Quote:
Originally Posted by Lain94
Yeah that makes sense to me I figured it was a capacitor issue. I traced down the likely origin of the problem as being somewhere in the power supply circuit.
Diodes going bad? I did not ever think to suspect diodes could fail, were early diodes more prone to failure back then?
Also what are your thoughts on there being performance issues caused by all those old carbon comp. resistors? I know they are notorious for drifting upwards in value as they age. They are also noisy usually. The issue though is that carbon film resistors will introduced inductance into the circuit which I heard apparently may cause issues in a vacuum tube circuit. Is it worth messing with replacing all the carbon comps and if so what should I replace them with?
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Shorting of electrolytics in the power supply could kill the diodes.
My approach to resistors would be to first see what circuits have problems and then test the resistors, rather than a blanket replacement. The small inductance of a spiral resistor is not likely to cause trouble unless it is actually carrying high frequency signals (IF or RF). In the typical case, resistors in these circuits are bypassed by small capacitors anyway. In tube circuits, stray capacitance can be an issue, so component placement and lead length can have an effect, again, mostly in the IF and tuner. So, I wouldn't worry about the resistor type in video and sweep circuits, but have a bit of caution when working in the IF and especially the tuner.