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Icom 746pro sudden death

boog351

boog351

Member
Jun 21, 2024
14
5
13
Indiana
Pretty common problem, dead ic-151, mine has signal on the input, dead output.
Does anyone know of a reputable source for the UPC1678G ?
My usual sources, rf parts, mouser, digikey didn't have it.
I don't like buying parts from ebay, 2 listings from 1 seller as of now.
 

boog351 said:
Pretty common problem, dead ic-151, mine has signal on the input, dead output.
Does anyone know of a reputable source for the UPC1678G ?
My usual sources, rf parts, mouser, digikey didn't have it.
I don't like buying parts from ebay, 2 listings from 1 seller as of now.
Click to expand...
It's a very common part I believe that ICOM should have them.
 
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Thanks, I'll try that route, from what I've seen the original NEC part isn't made anymore, they do make the same part in a smaller package, and I've seen a 3 pin part suggested, but I'd rather go withe the original.
 
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doffo said:
Hoping this isnt common in the 756-Pro II. :| Got that radio on the shelf next to me.
Click to expand...
From what I've found the problem was fixed in the 756pro and later models, the part is a driver for the pa section, in previous models, the 756 and 746/746pro, that part was prone to overheating, icom claimed esd issues as well,.
The part dissipates heat through it's ground legs, it's an 8 pin ic with input output v+ and 5 ground legs.
The problem is that theres is not enough ground trace around the part to dissipate the heat.
Some had success crafting a copper loop over the top of the ic connected to the ground pins on either side of the ic to help with cooling.
Another problem was that the ic had a constant 5v supply, so the part could fail in rx mode.
Later models, the 756pro on, the 5v to the ic is switched with tx and there is add low pass filtering.
 
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