Hot Rod Deluxe bailout needed

[eschertron]

Sorry, my meter skills are amateurish

Let's get some baseline readings and practice those meter skills at the same time

Touching the probes together should give you a 0.0 reading - or nearly so - on all but the lowest scale. Depending on the calibration of the meter, it may read a few tenths of an Ohm through the probes. Note the reading and the scale used.
Repeat the tests with the probes not touching - not the other, not anything. You should get the over-range indication for every scale. Some meters show OL, some show 1. (19., 199., etc depending on the range) or similar. Become familiar with the info the meter tells you that indicates an invalid reading.
Do you have a resistor laying around that you could measure? Try that too. Then, if all that looks good to you, poke again at the resistors in the amp.
Unplugged, power off, caps discharged, of course
I'd expect you to get a higher-than-normal reading if there's corrosion or a coating or something else that might interfere with getting a solid connection. I do NOT expect a seriously low reading, like the ones you posted earlier.

If the meter tells you wonky things when testing against 'standards', then I'd suspect bad batteries in the meter, or bad probe cables, or bad technique.

[g1]

Also, try measuring some of the other 100K plate resistors, there should be several in that amp.

[Oldmactech]

These resistors are white boxes, side by side with to markings. I believe they are 100k. Not 100% sure.

[Oldmactech]

Some good news -I went over the PCB looking for bad joints or weirdness and found a solder bridge across two pins on the backside of the V1 cable. I now have sound but decent volume hum, a lot louder when I engage the drive channel.

Glad to have sound back, amp still sounds bad, brittle, notes decay like shattered glass. Will be re-checking voltages later tonight.

[g1]

These resistors are white boxes, side by side with to markings. I believe they are 100k. Not 100% sure.

I don't think you are looking at the right resistors. Pg.2 of attached schematic has a layout with component locations.

[The Dude]

^^^^^^Agree. "white boxes" sounds like film caps to me. The plate resistors in a Hot Rod Deluxe should be your standard color coded resistor. Or, maybe we are reading the two 5W resistors in the low voltage supply? Either way, I think we're measuring the wrong parts.

[Enzo]

I saw "white boxes" and immediately thought the two power resistors for the low voltage zeners.

[The Dude]

That makes sense with his readings- "first is 481, second is 498".

[eschertron]

I saw "white boxes" and immediately thought the two power resistors for the low voltage zeners.

That makes sense with his readings- "first is 481, second is 498".

Right. R78 and R79 are the 5W 470 Ohm cement resistors. Opposite side of the board from R4 and R11. See my post #14

[Oldmactech]

Sometimes it’s the simple things.

Got two replacement 6L6’s today and the amp came back to life. Sounds pretty good, jagged decay is gone. Prett steady 60 cycle hum but I swapped in a spare 12AXT I think it was and the hum stops.

Sounds pretty good, will reset the bias (I think last read was 72) see if the new tubes caused that to change.
Both channels seem ok, more drive switch seemed to cause motor boating but I’ll never use that setting.

Pretty fun amp to play around with replacing caps and such. Good learning experience.

Probably take test reading following the drawing before putting it back in the closet.....


Thanks all for the help.