Sony Receiver power transistor question

jeepers59

Member
2019-11-08 7:29 pm
Hello,

I'm new to this forum. I have the Protector issue with my Sony STR-DE705 receiver and was able to troubleshoot it by reading some of the conversations on this forum.

I found 2 transistors that have 50v on both collector and emitter to ground and i will be replacing them. The transistors MN2488 63P and MP1620 63Y. i interpret the data sheet as 63 is year/month and the P and Y are hFE rank, what is that and do i need to stick with the P and Y? also the resistor package (dual .22ohm) tests good in the circuit and doesn't look fried, do i need to replace that too?

Thanks for your help in advance
 
I can't see why you should replace those resistors.
Are there any similar transistors in the circuit that haven't been blown? If so, you could compare their hFE and whether they are matched or not. hFE is the amount of gain the transistor applies to the incoming current. Since they are darlingtons, that figure is pretty high, what could make the circuit sensitive to even slight changes.
 
From another thread (Sony 5.1 output transistors repair) (however, no good news...):

"Unfortunately, the MN2488 and MP1620 are discontinued and not easy to find. They are not typical power transistors, they are darlingtons, and they have a fairly unique combination of voltage, current and power ratings. That makes them virtually impossible to substitute. Their popularity, especially with Sony, and their failure rate means a pretty consistent demand for replacements. That demand coupled with discontinued status means that fakes will likely be on the market. "
 
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jeepers59

Member
2019-11-08 7:29 pm

Hi jaycee, I ordered these transistors from digikey but one of them is now backordered and they are telling 6 months. But they are going to look into it further. do you have any other supplier recommendations in the states? thanks!

i think i would rather stick with Sanken, but are motorola transistors ok to use? there is an electronics store close by that cross referenced to motorola but they are like $12 each.

Thanks a lot,
mark
 

wg_ski

Member
2007-10-10 5:21 pm
Motorola would be On Semi, unless it were old stock. But they don’t make anything remotely close to Sanken darlingtons. TIPs don’t count, and they don’t make darlington versions of the 3281 family. If you don’t want to wait on the long lead time, you might consider a pair of the next size up in voltage/current/power from the Sanken line.
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
Newark is and always was a good supplier.

In the US, Sanken is distributed by Allegro and the link on Allegro sends you direct to Sanken's site.

I do not know if the suggested replacements are exact equivalents. However Sanken has made a lot of audio power transistors and getting them from Allied is a hundred times safer than eBay.