This would be a good time to try and measure the DC voltage of a 9V battery with your meter.
No good after speedball upgrade
- Thread starter hardisondan
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hardisondan
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Paul Birkeland said:
I like your logic! I was expecting it to be wrong, but I did that and I got 9.6V
hardisondan
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Sorry, I'm going back and forth. By pressing the Range button on the multi meter, I am getting 9.6.
When it was on mV it said 0L.
When it was on mV it said 0L.
Well, 1mV is 0.001V, so you don't want to be on that scale to try to read high voltages. There's probably a 200V setting, that would be what you'd want to be on.
If you were on that setting and the amp was plugged in and turned on and you still got all those zeroes, then your fuse is probably blown.
If you were on that setting and the amp was plugged in and turned on and you still got all those zeroes, then your fuse is probably blown.
hardisondan
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Paul Birkeland said:
I can confirm the fuse is not blown. I have attached a couple of photos. My meter doesn't have a 200 or 400v scale setting as such. There is a Range button, that cycles through different sensitivities. Basically moving the decimal point, then going into mV.
I've also attached a photo of me testing. Black lead is clipped onto 12 and I'm touching 1 with red lead. Can anyone see anything I'm doing wrong?
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Your meter uses its "Auto Range" capability to adjust to the voltages that it finds. It will jump to hundreds of Volts when it needs to and down to mV when you are measuring much lower voltages. You will always be at the correct setting by virtue of that function.
It looks like you are measuring 190 VDC in your picture. I can't tell from the picture, if there is a decimal point somewhere, because you focused on the probes and not the meter.
It looks like you are measuring 190 VDC in your picture. I can't tell from the picture, if there is a decimal point somewhere, because you focused on the probes and not the meter.
What is the stain on the chassis between the PT and the octal? It may be totally unrelated to your issue, but it's worth asking.
With your meter set to AC volts, what AC voltage do you get between terminals 1 and 2 on the power transformer?
With your meter set to AC volts, what AC voltage do you get between terminals 1 and 2 on the power transformer?
hardisondan
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How about the other pairs of terminals on the power transformer?
hardisondan
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So Paul do you mean like between 3 & 4, 5 & 6 etc? or what?Paul Birkeland said:
hardisondan
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V AC Between:
3 & 4: 5.8
5 & 6: 168.4
7 & 8: 168.1
3 & 4: 5.8
5 & 6: 168.4
7 & 8: 168.1
What DC voltage do you get between terminals 20 and 21?
hardisondan
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Paul Birkeland said:
239
How about between 14 and 15?
hardisondan
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Paul Birkeland said:
7.2 mV
OK, despite it looking OK, it seems very, very likely that the 270 ohm resistor that runs across the power transformer is blown open. It's either that, or one end of that resistor is not soldered, or the black wire that runs next to it is not well connected.
With that resistor open, that first 220uF power supply cap will stay charged up. You can use a screw driver with a well insulated handle to short its terminals to remove its charge, or check out a YouTube video on discharging a capacitor with a resistor.
-PB
With that resistor open, that first 220uF power supply cap will stay charged up. You can use a screw driver with a well insulated handle to short its terminals to remove its charge, or check out a YouTube video on discharging a capacitor with a resistor.
-PB
hardisondan
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Yes, precisely. This is not a lethal amount of energy thankfully. When the cap is discharged, you can use your meter to check the resistance of that 270 ohm resistor.
hardisondan
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OK. I did that. Even after a few hours, there was still over 200V in that capacitor. How long will they hold charge like that? (just out of curiosity).
I got a huge spark which scared the crap out of me, but then I tested it and it was almost completely drained. I couldn't seem to get it to zero. Even with more shorting it still had a volt or two.
I measured the resistance across the 270 ohm resistor and it was 0L.
I also noticed it now has a hairline crack right across it. I'm not sure if that was there before. See attached.
So what now?
I got a huge spark which scared the crap out of me, but then I tested it and it was almost completely drained. I couldn't seem to get it to zero. Even with more shorting it still had a volt or two.
I measured the resistance across the 270 ohm resistor and it was 0L.
I also noticed it now has a hairline crack right across it. I'm not sure if that was there before. See attached.
So what now?
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