Quote:
Originally Posted by Blast
Ed in Tx is ALL OVER this one. To both paraphrase him and add to what he said: You will need to find EVERY COMPONENT that is bad, or near-bad (read: resistors), before these power supplies will fully function and not take out most, if not ALL, of the components you've already replaced! Trust me! That's both on the "hot" side AND the secondary.
These pre-'86 Panasonic SMPS's were nothing but a nightmare for me as I was learning VCR repair in the late 80's. I got my ass kicked on several occasions. Fortunately, the senior tech (read: boss) was there to bail me out. Most of the time...
It wasn't until Panasonic's '85-'86 models where the power supply circuitry was finally 'trimmed down a bit' to my limited brain power before I would really start to get my wings on these. Then, in the late 80's I would develop a list of EVERYTHING that should be replaced before further diagnosing any ADDITIONAL problems.
Good luck, starbond, on your journey repairing this and ultimately playing back your tape collection!
Brian
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Oh boy, maybe I'm biting off more than I can chew haha. I wouldve hoped the primary side was the issue as I have only been focused there BUT maybe there's something obvious on the secondary side I have missed.
I'm no electronics pro, but this is the first time I've dealt with a bad power supply, in my limited years of working on VCRs, tape decks, receivers, etc.
It will be rewarding to get it working again, if not to see all the lights go on and putting a tape in and seeing the wondeful picture. Now if it turns out there's also a tape transport problem, well....
I want to thank all of you and Ed in particular for the help so far. I can give values and pull parts and replace them but where i struggle is intpresting what the values mean, and how to trace the board to the issue as I have no EE experience beyond self experimentation and all the folks at AK and VK
Vortex,
I admit i have no knowledge of diodes beyond that its kind of a one-way power direction-er, but I have seen conflicting information that varies from "it should be OL in reverse" to "getting a reverse measurement is OK"
Now that being said, these diodes are small and only have a colored band around them if anything, is there an easy way to identify how it should be replaced without a schematic?
Lastly, when I removed the bridge rectifier and turned the power on, there was no fuse blowing. Probably doesnt mean much but its the only time a pulled component prevented a blow (this was pre dim-bulb)