Tektronix 465B oscilloscope, one channel not working - UK Vintage Radio Repair and Restoration Discussion Forum

Richard · 3rd Feb 2009, 6:27 pm

Hi everyone

My scope is poorly, channel 2 has stopped working.

Channel 1 all works fine and does all it should.

Channel 2 does nothing, beam find shows it is off the top of the screen and the position control does not move it, if whilst beam find is pressed a signal is injected channel 1 shows it but 2 does not.

I have down loaded the manual from Bama, but the fault finding section has not been fully scanned and makes no sense.

I have to admit to being very lost in this unit, help please..............

Richard

Brian R Pateman · 3rd Feb 2009, 6:49 pm

Not the easiest of scopes to repair, I used to repair / calibrate them when they, and I were younger!

I have the manual for the 475 which is basically the same in this area. If you PM me your e-mail address I will scan the relevant fault finding section of the 475 manual for you.

Regards,

XTC · 3rd Feb 2009, 6:58 pm

Richard,

I think you've just got to get your hands on a usable copy of the manual for the 465B

http://www.eserviceinfo.com/download...ronix_465.html

http://www.***********/doc/2202941/Tektronix-465b-Manual

from Google, look like promising alternatives to BAMA.

Otherwise, I'm sure you can get it on a CD for a few quid.

After that, you've got the working channel to compare the duff one against.

Pete.

Mike-repairman · 5th Feb 2009, 6:46 pm

Hi Richard,

I had an exact same problem with a Tek 453. It was dirty contacts on the plug-in transistors on the Y amp board.

I ended up removing and replacing all the transistors in the unit in the end with a quick squirt of Servisol 10 before replacing them.

Worth a try.

Mike.

Top Cap · 5th Feb 2009, 9:23 pm

Like Brian, I used to repair and calibrate these in my younger days. Although probably not related, perhaps the following taken from an old log book may help in future-
1. +5V supply too high at approx 8.5V - short circuit darlington Q1556 (MPS-U45) TEK No. 151-0390-00

2. No trace visible at 0.1S/0.2S/0.5S or X-Y - Caused by blanking fault from R1462 going low, should be 2k4 and was found to be 0.74k!

3. No 'Ready' Lamp - Faulty U870

If the calibration lab was still operating that I worked in, I could have obtained heaps of service manuals for this scope but regrettably it was closed down for so called re-structuring by the parent company. As both scope channels will probably be a near copy of each other, use the good channel to provide you with some test voltages to check against the faulty one. But you will find doing this much easier with the help of a circuit diagram. If you can't get one, let me know and I will try to find something through a contact I have.
Les

AVO_VCM163 · 5th Feb 2009, 10:12 pm

465 Manual appears to be available here.

R

Richard · 6th Feb 2009, 12:56 am

Hi

Thanks everyone for the tips

I have found several manuals online, and on downloading they all appear to be from the same origin, with the fault finding sections not fully scanned

Brian - PM sent - thanks.

I will get some more time to study it next week and will report back

Thanks again

Richard

Richard · 22nd Feb 2009, 11:29 pm

Hi everyone

Had some spare time tonight so got around to having a look at this unit.

Measuring voltages from the inputs back I found an area with some big differences, so I swapped 4 transistors in the area from one channel to the other, hoping the fault would change Chanel's, and then both channels worked

Result, so looks like, as someone suggested, lose contacts on the transistor plug in bases.

Just got to fit a proper fan I managed to get in place of a noisy papst unit and put it all back together.

Thanks for all the help

Mike-repairman · 27th Feb 2009, 4:04 pm

Very pleased that you got the unit working again Richard.

That was the same fault that I described in an earlier post.

However when you get the time it may be worth removing all the transistors, one by one, and giving each socket a small squirt of switch cleaner before replacing them.

I know there are a lot of them, but it's good preventative maintenance as if one had a poor connection it's only a matter of time before others exhibit the same fault.

After this procedure I've found that my scope has performed flawlessly.

Mike.

3rd Feb 2009, 6:27 pm	#1
Richard Heptode Join Date: Feb 2003 Location: Garnant, near Ammanford, South Wales, UK. Posts: 657	Tektronix 465B oscilloscope, one channel not working Hi everyone My scope is poorly, channel 2 has stopped working. Channel 1 all works fine and does all it should. Channel 2 does nothing, beam find shows it is off the top of the screen and the position control does not move it, if whilst beam find is pressed a signal is injected channel 1 shows it but 2 does not. I have down loaded the manual from Bama, but the fault finding section has not been fully scanned and makes no sense. I have to admit to being very lost in this unit, help please.............. Richard __________________ BVWS member.

