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The very first thing I would do is check all voltages and ripple on J119.?? There is a table of specifications for this in the service manual section for power supply trouble shooting, just before the flow chart sections 10 and 11.??

If all J119 voltages and ripple are right I would use the working 2465 you have to check signals going to the CRT.?? Especially check the unblanking signals, VZOUT and VGOUT, the prescribed waveforms are given in the service manual (waveforms 65 and 66 in the 2465 Service manual).????If there is activity closely resembling the prescribed activity in shape and, especially, amplitude the scope is trying to drive the CRT.?? The problem is very likey the high voltage board (A9) or the CRT itself.

If you have a high voltage probe you can just measure the voltage on the CRT anode pole.?? But don't do this if you??lack experience with high voltage measurement techniques as the voltage here is 14,000 volts or more.

It sounds to me that the scope is trying to operate??and there are some good indications.?? When there??are faults known to the scopes computer (board A5) it presents an error message on the CRT ("Test xxx fail?? Push A/B trigger") and the scope then tries to operate.?? But since your screen is blank??you cannot see this message.?? If there were high voltage and a VZ signal you should at least see a bright spot on the CRT.?? Since you cannot, either there is no high voltage, no VZ, or the CRT may not be lighting up??(no filament or just a??bad CRT).

You can go to the Qservice web site and see pictures of every subassembly for reference of how they should look.?? Tektronix produced these scopes for several years and used different generations of capacitors.?? So boards will look different from generation to generation but the overall layout will remain the same and there whould be uniformity within a particular build.


________________________________
From: Sigur?°ur ??sgeirsson <siggi@...>
To: TekScopes@...
Sent: Sunday, January 26, 2014 11:38 AM
Subject: [TekScopes] 2465 no traces, no OSD



??
Hi y'all,

I just bought a 2467 on eBay. It came with option 9 - which I understand is the counter/timer? Unfortunately it doesn't seem to light up the CRT at all, no traces, no OSD.

On power-up, it does seem to go into diagnosis, as I have to hit one specific front-panel control before it'll respond to any others. After this, I can mess with the front panel controls, and e.g. the channel/trigger lights all toggle with their corresponding buttons. However, any time I change any setting, all the front panel LEDs flicker. Also, when I set channels 1/2 to the 50 Ohm input setting, they stick for about a second or so, but then I hear a relay toggle again, and the GND input lights up again.
Do those symptoms ring a bell with anyone here?

I took it apart and pulled the PSU??to see whether there's anything obviously broken. It looks to me like the PSU has been re-capped, as there's a mix of colors on there. I tested all the rails, and they look about right, though I couldn't load the 5V with more than a single 7.5 ohm resistance at a time. When I loaded J303, I saw an undershoot for a second or two, then it seemed to drop into regulation at ~4.9V. The 7.5 ohm on J232 didn't quite seem to be enough load, though the voltage dropped a fair bit when I did it. The 10V reference was spot on, as were e.g. the 87 and the +-15 rails.

The others were all high, but then they were unloaded...

I guess next I'll measure the rails with the PSU in-place, check ripple etc?
Are there any pictures here of 2467/2465A PSUs in original condition that I might use for comparison?
Are there other quick things I can look at to assess the damage/hopes of repair?
I understand the 2467 has a "screen saver" that'll shut down the CRT on a timer? Presumably this is under digital control - so I'm hopeful that the CRT or control circuitry isn't beyond rescue?

I have a functional 2465 I was hoping to replace with this one, so I can have peek around.

Siggi

If the power supply seems OK, just turn up the CRT Bias pot and see if it lights up. A common failure is the Z-Axis hybrid, which, if bad, will cause no display. If a display appears, you may be able to see which self test is failing, and take it from there.

On Sunday, January 26, 2014 10:10 AM, machine guy <machineguy59@...> wrote:

??
The very first thing I would do is check all voltages and ripple on J119.?? There is a table of specifications for this in the service manual section for power supply trouble shooting, just before the flow chart sections 10 and 11.??

If all J119 voltages and ripple are right I would use the working 2465 you have to check signals going to the CRT.?? Especially check the unblanking signals, VZOUT and VGOUT, the prescribed waveforms are given in the service manual (waveforms 65 and 66 in the 2465 Service manual).????If there is activity closely resembling the prescribed activity in shape and, especially, amplitude the scope is trying to drive the CRT.?? The problem is very likey the high voltage board (A9) or the CRT itself.

If you have a high voltage probe you can just measure the voltage on the CRT anode pole.?? But don't do this if you??lack experience with high voltage measurement techniques as the voltage here is 14,000 volts or more.

It sounds to me that the scope is trying to operate??and there are some good indications.?? When there??are faults known to the scopes computer (board A5) it presents an error message on the CRT ("Test xxx fail?? Push A/B trigger") and the scope then tries to operate.?? But since your screen is blank??you cannot see this message.?? If there were high voltage and a VZ signal you should at least see a bright spot on the CRT.?? Since you cannot, either there is no high voltage, no VZ, or the CRT may not be lighting up??(no filament or just a??bad CRT).

You can go to the Qservice web site and see pictures of every subassembly for reference of how they should look.?? Tektronix produced these scopes for several years and used different generations of capacitors.?? So boards will look different from generation to generation but the overall layout will remain the same and there whould be uniformity within a particular build.

