SM8927 transistors (NAP250 CB BU)

[neiljadman]

Why rebuild at all? Are the MJ15003s supposed to be superior to the BDY58s? Or is it likely the latter have degraded over time? All self-interested questions as my 250 has BDY58s dating from 1979.

Because this particular amp is blown in one channel - no rebuild = no use!

So while I'm about it I was considering ripping the whole thing apart after all so much was sub optimal in these amps - power supply arrangements, star ground between the speaker returns etc...


Strongly considering 2 of hackers boards before the regulators and a pair of new NJPA boards after - yet to decide what to do with the regulators...it'll be a slow work in progress with nothing to lose...

 

[ramona]

Ramona do you know where you read this? Also what do you mean by "used in the bid Naims amps" ... BIG maybe? Thanks.

The specs for BUX20 look very similar and they seem to be more available than BUV20 at this time.

IIRC, it was on DiyAudio sometime ago and I think the mention was for the Naim 500s (yes, I meant BIG) . It seems that no one has try them yet and I'm gonna make the lip first. I'm gonna report back. My boards are NCC200s but I see no reason why NAP250s can't have them on.

 

[mikesnowdon]

Ramona do you know where you read this? Also what do you mean by "used in the bid Naims amps" ... BIG maybe? Thanks.

The specs for BUX20 look very similar and they seem to be more available than BUV20 at this time.

bid = Back in the day?

 

[nonsub]

"....SM3282..."

As Neil indicated this is just the manufacturer + date code not the model. It SEEMs the 001's are BUV20s... and I think I will assume that "customized for NAIM" simply means the label lol.

 

[martin clark]

It could also mean other things, like selection from production for Hfe vs. Ic and/or other parameters we don't know about.

 

[nonsub]

Thanks. Whilst this thread has been revived I'll ask if anyone has experience. At some point it looks like 1 of my CB bolt ups at some point got upgraded to 001's the other 2 are BDY58:

a) Anyone hear or speculate even a sound/performance difference between BDY58 and 001's? Maybe I do the other 2 to BUV20s as well...

b) Should I be wary of fakes of either when looking to buy?

c) Whats the best way to match these? I have 4 blown


Thx

 

[nonsub]

Interesting/contradictory find, a post by the late Julian Vereker"

" *****jv: I guess it's one of those small oversights, the BUV20 series
of transistors are not even the same technology as our NA001s, but
they do reside in a similar sized case. A case of similarity being
just skin deep?

julian
"