900W H-class PA Amp with Limiter

Replace 470k with 47k...
Now the d.c protect trigger at +2v d.c and -3v d.c.
Here is the board after modification.
Now we have another problem.....when a little warm Tip31 and a d.c present simultaneously,the relay pulse continuously
 

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you have changed the time constant from 10seconds to 1second.

The DC detect should work with either time constant.

If it didn't work with that 470k, then there is something wrong. Is it leakage again? post3280.
Could the problem be that the electro is not charging up sufficiently, because the charging current is being wasted in leaking past the unreformed electrolytic.
 
Second 1N4148 stop condacting from inverting input of OP amp D (about +1V) to AMP OUT... measurements are OK, what is transformer specifications, you must have 24V on fan and relay.
I haven't connect a fan this time only a 1k resistor because i have a small transformer(2x20v a.c 2x0.9VA) just for test.btw +/-15v are ok but i have -21v on the relay (when relay contact) instead of -24v
 
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Now the d.c protect trigger at +2v d.c and -3v d.c.
Here is the board after modification.
Now we have another problem.....when a little warm Tip31 and a d.c present simultaneously,the relay pulse continuously

this was the reason i remove this protection after few tests.there is some issue first dc detect circuit trigger from +15 vdc and problem with negative dc voltage too.second relay not quickly off as it should be. i did few test with dc all my speaker coil (only speaker coil ) blow in second then i did some experiment to solve.other issue is if protection relay off due to dc detect luckily save speaker now operator don't know that amp shut down due to dc comes or overheat he surely try to reset the amp after few min. this protection circuit relay should not on this time but relay of this circuit on and then off.yes relay on for half second but half second is enough to blow speaker like fuse. other hand apex stereo protection is very good dc detect relay is very fast.where about concern about this thread h900 amplifier that is best from best.thanks.
 
Unbalance input for B600

Hello Mr. Mile.. I'd like to ask if its ok to cut-off the volume control based on the original schematic? I remove it because I wanna use input buffer. Hoping you can give an advice because I wanna build this amp in HB TEF version.

Many thanks

Hello Sir Mile... Please give advice on how to make this B600 input side unbalance.. I have already made the board but I'm not sure if it's correct or will work fine... I need your assistance so I can properly test my amp. I want it for unbalance input because I wanna use a buffer.

Thanks & Regards
 

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