MrPotatoSalad
New member
Same LEDs still lit. Voltage B2/B5: 71VCaucasian Blackplate said:
Noise, Heat, and Sparks: Oh My!
- Thread starter MrPotatoSalad
- Start date
MrPotatoSalad
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Should I replace the remaining two transistors on the top main board or do you have any other tests?
I've checked over every circuit on the boards and everything is in place. The only issue is that there has to be a bad part that needs to be replaced.
I could also try removing the smaller or larger boards and replacing them with their corresponding resistors if that would help eliminate extra variables.
What is the next step?
I've checked over every circuit on the boards and everything is in place. The only issue is that there has to be a bad part that needs to be replaced.
I could also try removing the smaller or larger boards and replacing them with their corresponding resistors if that would help eliminate extra variables.
What is the next step?
Running the amp without the 6080 and just the 12AU7 will allow you to test the functionality of the front two boards. Seeing 150+V at T2/T4 and something around 70-90V on T1 and T5 means that your small boards are good.
-PB
-PB
MrPotatoSalad
New member
6080 out gives:
1:80
2:230
4:229
5:77
1:80
2:230
4:229
5:77
Yeah, this is indicative of a short on the large Speedball board.
You can put the 6080 back in, then try removing one of the "O" wires and running the amp.
Then try putting that "O" wire back and removing the other.
Let me know what you find.
-PB
You can put the 6080 back in, then try removing one of the "O" wires and running the amp.
Then try putting that "O" wire back and removing the other.
Let me know what you find.
-PB
MrPotatoSalad
New member
Top O out:
1:68
2:70
4:70
5:21
LEDs same
Bottom O out:
1:83
2:204
4:204
5:78
All LEDs on except the bottom main board LEDs are out and top LEDs are bright.
Also, both LEDs on the 12AU7 socket went on with the 6080 out. All board LEDs were out.
1:68
2:70
4:70
5:21
LEDs same
Bottom O out:
1:83
2:204
4:204
5:78
All LEDs on except the bottom main board LEDs are out and top LEDs are bright.
Also, both LEDs on the 12AU7 socket went on with the 6080 out. All board LEDs were out.
That's the problem area.MrPotatoSalad said:
That side is good.MrPotatoSalad said:
The LED's on the small PC boards should've been lit up pretty brightly with the 6080 out. The LED's on the socket couldn't light unless this was the case.MrPotatoSalad said:
-PB
MrPotatoSalad
New member
You are correct, they just weren't noticeable with my lights.Caucasian Blackplate said:
Should I replace both transistors on top then?
I would go over that big board with a fine toothed comb. You have one side that is doing what it should, and one side that isn't. The most probable cause at this point is that two legs of a transistor on that side of the big PCB are soldered together.
-PB
-PB
MrPotatoSalad
New member
No visible connection or measured connecection with any of the transistor legs. Perhaps the TIP50 or 2N2222 is bad?Caucasian Blackplate said:
Yeah, I suppose swapping them both out won't hurt anything.
-PB
-PB
MrPotatoSalad
New member
Replaced the top transistors and started it up. All LEDs were lit except the one at terminal 3. The bottom main board was strong. The top was very faint along with the small boards. The top may have been lighting the whole time, but it was so dim that I never noticed (had to turn off all lights. Started voltage check and it was in the 68V area for the first 2 terminals so I turned it off.
MrPotatoSalad
New member
Resistance check on bottom TIP50 (black/red probe):
E/C:15M
E/B:15M
C/B:81K
Top TIP50:
E/C:infinite
E/B:15M
C/B:13M decreasing to 4M and now rising
Brand new TIP50 out of circuit:
E/C:infinite
E/B:16M
C/B:13M
When I removed the lower TIP50 because I was going to replace everything (but only did the top instead) the lower TIP50 measured then same as the new, so I didn't replace it. It seems that something in the board is causing a short.
E/C:15M
E/B:15M
C/B:81K
Top TIP50:
E/C:infinite
E/B:15M
C/B:13M decreasing to 4M and now rising
Brand new TIP50 out of circuit:
E/C:infinite
E/B:16M
C/B:13M
When I removed the lower TIP50 because I was going to replace everything (but only did the top instead) the lower TIP50 measured then same as the new, so I didn't replace it. It seems that something in the board is causing a short.
Yeah, a less fuzzy photo of the bottom of the board might reveal something.
-PB
-PB
MrPotatoSalad
New member
I can't do any better. Only have a camera phone and a webcam. Webcam will do even worse.
I checked over all the joints. Everything matched the pictures in the instructions. The only thing noteworthy is that I initially installed the TIP50/heatsinks on the wrong side. When I took them out, the heatsink on the bottom of the board's inner joint (the one more towards the center) had the metal ring inside the hole come out. I scraped off the surface to get to the metal path and then soldered the heatsinks on the correct side. When I test for connectivity between the heatsink metal lugs, each one has connectivity to the other 3.
(You can kind of thee the bottom left heatsink joint extends on the board a bit to connect to the path.)
I checked over all the joints. Everything matched the pictures in the instructions. The only thing noteworthy is that I initially installed the TIP50/heatsinks on the wrong side. When I took them out, the heatsink on the bottom of the board's inner joint (the one more towards the center) had the metal ring inside the hole come out. I scraped off the surface to get to the metal path and then soldered the heatsinks on the correct side. When I test for connectivity between the heatsink metal lugs, each one has connectivity to the other 3.
(You can kind of thee the bottom left heatsink joint extends on the board a bit to connect to the path.)
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MrPotatoSalad
New member
Also, is it of any concern if I had the large board out and replaced it with the 10W resistors but sill had the smaller boards in and got hardly any power in the left ear. If the small boards are fine, should they work as replacements for the stock resistors on T1/2 and T4/5?
MrPotatoSalad
New member
Small boards out gives:
1:61
2:70
4:72
5:20
All lights on at first (of course bottom board strong), but then the light on A3 goes out after a few seconds of glowing. Issue is definitely the main board as you said.
1:61
2:70
4:72
5:20
All lights on at first (of course bottom board strong), but then the light on A3 goes out after a few seconds of glowing. Issue is definitely the main board as you said.
MrPotatoSalad
New member
Large board out gives:
1:80
2:178
3:178
4:79
All LEDs on. Rest of voltages check OK for the Speedball manual. Some are a bit higher, but only 10% or so.
Sound is also OK. No distortions or noticeable issues vs the stock Crack.
1:80
2:178
3:178
4:79
All LEDs on. Rest of voltages check OK for the Speedball manual. Some are a bit higher, but only 10% or so.
Sound is also OK. No distortions or noticeable issues vs the stock Crack.
Yeah, with the big board out and the 3K/10W resistors in, the amp should work.
Beyond a problem on the big PC board, can you triple check the wiring hookup of the board itself? Depending on how your amp is wired, wiring one of the "O" pads to 6 or 10 accidentally could also cause your problem.
-PB
Beyond a problem on the big PC board, can you triple check the wiring hookup of the board itself? Depending on how your amp is wired, wiring one of the "O" pads to 6 or 10 accidentally could also cause your problem.
-PB
MrPotatoSalad
New member
Checked the four wires going into the large board and they are all in the correct place. Only thing I can think of is that one of the capacitors or wires is shorting T6/7 or T9/10, but then there should be some obvious voltage differences with the 3K/10W in, right?
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