ok... this is a weird problem with this amp. puzzling because it could leave you thinking you've fixed it - due to being fine one day- powered on all day! ...then the next, it starts acting up again within minutes of being powered on. 
here's my update upon several hours on the bench over multiple days since i last posted.
...after bypassing the TH1 polyswitch, the power on/off switch... basically everything, the only progress i found was when i bypassed everything between the ac plug inlet and the Vp.
- as well as re-flowing solder a bunch of places like fuse holders, the regulator & caps and then testing the caps affected in that area of the circuit...
from there i deduced perhaps the quick-dissconnects -of which there are many- conductors might be the culprit and now i believe (hope) that i was right...
There are a staggering 10 disconnect conductors just between the main ac power inlet & the Vp alone! (that's too many imho, but anyway) so I pulled each one off and re-smooshed each one individually so the both leafs of the conductor meet tightly flush against there male terminals mates on the board, switches and ac plug fixture. the amp has been on now for several days off & on for hours at a time and not once has it acted up again... (yet) ...and dare i suggest that the amp sounds a little better too than i did before!
Synopsis: several factors in play to conspire this one problem - the TH1 polyswitch does trip-out but not because it's faulty but because of the resistive heat build up from poor connectivity with in the main power circuit due to loose connector(s). it's probable more than one connector is just barely making contact since there are so many of them and this will cause unstable current flow and resistance will build up where it's not supposed to - add that to the executive tasks of the poly-switch and you've got a dysfunctional system causing failure in other areas of the circuit(s) that might not otherwise be to blame but easily misidentified as the sole problem.
possible permanent solution: i might remove the disconnect terminals and hardwire (solder) connect them from the ac inlet to the switch completely leaving only the ones that feed to the board stock. this will eliminate some of the possibility of the problem returning some time in the future.. and again... i can almost swear the amp sounds better more full & louder better tone... was it starving before? thanks for all the suggestions it helped me arrive at this point.
here's my update upon several hours on the bench over multiple days since i last posted.
...after bypassing the TH1 polyswitch, the power on/off switch... basically everything, the only progress i found was when i bypassed everything between the ac plug inlet and the Vp.
- as well as re-flowing solder a bunch of places like fuse holders, the regulator & caps and then testing the caps affected in that area of the circuit...
from there i deduced perhaps the quick-dissconnects -of which there are many- conductors might be the culprit and now i believe (hope) that i was right...
There are a staggering 10 disconnect conductors just between the main ac power inlet & the Vp alone! (that's too many imho, but anyway) so I pulled each one off and re-smooshed each one individually so the both leafs of the conductor meet tightly flush against there male terminals mates on the board, switches and ac plug fixture. the amp has been on now for several days off & on for hours at a time and not once has it acted up again... (yet) ...and dare i suggest that the amp sounds a little better too than i did before!
Synopsis: several factors in play to conspire this one problem - the TH1 polyswitch does trip-out but not because it's faulty but because of the resistive heat build up from poor connectivity with in the main power circuit due to loose connector(s). it's probable more than one connector is just barely making contact since there are so many of them and this will cause unstable current flow and resistance will build up where it's not supposed to - add that to the executive tasks of the poly-switch and you've got a dysfunctional system causing failure in other areas of the circuit(s) that might not otherwise be to blame but easily misidentified as the sole problem.
possible permanent solution: i might remove the disconnect terminals and hardwire (solder) connect them from the ac inlet to the switch completely leaving only the ones that feed to the board stock. this will eliminate some of the possibility of the problem returning some time in the future.. and again... i can almost swear the amp sounds better more full & louder better tone... was it starving before? thanks for all the suggestions it helped me arrive at this point.
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Problem solved! my TSA15C has been powered on for 3 days and power hasn't cut out once.
It was the disconnect terminals between the ac power inlet terminals and the power switch - which also include the Thermal Switch and fuse as part of that segment of the power supply.
soldered them in place ultimately hardwire those connections and... no mas problema!
It was the disconnect terminals between the ac power inlet terminals and the power switch - which also include the Thermal Switch and fuse as part of that segment of the power supply.
soldered them in place ultimately hardwire those connections and... no mas problema!
Hey Quatre got, is your amp still okay, after the fix you did in September?
However my tsa15 for whatever reason did not have the problem for maybe a year, it suddenly is back ... and more badly as ever before. It cuts more off than on. So time to do a real repair, think I will try what quatre got did.
However my tsa15 for whatever reason did not have the problem for maybe a year, it suddenly is back ... and more badly as ever before. It cuts more off than on. So time to do a real repair, think I will try what quatre got did.
Hello Mooly
I have the same TSA-15H with the same problem!
Where do you see any thermal fuse???
I have the revision 2.00 schematic (2011/03/08), same as Mustang76.
I see a NTC labeled TH1 but no thermal fuse!!!
Furthermore, when the power led is going out, whith a looper in the effect loop, I can hear it!!!
Have another solution ???
I have the same TSA-15H with the same problem!
Where do you see any thermal fuse???
I have the revision 2.00 schematic (2011/03/08), same as Mustang76.
I see a NTC labeled TH1 but no thermal fuse!!!
Furthermore, when the power led is going out, whith a looper in the effect loop, I can hear it!!!
Have another solution ???
Thanks Mooly
I think the thermal fuse inside transformer is on the wiring 14Volts only (P5 P6) and is resetable when a little bit cold!
When overheat, the power led fall off but the power amp is allways running (I put a mp3 in the effect loop and I can hear it)!
At 15W (11Volts rms and 8 ohms) after 2 hour, temperatur of transformer is about 45°C ... not very hot!!!
Another day, I try anything new !!!
Thanks for ideas ;-)
I think the thermal fuse inside transformer is on the wiring 14Volts only (P5 P6) and is resetable when a little bit cold!
When overheat, the power led fall off but the power amp is allways running (I put a mp3 in the effect loop and I can hear it)!
At 15W (11Volts rms and 8 ohms) after 2 hour, temperatur of transformer is about 45°C ... not very hot!!!
Another day, I try anything new !!!
Thanks for ideas ;-)
It would be very unusual to have such a fuse on a secondary winding.
When the fault next occurs measure the secondary AC voltage across that winding and see if it is present or not. From what you now say I would not suspect the transformer.
Check for drys on the regulator. Also very occasionally fuses (normal glass ones) can be faulty and the internal wire part from the end cap when hot. Extremely rare but I have had that happen once.
When the fault next occurs measure the secondary AC voltage across that winding and see if it is present or not. From what you now say I would not suspect the transformer.
Check for drys on the regulator. Also very occasionally fuses (normal glass ones) can be faulty and the internal wire part from the end cap when hot. Extremely rare but I have had that happen once.
Problem solved!
Dear all,
In my case the problem was finally solved: it was a poor DIODE.
That caused the failure in the power section. Causing the power cut out.
It took my tech a long time to find this, after he checked the usual suspects mentioned (fuses, solder joints, thermal fuse, regulator, trafo ...)
Hope the other diodes stay alive ....
Hope this helps everyone.
Best regards,
Peter
Dear all,
In my case the problem was finally solved: it was a poor DIODE.
That caused the failure in the power section. Causing the power cut out.
It took my tech a long time to find this, after he checked the usual suspects mentioned (fuses, solder joints, thermal fuse, regulator, trafo ...)
Hope the other diodes stay alive ....
Hope this helps everyone.
Best regards,
Peter
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