Re: Oh no - another V4!
Hello all,
I did a bit more and got some improvement but not much better on the width - I've ordered a PL81,PY81 and pair of PY82's in the hope that they will help - if not they'll be good for spares....
For now I've bypassed the PY82's with a big diode and 47ohm resistor and this has brought HT to bang on spec - I worked out that high AC on anodes and low HT on Cathodes must mean low current - I'm slow but I get there in the end. Then spent an age looking at PY82 characteristics to work out the correct series resistor...was a shock when it came out bang on spec. Just goes to show I really should just sell my valve tester!
Unfortunately that didn't improve width, EHT or boost - still comes out at 7kV on my measuring probe (380V for boost) so hopefully a new pair of valves in the LOP tin will help.
Then I decided I'd look in the tuner to find the most unhappy looking caps I've ever witnessed (see picture). They're still close on capacitance but quite leaky so I guess its something has reacted with (or eaten) the coating. Replacing these and resoldering a lot of dogy joints in the tuner has improved sensitivity on sound by about 40dB but picture is still odd.
Anyway now got a fairly good picture but the APC is playing up quite a bit so will attack that next whilst waiting for the new valves. There's also quite bad hum-bars but not sure if that isn't some sort of H-K leak in the line valves.
I'm a bit disappointed that I might not get to use my wobbulator - can just make out the 3 meg gratings when the APC decides to behave so it might not need twiddling! Pictures don't quite do it justice due to long exposure times and shaky hands!
What I am a bit worried about is that the focus assembly is quite off centre on the tube neck - and quite loose. Plus I can't get the picture to centre - John warned me off disturbing the CRT in case there's the cellophane coils so not sure what to do!
Dom
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