help with dead Klipsch ProMedia 2.1

[grjr]

I hope this is the right place to post this. If not, sorry I'm new

I have a dead Klipsch ProMedia 2.1 that I'd like to get working again. Haven't done any troubleshooting yet because there are a couple of resistors that are charred. I'd like to know what their values are suppose to be before I start working on this thing. I have a picture of the resistors on the power supply PCB here:

http://picasaweb.google.com/grjr2000/Electronics/photo#5065410765367966242

you can zoom in to see the location of the two burned resistors, I assume they are probably the same value. If anyone could help identify what value they are suppose to be I'd be really grateful

 

[gni]

There is probably another cause for the resistors to be that
badly burnt. Short somewhere else in the circuit. . .short
at speaker connection. . . you will need to think of what was
happening when this occured to prevent it again and fix what
ever else is malfuncting.

Someone will have the same unit and open it up. . .there is hope.

 

[grjr]

Yes, I know there is something wrong somewhere, would just like to know the value of the resistors

 

[gni]

It is possible that if you pull them. . .the bottom might not
be as blackened. . .less exposure to oxygen when it overheated.

Give it a try. . .

 

[djk]

Call Klipsch and have them send you the schematic.

 

[gni]

I hope Klipsch will send the schematic. . . they can be helpful. . .I was looking at a purchase of some old Cornwalls. . . they gave some
great advice on what to look for. . .

 

[SamGreen]

solution

I just had and repaired the same problem. Those two resistors are 82 ohms and are in the power supply for the control pod under one of the satellite speakers. They burned because something in the control pod is shorted. In my case it was a pair of transistors Q502, a 2N3904, and Q504, a 2N3906. Replace the burned resistors and figure out which transistors are shorted in the control pod and replace them. The schematics are helpfully provided by Dale Thompson at:

http://www.thompdale.com/bash_amplifier/2-1/2-1_bash_amp.htm

Thank you Dale Thompson. Cheers

 

[gni]

The schematic is always the best place to start. . . glad you were able
to get it and make the repairs. . . one less electronic land fill.

 

[Evan Shultz]

Re: solution

The schematics are helpfully provided by Dale Thompson at:

http://www.thompdale.com/bash_amplifier/2-1/2-1_bash_amp.htm

Thank you Dale Thompson. Cheers

Glad you got it working again! That's the whole reason I made the schematics

 

[warpkari]

Hi,

I got a set of these (Klipsch ProMedia 2.1) from the USA but I am in the UK so I was wondering whether it would be possible to change the internal power supply instead of using a step down converter.

What would you guys recommend?

 

[warpkari]

The speakers are rated as 120V - 60Hz

If I use a step down coverter to switch down to 120V, would the frequency be a problem?

(In the UK it's 230V - 50Hz)

Thanks.

 

[Th3 uN1Qu3]

Yes it will be a problem if you will use them all the time. Because of the lower frequency the mains transformer will saturate and get much hotter than normal.

I have replaced a mains transformer in a Logitech system (don't remember the model, Z-5300 i think but i'm not sure), and the downside is that it required an entirely new enclosure too because it was fully sealed, i had to smash it open. But honestly i think it sounds better in the 4th order bandpass that i built rather than the series tuned 6th order that it had. Not to mention better protection from over-excursion, as when i pulled the woofer out the spider had detached from the cone on about a quarter of the area. Glue to the rescue.

Anyway back on topic. If it's easy to gain access to the transformer in your system, replace it. Eventually the insulation of the wire will fail due to heat, and the transformer will start shorting out and sending higher and higher voltage to the amplifier ICs. Thankfully the Logitech had protections so the ICs survived, but don't rely on them, a shorted transformer can very well kill the amp entirely before it blows the fuse.