Amp has no output. Turns on, relay clicks, no protection light.... no output. Don't see anything other than flat line voltage on the output transistors when driven with a signal. No excessive current draw (about 1.8a). It's like it wants to play but won't.
Any ideas? Thanks in advance.
Any ideas? Thanks in advance.
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Replaced the regulator, even though it seemed fine when tested on diode check. Same as the one I replaced it with... now amp is playing audio perfectly. Should I be concerned an IC or something damaged it?
It is playing without R141 is circuit. Is R141 100K ohm??? This board is the 10ZX2500.1 REV.0 Should I replace it?
It is playing without R141 is circuit. Is R141 100K ohm??? This board is the 10ZX2500.1 REV.0 Should I replace it?
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Ok.. I'll reinstall it. Thanks
I did have it installed when I quickly tested the amp for sound after I replaced the +15v regulator. Amp played music even though I only powered it up for a few seconds. I cut out R141 after reading your post. Reinstalled the amp in the case. Powered it up to test it good and soon as I applied remote power it went into protect and C750 got really hot and started smoking... any idea what might have caused this?
I did have it installed when I quickly tested the amp for sound after I replaced the +15v regulator. Amp played music even though I only powered it up for a few seconds. I cut out R141 after reading your post. Reinstalled the amp in the case. Powered it up to test it good and soon as I applied remote power it went into protect and C750 got really hot and started smoking... any idea what might have caused this?
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This may get tricky. C750 couples AC from a tertiary winding of T1 and feeds a rectifier circuit comprised of D750 & D751 which is the DC supply for (VGATE-) R241,R245-220 ohm/5watt.
Check the two diodes with an ohmmeter/diode checker.
If they check good, visually inspect the R241,R245 and check with an ohmmeter.I suspect they will check good, but if they look discolored it will indicate that one of the SUB 1 or SUB 2 boards is shorted.
There are 12 volt zeners, two each on the SUB boards, D1 and D2 1N4742. Both D2's are tied to (VGATE-). Check both with an ohmmeter/diode checker.Compare to D1
If all check good, you will have to remove both sub boards and check all transistors and compare to each other, There are numerous resistors and a couple of inductors that you should check. If and when you get to this point take good pictures of both sub boards after you've removed them and post. I will mark any other components that are too numerous to list to be inspected.
Check the two diodes with an ohmmeter/diode checker.
If they check good, visually inspect the R241,R245 and check with an ohmmeter.I suspect they will check good, but if they look discolored it will indicate that one of the SUB 1 or SUB 2 boards is shorted.
There are 12 volt zeners, two each on the SUB boards, D1 and D2 1N4742. Both D2's are tied to (VGATE-). Check both with an ohmmeter/diode checker.Compare to D1
If all check good, you will have to remove both sub boards and check all transistors and compare to each other, There are numerous resistors and a couple of inductors that you should check. If and when you get to this point take good pictures of both sub boards after you've removed them and post. I will mark any other components that are too numerous to list to be inspected.
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Ok. Back to this amp...
Thanks for the info. D761 and 762 (rectifiers) test fine out of the circuit. So did D750, 751. The resistors R241 and 245 read 218ohms so good. I initially checked both D2's against the D1 on the sub 1 card (side with issue) and they tested ok. I removed the cards and when testing I found D1 on SUB 2 is reading shorted in the circuit. On SUB1 it reads same as the 2 D2's. I lifted one side of D1 SUB2 and it now reads OK.... something in that section must be messed up... but why SUB2 card and not SUB1 side. C750 that was smoking is on other side.
Thanks for the info. D761 and 762 (rectifiers) test fine out of the circuit. So did D750, 751. The resistors R241 and 245 read 218ohms so good. I initially checked both D2's against the D1 on the sub 1 card (side with issue) and they tested ok. I removed the cards and when testing I found D1 on SUB 2 is reading shorted in the circuit. On SUB1 it reads same as the 2 D2's. I lifted one side of D1 SUB2 and it now reads OK.... something in that section must be messed up... but why SUB2 card and not SUB1 side. C750 that was smoking is on other side.
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OK... sooo after removing testing and reinstalling Q50, 51, 52, 53, 54, 55, 56, 57, 58 and 59. I now checked across D1 and it no longer reads shorted. Not sure what that was all about...
So, back to the SUB1 card. I'll remove and check all the transistors tonight after work. Hopefully I can find a bad one.
So, back to the SUB1 card. I'll remove and check all the transistors tonight after work. Hopefully I can find a bad one.
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