Phoenix Gold sd1300.5

[shadetreetrader11]

Re: Phoenix Gold sd1300.5

P

[shadetreetrader11]

Re: Phoenix Gold sd1300.5

Pins 2,11,14,23 are all hooked together on both Ic4 and Ic5. I should have had the same readings on all 8 pins but I'm thinking a cap must have charged as I was probing and changed the readings. ?? not sure. I checked all the esr readings of the caps on those pins and they all seem very good. About ready to throw the towel in on this thing.

[shadetreetrader11]

Re: Phoenix Gold sd1300.5

If I'm understanding you redwire. Your saying that pin 16 shouldn't have any voltage on it.?

[madan1]

Re: Phoenix Gold sd1300.5

thats what I thought - the voltages should be the same. It is possible to have two separate power supplies for each of the ICs though. Without having good +/- 24 volts on each of the ICs, there is not much point of further troubleshooting. If I remember correctly there is limit in possible difference of the + and - power supply. You have 7volts diff. for ic4 which most likely exceeds that diff. and thus the ic does not want to start.

[shadetreetrader11]

Re: Phoenix Gold sd1300.5

But there's .02 ohms resistance between all the pins.

[redwire]

Re: Phoenix Gold sd1300.5

With no schematic, you need patience and best to understand the blocks of the amp.

one pic U9 (by pots) has a big blob of solder shorting pins 3-4? I would clean up the soldering (with wick), use a q-tip and IPA to clean up flux. Do a visual on the PC board. Toothbrush scrub the solder balls off. It can make more problems resoldering with too much solder and blobs - it doesn't fix anything if a part or IC has died.


IC4 Rear and IC5 Front, so that looks like 4-channels. The 5th subwoofer channel must be mosfets Q110/Q102?
If you are getting different voltage readings on IC4 and IC5 rails, either at the moment the SMPS shut off or the amplifier section probably floats from 12VDC GND so don't ground your multimeter there on the power input side.

Usually one channel has failed or a power supply rail.

There are two SMPS toroid power transformers, guessing one for front/rear and another for the sub amp. Check the power supply voltages at the big caps, C53 and other, C55, C64 etc. At least two pairs of +/- rails plus the pair for the pre-amp +/-15V.

The voltage readings on U4A TL494 PWM IC, show me it was turned off due to IC3A (4558 dual op-amp) which seems to be the supervisor looking for over-temp or amp channel shorted or over-current etc.
You can trace that circuit out but a lot of work. Just look for a problem with an amp channel or power supply rail.