Realistic STA-2000D Bad power transitors

Thread Starter

BFreemanNH

Joined Jan 6, 2013
20
Thank you Bountyhunter, Once I saw the name of your file, it gave me the idea of searching google for STA-2000D.pdf and after a couple of clicks, I found the exact service manual. What a difference that makes. I now have the right part#s and I found a miss-wire from the factory.
Two of the identical PNP transitors on the left side of the board had their base and emitter wires swapped. Although the collector wires went from the board to the proper transistors, both the B and E wires coming from the board went to the opposite transistors then that of the collector wires. one of the two that are crossed, is shorted. Not sure if it matters much, but it must have worked that way for many years or it died a short life and has been kicked around ever since.
Anyways, I am going to cancel my order (Still on backorder) and find a direct replacement for the HITACHI 2SD675A NPN and 2SB655A PNP transistor set.

Now that I have the schematics and parts list, I can do a better job checking their little friends.

As always, thanks again for all the help.
 

Thread Starter

BFreemanNH

Joined Jan 6, 2013
20
OK, Mouser once again is pointing me towards the 526-NTE285MCP part# based on a cross from the original HITACHI numbers. How do I go about finding the original HITACHI set?
 

Thread Starter

BFreemanNH

Joined Jan 6, 2013
20
I ended up finding the exact replacement transistors from a parted unit on ebay. $24. I installed them, cleaned up the chassis and fired it up. Works great!!!. I paired it up with a vintage set of Kenwood speakers with 15" subs. WOW, this thing is insane loud. This is my first experience with a vintage semi-monster (85w).
After listening to it for about an hour, i heard a pop and one of the channels started to cut out. I didn't smell anything. I turned it off, waited a minute, then turned it back on. Still works fine. Not too sure what it was but I can only assume it could use a recap after all these years. This thing has about 200 elec caps. Do most people replace all of them when they re-cap? Or just the power and output stages?

I would like to thank all who have contributed to this tread.
 

tmuzzy

Joined Oct 18, 2019
2
Thank you Bountyhunter, Once I saw the name of your file, it gave me the idea of searching google for STA-2000D.pdf and after a couple of clicks, I found the exact service manual. What a difference that makes. I now have the right part#s and I found a miss-wire from the factory.
Two of the identical PNP transitors on the left side of the board had their base and emitter wires swapped. Although the collector wires went from the board to the proper transistors, both the B and E wires coming from the board went to the opposite transistors then that of the collector wires. one of the two that are crossed, is shorted. Not sure if it matters much, but it must have worked that way for many years or it died a short life and has been kicked around ever since.
Anyways, I am going to cancel my order (Still on backorder) and find a direct replacement for the HITACHI 2SD675A NPN and 2SB655A PNP transistor set.

Now that I have the schematics and parts list, I can do a better job checking their little friends.

As always, thanks again for all the help.
 

tmuzzy

Joined Oct 18, 2019
2
Hello! I noticed that you were able to track down the service manual for the STA-2000D- is there any chance of sharing that? I have only been able to locate it for the STA-2000. Thank you!!
 

parker3w

Joined Dec 30, 2019
2
BFreemanNH, thanks for information, I think you're right on that one. Materials mean a lot in this business. As well as audio receiver which audiophile chooses for complete kit of audio stuff in your room. The best model for me, under $300, was Onkyo TX-8140 ( which I've got after reading this: https://chоoserator.com/best-stereo-receiver-under-300 ), and still I think that it wins in couple of certain characteristics among other audio receiver models.
 
Top