Products > Test Equipment
Tektronix 2235 repair thread
bd139:
Ok finally an update on this one. My projects take too long plus xmas went crazy wrong for me. Firstly the guy who was giving me the 2235 parts mule let me down. I don't have it. I managed to get the replacement HT transformer that arrived ages ago in this evening and it's working somewhat better than it did before. Off DC anyway. Can't hear any more ticking now which is good.
However it's still not totally healthy. It has still got somewhat jumpy focus (zips in and out) and shows some deflection changes when this happens. I'm going to measure, inspect and replace the remaining resistors in the HT section as I've done all the 510k ones now.
TERRA Operative:
How's the focus pot looking?
My 2235 was a little jumpy when focusing and a NOS pot from ebay has it all nice and smooth again.
bd139:
Seems ok. I can’t see any voltage jumps anywhere around it which I’d expect if focus was changing.
I’m wondering if this is leakage around the anode cap or in the tube base.
tautech:
--- Quote from: bd139 on March 07, 2019, 07:42:36 am ---Seems ok. I can’t see any voltage jumps anywhere around it which I’d expect if focus was changing.
I’m wondering if this is leakage around the anode cap or in the tube base.
--- End quote ---
Anode cap you'd hear it and CRT base is only at EHT voltages.
Either Focus, Intensity or EHT components breaking down.
bd139:
Yeah can't hear a thing. Anode cap is pretty noisy - been there :-DD
May replace all the HV capacitors in it and see if that helps as I have some of the right value. If that doesn't work I'll see if I can find a suitable focus pot. Seem to be unobtainum. It's a 5M AB modpot which has to withstand 2KV.
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