joocfpinto
New Member
Hello everyone!
I currently own a Sanyo DCX6000K with a problem in the main power amplifier section. This stereo receiver has two amplifiers (one per channel), one of which is giving random high volume noise spikes on the correspondent speaker while the other channel works perfectly.
Some tests/repairs I've done:
- This happens even without any volume on the receiver.
- I've tested the faulty amplifier outside the receiver powered with a dual power supply (with the input grounded): same thing happens on the speaker.
- I've replaced all caps with new ones.
- I've already tuned the amplifier bias with the help of the same dual power supply current measurement. Any time a noise spike occurs there is a current spike as well (which is obvious), and the current bias stabilizes when no noise occurs.
- I've replaced the output transistors 2SA764 and 2SC1444 with original ones (found from eBay).
I'm looking forward to replace the remaining transistors of the board, but I need advice on replacements for them:
- 2SA733 PNP
- 2SC875 NPN
- 2SC1175 NPN
- 2SA659 PNP
- 2SA532 PNP
The schematics may be found after login in the HiFi Engine site, for example. The faulty board reference shown on the schematics is 131-0-4001-33001.
Any help is welcomed!
João
I currently own a Sanyo DCX6000K with a problem in the main power amplifier section. This stereo receiver has two amplifiers (one per channel), one of which is giving random high volume noise spikes on the correspondent speaker while the other channel works perfectly.
Some tests/repairs I've done:
- This happens even without any volume on the receiver.
- I've tested the faulty amplifier outside the receiver powered with a dual power supply (with the input grounded): same thing happens on the speaker.
- I've replaced all caps with new ones.
- I've already tuned the amplifier bias with the help of the same dual power supply current measurement. Any time a noise spike occurs there is a current spike as well (which is obvious), and the current bias stabilizes when no noise occurs.
- I've replaced the output transistors 2SA764 and 2SC1444 with original ones (found from eBay).
I'm looking forward to replace the remaining transistors of the board, but I need advice on replacements for them:
- 2SA733 PNP
- 2SC875 NPN
- 2SC1175 NPN
- 2SA659 PNP
- 2SA532 PNP
The schematics may be found after login in the HiFi Engine site, for example. The faulty board reference shown on the schematics is 131-0-4001-33001.
Any help is welcomed!
João
