Hello,
I've been enjoying my TSSE for a while (since 2009) and tonight I smell something is burning after using my amp for an hour.
When I detached the board from the case C3 was blown as well as the fuse.
What may be the cause of this? I can see from the schematic that C3 is part of the power supply. I believe upon visual inspection that no other part was involved.
Thanks for your time.
I've been enjoying my TSSE for a while (since 2009) and tonight I smell something is burning after using my amp for an hour.
When I detached the board from the case C3 was blown as well as the fuse.
What may be the cause of this? I can see from the schematic that C3 is part of the power supply. I believe upon visual inspection that no other part was involved.
Thanks for your time.
Hi Mike,
Thanks for the response. R4 is ok at 147k ohms. R3 is unfortunately dead. It also has a darker color in the middle. Anything else I can check? Thank you.
Thanks for the response. R4 is ok at 147k ohms. R3 is unfortunately dead. It also has a darker color in the middle. Anything else I can check? Thank you.
R3, R4 and C3 provide a DC voltage of about 40 volts to bias up the 6.3 volt heater supply. This helps reduce hum in the 12AT7.
For R3 and C3 to blow a high voltage (200+ volts) got into this supply. The only place where this could easily happen is inside the power transformer. If the 6.3 volt winding shorted to the 5 volt winding or the HV winding these parts could fry. A short in the wiring to the power transformer could do it too.
Disconnect the 6.3 volt winding from the board and measure from the green wires to all other transformer wires with an ohmmeter. There should be infinite resistance.
For R3 and C3 to blow a high voltage (200+ volts) got into this supply. The only place where this could easily happen is inside the power transformer. If the 6.3 volt winding shorted to the 5 volt winding or the HV winding these parts could fry. A short in the wiring to the power transformer could do it too.
Disconnect the 6.3 volt winding from the board and measure from the green wires to all other transformer wires with an ohmmeter. There should be infinite resistance.
Thanks George. I'll check the tranny leads. The board if off the amp right now. I will measure from the green 6.3 leads. I'll let you know.
Hi George,
My power transformer is a Hammond 374 BX (same as my other Tubelab SSE which is working). I cannot measure anything from the green filament leads to the yellow, red, red/yellow of the secondary. Also, unable to measure anything from the green leads to the power transformer primaries (white, brown, blue and black).
However, the sad news is that I can see burn marks to all primary and secondary wires as they emerge from the power transformer.
I wonder what could cause the short? It was working properly before this happened. I have been using this amp in the last few days without a problem. Thanks again, George.
My power transformer is a Hammond 374 BX (same as my other Tubelab SSE which is working). I cannot measure anything from the green filament leads to the yellow, red, red/yellow of the secondary. Also, unable to measure anything from the green leads to the power transformer primaries (white, brown, blue and black).
However, the sad news is that I can see burn marks to all primary and secondary wires as they emerge from the power transformer.
I wonder what could cause the short? It was working properly before this happened. I have been using this amp in the last few days without a problem. Thanks again, George.
Cheezus, I hope I don't have to replace my power tranny to fix mine. (My SSE also blew C3, but after only a few hours of operation). Still haven't had the time (or sufficient knowledge) to figure it out.
cogitech, try this same test. It is obviously not a perfect test since it did not find his short, but burnt marks on the transformer wires provided the clue as to where the problem was.
Measure to chassis and power input wiring also. There should be NO continuity from the green transformer wires to ANYTHING on any resistance scale in the meter.
In your case you should also make sure that the unused center tap wires are not touching anything or each other.
SSE's have been around for 14 years and there has never been a blown C3 until now and now there is two, and both have Hammond transformers.
Measure to chassis and power input wiring also. There should be NO continuity from the green transformer wires to ANYTHING on any resistance scale in the meter.
In your case you should also make sure that the unused center tap wires are not touching anything or each other.
SSE's have been around for 14 years and there has never been a blown C3 until now and now there is two, and both have Hammond transformers.
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George,
I completely missed that last post. If I had seen it, I would have double-checked continuity from the greens to everything else and discovered my problem - which has turned out to be a fried Hammond.
I completely missed that last post. If I had seen it, I would have double-checked continuity from the greens to everything else and discovered my problem - which has turned out to be a fried Hammond.
I am sorry. I forgot to update my post.
I cannot blame Hammond for the transformer short. Upon further inspection, I think I did inserted one of the EL-34 tube incorrectly in the socket (the key was missing on this particular tube) and thus the resulting short.
I am no EE, but I think that's what happened.
Godspeed.
I cannot blame Hammond for the transformer short. Upon further inspection, I think I did inserted one of the EL-34 tube incorrectly in the socket (the key was missing on this particular tube) and thus the resulting short.
I am no EE, but I think that's what happened.
Godspeed.
Very interesting. I appreciate your testicular fortitude for reporting this.
However, I had the exact same symptoms as you with a days-old Hammond power transformer and I have recently discovered that it is defective. Resistance test between the 5v winding and 6.3v winding is .04 ohms.
Did you test your transformer?
However, I had the exact same symptoms as you with a days-old Hammond power transformer and I have recently discovered that it is defective. Resistance test between the 5v winding and 6.3v winding is .04 ohms.
Did you test your transformer?