My Yamaha CR-640 recently had a short, and unfortunately, one of the IG02980s was a casualty. I have seen a few posts about replacing the part, but I'm curious whether there are any updated sources for reliable replacement parts. I'd appreciate any advice on this topic. Thank you.
Needing Yamaha CR-640 IG02980 Replacement Advice
- Thread starter MGrady81
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On the thread where the quote above was taken, the STK0050ii was used to replace the IG02980 with success.
The original power packs are indeed equivalent to Sanyo STK0050II. If you don't want to take chances with sourcing a clone from, let's say, "overseas" suppliers, I believe you can use the discrete reproductions of STK0050 from Pyramid (no affiliation):
www.pyramid-audio.com
The Pyramid design, AFAICT, is a two-stage Darlington configuration instead of the original's three-stage. But they say they test them in a Marantz SR4000, which also used three-stage power packs (and in fact is a very similar power amp design to the Yamaha).
If you're interested in the Pyramid, check physical dimensions to make sure it will fit.
Regardless of what power pack you use, you'll want to also check the emitter resistors. These are the large 0.47 ohm ceramic resistors located in the vicinity of the power packs. You won't be able to measure them accurately with a typical ohmmeter, but just make sure they measure less than about 1 ohm.
Modules — PYRAMID AUDIO
www.pyramid-audio.com
The Pyramid design, AFAICT, is a two-stage Darlington configuration instead of the original's three-stage. But they say they test them in a Marantz SR4000, which also used three-stage power packs (and in fact is a very similar power amp design to the Yamaha).
If you're interested in the Pyramid, check physical dimensions to make sure it will fit.
Regardless of what power pack you use, you'll want to also check the emitter resistors. These are the large 0.47 ohm ceramic resistors located in the vicinity of the power packs. You won't be able to measure them accurately with a typical ohmmeter, but just make sure they measure less than about 1 ohm.
@chazix Thanks for the information regarding the Pyramid source. Can you provide more information on the ceramic resistors and why I can't accurately measure them with a typical ohmmeter (sorry, I'm a very green novice)? One at IC704 measured defective (sorry, I can't remember the exact reading). I want to make sure I am checking everything correctly so I don't replace parts when they aren't needed.The original power packs are indeed equivalent to Sanyo STK0050II. If you don't want to take chances with sourcing a clone from, let's say, "overseas" suppliers, I believe you can use the discrete reproductions of STK0050 from Pyramid (no affiliation):
Modules — PYRAMID AUDIO
The Pyramid design, AFAICT, is a two-stage Darlington configuration instead of the original's three-stage. But they say they test them in a Marantz SR4000, which also used three-stage power packs (and in fact is a very similar power amp design to the Yamaha).
If you're interested in the Pyramid, check physical dimensions to make sure it will fit.
Regardless of what power pack you use, you'll want to also check the emitter resistors. These are the large 0.47 ohm ceramic resistors located in the vicinity of the power packs. You won't be able to measure them accurately with a typical ohmmeter, but just make sure they measure less than about 1 ohm.
When I looked into this they seemed to cross to STK-0040II. I took my chances on the eBay modules from "semitronus". I swear they might be genuine. But without an x-ray machine I'll never know for sure. I did a video on them in a CR640 here:
I think there is a better chance of finding genuine "STK-00xxII" models than there are the non-II which seemed to be more common in some of the earlier amps.
They have been holding up fine... YMMV.
I think there is a better chance of finding genuine "STK-00xxII" models than there are the non-II which seemed to be more common in some of the earlier amps.
They have been holding up fine... YMMV.
Mainly because the ohmmeter leads themselves can contribute several tenths of an ohm to the reading - you can verify that by shorting the leads directly together and seeing what reading you get. You can use that reading as an offset to what you read across the 0.47 ohm parts, but at this range there are other appreciable sources of error, like imperfect contact between the meter leads and the parts.
A saving grace is that such resistors usually fail by going completely open, so if they don't read open-circuit, then they are very likely to be just fine.