KLH R3000 Stereo Receiver wont turn on.

[Rickedafied]

One day the stereo didn't want to turn on. I checked for cold solder on the boards and I found nothing. I had the stereo unplugged for about 3 weeks and when I tried turning it on, it worked. After a few days being plugged in, I went to turn it on again and it wouldn't turn on, but after leaving it unplugged again for a while, it did turn on again, but now when I try to select FM, CD, Tape or TV, it keeps going back to VCR by itself. So I removed the front control panel and had a look at the circuit board and found this square component with a crack on it.

It looks like this would be the reason why it wont let me select anything, but what kind of capacitor is this and how does it work?
Could this also be the cause of the power button not turning on the stereo?

 

[KrisBlueNZ]

It's a supercapacitor. 0.047 farads, 5.5V, polarity as marked. Here's a suitable replacement: http://www.digikey.com/product-detail/en/DX-5R5V473U/604-1029-ND/970190

 

[shrtrnd]

Hopefully it was just the capacitor. When I lose a small innocuous componet like this wthout explanation, I always follow the trace on the board to the connected components, just in case something ahead of the
cap failed, which resulted in the destruction of the cap. It's pretty common to just lose a capacitor like this, but as long as you've got access to the board, I'd take the time to look carefully at the rest of the board.
Just my 2 cents worth.

 

[Rickedafied]

Yeah, im hoping its just that capacitor too. I'm gonna inspect the rest of the board before I install the new one. Thanks guys

 

[Rickedafied]

Can the super capacitor be replaced with a regular capacitor?or even a non polarized capacitor?

 

[KrisBlueNZ]

Not if you want the unit to remember its settings during a brief loss of power, for example if you move it to a new power socket. But otherwise, yes.

 

[Rickedafied]

Ok. Could I use one like this? I'm not sure how these kind work.

 

[Rickedafied]

 

[KrisBlueNZ]

You could, but you'd might as well not bother. That's a 47 nF capacitor - one millionth of the capacitance of the supercap. If you're not going to replace the supercap with another supercap, just remove it.

 

[Rickedafied]

Ok I'm gonna try that and see how it works

 

[Rickedafied]

I removed the failed super capacitor and powered up the stereo to see if i can select the CD, Tape and FM buttons and so far its working. So I left the stereo plugged in and turned it off, I went back about an hour later to turn it back on and again it doesn't turn on. Usually I would hear the relay switch before it turns on, but I don't hear it. All I see is the little green light on the volume knob.

 

[KrisBlueNZ]

OK. Now do you think it might be a good idea to buy a supercapacitor and install it?

You may want to check the voltage across the supercapacitor position to make sure there's no other fault in the circuitry. If the voltage is greater than 5V that would explain why the original one failed, and it would tell you that you need to fix something before you install a replacement supercap.

 

[Rickedafied]

Its showing +4.88V
The stereo was working before I turned it off though. I was able to turn it off and on, over and over, but if I leave it off for a while, it won't turn on again.

 

[KrisBlueNZ]

Then I would assume the failure of the original supercapacitor was not caused by an external problem, and install a replacement.

 

[Rickedafied]

I can't find a replacement at the electronic stores. If its just for memory, why doesn't the stereo turn on?

 

[KrisBlueNZ]

I don't know. It may not be the only problem. There's one way to find out though.

 

[Rickedafied]

How?

 

[KrisBlueNZ]

By replacing it and seeing what happens!

 

[TVJohn]

I've got a similar symptom with a KLH R-3000 Receiver. It powers up most times, as I can hear the relay kick in and the unit runs fine. However, it also drops out power to the receiver sometimes and the relay will not kick in unless I try to unplug and plug back in the receiver, then it usually will allow me to power up.
I don't see that SuperCap on my unit, which seems odd, however I did notice the board looked like it may have gotten wet in an area, this would be the "R-3000 KLH Sub" PCA which looks to me like a P/S board. There is a physically busted diode "D158", but it is so tiny, I can't read any nomenclature of it. And I cannot find a schematic for the KLH R-3000 Receiver. Anybody have any ideas what I part number I might be able to replace this diode?

Pictures attached

 

[gahamby]

Greetings,
I know I'm chasing an old post here, but this is what came up. I have a KLH R3000 that switches, unbidden to AM from CD. Inspection of the PC boards reveals no obviously blown components. There is no super capacitor on the Front Control Board.
I do not have a remote for this receiver. Any help greatly appreciated.