Author Topic: Tektronix 2465A troubleshooting  (Read 6924 times)

0 Members and 1 Guest are viewing this topic.

Offline MarkL

  • Supporter
  • ****
  • Posts: 2120
  • Country: us
Re: Tektronix 2465A troubleshooting
« Reply #25 on: December 15, 2018, 09:00:08 pm »
One thing to note, because your scope has options, is that the data and address buses are connected to the options buffer board via J500.  If scope's problems are the result of a bus problem, there's a non-zero chance that the problem is on the options buffer board and not on the A5 board.

The "24X5A/2467 Options Service" manual (separate from the regular service manual) outlines the procedure to disconnect all the options so the scope operates as the base model.  Ribbons need to be moved/removed and jumpers need to be installed in a few places.  See "Instrument Troubleshooting Without Options", on page 5-15 or thereabouts.

If, at some point, you're able to reproduce any problems, this is something you could try to see if the problem clears.

My bet is still on the A5 board, given the U2410 strangeness, but it's not as certain with the options in the mix.

Are your CT and DMM options operating ok?
 

Offline stfjohnTopic starter

  • Contributor
  • Posts: 23
  • Country: it
Re: Tektronix 2465A troubleshooting
« Reply #26 on: December 15, 2018, 10:37:46 pm »
CT and DMM options operate OK.
I also tried to disconnect the DMM, but nothing changes. I still suspect that the ram I bought new has some problems: the seller kept it in a drawer without any protection (and with CMOS devices it is not very hygienic!). Among other things, there is a way to test a RAM?
About the U2410, the thing perhaps can be explained by the fact that, being the board a damn multilayer, some welding probably did not make good contact and, after having resolded the socket, everything is back to normal ...
« Last Edit: December 15, 2018, 11:43:18 pm by stfjohn »
 

Offline MarkL

  • Supporter
  • ****
  • Posts: 2120
  • Country: us
Re: Tektronix 2465A troubleshooting
« Reply #27 on: December 16, 2018, 04:36:36 am »
CT and DMM options operate OK.
I also tried to disconnect the DMM, but nothing changes. I still suspect that the ram I bought new has some problems: the seller kept it in a drawer without any protection (and with CMOS devices it is not very hygienic!). Among other things, there is a way to test a RAM?
About the U2410, the thing perhaps can be explained by the fact that, being the board a damn multilayer, some welding probably did not make good contact and, after having resolded the socket, everything is back to normal ...
The scope does a read/write test of all RAM locations on boot.  If that fails, it is fatal and the TRIG'D LED will flash with the error status shown by various LEDs on/off according to tables 6-6 thru 6-8.  I think the RAM is ok.  You could always put the old one back in if you suspect an intermittent issue with the new one.
 

Offline stfjohnTopic starter

  • Contributor
  • Posts: 23
  • Country: it
Re: Tektronix 2465A troubleshooting
« Reply #28 on: December 16, 2018, 12:31:58 pm »
Yes sure! Only then I'll have to recalibrate everything again! Ouff !!
By the way: can the calibration be done in stages or must it be completed at once?
« Last Edit: December 16, 2018, 12:33:53 pm by stfjohn »
 

Offline MarkL

  • Supporter
  • ****
  • Posts: 2120
  • Country: us
Re: Tektronix 2465A troubleshooting
« Reply #29 on: December 16, 2018, 07:07:43 pm »
Yes sure! Only then I'll have to recalibrate everything again! Ouff !!
If you have the GPIB option you can backup up the cal data, replace the RAM, and then put the cal data back.

Otherwise, you're right, it's probably not worth the time.

Are you still seeing the TEST 04 FAIL 12 message?

Quote
By the way: can the calibration be done in stages or must it be completed at once?
The service manual says that you can do a section at a time, but it's not recommended.  There's a couple of paragraphs about it at the very beginning of section 5, and repeated throughout the procedure along with specific caveats about skipping some of the steps.

If would be nice if it would say *which* value was out of range, so you could try re-calibrating just that section (if that's what you're thinking), but I don't know of a way to figure it out except by trial.

If you want to try removing J500 and J101, and putting in two jumpers on J101 across 1-3 and 6-8 (you'll see those positions marked on the board), the scope will think it doesn't have any options installed.  In this configuration many things won't work, but it should boot without error.  I'm going to guess that it won't check for limit errors associated with options if it doesn't think there are any installed, so if the TEST 04 FAIL 12 goes away, the bad calibration value is probably associated with one of the options.  At least that would narrow it down.
 

Offline stfjohnTopic starter

  • Contributor
  • Posts: 23
  • Country: it
Re: Tektronix 2465A troubleshooting
« Reply #30 on: December 17, 2018, 04:29:03 pm »
I did as you suggested (unplug options) and nothing has changed. So, given what happened with the U2410, I redid the welds also on U2350 and U2450 and ... incredible... everything is fine! I do not know how to thank you MARKL for your availability and courtesy. Thank you so much. I will report to the moderators your competence and great kindness.  :clap: :clap: :clap:
 

Offline med6753

  • Super Contributor
  • ***
  • Posts: 11313
  • Country: us
  • Tek nut
Re: Tektronix 2465A troubleshooting
« Reply #31 on: December 17, 2018, 04:55:43 pm »
Yes, MarkL is one of those very helpful and knowledgeable individuals who make this forum a great resource. He has helped me several times with my 2465.

Might I suggest that any further issues with your 2465A be posted here....

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/

This is the "catch all" thread for all issues concerning the 2445/2465 series. 
An old gray beard with an attitude.
 
The following users thanked this post: stfjohn

Offline MarkL

  • Supporter
  • ****
  • Posts: 2120
  • Country: us
Re: Tektronix 2465A troubleshooting
« Reply #32 on: December 17, 2018, 07:07:53 pm »
Hey, you're welcome!  I really enjoy working on this old equipment.  You don't have to report me to the moderators, but you can hit the "Say Thanks" button if you want.

I'm glad the scope is working for you now, but I'm always extremely wary when things fix themselves without a clear diagnosis.  Those kinds of problems always seem to come back at the most inopportune time.
 
The following users thanked this post: stfjohn

Offline BravoV

  • Super Contributor
  • ***
  • Posts: 7547
  • Country: 00
  • +++ ATH1
Re: Tektronix 2465A troubleshooting
« Reply #33 on: December 17, 2018, 08:13:13 pm »
Congratz on the fix, and also prop to MarkL,when it comes to Tek 2465 series, MarkL is a guru Bodhisattva here as he is willingly to jump in and offer helps with his vast understanding on this scope.  :clap:

Offline stfjohnTopic starter

  • Contributor
  • Posts: 23
  • Country: it
Re: Tektronix 2465A troubleshooting
« Reply #34 on: December 17, 2018, 11:01:05 pm »
You're right MARKL: I had bought this scope 4 or 5 years ago and I start to think that the previous owner had kept it in a too wet environment probably ... This could explain the "cold" welds. I really hope that it does not happen again! In any case, I learned a lot from you. Thanks again.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf