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Philips 22AH380 in protection

paul_ral

paul_ral

Well-Known Member
I have a beautiful 22AH380 on my bench with 22AH180 tuner and 22AH280 preamplifier, so entire Black Tulip line. I recapped all but I have a problem with power amp. As I said before, it was recapped, I changed two power outputs (2SD732 leakage). I can adjust DC out voltage and BIAS voltagen as in manual. The amplifier passed the DBT test and it sound very good. When I switch to the wall it stay in protection mode and the DC protection led is on. I then measured voltages on protection circuit inputs resistors and I have a few milivolts. It was an old discussion about this strange behaviour on AK but there are no answers.
 
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TS404 and TS405 voltages ?
also be sure c405 is correct way round
also check voltages at R420 and R421
 
On DBT all values are as in Service manual and the relay click.
Without DBT no relay click, I have 56V on R413, resistor is good, 47kohms. The voltages on transistors are
TS405: E=0, C=55V, B=-0.5V
TS404: E=-0.5V, C=55V, B=0V
TS403: E=0V, C=0V, B=-5V
TS402, TS401 all pins 0V
tested all resistors and transistors and they are good. C405 is in correct position.
 
With R411 lifted relay click but only with speaker selector on A or B position. Power amp disengage after 4-5seconds from turn off
 
speaker selector needs at least one set selected for the relay to click .that is normal by the looks of it .

TS403 might be a bit leaky put R411 back in then see if relay clicks .. theory says not .. if not pull TS403 or at least disconnect its collector then see if relay clicks . if so replace TS403 .
 
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So, I put R411 back and I replaced 2TS403 (2SD545) with KSC1616A. Same behaviour, clicks on DBT and stay in ptotect mode without DBT. No DC Out voltages in both cases.
 
looking like the problem is TS401 TS402 then .. best replace them and see .. they are common enough so easy to find . maybe easier to find the ksc1815 . same thing different id .
 
I replaced two 2SC1815 (no leakage) with new KSC1815 and no effect. It is still stuck in protection.
 
Few milivolts. But I notice that big cans were replaced with 5pins Kemet at 24.000uf and the solders are not very good. The original filter caps are screws connected. Could be this an issue?
 
yes it might cause issues .
have another check of ts403 base .
it looks to me ts403 along with r409 r410 voltage divider and r425 d401 are for ac detect . anything wrong here would cause issues
 
I have -5V in TS403 base only, I must have -8 according the schematic. In DBT mode I have the right voltage. I ll check for a leakage in ac detect circuit.
 
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