display and controls active, no rail voltage. No 5V from pin 19 of ic301. Everything else seems to be correct for voltages around the IC per the service manual other than pin 23 vol_det. but that looks like it will be dead with no rail voltage. Only .2V on ic606 pin 1 (power supply control) manual says 2.5. 4V on pin 2 when should be 2.5 as well. Most of the chip is missing power from the lack of 5v from ic301. No shoirted outputs or power supply transistors. Is there something im missing that would shut down power to that pin or??
Thanks
Thanks
Does IC601 have 5v out?
If so, Q702 could be shutting down the amp due to a fault in the output stage.
If so, Q702 could be shutting down the amp due to a fault in the output stage.
ic 601 has 5v, can q702 be tested in circuit? Have 10kohm between C and E testing against Q302 (same part) has nothing. I dont see a connection, but may be missing something
I don't know if Q702 can be tested without lifting it. It's the only component that I can see that could be pulling the voltage detect down.
Q 702 has 5v on base, so looks like it's being activated. All outputs are removed and none are shorted. Looks to me like q701 and q705 should pull down the 5v on q 702 to shut it down.
well I must say, I feel really stupid about right now. Couldn't understand how any of those protection circuits could work without some sort of output from the power supply. Figured it was mostly cause I am just learning and just dont know. Decided to download the owners manual to see if it displayed the fault if the amp is in protect mode. Turns out there is an output disable option in the menu. Turns out the output was disabled. enabled the output, shut down amp and turned it back on and now +27V and -27V. Who in their right mind puts a disable output option in an amplifier??? Oh well i guess ill put the output FETs back in tomorrow and see what happens. If it works the guy that was throwing it out will be pissed, ill have a new amp for my truck and learned a few things along the way.
Thanks for your time Perry
Thanks for your time Perry
- Status
- Not open for further replies.