Riddled TV Repair Forum

kuhurdler · Joined: 28 Dec 2006 Posts: 2879 Location: Overland Park, KS

Polycom Soundstation speakerphone model number 2201-00106-001-H9
Power supply: 2201-00181-001-H

Symptoms: works, but stinks. Phone works great. But the power supply smells like burnt plastic if you leave it plugged in.

It appears replacement power supplies (even used) are way more than the price I paid for the phone. And from the looks of it, the power supplies were inadequate in their design.

I couldn't figure out how to disassemble the case, so I used my dremel tool to cut all the way around it.

with the unit plugged in to AC power, but not the speakerphone, I took measurements of the Voltage (DC) at the pinouts:
Black:37.2V
Brown:0V
Red:0V
Orange:0V (connects to outer aux jack)
Yellow:36.4V
Green:.12V
Blue:0V
White:0V

It looks to me like the problem is the wire-wound resistor shown here:

in fact, if you turn the board over, you can see the scorch marks around that area.

Google

kuhurdler · Joined: 28 Dec 2006 Posts: 2879 Location: Overland Park, KS

I was originally hoping to figure out the wiring and replace it with a common wall wart, but I think it has some kind of audio amp and a control device that I don't really understand. So instead I'm planning to replace the capacitors and solder some thicker metal traces on the backside to reduce the impedance. I suspect the root cause is that the C1 filter capacitor is no longer filtering well enough. The solder joints around the resistor and capacitor there also look suspect.

Here's the component values I plan to replace:
C1: 2200uF 50V
C6: 10uF 35V
C7: 33uF 35V
C8: 10uF 35V

other additional info: the PCB is labeled 1380-00123-001 Rev. E

other pictures:

Davy · Joined: 04 Mar 2012 Posts: 13

I don't know the unit.

Did you not measure the resistance of the ww resistor? These things can run mighty warm and 'bake' the pcb area, remember the leads will also conduct the heat, with wire wound resistors the value will marked on it.

I've seen scorch marks worse than that in TVs and yet the component and the circuits that it feeds have been alright.... the soldered joint on any component that generates heat can of course deteriorate or may even form a hairline crack around its leads causing it to either become intermittent, open circuit or even high resistance when measured on the circuit board but not actually on the resistor in question.... so worthwhile checking its value with a test meter.

Dave