G-8000 Output Transistor Recommendations

[MAXZ28]

What do you use to replace original output transistors when upgrading or repairing a G-8000/801 or a G-9000/901?

Are they readily available or where can I purchase a suitable substitute?

Thanks in advance! :thmbsp:

 

[EchoWars]

If the originals are installed and working, the first choice is to leave them there. Otherwise, the MJ21193/94's make fine substitutes.

 

[MAXZ28]

Thanks, Echo. I haven't delved into the troubleshooting yet but I have a DOA unit the PO said had blown outputs and I wanted to find out if there were preferred suitable substitutes.

I referred to MCM Electronics and the Sanken's are discontinued.

2SC1403 with a substitute 2SD424 $5.69 each
2SA745 with a substitute 2SA747 $8.59 each

 

[Bigears]

I referred to MCM Electronics and the Sanken's are discontinued.

2SC1403 with a substitute 2SD424 $5.69 each
2SA745 with a substitute 2SA747 $8.59 each

I'd be very carful with sub's. I would go with the MJ21193/94's like EW suggests. The subs MCM is selling may be NTE, which you don't want. There may be some good originals floating around too. Check yours and see if they are really blown.

 

[MAXZ28]

That's why I always ask the experts before buying. :yes: Thanks, guys.

 

[ccheath]

MJ21193/94's are very good transistors. I used them in my SX-1010 with great success.

 

[Kale]

MJ21193/94's are very good transistors. I used them in my SX-1010 with great success.

Yes I agree with you about MJ21193/94, they are stable like a rock! But also the are much slower than original Sanken.
If you wish to make output like Sansui did, I used today production of Sanken LAPT transistors 2SC3263/2SA1294 but they are TO3P case, not TO3.
So I adopted them to TO3 socket (look at attachment)

Scope shows you 300kHz sine wave on speakers output!

 

[Hyperion]

Interesting modification with the aluminium blocks epoxied? to the transistors - does that make a significant difference to the maximum heat dissipation from those devices?

Neat work Kale - as usual !

John

 

[LBPete]

Thanks, Echo. I haven't delved into the troubleshooting yet but I have a DOA unit the PO said had blown outputs and I wanted to find out if there were preferred suitable substitutes.

I referred to MCM Electronics and the Sanken's are discontinued.

2SC1403 with a substitute 2SD424 $5.69 each
2SA745 with a substitute 2SA747 $8.59 each

MCM has a whole range of transistors they sell under the original OEM code numbers like the ones you listed. The originals are long out of production so there is a very good chance they are either counterfits or re-labled ala NTN.

You are better off with the onsemi's recomended earlier. They are cheaper too! I would get them from Digikey because MCM can't be trusted for transistors. You may have to add a "G" to the part number to get the lead free compliant ones. In most cases, the originals (no "G") were discontinued long ago.

- Pete

 

[Kale]

Interesting modification with the aluminium blocks epoxied? to the transistors - does that make a significant difference to the maximum heat dissipation from those devices?

Neat work Kale - as usual !

John

Yes, I fixed that aluminum block to transistors case by thermal compound, and it is not only because of better thermal protection, that is for mechanical protection too, because TO3P transistors are fixed with one screw only (TO3 with two) and that aluminum block prevent damage of transistors case if you over tighten the screw.
And those insulators on base and emiter legs are made of teflon.

 

[Hyperion]

The spec' of those transistors is really excellent, I just looked them up - the only downside is the slight difficulty when mounting the TO3P's - but you seem to have sorted that out !

I did wonder about that insulation - teflon = perfect choice.

John

 

[tarior]

Yes I agree with you about MJ21193/94, they are stable like a rock! But also the are much slower than original Sanken.
If you wish to make output like Sansui did, I used today production of Sanken LAPT transistors 2SC3263/2SA1294 but they are TO3P case, not TO3.
So I adopted them to TO3 socket (look at attachment)

Scope shows you 300kHz sine wave on speakers output!

Nice work!:ntwrthy:

 

[MAXZ28]

Yes I agree with you about MJ21193/94, they are stable like a rock! But also the are much slower than original Sanken.
If you wish to make output like Sansui did, I used today production of Sanken LAPT transistors 2SC3263/2SA1294 but they are TO3P case, not TO3.
So I adopted them to TO3 socket (look at attachment)

Scope shows you 300kHz sine wave on speakers output!

When I look at your third picture, Kale those modded transistors look to me like sophisticated, futuristic nano tanks.