Essyx
New Member
Hello everyone.
I recapped an Akai PS200C pre-amp, and now when I turn it on, it severely overheat.
What I have done:
Change all polarized electrolytic capacitors, replace them with the same capacity values and for some off them a superior voltage value.
Change all the bipolar electrolytic capacitors, replace them with same capacity values and voltage. The small one’s (4,7µF and below) where replaced by Wima film capacitors. On board PC2056, C08, C23, C32, C50 and C51 where replaced by Wima MKS2 as the C5 on the board PC2033. The C49 of the PC2056 where replaced by Wima 1µF 50V MKS4. All of them are going by pairs.
All VD1222 where replaced by a twin 1N4148 “tipi montage”.
On the PC2035, the C904, C905, C906 and C909 where fried and replaced by KEMET PME264NE5470MR30.
Now when I turn the unit on, the TR3 and TR4 of the PC2003 board are quickly overheating, more than 50°C (120°F) in less than five minutes. If I don’t turn it off within five minutes, I can hear one of the reed relay switching. Those transistors showed traces off heat before my intervention, but the unit was playing for several hours without any problems.
I checked all the soldering I’ve done looking for a bridge and have not found one. Checked all the polarity of the capacitors and the diodes and everything looks good. If I connect the pre-amp on a power amplifier, it sounds good. No hum or noise.
If anyone can provide some guidance on what I’ve done, if something is wrong within my parts choices or guide me to the next step I would much appreciate.
I recapped an Akai PS200C pre-amp, and now when I turn it on, it severely overheat.
What I have done:
Change all polarized electrolytic capacitors, replace them with the same capacity values and for some off them a superior voltage value.
Change all the bipolar electrolytic capacitors, replace them with same capacity values and voltage. The small one’s (4,7µF and below) where replaced by Wima film capacitors. On board PC2056, C08, C23, C32, C50 and C51 where replaced by Wima MKS2 as the C5 on the board PC2033. The C49 of the PC2056 where replaced by Wima 1µF 50V MKS4. All of them are going by pairs.
All VD1222 where replaced by a twin 1N4148 “tipi montage”.
On the PC2035, the C904, C905, C906 and C909 where fried and replaced by KEMET PME264NE5470MR30.
Now when I turn the unit on, the TR3 and TR4 of the PC2003 board are quickly overheating, more than 50°C (120°F) in less than five minutes. If I don’t turn it off within five minutes, I can hear one of the reed relay switching. Those transistors showed traces off heat before my intervention, but the unit was playing for several hours without any problems.
I checked all the soldering I’ve done looking for a bridge and have not found one. Checked all the polarity of the capacitors and the diodes and everything looks good. If I connect the pre-amp on a power amplifier, it sounds good. No hum or noise.
If anyone can provide some guidance on what I’ve done, if something is wrong within my parts choices or guide me to the next step I would much appreciate.