Pioneer X-HM72 (and X-HM82) power supply repair

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gadgetmind

Joined Apr 19, 2024
5
Hi, first posting, so hope all OK.

I fixed one of the above Receivers at a Repair Cafe recently and wanted to post somewhere so that others could see what was wrong and how to fix.

When the chap first brought it in, I did the usual visual checks and the SMPS controller (CoolSET ICE3BR0665J) had its top blown off, so that was obviously where to start. I found the service manual with schematics online and contacted the guy suggesting he buy the chip (now we knew what it was!) and bring it and the receiver along the next time.

I checked the likely route of the high current carefully, starting with the transformer as it was game over if that was dead, but it was fine. I then checked the source current sense resistors (1.5ohm and 1.8ohm in parallel) and both were open circuit. Fortunately they are 3216 (1206 in legacy units) packages so easy enough to hand solder and I removed the CoolSET chip at the same time to make life easier. I also found two bridge diodes (1N4007) open and swapped those, replaced the CoolSET, wired a radial fuse across the radial one for a quick test, and it powered up! Yay!

I then did a cap safety discharge and fitted a better fuse.

Happy customer and a fairly cheap repair. Everything except the CoolSET was in my mobile set of parts as I'd bought the resistors just in case as I guessed they'd be dead.

This all took 80 minutes, which is very much at the top end of what we can allocate to a single fix at a Repair Cafe, but it was a nice bit of kit, expensive to replace, and the blown chip was a bit of a give away.
 
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