Question about NAD 712

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NAD 7155 with one speaker channel not working

Found no info on this site for my OLD 7155, but the 712 looks very similar and may be an updated product...? One speaker channel isn't working. Any suggestions? Any "testing" I can do to help isolate the problem? I've never worked on electronics, but have on most other items and have basic good sense. I'm not afraid to attempt a minor repair or part replacement.

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In my case, if I push in on the balance knob, I can get the channel that quits to work for a while.
This leads me to believe that the pot is dirty as opposed to a circuit or component failure.
A couple of years ago, I sprayed circuit cleaner into the pot as best I could and the problem disappeared but, it has returned.
My next attempt will be with one of the newer cleaner/lubricators that are available now.
I don't know if this will solve your problem but, it might be worth a try.
BTW, getting access to the volume/balance pots takes some doing. As long as you are there treat both pots.
Greydog(1)
G

Posted on Sep 22, 2008

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Hello All, No sound out of one channel on NAD 7155 (Others as well) is usually a loose solder connection on the Balance/Volume switch.
1. Disconnect everything from 7155 and unplug and remove it
from whatever it's on or in.
2. Place it upside down on a table you can work on near an outlet.
3. Remove all screws from bottom panel, remove bottom panel and
set it aside. You should now be looking at bottom of main circuit
board.
4. Attach 1 speaker to the channel that is failing (Left or Right) on
the A speaker panel jack set.
5. Make sure power switch is set to off.
6. Make sure speaker selection is set to A.
7. Set listen switch to tuner.
8. Set volume at lowest (off) setting.
9. Plug receiver into outlet. Turn power on.
10. Tune in a station, you might need to hook a wire up to antenna.
11. Advance Volume to about 15 percent.
12. Locate where the Volume/Balance control is mounted and
soldered to circuit board.
13. Using a flat head screwdriver or the like, start pressing on
and messing with each pin that is soldered to the board to
locate the one that is faulty. There are about ten. One of these
pins (Hopefully only one) is either loose or cold soldered.
The sound cuts on when you found it.
14. Turn off receiver power and unplug.
15. Re-solder the faulty pin. Also a good idea to re-solder other
pins that look weak.
16. Reapply power to ensure connection is now solid.
17. If still a problem, repeat troubleshooting procedure, but, you
should be golden.
18. Reverse dis-assembly procedure and you got it from here.

HISTORY:

This is a very common problem with the older NAD equipment.
They made great equipment for the price. They soldered all switches
directly to the circuit board to cut down on costs. After years and years of pushing and turning the switch's, the solder points weaken and can break.

MY PROBLEM.
Right Channel not working.
Removed Volume/Balance knobs.
Applied different directional pressure to balance switch and Right
Channel would intermittently come back on.
Thought switch just needed cleaning, bought electronic switch cleaner
and drowned switch.
Still a no go.
Searched web and found story about weakened solder points on old
NAD switches.
You know the rest. It is a good idea to use electronic cleaner on this old equipment anyway. Remove covers and just attack switches from any vantage point you can find. Remember to also work the switches. This usually will quieten all the switches and fix a stuck AM/FM switch which is very common. People will often say tuner is broken on a NAD receiver they are selling cheap. It is almost always a sticky AM/FM selector switch which can be fixed by electronic cleaner. (HINT,HINT)
REMEMBER TO REALLY LET EQUIPMENT DRY AFTER USING ELECTRONIC CLEANER. THAT STUFF POOLS ALL OVER THE PLACE, OFTEN OUT OF VIEW, AND IS EXTREMELY FLAMMABLE AND EASILY IGNITED.


Posted on Jul 20, 2014

Just last night I took my 7155 apart for this same problem.
If you take the screws that hold the top circuit board in place out, you can lift the board out of the way enough to get your cleaner nozzle right to the opsening on the sides of the pots.
In my case, the balance pots seemed to be the problem. I sprayed a lot of cleaner through both of the balance pots and gave the volume pot a pretty good soaking, too.
After the solvent dried, I used some contact lube before I buttoned everything up.
Worked great. Good luck.
BTW, my usual nick is Greydog, too. Greyhounds?
G

Posted on Nov 05, 2008

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