Telequipment D83, Ch1 trace hard at bottom of screen

[NormalForNorfolk]

Hello folks.
I had the opportunity of being gifted a Telequipment D83. After freeing a gummed up power/intensity control (WD40 and brute force) It seems mostly ok, powering up and with a nice bright in-focus trace.
There were a few loose grubscrews in knobs and some internal control linkages that needed sorting but we're more or less there, though calibration is likely some way off.

Channel 2 is good but the big issue I have is that Channel 1 is resolutely hard down beyond the bottom of he screen, even with it's input grounded. I can bring it into view with the Trace Locator button but Ch1 vertical position adjustment doesn't have any effect, although the stone age test method of a fingertip on the probe shows a bit of mains hum pickup on Ch1, so all is not completely dead.

I'm _fairly_ sure the transistors and diodes on the V4 2 channel module check out ok with a DMM.

Before I start delving further, I wondered if anyone recognises this issue or similar, or can make any constructive suggestions.

 

[Delta Prime]

gummed up power/intensity control (WD40 and brute force) It seems mostly ok,

Is this the WD-40 you used?


If not, I hope this helps.
TELEQUIPMENT D83 OSCILLOSCOPE MAINFRAME V2 2X10MV 50MHZ VERTICAL AMPLIFIER CA 1976 SM.
The service manual can be downloaded for free.

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[NormalForNorfolk]

Straight WD40. The issue was simply where the shaft goes through the brass bushing on the front of the potentiometer body, so purely a mechanical issue.

Thanks for the service manual link.

A closer look at the innards suggests one or more of the 3 big caps on the PSU are leaking. Any views on suitable replacements? Big snap in ones are available but you don't get much change from an arm and a leg. I'm wondering if modern 105deg rated, radial lead jobbies would be ok for light use.

 

[Martaine2005]

I'm wondering if modern 105deg rated, radial lead jobbies would be ok?

If the specs are the same, they will be better than old factory ones. And not just for light use.