Sanyo AVM-3659G Problems

[radiotvnut]

I don't recall seeing that many flyback failures in these later model Sanyo's; but, it can happen. When a HOT shorts in one of these, it's usually due to bad solder connections and/or bad electrolytic capacitors in the horizontal driver circuit or in the B+ line that provides voltage to the horizontal output circuit. In a few cases, I've seen the switching power supplies run away with themselves and send hundreds of volts over the B+ line to the horizontal output circuit. When this happens, it usually burns up a whole bunch of stuff all over the chassis and makes the TV not worth repairing. The best way to test a flyback is with a piece of equipment called a "ringer". The older models, like what I have, require that the flyback be removed from the circuit. Later models allowed for testing while the flyback was still in circuit. Back in the late '90's, a friend had about $10K worth of Sencore equipment that would do this.

I've also placed an ordinary 100W incandescent light bulb in place of the B+ fuse (or, fusible resistor if the set does not have a B+ fuse). The light bulb will act as a load and will help prevent damage, in the event of a short.

When ordering a new HOT, you might want to order 2 or 3 of them. If the fly is bad, the new HOT will often short instantly. That's why I check everything carefully before applying power because I don't like blowing up new parts if I can help it.

Once you get it going, check the B+ for the proper voltage. It's usually between 120V and 130V.

Here's a video I made of me using a light bulb in place of the B+ fuse and testing the flyback in an '82 Sylvania. I realize it's an older TV of another brand; but, the concept is still the same.

http://www.youtube.com/watch?v=IV4M7SqmAqo