Problem with my G5 amp

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louphil
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Re: Problem with my G5 amp

Message non lu par louphil »

Before you unsold anything and rewire, just perhaps could you do a little test with your DC-voltmeter :

Just connect speaker normally, the common of voltmeter on ground of the circuit, and open fully all control pots . Then measure all voltages plates and grid G1 on the tubes from plate of the power tube to the grid first stage ... Normally, noise have to be audible when putting the red proble on the measured point . These noises will be very tiny on the power stage, but become stronger and stronger as you go to the first stage ... If you have sound on a stage and not on the previous one, you just have located the problem ... ;-)
Papa_Mateo
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Re: Problem with my G5 amp

Message non lu par Papa_Mateo »

Input Jack from speaker. I touch one stick from multimeter to star ground and second one to signal pin in speaker Jack and i have connection. Signal and ground is connected. IT shouldn't be?
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bilbo_moria
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Re: Problem with my G5 amp

Message non lu par bilbo_moria »

The pin signal and the ground are connected to the secondary of the OT, which has a very low impedance, which may lead us to think that the pin signal and the ground are connected in a "short circuit".
You can temporarily unsolder the wire leading to the pin signal and retest your jack to make sure there are no shorts.
Papa_Mateo
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Re: Problem with my G5 amp

Message non lu par Papa_Mateo »

Thank you very much 🤘
Papa_Mateo
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Re: Problem with my G5 amp

Message non lu par Papa_Mateo »

Good Today,
I finished rebuild my amp. When i turn the pre Amp on, i have something like this. When i turn power Amp, everything is quite normal, but in speaker is no sound.
Maybe el34 is broken down?
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IMG_20240424_103433.jpg
Papa_Mateo
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Re: Problem with my G5 amp

Message non lu par Papa_Mateo »

The colour of this light is rose.
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Dr. Nonosse
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Re: Problem with my G5 amp

Message non lu par Dr. Nonosse »

This is an inter-electrode ignition: The vacuum if bad. You will have to change the EL34 tube.
Quand le sage montre la lune, l'idiot regarde le doigt
Papa_Mateo
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Re: Problem with my G5 amp

Message non lu par Papa_Mateo »

I must say, my el34 died. 😟 I will order a new one and then everything must work. Thank you Guys very much 🤘
Papa_Mateo
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Re: Problem with my G5 amp

Message non lu par Papa_Mateo »

Good Today, i have only one question. Should i change only el34 or together, 12ax7 and el34?
Best regards
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Dr. Nonosse
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Re: Problem with my G5 amp

Message non lu par Dr. Nonosse »

I think you only need to change the EL34 tube.
On the other hand, before checking the voltages, particularly, the level of the grid G2 and G3: Check the G5 assembly instructions.
Quand le sage montre la lune, l'idiot regarde le doigt
Papa_Mateo
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Re: Problem with my G5 amp

Message non lu par Papa_Mateo »

Thank you Guys very much. I think, all the time the el34 was broken down. When i rebuild my amp, probably i made everything good, but the power tube was dead.
I haven't meet so helpfull people. Thank you.
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Dr. Nonosse
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Re: Problem with my G5 amp

Message non lu par Dr. Nonosse »

So it's okay, everything works now?
Quand le sage montre la lune, l'idiot regarde le doigt
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