Tektronix 2465 Repair

[Giovanni28]

As you can see in the linked video, when I turn on the oscilloscope nothing is displayed on the screen, but when I press the "A/B Trig" button, the trace of channel 1 appears; furthermore, turning the focus knob and the Readout Intensity knob does not produce any results. Any ideas on what I can check?
I have already checked the voltages at the J119 test point, and almost everything is ok, except the Digital +5V voltage is out of range 4.75V (table 5-1: 4.85 to 5.15).

https://drive.google.com/file/d/1qzwuWtDS3CFEqCaMVBuKB84lXT11G0MJ/view?usp=sharing

[tautech]

Just because your 2465 lacks the B don't discount answers are not in this thread:
https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/

[Giovanni62]

Excuse me, the video is now accessible to everyone.

[jonpaul]

Hello:

1. DL or buy full service manual for your scope model $ SN.

Sww W140, TekWiki, printed copy from Artech.


2. check DAC REF proceedure

Do self tests.

3. Most likey A5 RAM backup lost and failed backup battery.

4. See both 2465B teardwon thread (80 pages!) and groups.io Tekscopes, Tekscopes2.

5. Parts and tips at Qservice Greece and Conrad Audio, Isreael

Bon chance


Jon

[Edison]

3. Most likey A5 RAM backup lost and failed backup battery. Jon

Hi, it has been said perhaps hundreds of times across the entire forum here that the Tektronox 2465 DOES NOT HAVE A BACKUP BATTERY, it uses a different type of memory.
I can confirm this with 100% certainty, I have one piece hanging around here 😁

[Giovanni28]

I confirm, there is no battery.

[factory]

There is no readout, you could try starting with the readout troubleshooting procedure.

The focus pot goes directly to the HV board (A9) via A1 and the readout intensity pot goes to the U650 display sequencer via U350A on the A1 board and to via U350B to A5 for the readout on signal. Neither of these are stored in the EAROM.

David

[MarkL]

It's very odd the focus is not working since that does not involve the processor or much else besides the CRT HV supply.

The intensity control is also in the same physical area.  Do the ASTIG and TRACE ROTATION work ok?  Do those pots have the voltage shown on schematic <8> on the ends of the pots?  How about the intensity and readout pots shown on schematic <5>?

All of those controls land on headers on the A1 board right at the front.  I would check that someone didn't forget to re-seat them if this scope is new to you.

Also, you need to figure out why the 5V supply is low before you go too far with other troubleshooting steps.  It could be a symptom that a faulty component somewhere is dragging it down.

[jonpaul]

Try Contact cleaner on focus, inten, astig controls.

j

[ddosegov]

As you can see in the linked video, when I turn on the oscilloscope nothing is displayed on the screen, but when I press the "A/B Trig" button, the trace of channel 1 appears

Readout board? Probably it tries to write "Error xx Push A/B trig to exit".

[Giovanni62]

The voltage in pin 2, +5V digital, has dropped to 0.4V and now the display is off.