Need some help with my Sansui 5000X

Thank you all for your help. I will try the suggestions when I return from seeing my grand babies (twin 5 year old boys) over the weekend and maybe some time in rehab when I get home.
Jim
 
Some update on my project. I pulled the jumper out between the preamp and output board and still had the popping noise so I shorted the input to the output board and the noise was gone!
I am trying to figure out the replacement transistors but having a hard time on some of them. If anyone has any suggestions I would greatly appreciate it. I do have new output transistors and some possible replacement for the npn, pnp pair but the other 3 are questionable.
I guess I should list the ones that I have trouble with.
2sc281 (b)
2sc627 (3)
2sc871 (r) f
Thanks, Jim
 
Jim Carr said:
Some update on my project. I pulled the jumper out between the preamp and output board and still had the popping noise so I shorted the input to the output board and the noise was gone!
I am trying to figure out the replacement transistors but having a hard time on some of them. If anyone has any suggestions I would greatly appreciate it. I do have new output transistors and some possible replacement for the npn, pnp pair but the other 3 are questionable.
I guess I should list the ones that I have trouble with.
2sc281 (b)
2sc627 (3)
2sc871 (r) f
Thanks, Jim
Click to expand...

A good place to start looking for transistor replacements is here: Top Ten Worst Transistors - noisy, failure-prone, whatever... and replacements

I've had good luck searching here with just the transistor part number when looking for other substitutions:



The ever present caveat applies to all substitutions, be careful with transistor pin ordering when using the substitute transistor
 
Thanks for the link to the 10 worst transistors. So far I have found one of mine in the list but every substitute is now obsolete.
The ones I have trouble with are the 2sc281 and 2sc627. I wish I knew more about the transistor nomenclature as I look them up they will be a list of them with an alphabet soup after the number that I don’t understand so I don’t know which one to choose.
I was hoping that maybe someone might have figured it out and would be willing to share it.
Thanks, Jim
 
There's a guy on Ebay, Peacelovemusic, or something like that. Sells rebuilt kits for the Sansui driver amps. Good reviews here on AK for his kits. Might look into this and just do a complete rebuld? A 5000X is well worth the time and money.
 
tom3 said:
There's a guy on Ebay, Peacelovemusic, or something like that. Sells rebuilt kits for the Sansui driver amps. Good reviews here on AK for his kits. Might look into this and just do a complete rebuld? A 5000X is well worth the time and money.
Click to expand...
Thanks I will check it out
 
He's also findable as Affinity for Artifacts, and a contributor here on AK (@EastPoint ), here's a link to the F-6013 kit he has listed, but it's probably worth your time to search his store 5000x items and some of the transistors:



The kit for the F-6013 only includes a pair of transistors, probably the replacement for the 2SC871. Replacements for the others will require a little more thought.
 
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Here's some instructive reading, it's worth the time to digest:

dlucy

Thread 'dlucy’s guide - how to find replacement transistors'

Do you have a transistor that needs to be replaced?

Figuring out what to look for in a replacement transistor can be difficult, especially if you haven’t been doing this for decades.

The following guidance may help you understand how to better find and select a modern equivalent transistor that will work well as a replacement.​

Background and disclaimers

AK has been a wonderful place for me to learn about electronics and vintage audio gear repair and now I find myself answering “how to” questions frequently. That’s a laugh in itself as I’m just a...​
  • dlucy
  • find transistors replacement transistor replacements substitutes
  • Replies: 42
  • Forum: Solid State
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And for your other 2 transistors:

C

Thread '555a Transistor Question - 2sc871 R (E,F) ?'

Hello - Transistor replacement is a rabbit hole with no answers it seems.
Can anyone help guide me on what to use here on the EQ board of a 555A.
Spec says 4 of 2sc871 R (E,F) but in the unit was 2 of C632 and 2 of C631?
Just to be clear im referring to TR601 - 604 on Board F-1267

I replaced with 1845fta before I read how quiet they are I want to replace these correctly today if possible?
Would 2SC1845 work - or is thier a sub thats easy to find that sounds correct.
Thanks !
Chris
  • Like

Hyperion

Post in thread 'Eight driver board issue'

A good replacement for a 2SC627 is ZTX694B. ;) (available from Mouser)
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Thanks everyone for all your help. I am going through all the reading links to get a better understanding of what to do about this. I will give an update when I finish or maybe have even more questions.
Thanks again I really appreciate it.
Jim
 
Well I am back with even more questions after I got the parts I ordered. I ordered a mje15033g for the 2sa566 and a mje15032g for the 2sc680 as they were recommended and were supposed to be a matched pair.
On DigiKey they were listed as having a gain of 10 each but when I got them the gain was very different with the pnp having a gain of 90 and the npn having a gain of 160! So now I wonder why the big difference and does it matter. What determines a matched pair is it the ac gain and not the dc gain that is listed? Do I need a curve tracer to determine a matched pair instead of the cheap transistor tester I have?
Again thanks to anyone that is willing to help me. Jim
 
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Jim Carr said:
... mje15033g ... and a mje15032g ... a matched pair.
Click to expand...
In reality they are a complementary pair which is interpreted differently than what you might expect. They are complements since one is PNP and the other is NPN but they are not expected to have the exact same hFE performance, just very similar behavior overall.

Jim Carr said:
On DigiKey they were listed as having a gain of 10 each but when I got them the gain was very different...
Click to expand...
The hFE difference is pretty typical between NPN and PNP devices even complementary devices. The hFE of 10 that you see on DigiKey is the minimum value for a fairly atypical operation condition (Ic = 2A, VCE=5V) that is reported in the datasheet. The hFE that your tester measured is done under closer to typical conditions and it's not unexpected that it will be higher than the minimum you see reported by DigiKey. In this part of the circuit there is a fair bit of latitude about how similar those transistors need to perform and you can be confident that the new ones will work just fine to drive the output transistors. You won't need a curve tracer unless you're after the absolute best performance matching and are willing to buy and test more than a handful of parts.

Maybe more of an issue will be physical differences between the TO-220 and TO-66 packages. Judging from the pcb layout, you might have to solve some component clearance concerns with the squared collector tab of the TO-220 parts.
 
jmjrcv said:
In reality they are a complementary pair which is interpreted differently than what you might expect. They are complements since one is PNP and the other is NPN but they are not expected to have the exact same hFE performance, just very similar behavior overall.


The hFE difference is pretty typical between NPN and PNP devices even complementary devices. The hFE of 10 that you see on DigiKey is the minimum value for a fairly atypical operation condition (Ic = 2A, VCE=5V) that is reported in the datasheet. The hFE that your tester measured is done under closer to typical conditions and it's not unexpected that it will be higher than the minimum you see reported by DigiKey. In this part of the circuit there is a fair bit of latitude about how similar those transistors need to perform and you can be confident that the new ones will work just fine to drive the output transistors. You won't need a curve tracer unless you're after the absolute best performance matching and are willing to buy and test more than a handful of parts.

Maybe more of an issue will be physical differences between the TO-220 and TO-66 packages. Judging from the pcb layout, you might have to solve some component clearance concerns with the squared collector tab of the TO-220 parts.
Click to expand...
Thank you very much, I sure have learned a lot from people like you and I appreciate it.
 
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