Problem with my Tektronix 2465

[McBryce]

Hi all,
      after several months of non-use, I decided to check the accuracy of my trusty Tektronix 2465 scope (the original non A/B version with lever switches), to see whether it's doing what it should. Luckily, it seems to be still as accurate and reliable as always. All channels are still spot on as far as voltage and frequency are concerned, however I've found one minor problem that I'd like to sort out: On channel 2, when set to 2mV/Div, the DC offset is so far out that I can't even get the beam onto the visible screen area (with input shorted). Channel 1 isn't great either. I have to turn the Y-Pos all the way to the right to get CH1 beam into the centre of the screen, but I can get it there, whereas CH2 never makes it back onto the screen at all. I've browsed the Service Manual, but I can't find any internal pots to tweak this.
Can any Texperts here point me to the right place?

McBryce.   

[Orange]

Have you tried to run the auto balance routine ?

You can invoke this by pushing up both input coupling levers at the same time.

[Alex Nikitin]

Here is what the user manual says:

Cheers

Alex

[Analogdevice]

Hello,

I have Tektronix 2465B and during selftest or pressing the switches the LEDs and scale illumination flashes. Everything works fine besides that. Any reason or idea?
I have SMD version of vertical board, caps are changed and power supply is in good condition.

Thanks!

[McBryce]

Here is what the user manual says:

Cheers

Alex

Thanks, I wasn't aware of that feature, I'll give it a go tonight.

McBryce.

[McBryce]

Tonight I tried the Auto balance routine. It goes through the process and relays can be heard clicking while a dot jumps around the screen, but unfortunately when it's finished the situation is still the same Any tips on where I should be looking inside the case?

McBryce.

[tautech]

Tonight I tried the Auto balance routine. It goes through the process and relays can be heard clicking while a dot jumps around the screen, but unfortunately when it's finished the situation is still the same Any tips on where I should be looking inside the case?

McBryce.

The obvious?
PSU to spec?

[McBryce]

I'll open it up and start checking things like that at the weekend. The fact that the problem is only on Channel 2 (Channel 1 works perfectly) makes me think that it's something that won't be common to all channels like the PSU.

McBryce.

[tautech]

I'll open it up and start checking things like that at the weekend. The fact that the problem is only on Channel 2 (Channel 1 works perfectly) makes me think that it's something that won't be common to all channels like the PSU.

McBryce.

Sure, but if local capacitance to Ch2 was sick as well as the PSU caps that might explain your symptoms. 

[McBryce]

That was my thought too. The caps have never been changed in this scope, so it might be time to do a complete re-cap.

McBryce.