Ok, I received this radio knowing it had this fault. Described in the auction as "noise in left channel, due to faulty contact (easy fix for professional)".

I go hunting on here for ideas as to what it might be and it narrows down to a blown amp chip that needs replacing. Two weeks later both are replaced and noise in left channel is there.

Here are the facts:

The noise sounds a lot like radio static, with pops and white noise. It isn't constant and can seemingly randomly increase or decrease at any time. It seems to be 'on top' of the audio coming out of the left channel and doesn't actually distort what's coming through.

It registers on the VU and LED meters and is also recorded to tape.

It comes through on all Functions, but seems to be less prominent on the Phono/Aux input.

It does not affect the right channel whatsoever.

It sounds to me like a bad earth or something similar, which would get back to the sellers original point about it being a faulty connection inside somewhere, but my extremely limited modicum of knowledge of radio electronics does me no favours here. I've De-Oxited the internals rigorously and even tried tapping different clip connectors with her going to test it out and I couldn't isolate it at all to a specific component.

Well, that's about where I'm up to, I'll be taking it to a professional repairers next week unless one of you mighty fine lads can give me any suggestions.

Of note, this was JLF's old Conion, procured through ErnieJade. It was serviced before it was sent to the original australian buyer, so the problem is a new-ish one, though I'm not sure how long ago JLF sold her.


Any help or suggestions would be very, very graciously accepted. I'm at my wits end with this radio and just want to sit back and enjoy her already.

Thanks for reading.



Rock On.

Kittmaster really needs to chime in on this. With as much time as he spent inside of his Conion, he probably has every little thing memorized.

Try warming up small areas of the circuit board with a blow dryer.

Might locate the bad part that way.

ok the conion needs a real good cleaning on the switches i mean real good and the rear phono line in switch i have the conion which had a simular problem lets say the same the cleaning took care of that,the m90 excibits basicly the same problem with that rear line in phono switch in the the back panel before repairing the amps give it a good clean with deoxit.. belive me the conion likes to play dead channel

Unfortunately no luck with either idea, thanks much though guys.

A new revelation: When I put Tape One in Record mode with the Function on Tape One the noise in the left channel COMPLETELY disappears.

The riddle grows further...



Rock On.

Hi glue, what about thru the headphone output

Heya TSHORBA! Hope you had a rockin xmas.

Yeah, the noise comes through the phones socket too.

Heres a capture of the noise, in case it helps. PC only records mono though.

3.43 meg. Recorded with selector on Tape 1, nothing being adjusted at all on the radio.


Rock On.

Sounds like its an Orange Capacitor thing.


link

Ahh indeed Transwave5000 that was one of the things I'd been contemplating, in which case my local repairer dude can sort it out.

Finding/replacing a screwy capacitor is a job very much placed in my Too Hard basket.

Thanks brother!



Rock On.

have you tried to dox the tape record switch and/or move it back and forth to see if the noise stops?

It sounds like problems in the preamp section if all the sources have it. LMK

Hi Kittmaster

Yeah, I cleaned the tape record switch. I've followed all the instructions given in this thread with no improvement at all,.. and unfortunately that thead ends without any kind of conclusions.

Thanks very much for the help and reply!



Rock On.

Oh crap, I think I know what could be wrong, I'm betting two of the wire connectors are mixed up. I've done this twice. But you say it plays, mine didn't play.

It had to do with the identical 3 pin connectors that caused this, and it only affected one channel. It was "humming"......is yours humming regarless of volume position?

The static/white noise and popping sound does get louder or quieter depending on the volume. So if I take the volume down to zero, then the noise disappears.

Both decks play fine on this Conion, all new belts and such, JLF had them fully serviced before it was sold.



Rock On.

There have been some defective ha1392 floating around,maybe this is the problem here.Mine did the same thing until 2 chips replacements later.I finally went with a NTE1606 on both sides problem solved.Apply pressure with finger to the amp chips while playing ,applying pressure seemed to fix the poping until u let it go.

Hi Jimski

I tried that pushing on the amp chip test and it didn't change the noise level at all, before the amp chips were replaced and on the new ones.

It's at the repairers now, so I'll be sure to post a full debriefing when I get her back. He was of the impression it was something in the pre-amp section that was causing it, based on my 2 minute conversation with him, so we'll find out soon enough.

Thanks for all the help and suggestions brothers.



Rock On.

UPDATE!

Repairer dude has narrowed the issue down to an IC before the volume control.

He's planning on having it all fixed by the end of the week, so I'll post more information when I pick it up. I'll be sure to get a detailled description of the problem and fix for it to post here for any other unfortunates who have/develop this C-100 affliction.



Rock On.

Great News!

My C-100F's back from the repairer and the fault's been fixed!!

The issue ended up being voltage leaking through the mode selector switch. He said 5v was coming through the left channel and causing the noise. He said he's repaired a few very similar switch types like this that developed similar problems and it's probably an inheirent design flaw in them. The soloution was to rewire those connections to a different point on the switches boards using ribbon cable and bypassing the problem area.

I was told this an hour ago and am hoping I got it all correct as I was trying to remember all he was saying and trying to contain my excitement at the same time.

I hope this helps someone else some day who ends up scoring a Conion with static or noise coming through a channel.


Thanks for helping me through this trying experience brothers, the repairer has my Lasonic 931 to work his magic upon now. Thank ghettoblaster gods that I hooked up with this guy thats for sure.



Rock On.

That sounds like great news, but now you have a modified radio. If he found the root, you should have mentioned that you could get replacement parts here, then all he would have had to do was swap out the part. I'm not a fan of hacking up a circuit as you describe, but if it works, then I guess its a win/win

Congrats

Thanks Kittmaster! I don't mind having non-stock radios. Hell, hardly any of mine are, I always seem to be tweaking/adding/modding something. Fully functioning is what I value the most.

It's more knowledge for the s2go community either way!



Rockin on to Ultramagnetic MC's on my C-100F!