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KLH R3000 Stereo Receiver wont turn on.

gahamby

Nov 19, 2021
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upload_2021-11-19_18-26-40.png

Is the solder bridge in the upper right of IC202 ADI6312 supposed to be there?
 

73's de Edd

Aug 21, 2015
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Look . . .VEWY-VEWY_VEWY CAWEFUWWY . . . . .( a la ElmerFudd) . . . . . at the right top corner post near that questioned area.
You will find that it connects into the ground plane in that immediate area . . . . . and then . . . .AND THEN ! see if that ground plane, then doesn't short out those 4 pins to its left, since YOU have the board in hand, and can microscopically inspect it..
If being so, it wouldn't matter.

I do not have a remote for this receiver.
Whats even worse is . . . . .I don't even have a schematic for this unit, nor anything close, so I can't analyze that associative circuitry. . . . . . relating to your mystery function switching.
A pipe dream . . . .is there a possibility that a TV or other remote in the area is being used and that one of its buttons digital codes might be coincidental with the function change of the KLH ?
 
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gahamby

Nov 19, 2021
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Yep, right after I pulled my head out from trying to post that shot, I noticed that ground plane. DOH!
Thanks for the reply. This receiver is a cheap POS. It's bound for the Freecycle as parts.
I might just remove the remote receiver from the board just to see if this is the culprit.
 

73's de Edd

Aug 21, 2015
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If triggering by my just mentioned situation . . . . and YOU should know of any remotes being within range.
With the greatest possibility, if feeding your TV receiver into this system and its speakers for an ENHANCED TV audio effect. PLUS your being able to associate the function change to an instant of your pressing a particular key on the TV remote.
HOWEVER you would typically have the KLH in auxiliary mode, not your mentioned mode.

Instead of pulling the remote or disabling its 5 volt supply to its sensor, you might just put a 6 square layer of BLACK insulating electrical tape on the clear plastic escutcheon in the front, and centered on that sensor.

Afterwards if you might trace that infrared sensor to the IC on the circuit board that it is connecting with ( probably a mu.u.u.u.u.u.u.u.u.u.u.ti pinned u/Processor) and get its identification maybe we can work with photos and a possibility that we can work with another KLH that was using a SAME tried and testing design for this circuitry. They don't just change design from year to year you know !

And . . . .no . . . . the AD16312 will not be our problem, since that is being associated with your units frontal Vacuum Fluorescent Display

http://www.datasheetq.com/datasheet-download/735181/1/Analog-Technology/AD16312

73's de Edd . . . . .
 
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gahamby

Nov 19, 2021
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Thanks for the reply, This receiver has coexisted with the TV, DVD, and Apple TV (wifi, not IR) remotes for some time now while being connected to the line level out on the TV without manifesting this fault. This began after reassembling the system when I moved it back into position after painting the room. The remote sensor looks to be the low hanging fruit here. It looks quite easy to remove and restore. I don't know what else would randomly cue an input change, unless it's the AM select switch itself. The CD and AM select switches share common plane for one of their pins on the PC board that traces nowhere else Thanks for the link on the VFD chip. That clears up the mystery there.
 
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gahamby

Nov 19, 2021
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Well, I don't think it's the IR sensor. I lifted the sensor, reassembled the receiver, and powered it up. No smoke, so a good start. It stayed stable on CD until I put a line level input on the CD connectors. It switched right to AM. I could switch back to CD and it would hold for a while then it would switch randomly to AM. The AM tuner seems shot to boot. The differences in situation are:The receiver is in a different room. There is no line level input from a TV. The CD player is a battery powered portable. The speakers are different. The cover is off the receiver. I think I'll go back in, restore the IR sensor, and lift the AM select switch. One thing I noticed is that once it switched to AM it did not want to switch to any other input right away. It required multiple presses of another input switch to select another input.
 
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73's de Edd

Aug 21, 2015
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How about a component side GOOD board shot as well as passing on the IC numbers to see which ones would be involved with AM-CD switching / handling your circuitry. If audio switching is done outside of a chip, CD4052's are popular choices. Then one could see if that circuitry is routed thru some of those and monitor for its switching voltage presence.
 

gahamby

Nov 19, 2021
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I removed the AM select switch and the issue went away. The receiver is reassembled, reinstalled, and working. This is a second rate component at best. It will do to be going with. Would noise from the failed AM section of the tuner card leaking into the switching section have caused the fault? Thanks again for your interest.
This forum is not cooperating with the uploading of images. I tire of being told there is an error but not what error. If I I can resolve this I will post front and back shots of the from panel card.
 
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73's de Edd

Aug 21, 2015
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but . . . .BUT . . .BUT . . .BUT . . . . . . I aren't finding any 2 images, nor even wurds, whut likes are being hotly linked . . . . . . . .any chance, that in a full blown state of mental disarray (or dementia) , that you done went and forgetted them ?
 
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gahamby

Nov 19, 2021
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but . . . .BUT . . .BUT . . .BUT . . . . . . I aren't finding any 2 images, nor even wurds, whut likes are being hotly linked . . . . . . . .any chance, that in a full blown state of mental disarray (or dementia) , that you done went and forgetted them ?
I think we're all done here. out
 

73's de Edd

Aug 21, 2015
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GRE E E E E A A A A A T ! . . . . .I CAN SEE them now. . . . and in referring to your units display board and the AM radio functions activation being done with a tact switch, it would seem that it has / would seem to have a micro-mini sized trace of metal shard or small resistive "element" loose inside, and it can/could/would make intermittent contact and fake a push button action, then AM radio mode activates.
If it now plays flawlessly, without fault for days, one could then suspect that a total replacement of that tact switch should have all functions going to normal again.
Possibly your having physically moved the location of the unit and it responding in kind in letting that intermittent condition then rear its ugly head.
Should you unknowingly had the hindsight in this troubleshooting quest, to have placed the unit with display boards , face to the floor I think that it might have run without this one tact switches intermittency quirk, showing up . . .for . . . .days . . .weeks. .

73's de Edd . . . . .
 
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