First Time Crack Builder Need Assistance [solved]

[Paul Birkeland]

Hmm, try running the amp without the 6080 to see if the voltages at terminals 1-5 look to be about correct.

 

[prtuc2]

Terminal 1-5 voltages shown as 0.  The 6080 tube is taken out and the 12AU7 tube isn't lighten up either.  I am sure there is power cause I got a shock accidentally touching the power supply.

 

[Paul Birkeland]

If the 12AU7 isn't glowing, then there is an issue with the twisted pair of wires going from power transformer terminals 4 and 5 to B7/B8 and A4,5/A9. 

We have been seeing some builders lately who accidentally cut one of the wires coming out of the transformer itself, so that's worth looking at as well.

 

[prtuc2]

I recheck those terminals and found the A9 wires snap off when I pull on it, then I resolder that terminal same result.

 

[Paul Birkeland]

If the 6080 is in the socket, does it glow?

 

[prtuc2]

Both tubes does not glow, seems the current is not going through the socket.  Matter of fact the led does not glow, before the problem occurred all the led lit up just fine.

 

[Paul Birkeland]

What is the AC voltage between power transformer terminals 4 and 5?  (Put one probe on each terminal)

 

[prtuc2]

Both terminal AC voltage is 0.  Seems no power is going through the unit, could it be the power cord module overheat or damage?

 

[Paul Birkeland]

What about the AC voltage between power transformer terminals 1 and 2? 

 

[prtuc2]

All the terminals include the B socket and A socket all the AC voltages are at 0.

Except B6 and terminal 9U both show 0.588V, B6 is connected to 9U and that is the only spot on the amp actually got any voltage reading, while the rest of the amp is at 0.

 

[Paul Birkeland]

Power transformer terminals 1 and 2 receive the incoming AC line voltage.  If you have 0V there, your amp isn't plugged in, your power switch is off (or melted), or your fuse is blown.

-PB

 

[lordnikon]

Your picture below indicates you have the wrong orientation of the Speedball PCB board (with the large heat sinks) The printed words "TOP" should be facing south towards the 12AU7 socket and not the 6080 socket.

http://s828.photobucket.com/user/prtuc2/media/P1000273_zpsc6f95926.jpg.html

 

[prtuc2]

I have been suspecting the power switch probably melted when I desoldering the solder iron, just going to re-order an exact pair of fuse and power switch to see if that was the problem or not. 

Thanks for pointing out my large PCB is reversed, I will fix it this weekend.

Really appreciate all the help, so far.

 

[Paul Birkeland]

The board is functionally the same in either orientation, and will work provided you have the connections attached in the correct positions. 

 

[lordnikon]

I came across the same problem as I reversed the orientation of the Speedball PCB. The LEDs didn't work. Once I rotated the board, it worked.  ???

 

[prtuc2]

There is still a problem with the voltages.

Terminal 1              42V
Terminal 2              42V
Terminal 3              0
Terminal 4              42V
Terminal 5              3.3V
Terminal 6              0
Terminal 7              42V
Terminal 8              0
Terminal 9              0
Terminal 10            0
Terminal 11            0
Terminal 12            0
Terminal 13            45V
Terminal 14            0
Terminal 15            112V

I didn't finish taken the voltage on terminal 20 and 21.  Since, the capacitor between terminal 14 and 15 starts to see smoke, which is the same capacitor that heats up before.

 

[Paul Birkeland]

Can you run the amp without the 6080 and post terminal 1-5 voltages?

 

[prtuc2]

Here are the voltages without the 6080 tubes.

Terminal 1                  63.2V
Terminal 2                  213.4V
Terminal 3                  0
Terminal 4                  213.2V
Terminal 5                  65.8V

The interesting thing is the capacitor between Terminal 14 and 15 does not even feel warm without the 6080 tube.

 

[Paul Birkeland]

This is as I expected.  When the 6080 attempts to operate, it draws excessive current.

Other than a miswire on the large PC board installation, the main cause of a problem like this is the metal on the TIP50 transistors touching the heatsinks. 

You should triple check the hardware on these, the shoulder washers and mounting tabs in particular need to be properly placed to keep these parts from shorting out.

-PB

(Your small boards are working perfectly BTW)

 

[prtuc2]

I see my power transformer started to get oxidized and I took some pictures of the heatsink.











I wasn't 100% sure I got all the parts install on the heatsink correctly, since the description of fibre washer looks like at least the kit I had wasn't the exact one on the instruction packet. 

I didn't understand what you meant by TIP 50 transistors touching the heatsink?  Aren't they parallel to each other?