Toshiba 2SD424 and B554

s 8 per channel). Original outputs are Toshiba 2SD424 and B554. QSC doesn 't sell parts for this amp any longer because of it's age. Is there a reli able source of these outputs, or should I replace them all with something n ewer?

These are a common output transistor and are readily available. MCM electr onics has them as does MAT Electronics and others. Look around. Dalbani o ut of Florida should have them as well. IRRC Dalbani is hte least expensiv e. That being said, these are usually $4-$6 each.

Dan

ses 8 per channel). Original outputs are Toshiba 2SD424 and B554. QSC doe sn't sell parts for this amp any longer because of it's age. Is there a re liable source of these outputs, or should I replace them all with something newer?

tronics has them as does MAT Electronics and others. Look around. Dalbani out of Florida should have them as well. IRRC Dalbani is hte least expens ive. That being said, these are usually $4-$6 each.

Yes, I see them all over the net. It's been years since I've done much audi o but I remember the counterfeit invasion of Toshiba plastic transistors an d just want to be sure the supply of these particular outputs is safe.

I've used them from all the suppliers that I have listed as well as others without any problems. I have not had any returns due to defective parts. Been doing audio repairs for 35 years now.

Dan

s without any problems. I have not had any returns due to defective parts. Been doing audio repairs for 35 years now.

Excellent. I'll get them ordered if the estimate gets approved.

Trevor: I used to do a lot of business with Dalbani and never had a problem , and I've ordered a few small things in recent years, so I'd say that that was not their normal method of doing business. They don't carry what I ne ed anymore so I rarely buy from them nowadays, but I'd venture it was a typ o on that part. If they had any brains, they'd have told you it was sold o ut instead of trying to bang you 10x, then relist it at the right price.

Actually you should be looking for NOS 2SD427 and 557, the highest power of the series.

My standard go to is the MJ15024 and if necessary its complimentary which I think is the 15025 but not sure, check the data at Digikey. Onsemi, about six bucks. Some people prefer other MJ series in the audiophile world, but these are sported to have "the largest die size for this class" or somethin g like that. I have them in my amp and my speakers are blown but not the am p.

Another decent set is the 2N3773 and 6609. Nice smooth gain. But they are n ot as good for as much power. Better than a 2N3055 and MJ2955, but not a 15

Hello,

Toshiba discontinued these years ago, and anything on the market today is likely to be a 'fake'. I would tend to use a device like the these from Motorola/ ON Semiconductor:

For the 2SD424 use an MJ15024G

MJ15024 spec: 250V 16A 250W 15-60 beta. 4Mhz

The PNP compliments are 2SB554 and MJ15025G.

Order genuine On Semi ones from a source like Mouser or Digikey for around $6. If you have the ability to, then I would try to beta match each bank of NPN's and PNP's. It is not as important that the betas of the NPN's match the PNP's. OnSemi is not a consistent as the old Toshiba devices, where all of the transistors of a lot number were quite close in beta.

CHECK THE BIAS CIRCUIT, or you might be replacing them twice.

Regards, Tim Schwartz Bristol Electronics