Proton AT-470 needs ICU

[Dr.Turner]

Hi everybody,
before proceeding with my next repair as voted here, I would like to revive the Proton AT-470 tuner, companion to the Proton AM-452 amp I recently recapped and restored.

Problem: the tuner is not turning on at all.

I started with DBT (fine) and visual inspection:

• two jumpers were cut [???]
  
  
  
  
• there is a spot on the display glass
  
  

The mains are OK, and the transformer is correctly fed with 220V:




But the output from the transformer has no voltage, neither at the board (orange-orange-blue-blue-white output wires) nor at the power switch:

.....

Here is the main board:




Apparently the power transformer is dead, showing no visual sign of failure.
Do you suggest to remove and test it out of circuit?

Something else to perform first?

.

 

[Dr.Turner]

Unfortunately I have no Service Manual.

Therefore I have bought one from servicemanuals.com but after the processing time is well past their statements, and one email unanswered and one form-message ignored, I'm starting to get worried...

Do you have any experience with servicemanuals.com?


.

 

[Dr.Turner]

Service manual received, with only a slight delay!

 

[Dr.Turner]

Please find attached the Proton AT-470 schematics, FYI.

 

[audiotemp]

Please find attached the Proton AT-470 schematics, FYI.

It's not legible.

 

[Dr.Turner]

Dear audiotemp, thanks for your observation.
You mean it's a poor scan? You're right, one of the worst I've ever bought!

But please confirm it's not legible only in the gray PS area (unfortunately the one I need more...)

I will try to redraw that area based on actual components and live observation of PCB.
And post again...

 

[audiotemp]

You mean it's a poor scan? You're right, one of the worst I've ever bought!

It's completely and entirely illegible. Was the document degraded when you uploaded it here? Download a copy from your own link above and compare what you get with the original file that you uploaded. Large documents are sometimes degraded when you upload them to the forum.