No, they are not. Maybe it says -18mV? Or Maybe -0.018 or -0.18? If in doubt, you can post a photo of what your meter is showing for one of those readings.soundfel said:
Resistance issue [resolved]
- Thread starter soundfel
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When I turned the amp to test these voltages again, tubes were glowing. I tested the voltages and they were OK, but afterI flipped the amp to test it with my headphones, tubes went back off and the voltages are wrong again. This is what I get between H2 and H4. It´s the same on H5-H7.
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Deke609
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It could just be an effect of the photo, but in the first pic you posted in this thread it looks like one of the ends of the thick solid green wiring isn't connected to a terminal of the power transformer (or is poorly connected).
You may also want to take a look at the condition of at least one of the 1.5uF capacitors (big black ones). It looks like it got pretty toasted. From the first pic you posted it looks like the internal metalized film is exposed and possibly damaged.
cheers and good luck, Derek
You may also want to take a look at the condition of at least one of the 1.5uF capacitors (big black ones). It looks like it got pretty toasted. From the first pic you posted it looks like the internal metalized film is exposed and possibly damaged.
cheers and good luck, Derek
What is your incoming AC line voltage? Having 20V there makes me think you are outside of the US.
When you flip the amp over and that changes the glowing behavior, that means you have a loose connection. This could be in the green twisted pair of wires going from the power transformer to the H terminal strip, on that terminal strip itself, or back up front where the 10,000uF cap and 0.1 ohm resistor are. This is not a bad component.
When you flip the amp over and that changes the glowing behavior, that means you have a loose connection. This could be in the green twisted pair of wires going from the power transformer to the H terminal strip, on that terminal strip itself, or back up front where the 10,000uF cap and 0.1 ohm resistor are. This is not a bad component.
Thanks foryour reply Derek. Those capacitors have suffered my clumsy soldering indeed, but I’m guessing that wouldn’t have to do with my tubes not glowing, so I could deal with them later. Am I right? And Paul, I am outside of the US but we have 120v. The AC on the IEC measured 123. I’m going to check those connections and will report back. Thank you.
I would be inclined to tell you to change the batteries in your meter too.
The power transformer has a 6.3V winding feeding those terminals. You shouldn't see anything above 10V there.
The power transformer has a 6.3V winding feeding those terminals. You shouldn't see anything above 10V there.
Hello there, I just wanted to report back. I checked the soldering and now all voltages are normal. I’m glad to inform that sound is awesome on both channels so I think I’ll try to install the C4S upgrade. BTW, I checked those H voltages before resoldering with brand new batteries on my meter and I got the same 20v. Now, I get 6v.
Thanks for all your help!
Thanks for all your help!
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Deke609
Guest
The issue is "academic" now that the amp is working, but I find it really curious that there was 20V DC on the heater wiring. How could that happen? I thought that maybe B+ and the heater wiring were accidentally connected, which at the high current draw of the heaters might produce serious voltage sag on B+ and result in an additional 10 or more DC volts on the heaters. But if that were the case, I would expect B+ to be tiny (as a result of the very same voltage sag), but that doesn't appear to have been the case. Weird.
@PB or anyone else: any guess as to how this happened? Just curious.
cheers, Derek
@PB or anyone else: any guess as to how this happened? Just curious.
cheers, Derek
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