0
\$\begingroup\$

I have problems with this Philips FWP3100 mini Hi-Fi sound system because it does not produce any sound at all. I dismantled the said unit, and come across the AMP+Power Board, the said board should have the following voltage rails, 5V, 12V and 32V. (According to the schematic) Unsurprisingly, the 32V rail is to be fed to the amplifier but as I voltage test across the filter caps, it only shows around 1V.

I hooked an external 19V power supply to the 32V rail and the amplifier worked but not to its full potential. My goal though is to find the bad component to be replaced.

Anyways here's what I've tried so far:

  1. Connected the 5V rail to the optocoupler (IC700) responsible to feedback "ON" (to turn on the oscillator chip SSC6200)
  2. Removed the voltage feedback optocoupler (IC702) to test if it is working, and after knowing it is functional, I returned it
  3. Resistance across the FB pin of the oscillator chip and the ground is 63.5 Ohms, the same resistance across the other side of the optocoupler (IC702)
  4. Visual inspecting all the electrolytic caps, no bulging sighted
  5. Changed the TL431 as an assurance maybe it could be the problem
  6. Resistance across the 32V electrolytic caps is 99.6 Ohms (maybe this could be the problem?) PARTIAL SCHEMATIC DIAGRAM

Could it be the feedback circuit causing the problem? or could it be the oscillator chip is bad? Btw the datasheet of the oscillator chip (SSC6200) is japanese, and I am a noob at looking at specifications.

Any help would be much appreciated! ;D

Here's the link for the service manual, it contains the the whole schematic diagram of the said unit https://elektrotanya.com/philips_fwp3100_05_55_sm.pdf/download.html

Here's the link for the oscillator chip responsible for driving the bigger chopper transformer https://datasheetspdf.com/pdf-file/822984/Sanken/SSC620D/1

\$\endgroup\$
  • \$\begingroup\$ ”Resistance across the 32V electrolytic caps is 99.6 Ohms (maybe this could be the problem?)” Sounds low. Is is stable at that value if you leave your multimeter or are you charging a capacitor? Any difference with your speaker load connected? Is anything running hot at 19 V? \$\endgroup\$ – winny Mar 30 at 15:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.