From: Sigur?°ur ??sgeirsson <siggi@...>
To: TekScopes@...
Sent: Sunday, January 26, 2014 11:38 AM
Subject: [TekScopes] 2465 no traces, no OSD



??
Hi y'all,

I just bought a 2467 on eBay. It came with option 9 - which I understand is the counter/timer? Unfortunately it doesn't seem to light up the CRT at all, no traces, no OSD.

On power-up, it does seem to go into diagnosis, as I have to hit one specific front-panel control before it'll respond to any others. After this, I can mess with the front panel controls, and e.g. the channel/trigger lights all toggle with their corresponding buttons. However, any time I change any setting, all the front panel LEDs flicker. Also, when I set channels 1/2 to the 50 Ohm input setting, they stick for about a second or so, but then I hear a relay toggle again, and the GND input lights up again.
Do those symptoms ring a bell with anyone here?

I took it apart and pulled the PSU??to see whether there's anything obviously broken. It looks to me like the PSU has been re-capped, as there's a mix of colors on there. I tested all the rails, and they look about right, though I couldn't load the 5V with more than a single 7.5 ohm resistance at a time. When I loaded J303, I saw an undershoot for a second or two, then it seemed to drop into regulation at ~4.9V. The 7.5 ohm on J232 didn't quite seem to be enough load, though the voltage dropped a fair bit when I did it. The 10V reference was spot on, as were e.g. the 87 and the +-15 rails.

The others were all high, but then they were unloaded...

I guess next I'll measure the rails with the PSU in-place, check ripple etc?
Are there any pictures here of 2467/2465A PSUs in original condition that I might use for comparison?
Are there other quick things I can look at to assess the damage/hopes of repair?
I understand the 2467 has a "screen saver" that'll shut down the CRT on a timer? Presumably this is under digital control - so I'm hopeful that the CRT or control circuitry isn't beyond rescue?

I have a functional 2465 I was hoping to replace with this one, so I can have peek around.

Siggi

--- In TekScopes@..., Bob Koller <testtech@> wrote:

If the power supply seems OK, just turn up the CRT Bias pot and see if it lights up. A common failure is the Z-Axis hybrid, which, if bad, will cause no display. If a display appears, you may be able to see which self test is failing, and take it from there.

Sadly no joy on cranking the bias pot up. Thanks for the hint, though.

This is my first group post, so don't hesitate to correct my citing style. I'm using yahoo's online web post function.

Regarding your problem: I think I had similar problems (flickering, 50 Ohm Overload) with my 2440 as I bought it. There was a 0.1 Ohm overcurrent sensing resistor in the 5V supply which changed its value over time (0.11 Ohm @ 5% tolerance). It sits between two heatsinks, that may have caused the massive change in value. It looked also burned.

Good luck!

This is my first group post, so don't hesitate to correct my citing style. I'm using yahoo's online web post function.

Regarding your problem: I think I had similar problems (flickering, 50 Ohm Overload) with my 2440 as I bought it. There was a 0.1 Ohm overcurrent sensing resistor in the 5V supply which changed its value over time (0.11 Ohm @ 5% tolerance). It sits between two heatsinks, that may have caused the massive change in value. It looked also burned.

GREAT NEWS.

Faulty power supplies can cause a variety of misleading symptoms but I don't think that is what is happening here.?? Double check the voltages on J119 and if they are reasonably close move on for now.?? Tek gives specs for an instrument that does laboratory quality measurements so small amounts of ripple are detracting.?? But you aren't looking for a small error.?? I suggest you find that first unless voltages and ripple are far out of spec and/or changing during operation.

It sounds like you may have a control board (A5) issue.?? Since the case is open you can easily do a visual check of the A5 board.?? Look for leaking or bulging caps and check the date on the memory chip and its battery.?? The 246x scopes (except for the 2465 and 2445) used a battery backed ram to save memory contents.?? These batteries are known to fail after many years and must be replaced before all memory is lost.?? There is a procedure to do this replacement.?? Its necessary to provide temporary power to the memory chip while you remove the battery and connect a new one.?? Even a momentary loss of power to the chip will lose all contents and a full calibration will be necessary.??

A failing A5 or its memory could explain all the problems you are seeing.?? I suggest you??focus on that for now.??

Thanks, this looks promising (not to mention fun:).

Are we having fun yet??? lol.??

I wont be much help to you with the control board.

Last night I found that VR2420 was shorted, and was pulling the -1.25 reference to ground at ~10Ohm. This is a 3V zener that's presumably there to clamp the reference to +.7- -3V.
It looks like whatever took out the zener also burned U2420D (1/4 TL074), as when I removed the zener, the rail went to -5V, irrespective the drive on the input.

So, whatever happened there may have been a fairly violent event. I'm guessing downstream from the -1.25V rail from A5 I may find more trouble.

I'll have to buy some parts and replace the op-amp, see what happens next.

I'm also getting traces, but only sporadically - even on auto, and she's glitchy as hell. The "C" in the "DIAGNSTIC" flickers, and spurious pixels appear here and there on the display with the same kind of frequency.
When I manage to get an A/B trace of the calibration signal, has weird fading, which likely means I need to re-tune the Z response.

I've seen talk of corrosion on the hybrids causing this sort of symptom, and there's certainly plenty of corrosion on the BNC connectors, pots and switches. Looks like the poor thing was warehoused somewhere terrible, probably for years.