Measure the one that's not broken and see if you get a solid ohm reading or not. In-circuit is fine.
Vintage -- The components you refer to are capacitors, and of very small value -- typically less than 1 pF. On the 299C-C1 schematics I have, these would be identified as components C9 and C109, with a value of 0.68 pF each.
Their purpose is to counteract cross-talk that would otherwise occur at very high frequencies between the channels due to the small capacitance values that exist between the various switch terminals, between the channels, on the Mode switch. If you remove them, you will almost certainly not be able to hear any difference, with the benefit they offer really only being demonstrable on an O-scope. To replace it, you will need to go to one of the large part houses like Mouser or Digikey to find a replacement. The voltage rating of the component is quite uncritical, as there is no DC voltage impressed across these caps. Therefore, even the lowest voltage rated piece will work.
I hope this helps!
Dave
I kick myself every restoration job, cause I ALWAYS seem to make a bone head mistake. Fortunately, tube amps are troopers and I haven't destroyed anything yet. But I kind of think it's that extreme stress, despair and frustration...followed by the glorious relief and satisfaction (when you discover and correct the problem ) that make this hobby so addicting.Let me say how any of us can make a dumb mistake that will make a body go crazy..
If you are measuring between pins 8 and 2 of the rectifier socket that is not unusualI kick myself every restoration job, cause I ALWAYS seem to make a bone head mistake. Fortunately, tube amps are troopers and I haven't destroyed anything yet. But I kind of think it's that extreme stress, despair and frustration...followed by the glorious relief and satisfaction (when you discover and correct the problem ) that make this hobby so addicting.
Kind of reminds me of the Dennis Leary quote.." Smokers are the only people who know what it's like to want something REALLY F***KING BAD and get it, over and over and over again"
I was measuring voltages on my LK-72 this weekend and measured 724 VAC on my PT secondary. DC voltage after the GZ34 was 426. Does that make sense? OP said his Heyboer was 370V secondary. These are supposedly the same amp I thought.
Voltage after the first 33ohm 10W resistor in the filter was 419 (should be 455 per the schem....8% low).
AHA! I've been staring a hole through C9 and C109 on my 299C and LK-72 schematics, hoping in vain for some enlightenment to strike me, wondering why on earth there are 0.47µF (on the LK-72) or 0.68µF (on the 299C) caps connecting the two channels, and where the heck they are on the chassis. Well, so you're telling me they're 0.47 PICOFarad caps, and they're for high-frequency crosstalk prevention?Vintage -- The components you refer to are capacitors, and of very small value -- typically less than 1 pF. On the 299C-C1 schematics I have, these would be identified as components C9 and C109, with a value of 0.68 pF each.
Their purpose is to counteract cross-talk that would otherwise occur at very high frequencies between the channels due to the small capacitance values that exist between the various switch terminals, between the channels, on the Mode switch. If you remove them, you will almost certainly not be able to hear any difference, with the benefit they offer really only being demonstrable on an O-scope. To replace it, you will need to go to one of the large part houses like Mouser or Digikey to find a replacement. The voltage rating of the component is quite uncritical, as there is no DC voltage impressed across these caps. Therefore, even the lowest voltage rated piece will work.
I hope this helps!
Dave