The Amp Garage

I found it! Pin 1 on the v3 tube is broken! Thanks everyone for their help

sluckey wrote: ↑Tue Jul 30, 2019 1:53 pm Wiring error(s). Pin 3 and pin 8 should be the same since they should be tied together.

I checked, there is no problem with the wiring of v3, I am sorry to forget to modify the pin8 value, it is the same as pin1.

As you can see, the voltage of P1 and P3 in V3 is very high. Can anyone tell me what's wrong? Thank

You need to make R29 smaller to get more negative voltage at the bias pot. I got this! I changed the R29 to 150k and adjusted the bias potentiometer. It is now down to 9W (0.0214*410=8.774; 0.0186*410=7.626), which is the latest reading. I added shielded wire and 820R to V1 pin 2, everything is so ...

Those voltages look better, but the dissipation is still too high: 0.0392 x 400 = 15.7W. You need to get that down to about 9W by making the bias voltage on Pin 5 more negative. I don't understand how the plate voltage (Pin 3's) has dropped since last time, and even more since the time before that....

How can I lower the voltage on pin 3. Can I replace 220k with 150k? You want to lower the voltage on output tube pin 5's (make it more negative) to reduce the idle current. If you don't have enough range on the bias pot, then reduce R29 in the schematic, as mentioned above. If you have a 220k there...

I now note you posted two posts with differing information but the same basic data. Was the other post asking this same question? You need to know how to calculate the tube current to get the right data for this question, these voltages only help in knowing what rating it 'should' be at. Since the ...

RockinRocket wrote: ↑Sat Jul 20, 2019 4:37 pm The yellow Mallory cap is in the wrong spot.

Needs to couple v1 to v2. You have it placed between V1/A V2/B plates.

Check the schematic and go over the whole amp.

tanks man！
I will recheck all wiring.
It was originally soldered in the correct position, and I made a mistake when I changed it!

Voltages don't look bad in general, but the idle current is way too high for 6V6's - 18W and 20.5W dissipation in 12W tubes :^0 As mentioned above, the output tubes are not well matched, but that won't stop it from making sound. Don't rely on pin 5 voltage to set bias. Calculate dissipation as Pin ...

Sorry, guys I added the measurement, The installation process was smooth, and he was able to start up normally a few days ago, but with noise. I tried to adjust by various methods. But after the adjustment, it can no longer continue to work, no sound, I don't know which part of the problem. http://...

HI, everyone.
Can someone help me? I don't know where the problem is, V4 pin1=24.9mv Is this normal?
use 240v