I have an older QSC model 1400 in with some blown output transistors (uses 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 reliable source of these outputs, or should I replace them all with something newer?

On Tuesday, April 12, 2016 at 2:34:42 PM UTC-4, wrote:
I have an older QSC model 1400 in with some blown output transistors (uses 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 reliable source of these outputs, or should I replace them all with something newer?

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

Dan

On Tuesday, April 12, 2016 at 2:56:19 PM UTC-4, wrote:
On Tuesday, April 12, 2016 at 2:34:42 PM UTC-4, wrote:
I have an older QSC model 1400 in with some blown output transistors (uses 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 reliable source of these outputs, or should I replace them all with something newer?

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

Dan

Yes, I see them all over the net. It's been years since I've done much audio but I remember the counterfeit invasion of Toshiba plastic transistors and 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

On 13/04/2016 4:56 AM, wrote:
On Tuesday, April 12, 2016 at 2:34:42 PM UTC-4,
wrote:
I have an older QSC model 1400 in with some blown output
transistors (uses 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 reliable source of these outputs,
or should I replace them all with something newer?

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


**I tried doing business with Dalbani about 5 - 6 years ago. I did a
search for a NLA LED display for a Krell CD player. They had the part
advertised for about $20.00. When I ordered the part, they suddenly
raised the price to more than $200.00. I have not dealt with them since.
Is this their normal method of doing business? Have they improved?

FWIW: The customer baulked at the revised repair cost and decided not to
go ahead. The client lost, I lost and Dalbani lost.



--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
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On Tuesday, April 12, 2016 at 5:47:35 PM UTC-4, Trevor Wilson wrote:
On 13/04/2016 4:56 AM, wrote:
On Tuesday, April 12, 2016 at 2:34:42 PM UTC-4,
wrote:
I have an older QSC model 1400 in with some blown output
transistors (uses 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 reliable source of these outputs,
or should I replace them all with something newer?

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


**I tried doing business with Dalbani about 5 - 6 years ago. I did a
search for a NLA LED display for a Krell CD player. They had the part
advertised for about $20.00. When I ordered the part, they suddenly
raised the price to more than $200.00. I have not dealt with them since.
Is this their normal method of doing business? Have they improved?

FWIW: The customer baulked at the revised repair cost and decided not to
go ahead. The client lost, I lost and Dalbani lost.



--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

I never had that problem with them. As a matter of fact, I purchased a quantity of Sony optics assemblies from them a while ago and never had any issues. They had a big sale a long time ago and I picked up belts for $.03 each. Still have that stock and they are in good condition. Used enough so that the remainder are pure profit.

I did a bulk buy of transistors to stock up form them too and never had a problem except for one value. When I called, they replaced them as it seems it was a bad lot.

Dan

On Tuesday, April 12, 2016 at 4:48:48 PM UTC-4, wrote:
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

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 need anymore so I rarely buy from them nowadays, but I'd venture it was a typo on that part. If they had any brains, they'd have told you it was sold out instead of trying to bang you 10x, then relist it at the right price.

wrote:



These are a common output transistor and are readily available.

** Not true for a long time.

Fakes are readily available though - I can see that Ebay is full of them.

http://www.diyaudio.com/forums/parts...ke-2sd424.html


MCM electronics has them as does MAT Electronics

** No sign of them on either's web site.


Dalbani out of Florida should have them as well.


** Dalbani are offering "pulls" on Ebay for $9.25 each.

At least they are not very likely to be fakes.

http://www.ebay.com.au/itm/2SD424-Or...AOxyUrZSq2G ~


I suggest the OP goes to Newark/Element 14 and buys some "ON" MJ15003s and MJ15004s for about $4 each.

Certain to be new and genuine plus do the job better too.




..... Phil

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 something like that. I have them in my amp and my speakers are blown but not the amp.

Another decent set is the 2N3773 and 6609. Nice smooth gain. But they are not as good for as much power. Better than a 2N3055 and MJ2955, but not a 15024.

"Trevor Wilson" wrote in message
...
On 13/04/2016 4:56 AM, wrote:
On Tuesday, April 12, 2016 at 2:34:42 PM UTC-4,
wrote:
I have an older QSC model 1400 in with some blown output
transistors (uses 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 reliable source of these outputs,
or should I replace them all with something newer?

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




Unless you can find "New Old Stock" you should go with modern equivalents.

Toshiba hasn't made these in many years. Any so-called "new" stock are
FAKES.

Onsemi (previously Motorola) MJ15003G and MJ15004G.

In the United States, B&D Enterprises (Bdent.com) is a very reliable
distributor.

1-800-458-6053

Mark Z.

On 4/12/2016 2:34 PM, wrote:
I have an older QSC model 1400 in with some blown output transistors (uses 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 reliable source of these outputs, or should I replace them all with something newer?


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

2SD424 spec:180V 15A 150W 40-140 beta. 5Mhz

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