Technics SU-V1X (1986) left channel failure

[pd44]

I dusted off this fine old amp yesterday. Alas, left channel is one of completely soundless, almost soundless, fuzzy/distorted lower range or very occasionally absolutely fine. Same whether on "main" or "remote" speakers.

I thought I'd see if any one knew of any simpler hacks/fixes I could try? Obviously 40 year old circuit boards may have issues requiring more specialist endeavours ...

 

[Gray]

I dusted off this fine old amp yesterday. Alas, left channel is one of completely soundless, almost soundless, fuzzy/distorted lower range or very occasionally absolutely fine. Same whether on "main" or "remote" speakers.

I thought I'd see if any one new of any simpler hacks/fixes I could try? Obviously 40 year old circuit boards may have issues requiring more specialist endeavours ...

A can of 'Servisol Super 10' will (almost certainly) cure your problem.

 

[pd44]

A can of 'Servisol Super 10' will (almost certainly) cure your problem.

where? everywhere? I'm pretty sure I tried this a few years ago, to little effect, but can try again, I have Deoxit D5, which is what music shops over here sell ...

 

[Shrek]

where? everywhere? I'm pretty sure I tried this a few years ago, to little effect, but can try again, I have Deoxit D5, which is what music shops over here sell ...

Dissconect from the mains.Take the cover of and spray inside the switches rotate or press them and the same time.
If its very dusty inside gently brush the dust away and hoover very gently carefully .

 

[pd44]

where? everywhere? I'm pretty sure I tried this a few years ago, to little effect, but can try again, I have Deoxit D5, which is what music shops over here sell ...

Dissconect from the mains.Take the cover of and spray inside the switches rotate or press them and the same time.

Switches? It's the whole channel I've not got - although could it be the "balance" button messing stuff up? I have sprayed the plates at the back, where I connect the speakers, without success. I'm suspecting the large flux capacitor by the speaker out channel (on the right in the image) Can't access the "balance" button from inside, shall try spraying from outside ...

 

[Gray]

where? everywhere?

In all critical places.
It must hit (and get between the contacts of) all signal switches and between the wipers and tracks of all rotary controls.
Switches can be mostly sealed, but contact cleaner can get in - in the same way the contamination did.
Rotary controls have spray access where their PCB pins enter their screening bodies.

If your channel dropout is common to all inputs then volume or balance control could be the cause - but, especially tone defeat switches are troublemakers.
Input switches would effect only individual inputs - but do everything.

If (big if) your Deoxit is as good as Servisol, it will do the trick 👍

(If it was me, I'd be buying the Servisol).

 

[Shrek]

can you take the balance button of? will give you better access spray the volume button too.

 

[Gray]

I have sprayed the plates at the back, where I connect the speakers,

As you've found, no chance of that curing your symptoms.
You must get the cleaner inside the critical places I've mentioned.