No Stereo - Only Mono Playback Question?

I just hooked up an old Kenwood KR 6600 and the left channel is out until I hit the mono button and then both sides play. What could the problem be and how can I trouble shoot? Total novice here and any help appreciated!

OK I got the stereo playback to work but it goes on and off. Is this a heating problem that happens when the receiver gets heated?

 

Is this the case with all inputs?

 

Yes, it was the same with the turntable and CD player.

 

One channel appears to be intermittent in your amplifier. When you hit the mono switch you are hearing one channel through both speakers.
It may be just a dirty volume or balance control. Try cleaning it.
Otherwise you may have to get it professionally serviced.

 

Thanks! I pulled the knobs off and blew some air. Its working right now but I'm waiting to see if it cuts out again when it heats back up.

 

Wouldn't be the amplifier or mono would only work with one speaker. Must be something before the actual amplifier.

 

Could it be something in the phono pre-amp?

 

I plugged the turntable directly into the phono output. Its playing right but I'm once again waiting to see what happens when it heats up.


Listening to sides 3 & 4 of The Byrds - Untitled and it is sounding wonderful!

 

Dirty pot, or switch. When it's intermittent like that, I've always found that getting some contact cleaner in the pots and switches will clear it up.

 

+1

 

Sure if it only does it when using that input.

It's somewhere in the circuit before the mono switch because it's fine after that point. It could even be a switch contact, but it should be easy enough to troubleshoot. If it's only when you're listening to the phono, then reverse the phono inputs. If the outage goes to the other side, it's something in the record playing system, which includes the cartridge and all wiring from it to the phono preamp. If it stays on the same side, it's most likely the phono preamp, but it still could be a bad switch or in the line stage of the preamp, if there is one.

 

great, great album...glad it's working for you so far!

 

No, you have a dirty stereo/mono switch most likely. Other switches may be causing one channel to cut out, Loudness switch, function selector (it has a common contact to the pre-amplifier stage) sometimes a dirty volume or balance pot.

Clean with straight contact cleaner, no de-oxit. It's only dust and sticky resin naturally airborne, that causes dust to adhere to electrical contacts. If contact cleaner does not work, then try deoxit. (do not use deoxit first as it contains acid, and causes eventual re-oxidation of the contacts... plus electrically conductive preserver... not good for the electronics)

 

Hi there,

I have a similar noise problem with my balance switches contacts. I have just bought Nortek Contact Cleaner hoping it will solve this problem. According to the date stamped on the bottom face, it was made in September 2016:
https://www.amazon.com/Nortek-Contact-Cleaner-312g/dp/B0778RNL2W

1) Is it still good to use for this purpose?

There was another one (with a lube) in the store:
Contact Cleaner & Lube - 340g - Buy Online in Oman. | Industrial Products in Oman - See Prices, Reviews and Free Delivery in Muscat, Seeb, Salalah, Bawshar, Sohar - Desertcart Oman
I did not buy it yet.

2) Which one of two would be the best to use?

Thank you!

 

Hi,
Of the several products on the market, all of them contain mostly contact cleaner. The other additives are not beneficial, and even detrimental to the performance of an amplifier or receiver.

I suggest the first one (Nortek)

I have been using regular contact cleaner for decades, my restos last for decades trouble free. A 2016 dated product is good to go.
Just to summarize, contact cleaner with lube contains light oil, and oil is a conductor of electricity (dielectric) and also an insulator. Oil between contact points is not good. Oil in a potentiometer "turns it into a capacitor", which can color the sound. Other types of lube contact cleaner contain dry silicone lube. I believe this type of cleaner is safe to use, and does not change the specs of the pot (and the circuit)

Deoxit is even worse. The very mild acid can have a long term oxidizing effect on internal metal parts, so I avoid it. I have used acid to clean metal for paint prep, however the primer seals out oxygen. Deoxit products contain also a preservative to keep out oxygen and future oxidation (acid is a deox agent, but also an oxidizer just the same) The preserver is oil based, and also contains a conductive additive (to help contact points to make positive contact) however this came conductive additive also conducts to ground, and (probably) alters the value of a potentiometer, and may cause signal bleed in a switch. I have yet to measure this effect, but very, very suspicious, and avoid this product.

Thirdly, a noisy switch or pot should not be assumed to be oxidized. What occurs in most cases, the air contains particulates of resin (which leaves an oil based deposit on literally everything) from trees, household cooking, tobacco smoke, neighbors burning wood, etc. This collects on internal parts, plus dust which adheres to the resin. Contact cleaner effectively dissolves and displaces this "oil/ dust sludge" ... only a microfilm is enough to cause static and noisy operation. So, in most cases the switch or pot is not oxidized.

If contact cleaner fails to do the job then apply deoxit.

Very important when cleaning, just apply one or two short bursts of contact cleaner, operate the control over its full range, and repeat. Never "firehose" the pot or switch, since lube in the bearings will be washed on the electronic contacts... and we don't want that. How we apply the contact cleaner is important. Find an opening in the pot or switch to spray, and try to aim in two directions, if possible.

good luck,
Steve VK

 

I doubt if it is a thermal related problem. more likely a mechanical one with an intermittent connection.

This would be before the power amplifier section of your integrated. This is why when you hit the mono switch that the sound from one channel was delivered to the two inputs of your power amplifier section and why the sound came out of both speakers.

If the problem was in the preamp section, I doubt that it would be intermittent.

 

In addition to my previous comment,

Pots are self lubricating, only very cheap pots contain lube on the trace and wiper. Linear pots likewise have no lube on the trace and wiper, but the other bearing surfaces do contain special silicone lube for smooth operation. (cleaning these is very difficult since the lube may be "washed" on the wiper and trace)

Secondly, switch contacts never need any lubrication (but the other moving parts are lubricated as manufactured.. only sometimes) The contacts should be clean and dry. Dry Silicone lube can be applied, but not necessary.

 

I've been "firehosing" pots for years with zero problems, lol. I'm sure your info is spot on, but I'm OCD and I keep spraying and working those knobs until they're silky smooth I'm a rebel without a cause.

 

Sounds like it could be an easy or hard fix. Either a dirty pot or a capacitor blown.

 

Yes, I have fire-hosed also (stopped doing that eons ago) because eventually all the shaft lube gets washed out, and we've got a very clean pot and it operates freely. The lube on the shaft and bearing are what dampens the action. Some pots operate more freely than others, such as CTS pots for guitars... but most pre-amps/ receivers have a damped feel of the controls, as shipped from the factory. I do my best to preserve this like-new physical "feel" of the pot. The vintage Pioneer products, and others have soft click-stops, which these need to retain their special lube to operate with that nice touch. The switches and pots on many vintage products are rebuildable, and I'm that crazy!

 

And on some models of Kenwood amplifiers, and receivers, soldering has been a known issue causing such intermittent loss of a channel. And it losing the channel as the amplifier gets warm points to this as a possible cause or an intermittent component.

 

If a cap was blown, it could just be replaced. If it was a cap, the OP would not be able to have gotten it working on a temporary basis.

 

Possible, but I am not getting the impression that it is heat related. The OP was just assuming that it was because it was on for a while and so it must be heating up. Although this is a possibility that can not be ruled out, I remain skeptical and feel that it is a simple connection issue. Placing jumper wires with alligator clips and effectively by passing switches and pots will tell a better story.