blew up the gemini

[Fred Rocker]

Had everything turned two 11 and the tube screamer crankEd. it's still Powers up and playsbut has no Reverb and no sustain now. I tested the speaker was still good and tubes are still good. getting the tester out. where to start?

[Fred Rocker]

Had everything turned two 11 and the tube screamer crankEd. it's still Powers up and playsbut has no Reverb and no sustain now. I tested the speaker was still good and tubes are still good. getting the tester out. where to start?

[Fred Rocker]

I see a small blue resistor highlighted by my pencil that doesn't look original. I noticed the board is a little bit chard on the resistor below it. I'm ready to remove the death capacitor and add mygrounded cordbut this one has a standby switch so I'm a little confused. My father was an electrician he was blind in one eye I did tons of soldering jobs for him at homeI can replace components and capacitors and resistors all day but I don't have a knowledge of the circuitry. I'm hoping I don't have to pull each piece and test it. is that how it's done?

[Hangman]

Which Gemini model do you have again?

That looks like it would be the resistor feeding the screen supply. It also looks like they upped the value to 1k? though its hard to tell since its toasted.

follow the red wire on the right side of that resistor. where does it go?

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I tend to think that adding screen resistors is a good idea in any amplifier that doesn't have them. So once you replace that resistor, you may consider adding some screen resistors. I added some 220 ohm resistors in my G12 (gemini 1)

[Fred Rocker]

Which Gemini model do you have again?

That looks like it would be the resistor feeding the screen supply. It also looks like they upped the value to 1k? though its hard to tell since its toasted.

follow the red wire on the right side of that resistor. where does it go?

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I tend to think that adding screen resistors is a good idea in any amplifier that doesn't have them. So once you replace that resistor, you may consider adding some screen resistors. I added some 220 ohm resistors in my G12 (gemini 1)

i thought it looked like 900 ohm? the red wire goes to that giant multi cap.
this is a gemini 2.
what should that resistor be?
having some difficulty finding components locally.
what wattage are these resistors?
thanks Hangman.
i'll be posting more soon.

[Hangman]

Can you post another pic showing more of the tag board and the power tube sockets? I think that is the resistor for the screen supply. Its clearly not original though.

[Fred Rocker]

have replaced that resistor with another 900 ohM and its working again. I want to replace all of the capacitors and resistors in the vibrato. can you tell me which ones they are? my vibrato works but it is weak

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Is the copper capacitor wired correctly? The side that says "positive" is wired to the side i thoughe was negative? Everything works fine, i just noticed that its opposite of the other large cap.

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thank you hangman. I will get those pictures up ASAP. I don't have internet at the house right now working from my phone it's very slow

[Hangman]

900 is higher than the schematic. I would suggest replacing it with a 470-500 ohm and then using 220-500 ohm screen resistors.
The copper cap is wired correctly. It is the filter for the bias supply. The bias voltage is negative with respect to ground, so the cap must reflect that polarity.
it is very common to think of the negative terminal of the electrolytic as ground, but there are many situations where the negative terminal is not connected to ground.

[Fred Rocker]

900 is higher than the schematic. I would suggest replacing it with a 470-500 ohm and then using 220-500 ohm screen resistors.
The copper cap is wired correctly. It is the filter for the bias supply. The bias voltage is negative with respect to ground, so the cap must reflect that polarity.
it is very common to think of the negative terminal of the electrolytic as ground, but there are many situations where the negative terminal is not connected to ground.

exactly what should it be? I only put 900 back in there because that's what I took out and it works but I'd rather have the correct piece in there.
I'd like to rebuild the vibrato section. it works but it's not snappy like it should be. I want to replace all the capsand I will either buy a new bug from flip top or make my own but I can't really read a schematic LOL.I have a list of every capacitor in there and I decoded every resistor in there. I just don't know which ones R4 The vibrato circuit

[Hangman]

it should be 470 ohm, at least 2 watts.
Adding screen resistors will just help with the stability of the amplifier. without screen resistors the power tubes have a tendency to start oscillating at really high (out of the range of hearing) frequencies. The screen resistors help to eliminate that problem, at the cost of about 1-2 watts of output at full power (not noticeable)

take a picture of the guts of the amp and I will point out which ones are for the vibrato.