Thanks!

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Thanks for the info and steering me on this Dr. G.... so the polarized electrolytic caps at the top and bottom of pic are both 20uf--I traced them to cathodes of respective tubes and they are, indeed, cathode bypass caps. the middle cap, .03uf, is a coupling cap belonging to tremolo circuit.
Now, when replacing these non-polarized caps I'm a little thrown off with "stripe indicates foil side down." With modern non-polarized caps we don't have to think this way? Correct? Either end will do? 

Looks like there are three ceramic caps in the tremolo circuit...as for the fourth one under the resistors  will need to follow the schematic as you suggest...still wondering about the black caps and the Sprague ones with the ring in the end...

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Looking to change caps but not 100% sure how to identify. See pic....the large black Sprague caps have a red ring on them but I don't think they are polarized. The smaller black caps--how to identify? One of the caps tells us it is .03 ohms. Under the resistors there are 4 caps that have been flattened... can't read them--coupling caps? Guess I'll have to remove resistors to get at these caps. Thanks!http://cloud.tapatalk.com/s/5aeca230849eb/gibson-ga-1rvt-amplifier-schematic.pdf

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Thanks!

I might need to replace a multi cap--Astron Duplex multi-cap on a Gibson Maestro Reverb Echo amp. Haven't tested it yet but I want to understand how it works before I check it out.  On the side of the cap is says that the black wire is common. The other wires are for 20,10, and 10 ufd. Is the black wire the common ground wire for all three caps and does it tie the negative ends of all the caps to ground? Are the other wires the positive ends of the 20,10 and 10 caps and got to circuit? Thanks

Quote from: Enzo on April 24, 2018, 12:40:37 PM
8 ohms is close enough for any amp in the world to run through.

Is this 0.7 ohms taken while the speaker is still connected to the amp?  If so, pull the wire off the speaker, as you would be measuring the output transformer winding, which has naturally VERY low resistance.

Thanks Enzo... lesson learned--speaker is good!

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I'm troubleshooting a Gibson Maestro Reverb Echo amp and wondering if anyone knows the impedance of the 8 inch speaker? It shows a very low resistance reading .7 ohms so I know it's done.
Thanks.

Perseverance...broken solder trace... repaired. Pushbutton and effects back in action! :cheesy:

Here's the schematic....

Okay so for the heck of it I plugged a foot switch and bingo!!! Digital effects works! But when I unplug and try to turn on the effects using the panel pushbutton: nothing! There a number of pins on these little black pushbuttons. How do I measure these pins to see if this pushbutton is defective. Does this sound like the problem? I reflowed the solder joints and they look good. Thanks!

All of a sudden the digital effects aren't working. The adjustable programming knob clicks into position as turned but it doesn't stop at 7 and 5 o'clock and it just keeps turning (is it designed that way?). Also the large IC with all the pins is quite hot--is that normal?

Great, thanks g1!

3.7 ohms with Meter, so 4 ohm impedance?

So according to manual this amp had an 8 ohm output impedance, but it has two 8 ohm speakers...how are these to be hooked up? Parallel 4 ohms, series 16...I must be missing something...the celestion G12N-65 are 8 ohms each according to spec sheets in net...hmmm