Hello folks....I'm currently trying to refresh my Nikko 220 amp with a recap and I'm having a hard time finding replacement mica insulators for the power transistors. They must fit a 2SC2565 transistor as an example this being one of them. The old insulators measure 38mm long by 20mm wide with holes centred 25mm between. If I can't find new ones I'll have to clean and reuse the old ones but I'd rather not do that as one of the old ones is cracked. I've done a Google search and checked Mouser but can't pin it down to a correct one. Any help is appreciated.
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I think those are MT-200 outline insulators.
Mica Transparent Insulator MT-200 Package (5 Pieces) - Arcade Parts and Repair
Mica Transparent Insulator MT-200 Package (5 Pieces) - Arcade Parts and Repair
Thanks a bunch Mooly for the link. That does look like them. I guess if I can't find them in Canada I'll have to purchase from there. Might take a while to get them is the only issue.
You'll have to search the catalogues but it seems that is the correct outline.
You can also get the more modern silicon rubber as a plain sheet and perhaps cut your own. You would have to be able to drill mounting holes in it though.
Hopefully you'll be able to source some 🙂 Good luck.
You can also get the more modern silicon rubber as a plain sheet and perhaps cut your own. You would have to be able to drill mounting holes in it though.
Hopefully you'll be able to source some 🙂 Good luck.
I just checked it out and it will cost more to ship it than what the order cost. Thought I'd order 10 packs to have extras on hand and with shipping it's almost $50.00 CDN. Will have to try another source. Thanks again.
BD Ent is a little cheaper. Thanks for that link. May have to just pull the trigger but I hate having to pay $20 USD ( $25 CDN ) for shipping a package the weight of a Kleenex but seems I don't have a choice.
Would it be a terrible thing to clean and reuse with new thermal paste the old insulators if they have a crack but still intact I wonder.
Would it be a terrible thing to clean and reuse with new thermal paste the old insulators if they have a crack but still intact I wonder.
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BDent is a good place for Japanese transistors, many long out of production, so maybe stock up on a few common ones.
Craig
Craig
Thanks for the advise. I'm no tech for sure and more of a parts changer. Done a bunch of Marantz units with help from the good folks on the forums like yourself. This Nikko unit is the first in this product line that I've worked on aside from the Beta 20 pre that I recapped last week. These Power transistors are new to me. I have some mica for outputs used in Marantz units but not like these. I've run out of Marantz to tinker with so the Nikko is filling the void.
I only removed the aluminum heat sink on one side only this morning after working the night shift. The output transistors on that side had Mica insulators. I just removed the heat sink on the other side and low and behold the output transistors have no insulators under them at all just old dried up compound. Would there be a reason why only one side had insulators and the other side didn't? I can only assume that somebody's worked on this amp before.
Another question... There are 4 small capacitance electrolytic caps on this board at 100V 1uF. Should I replace them with the same or could I use film capacitors in these four locations such as Wima.
You can probably use film caps but electrolytics can be more suitable in some positions. It all depends what there function is.
The missing mica washers sound suspicious. If the transistors are metal backed and that backing is the Collector then I would assume that they would place a short across the supply if the insulators were missing or depending on the configuration, apply a dead short to the speaker output. All depends what the output stage configuration is.
The missing mica washers sound suspicious. If the transistors are metal backed and that backing is the Collector then I would assume that they would place a short across the supply if the insulators were missing or depending on the configuration, apply a dead short to the speaker output. All depends what the output stage configuration is.
I have some small value caps on order. Oh and I must have had a senior moment... I hate to admit it but my lazy susan was spun around and I was looking at the same darn heat sink from the morning. I also have new Mica on order so now its a waiting game.
sounds like a plan.