Fun with radio repair

Ikarus1

Avtomat Krishna-kov
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So after I finally got a microphone for my 2 meter Alinco, I discovered that I have no transmit power. At all. None. The receiver works great, much better than I expected. But I want to transmit, so I did a little research. Turns out all the Toshiba finals (S-AV 17 and S-AV24) like to get hot and crack. Lo and behold, the modules are more than the radio is worth. So I may decide to try a circuit repair. These traces are literally too small to see...
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cleaned off and inspectes the mounting surface, no really bad spots. I think I can lap the back of the IC module once I get it making power again, put some thin CPU paste and see what happens. Got the schematics from a PDF. The DR130 has an SAV17 but the T model has the broadband SAV24... Of course, nobody makes an equivalent module. They are interchangeable on the 2 meter band.

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If the cracks in the traces aren't readily repaired with soldering techniques because of temperature concern, another option is the Permatex Rear Window Defroster Repair Kit.

It's a tiny bottle of conductive paint.

I've used it to repair cracked traces on TV remotes, worn off contact pads on PC boards where push buttons are supposed to make contact, etc.

https://shop.advanceautoparts.com/p...ar-window-defogger-repair-kit-09117/7160063-P
 
Tagged to see how this turns out.. I had to replace a s-av32 in a ICOM rig a while back due to the same issue (no vhf tx power) but fortunately that was a $40 repair.

What purpose would lapping the back of the module serve?
 
Tagged to see how this turns out.. I had to replace a s-av32 in a ICOM rig a while back due to the same issue (no vhf tx power) but fortunately that was a $40 repair.

What purpose would lapping the back of the module serve?
better thermal transfer to th heatsink. same as CPU thermal paste applications
 
The silicon rubber blob over the bare die (if that's what it is) doesn't help. That's a cheezy way to "protect" die and has NOT worked out well , especially in a PA application with significant thermal excursions. Toshiba should know better (maybe they do now!)
 
The silicon rubber blob over the bare die (if that's what it is) doesn't help. That's a cheezy way to "protect" die and has NOT worked out well , especially in a PA application with significant thermal excursions. Toshiba should know better (maybe they do now!)
Yeah I wasn't impressed with the snotblob on the IC...may figure out some tiny heatsinks
 
Did you find the actual crack in a trace somewhere? (One of the things I do is design PAs.) If so, and nothing else is toasted, it's repairable. But it doesn't fix the root cause (meaning, it might happen again later).

Unfortunately, if you have an older radio, you are going to have older RF parts in it. That module is already obsolete; the datasheet is from 2001. Separate rant: the Japanese have the shortest, least-useful datasheets for their RF devices of ANYONE.
 
Did you find the actual crack in a trace somewhere? (One of the things I do is design PAs.) If so, and nothing else is toasted, it's repairable. But it doesn't fix the root cause (meaning, it might happen again later).

Unfortunately, if you have an older radio, you are going to have older RF parts in it. That module is already obsolete; the datasheet is from 2001. Separate rant: the Japanese have the shortest, least-useful datasheets for their RF devices of ANYONE.

nah, I need a scope but it looks like faint lines directly thru that squiggly part my pencil is pointing at. At this point I may just ditch the POS and order one from Ghina

If you wanna take a look at it for me I'll drop it in the mail ;)
 
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nah, I need a scope but it looks like faint lines directly thru that squiggly part my pencil is pointing at. At this point I may just ditch the POS and order one from Ghina

If you wanna take a look at it for me I'll drop it in the mail ;)
Sure, even if just to do a bit of FA (failure analysis). I have magnification (when you get old, you need it ;) ). PM for address incoming.
 
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