No good after speedball upgrade

[hardisondan]

Just checking: when you say you measured resistance between terminal 12 and the "fins" of the heatsink, did you touch the lead to the body of the heatshink itself (big black block of finned aluminum) or to each of the skinny silver legs (what PB called "tabs") that are soldered to the pcb board?

I imagine you did the latter (the legs/tabs), which is what I think PB wanted?, but thought it might be good to be sure.

cheers, Derek

I actually did both as I was unsure, but same reading either way.  Thanks Derek

[hardisondan]

OK, that's a good sign with the resistances, go ahead and move on to voltage checks.

The forum will give that error if the photos are huge, I use a simple resizer to reduce them by 80% or so if they are too big.

So do the voltage checks as per the manual? Are they still valid given my cooked 270 ohm resistor?

[Paul Birkeland]

The voltage checks will give us a pretty complete picture of what's going on with your amp.  It will be helpful in identifying any potential problems, including issues with that resistor, though based on its appearance it is probably still functional.

[hardisondan]

The voltage checks will give us a pretty complete picture of what's going on with your amp.  It will be helpful in identifying any potential problems, including issues with that resistor, though based on its appearance it is probably still functional.

Thanks Paul. I have to go away for a few days.. just when I was getting excited about this. I'll resume next Wednesday. I really appreciate your taking the time to help.

[hardisondan]

OK here goes. They are nothing like the manual.. Voltages at:
1:   0.4
2:   0.01
3:   0
4:   0.005
5:   0.4
6:   0
7:   1.3
8:   0
9:   0.8
10: 0

On a side note. I bought some new leads for my multi meter because the ones it came with didn't have alligator clips. Then I forgot which terminal was which colour. After some quick research I found that black goes in the terminal marked COM (for common I guess?). But then nearly all the readings had a negative in front of them. I read that it doesn't really matter, so I switched the leads around again to test. I left the negative off my measurements above.

[Paul Birkeland]

This would be a good time to try and measure the DC voltage of a 9V battery with your meter.

[hardisondan]

This would be a good time to try and measure the DC voltage of a 9V battery with your meter.

I like your logic! I was expecting it to be wrong, but I did that and I got 9.6V

[hardisondan]

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.

[Paul Birkeland]

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.

[hardisondan]

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.

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?

[grufti]

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.

[Paul Birkeland]

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?

[Deluk]

The B numbers are written on the "stain" so likely a left over from painting the topside. Note paint runs around the edges of the plate.

[hardisondan]

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.

Thanks. I'm pretty sure it was 0.19, but I'll check again.

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?

Yes, the stain was just from painting the other side. Assuming you mean 1 and 2 as per the attached diagram, I got 239V AC.

[Paul Birkeland]

How about the other pairs of terminals on the power transformer?