Crack was working well but after upgrade to speedball
- Thread starter vpcrack
- Start date
Grainger49
New member
The place to start here is with the power off and make the resistance checks. Post any resistances that are +/- 15% out of spec.
Then see if you can determine what resistor burned. You might be able to measure its resistance in the circuit. If not you will need to unsolder one end to measure it. It depends on which it is. Post which it is first and one of the Bottleheads more familiar with the C4S circuit can answer whether you need to lift one lead.
Hang in there, these things get solved if you stick with it and answer the questions asked.
Then see if you can determine what resistor burned. You might be able to measure its resistance in the circuit. If not you will need to unsolder one end to measure it. It depends on which it is. Post which it is first and one of the Bottleheads more familiar with the C4S circuit can answer whether you need to lift one lead.
Hang in there, these things get solved if you stick with it and answer the questions asked.
vpcrack said:
Unfortunately it is most likely that something was done wrong to create that situation. First carefully check all of your connections against the photos and instructions in the manual. The most likely thing is that a wire is connected to the wrong terminal somewhere, or a bare wire is touching something that it should not touch. Next redo the resistance measurements and post any that are not within the specification of the manual. Don't turn it on again until you have done those two steps.
The thing is I haven't even got to the resistance check part yet. I only got to the "turn on the power"part that smoke started coming out of the amp. It appears that the resistor and the capacitor were so hot that it even melt the solder. Anyhow I will check and recheck the wiring and the soldering again. Please be patient with me as I'm really new to this hobby.Grainger49 said:
This would indicate a short in the circuit.
When I have seen repairs that began with these symptoms, it was a loose connection that connected two adjacent terminals right by the burned resistor in question. You would want to look at terminals 14, 15, and 16. If any adjacent pair has metal between them allowing them to touch, that would cause a short and the entire power supply voltage would be cooked of by the resistor you are referring to.
Since the other 270 Ohm resistor isn't exhibiting this behavior, we are able to narrow down the source of the issue quite specifically. (If it was a short in the upgrade, both resistors would be burning hot)
When I have seen repairs that began with these symptoms, it was a loose connection that connected two adjacent terminals right by the burned resistor in question. You would want to look at terminals 14, 15, and 16. If any adjacent pair has metal between them allowing them to touch, that would cause a short and the entire power supply voltage would be cooked of by the resistor you are referring to.
Since the other 270 Ohm resistor isn't exhibiting this behavior, we are able to narrow down the source of the issue quite specifically. (If it was a short in the upgrade, both resistors would be burning hot)
I'd suggest going back to the basic Crack manual and go through the entire resistance check procedure from the start. It starts on page 37 and mentions that it is intended to be a way to check the amp out before you plug it in and apply AC voltage to the amp. That gives you a way to test for the correct connection of the parts without risking further damage.
Yes Doc, the resistance checks are as followed:
terminal1 no reading
2 no reading
3 0
4 no reading
5 no reading
6 2.48
7 0
8 0
9 0
10 2.48
12 0
13 no reading
14 0
20 0
22 0
B3 0
B6 no reading
Rca Jacks: ground lug 0
center pins no reading
Am I missing something?
Those numbers don't look good, am I right?
terminal1 no reading
2 no reading
3 0
4 no reading
5 no reading
6 2.48
7 0
8 0
9 0
10 2.48
12 0
13 no reading
14 0
20 0
22 0
B3 0
B6 no reading
Rca Jacks: ground lug 0
center pins no reading
Am I missing something?
Those numbers don't look good, am I right?
That is not good.vpcrack said:
Remove the large PC board (heat each joint and pop the wire out), then run the amp without the 6080 tube and without the big PC board.
DenverDude
New member
Hang in there, vpcrack. Paul and Doc B. are EXTREMELY helpful and walked me through a few speedbumps I had and all is working great now. Just give them answers to their questions and have patience and you will get this sorted out. It is totally worth it.
I apologize that I was not able to get back to you within a few hours yesterday. It was my birthday, and I took a day off. (Generally you will find me posting nearly every day of the year, even Sundays, Christmas, Thanksgiving, Easter, etc)
Can you post a couple photos of how the big board is wired?
I believe you have the hardware for the TIP-50 transistors installed incorrectly, which is allowing the metal tab of the transistor to touch the metal heatsink, which is creating the short you measured. Please review the installation instructions in the manual and be sure you have the hardware mounted appropriately.
-PB
Can you post a couple photos of how the big board is wired?
I believe you have the hardware for the TIP-50 transistors installed incorrectly, which is allowing the metal tab of the transistor to touch the metal heatsink, which is creating the short you measured. Please review the installation instructions in the manual and be sure you have the hardware mounted appropriately.
-PB
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