3rd Feb 2009, 6:49 pm	#2
Brian R Pateman Nonode Join Date: Jun 2005 Location: Western Lake District, Cumbria (CA20) - UK Posts: 2,136	Re: Tektronix 465B oscilloscope, one channel not working Not the easiest of scopes to repair, I used to repair / calibrate them when they, and I were younger! I have the manual for the 475 which is basically the same in this area. If you PM me your e-mail address I will scan the relevant fault finding section of the 475 manual for you. Regards, __________________ Brian

3rd Feb 2009, 6:58 pm	#3
XTC Retired Dormant Member Join Date: Oct 2004 Location: Bristol, UK. Posts: 837	Re: Tektronix 465B oscilloscope, one channel not working Richard, I think you've just got to get your hands on a usable copy of the manual for the 465B http://www.eserviceinfo.com/download...ronix_465.html http://www.***********/doc/2202941/Tektronix-465b-Manual from Google, look like promising alternatives to BAMA. Otherwise, I'm sure you can get it on a CD for a few quid. After that, you've got the working channel to compare the duff one against. Pete.

5th Feb 2009, 6:46 pm	#4
Mike-repairman Heptode Join Date: Jun 2008 Location: Cambridgeshire, UK. Posts: 613	Re: Tektronix 465B oscilloscope, one channel not working Hi Richard, I had an exact same problem with a Tek 453. It was dirty contacts on the plug-in transistors on the Y amp board. I ended up removing and replacing all the transistors in the unit in the end with a quick squirt of Servisol 10 before replacing them. Worth a try. Mike.

5th Feb 2009, 9:23 pm	#5
Top Cap Octode Join Date: Mar 2006 Location: Watford, Hertfordshire, UK. Posts: 1,270	Re: Tektronix 465B oscilloscope, one channel not working Like Brian, I used to repair and calibrate these in my younger days. Although probably not related, perhaps the following taken from an old log book may help in future- 1. +5V supply too high at approx 8.5V - short circuit darlington Q1556 (MPS-U45) TEK No. 151-0390-00 2. No trace visible at 0.1S/0.2S/0.5S or X-Y - Caused by blanking fault from R1462 going low, should be 2k4 and was found to be 0.74k! 3. No 'Ready' Lamp - Faulty U870 If the calibration lab was still operating that I worked in, I could have obtained heaps of service manuals for this scope but regrettably it was closed down for so called re-structuring by the parent company. As both scope channels will probably be a near copy of each other, use the good channel to provide you with some test voltages to check against the faulty one. But you will find doing this much easier with the help of a circuit diagram. If you can't get one, let me know and I will try to find something through a contact I have. Les __________________ Whether the Top Cap is Grid or Anode - touching it will give you a buzz either way!

5th Feb 2009, 10:12 pm	#6
AVO_VCM163 Retired Dormant Member Join Date: Mar 2008 Location: Hampshire, UK. Posts: 297	Re: Tektronix 465B oscilloscope, one channel not working 465 Manual appears to be available here. R

6th Feb 2009, 12:56 am	#7
Richard Heptode Join Date: Feb 2003 Location: Garnant, near Ammanford, South Wales, UK. Posts: 657	Re: Tektronix 465B oscilloscope, one channel not working Hi Thanks everyone for the tips I have found several manuals online, and on downloading they all appear to be from the same origin, with the fault finding sections not fully scanned Brian - PM sent - thanks. I will get some more time to study it next week and will report back Thanks again Richard __________________ BVWS member.

22nd Feb 2009, 11:29 pm	#8
Richard Heptode Join Date: Feb 2003 Location: Garnant, near Ammanford, South Wales, UK. Posts: 657	Re: Tektronix 465B oscilloscope, one channel not working Hi everyone Had some spare time tonight so got around to having a look at this unit. Measuring voltages from the inputs back I found an area with some big differences, so I swapped 4 transistors in the area from one channel to the other, hoping the fault would change Chanel's, and then both channels worked Result, so looks like, as someone suggested, lose contacts on the transistor plug in bases. Just got to fit a proper fan I managed to get in place of a noisy papst unit and put it all back together. Thanks for all the help __________________ BVWS member.

27th Feb 2009, 4:04 pm	#9
Mike-repairman Heptode Join Date: Jun 2008 Location: Cambridgeshire, UK. Posts: 613	Re: Tektronix 465B oscilloscope, one channel not working Very pleased that you got the unit working again Richard. That was the same fault that I described in an earlier post. However when you get the time it may be worth removing all the transistors, one by one, and giving each socket a small squirt of switch cleaner before replacing them. I know there are a lot of them, but it's good preventative maintenance as if one had a poor connection it's only a matter of time before others exhibit the same fault. After this procedure I've found that my scope has performed flawlessly. Mike.