When I got my ivory DAC90a I found that it's UL41 was leaky, having the best part of 2v on pin 6.
I got another off e-Bay which was even worse, having 3.6v. I can't complain as the description said it had been tried in a radio and worked well. This is perfectly true and it's only when the voltmeter comes out that the trouble is found.
I don't need telling that buying it was silly but it may not go amiss to tell me that it's even sillier leaving my lap-top by the bed where things can be ordered while half-asleep - I had no recollection of bidding on this until I got the request for payment. At least it wasn't a telly!
I've done bit of research and found a couple of techniques for clearing these internal shorts. One is to apply a sustained high voltage, in the 3kV region, and the other is to blast them with the spark from the ignition of a gas cooker.
Now I don't have either a gas cooker, though will have access to one next time I'm cat-sitting, or a high voltage source. I therefore tried wiring the pins, except number 6, together and discharging a 32uF capacitor across them but it it wouldn't discharge. I then tried the piezo igniter off my flame-thrower and this did produce a few internal flashes but had no other effect.
I was wondering if any of our members had the necessary gear and fancied a fiddle - the TV bods have got access to voltage-tripplers for a start. I certainly won't yell if the valves end up utterly wrecked as they're no use to me like they are. Certainly having two would seem to give a chance for one to be practised on and then the other one properly sorted.
Any other ideas would also be interesting.
Cheers
- Joe
I got another off e-Bay which was even worse, having 3.6v. I can't complain as the description said it had been tried in a radio and worked well. This is perfectly true and it's only when the voltmeter comes out that the trouble is found.
I don't need telling that buying it was silly but it may not go amiss to tell me that it's even sillier leaving my lap-top by the bed where things can be ordered while half-asleep - I had no recollection of bidding on this until I got the request for payment. At least it wasn't a telly!
I've done bit of research and found a couple of techniques for clearing these internal shorts. One is to apply a sustained high voltage, in the 3kV region, and the other is to blast them with the spark from the ignition of a gas cooker.
Now I don't have either a gas cooker, though will have access to one next time I'm cat-sitting, or a high voltage source. I therefore tried wiring the pins, except number 6, together and discharging a 32uF capacitor across them but it it wouldn't discharge. I then tried the piezo igniter off my flame-thrower and this did produce a few internal flashes but had no other effect.
I was wondering if any of our members had the necessary gear and fancied a fiddle - the TV bods have got access to voltage-tripplers for a start. I certainly won't yell if the valves end up utterly wrecked as they're no use to me like they are. Certainly having two would seem to give a chance for one to be practised on and then the other one properly sorted.
Any other ideas would also be interesting.
Cheers
- Joe
