Intermittant receiver again!

[paul_h]

I've got a rebadged LG, similar to the LS-k2460hl that doesn't respond the the remote.
I puled it all apart to get the the reciever and the odd thing was Vc 5v to ground and Vo 5v to ground.

While testing it I accidently shorted Vc to ground, after that the unit made 5 beeps and then the remote started working. Vo to ground dipped to 4v whenever it registered the IR signal (all the ones I've seen have low Vo that goes up :confused: ?)
The pin outs must be different because I used a spare reciever that I've used fine in hitachi, fujistu and mits. But the new reciever did not work and in fact got hot to touch!
So I put the old reciever back in, checked the PCB solders, cable etc, everything working fine except the backwards (IMO) signal. But the controller did not stop working.

Today I got a call back with the same complaint, this time brought a universal remote. receiver completely dead, static 5v on Vo. I did the same thing again accidently, short out the Vc, the a/c unit made 5 beeps and the remote controller started started working again! Again every button on the remote worked, and Vo dipped to 4v everytime a signal was sent.
Any gurus want to tell me what they think is going on?
I'm probably just going to replace the main PCB and reciever PCB but looking for some insight.

[nike123]

Do you have diagram to post?
Or maybe receiver model#?

[paul_h]

Sorry, I didn't see anything written on it, and I have no diagrams for LGs or Kelvinators.
The reciever was flush mount, it was the normal 3 pin bent leg shape, but didn't have the 'arms' to solder to the board for support of the receiver, so the back of the reciever was sitting tightly against, but un-attached to the board (no gap between the back of the reciever and the PCB).


edit:
Also on this receiver, the middle pin was ground I just realised. I looked at the ones I use as spares that work on the other brands I repair, (with sharp GP1U271R sensor). On those, the middle pin is Vc. No wonder my spare didn't work :D

[nike123]

Sorry, I didn't see anything written on it, and I have no diagrams for LGs or Kelvinators.
The reciever was flush mount, it was the normal 3 pin bent leg shape, but didn't have the 'arms' to solder to the board for support of the receiver, so the back of the reciever was sitting tightly against, but un-attached to the board (no gap between the back of the reciever and the PCB).


edit:
Also on this receiver, the middle pin was ground I just realised. I looked at the ones I use as spares that work on the other brands I repair, (with sharp GP1U271R sensor). On those, the middle pin is Vc. No wonder my spare didn't work :D

I would also check electrolyte condenser between Vc and ground (i suppose it is existing in your case), just to be sure!
What is possible in your case is that receiver for some reason block itself and when you short supply (Vc) you are in fact resetting him. Maybe electrolyte has some role in that.

[paul_h]

Sorry, didn't mention, no capacitors on this board. Just reciever and LEDs.
I would have changed the capacitor if there was one, as I've asked you about them before and you recommended changing capacitor first. :D

[nike123]

Sorry, didn't mention, no capacitors on this board. Just reciever and LEDs.
I would have changed the capacitor if there was one, as I've asked you about them before and you recommended changing capacitor first. :D

Then, capacitor is probably on main PCB!
If you could return PCB-s to supplier without problem, then find matching replacement receiver and bring along replacement PCB-s. That could save you and customer some money.

[brunstar]

how long has this system been installed?
It sounds like it could be induced voltage on the unit, especially if the interconnects are passing by the extra low voltage on the pcb, this is usually controlled by installing a ferrite core.
check to make sure that the 240 v cables and the extr low voltage are not crossing paths..
although this should show up on your meter, when you are earthing it out you may be collapsing the magnetic field?

[paul_h]

Thanks for the input. This system is probably 5 years old, otherwise they'd be calling warranty authorised service agents. So it's not a design or install problem.

Nike123, It would be nice to have the option of returning parts, but it wouldn't be possible here with anyone. Especially when they have to order parts in for me, (no one stocks any domesic parts at all in western australia, everything is ordered in from sydney on the eastern coast, or shipped in from overseas). So there's no option playing around with the system and trying back up purchased replacement PCBs.

I normally learn from one system and apply it to the next, this seems to be an odd reciever though, so in my quiet times I will try to look for it and stock it. But right now I will admit defeat and just order the PCBs and maybe examine later.
Same deal with the whirlpool fridge I'm looking at. No time to examine board and capacitor issue, I'm just replacing PCBs and will look at the issue later, especially when there's the possibility of re-occuring isses, I don't have time for free labour and call out, I'd prefer it to work guaranteed
.
There's no time to look closely at this type of stuff when the phone never stops ringing, I just need to add it to experience and make a solution for instant "on site" repairs with parts I have in stock for the next one I come across this reciever and model a/c.
Cheers.

[nike123]

Thanks for the input. This system is probably 5 years old, otherwise they'd be calling warranty authorised service agents. So it's not a design or install problem.

Nike123, It would be nice to have the option of returning parts, but it wouldn't be possible here with anyone. Especially when they have to order parts in for me, (no one stocks any domesic parts at all in western australia, everything is ordered in from sydney on the eastern coast, or shipped in from overseas). So there's no option playing around with the system and trying back up purchased replacement PCBs.

I normally learn from one system and apply it to the next, this seems to be an odd reciever though, so in my quiet times I will try to look for it and stock it. But right now I will admit defeat and just order the PCBs and maybe examine later.
Same deal with the whirlpool fridge I'm looking at. No time to examine board and capacitor issue, I'm just replacing PCBs and will look at the issue later, especially when there's the possibility of re-occuring isses, I don't have time for free labour and call out, I'd prefer it to work guaranteed
.
There's no time to look closely at this type of stuff when the phone never stops ringing, I just need to add it to experience and make a solution for instant "on site" repairs with parts I have in stock for the next one I come across this reciever and model a/c.
Cheers.


OK, I understand your points. Good for you that you are busy now in recession. For good service engineer there is no fear!

[paul_h]

Sorry, I didn't see anything written on it, and I have no diagrams for LGs or Kelvinators.
The reciever was flush mount, it was the normal 3 pin bent leg shape, but didn't have the 'arms' to solder to the board for support of the receiver, so the back of the reciever was sitting tightly against, but un-attached to the board (no gap between the back of the reciever and the PCB).


edit:
Also on this receiver, the middle pin was ground I just realised. I looked at the ones I use as spares that work on the other brands I repair, (with sharp GP1U271R sensor). On those, the middle pin is Vc. No wonder my spare didn't work :D
I've been browsing RS spares, and I think I've found the alternative receivers.
I've been buying the sharp GP1U27R Receivers, as that's what fujitsu, mits, and the mainstream brands I'm used to repairing have. Its pins are laid out Vout, Vcc, Gnd.

It seems LGs, carrier, kelvinator and others use the panasonic PNA4601M or similar, which has it's pins Vout, Gnd, Vcc, and others use Vishnay TSOP1738, pins Gnd, Vcc, Vout.