some readings that do not match the schematics The voltage reading according to the power supply overcurrent check page 478 of the manual do not match. The voltages on the side board are correct so I am not sure where to proceed. I have attached a - of the readings I got from the power supply. Any help is greatly appreciated. Thank you, Rich /g/TekScopes/files/015-0282-00/TEK%202440%20Power%20supply%20test/TEK2440%20Curret%20test20180627_12351992.pdf
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Anybody need some Tek 369-0031-00 Fan Turbines?
Doing more clean up at Sphere, I found a factory bag full of the 2.5 inch black fan turbine blade assemblies used in many Tek scopes (465, 475, 2465, etc.). sorry, no fan motors to go with them, but if you have a damaged fan assembly, I can help with that! i think they are too fragile to send in a padded bag, probably needs a box to ship safely. There's 4 new turbines in the bag, US$5 each if anybody can use them.
Lots of over-stocked Tek, HP and Fluke bits to clean out, if you will be up this way (Kelowna, BC, Canada) please stop by, we can load you up with cheap and free stuff, and tons of factory manuals. Just WAY too much stuff here. There's not another stuff day scheduled for the rest of this year, but we have extra stuff all the time, so visitors are welcome!
All the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.
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OT: Film of Phillips plant in the 1930s
Including production-line hand blowing of tube envelopes:
<> &t=405s
Albert
|
Hi Musicamex,
You might find this video helpful, from the YT channel "the Radio Shop", posted just 4 days ago.
Chap is fixing a 465 with similar LV issues.
You might have to skip the first 20 minutes to get to the start of his repair.
IIRC he had bad filter caps (the cans), then bad pass/power transistor, then bad small signal transistor, the one that's between the op-amp and the pass transistor.
Hope this helps,
Vincent Trouilliez
|
--------------------------------------------
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On Wed, 6/27/18, Jeff Urban <JURB6006@...> wrote: Subject: Re: [TekScopes] Dead 7603 To: [email protected] Date: Wednesday, June 27, 2018, 11:24 AM Ten 10 meg resistors in series. The same stack can be used to multiply your voltmeter range. Should use resistors made for high voltage use. Normal Carbon Composition resistor may have ratings of 250-500V each. 10 in series maybe 5KV. Carl Hallberg W9CJH
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Ten 10 meg resistors in series. The same stack can be used to multiply your voltmeter range.
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Sorry. that should read "NONE of them can short it out"
The sources are only using the 55 volts for reference, it does not feed them. If all of them are out, it is unlikely that they all just got that way and that the problem is with the 55 volts.
You should see some of my other typos.
|
Ok. I read a post on 485 troubleshooting recently that suggested to wait at least 6 hours to let the
CRT
charge fall off before pulling the lead to prevent killing that IC. It is more than possible that
I
misunderstood. U660 is the vertical output amplifier in a 485. You must mean U1600, which is the x6 voltage multiplier. Can't think of a mechanism by which unplugging the CRT could zap it. Internally it is protected by a series resistor in the tens of megohms range so that if the output is totally shorted out, the current is sufficiently low to not damage the internal components. But let's do some what-if sums. I'm not sure what the capacitance of the DAG coating is, but let's assume 100pF. Accelerating voltage is 18kV. Let's say we wait those 6 hours before we unplug the HT connector - what sort of leakage resistance will we need to reduce the voltage? 6 hours is ~20,000 seconds. Let's say that is ten time constants, so the voltage will decay to ~100V and let's say, for argument's sake, that is low enough. So one time constant has to be less than 2000 seconds, which is the product of the CRT capacitance and the leakage resistance. Which works out at a leakage resistance has to be less than 2e13 ohms, and an initial discharge current of 0.9 nA. I would say that is entirely possible. Reverse leakage of the multiplier diodes should be more than enough in itself, not counting other leakage paths. So waiting 6 hours should indeed discharge the CRT. But it makes fault finding the restorer circuits a bear - wait 6 hours, try something, turn on scope - oops it wasn't that, wait 6 hours etc etc. And whether or not it is necessary to wait that length is time is anyway moot. The other way to see if the multiplier is faulty is to disconnect the input. The main symptom of a dead multiplier is that it loads down the high voltage transformer, so the -3kV test point reads low - a few hundred volts typically. If disconnecting the multiplier input results in the -3kV coming back up and reading correctly, then the multiplier is dead. Craig
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Fabio Trevisan
Vince
Jeff Urban