1980s QUAD 34 Audio Control Unit - Troubleshooting One Dead Channel 

If I was the owner of that lovely Quad 34, I would be extremely upset. I'm afraid you're out of your depth, it WAS a very cool device.

Breaking the rules of his capability limits: Do NOT touch anything that has transistors, chips or PCB (even single-sided through holes). Extensive to any gear that you plug, has more than two knobs, two switches and more than a single scale.

what is good about this so-called repair it is no problem to fix for an authorized repairerman later

31:04 NO! You should never ever use just a clip lead to bridge out or across components or to combine channels in an audio circuit! Especially not with solid state and without analyzing the schematic! This solid state stuff with opamps uses DC bias voltages. Nilly willy shorting between circuit nodes may introduce new or kill existing bias voltages. This may damage components! Use a capacitor in series with the clip lead to have audio pass but block any DC biasing. He is lucky this device is so forgiving! Poor owner.

Yep I have serviced a couple 34's and the ones with the small black 100uf 6.3v caps all leak and have to be replaced and corroded traces repaired. The 34 I am currently working on also has a failed balance slider pot but I removed and took it apart to discover one of the wiper's plastic clips broke breaking the contact to the carbon track. Glue the wiper back and its good.

But the pre amp is not fixed !!! Bypassing the balance control is not a repair !!! Probably the balance pot just send to voltages to amp-ops and these are the chips that control the volume of Left and Right channel... So he bought TWO sets of caps, didn't used ANY and is calling this a success repair ?!?!?!?

As customary, hide schematic, no troubleshooting as defined by civilized world, blame manufacturer for poor soldering, no identification of fault or defective components, random pocking with rusted screwdriver and finger, no understanding of anything, ending with crippling the balance control grand finale. If this dude has the nerve to bill this as a repair, he should be taken to court. Hopeless.

Man, when I seen the PCB I knew this would be a disaster. He can’t follow schematics on a big old easy tube radio. He would be clueless on a somewhat complicated modern piece of gear. Good point by another poster, this radio plays great in his shop but all radios he repairs that don’t perform it is caused by noise in his shop. Complete useless excuses for lack of skill in this type of work. Maybe he should make funny cat videos, they are more inquisitive on what is on the bench than he is.

I have the very same problem on my 34...I packed it away 10 years ago with the 306 thinking one day I'd pay a TEC Wizard to repair it...I still wouldn't attempt anything myself..its way outta my skill level....hopefully its the same fault as yours

See how a good radio works perfectly well inside his shop? That story of "excessive noise" is just BS... Doesn't he have a signal generator, I mean, to use a small screwdriver to poke around the PCB ?! WE DON'T GET TO SEE THE SCHEMATICS !!!

UNBELIEVEABLE ! Again a half ass repair of a nice piece of audio gear. I wonder who paid for the capacitors....Twice.

Are ya gonna jabber about it or do it?

the input is of the Class A type to the cleanest signal possible so you have a complementary pair so both of the transistors need to be replaced.

And I have the CBC app as well

I used to listen to that show when it was on Sirius (now CBC Radio 1 is on XM but I don’t know when that is on now because they changed the time it airs)

Or the chip

The two points are a failure in soldering. Thats not hand soldering. I hate chips soldered in. Yup its a manufacturing defect of the wave soldering bath.

Op Amp crap! No fun here.