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-   -   Which replacement transistor for Sanken C3856/A1492? (http://www.diyaudio.com/forums/parts/68071-replacement-transistor-sanken-c3856-a1492.html)

rkc7 17th November 2005 11:09 PM

Which replacement transistor for Sanken C3856/A1492?
 
I'm looking for some replacement transistors for Sanken (2S)C3586 and (2S)A1492, can't seem to find them anywhere.

Mouser lists NTE2328/NTE2329 as equivalent replacements and I saw on another post on here about someone using Toshiba 2SC5200/2SA1943 as replacements.

Which would be a better match and/or sound better, etc... these would be used in a Samson S1000 power amplifier.

The Toshibas are much cheaper at $2.25 each while the NTEs are $6.12 and $7.25. If the Toshibas would work, they seem to be the better deal.

Also, anyone know where I can find schematics/service manual for the Samson S1000?

anton 18th November 2005 10:29 AM

I suggest you to use google or similar and find the transistor that you have, usually you reach a site with complementary components useful to replace your sanken. I did that and found transistor complementary for my PPI amp.

rkc7 18th November 2005 01:13 PM

I tried searching individually before with no results. So after your suggestion, I searched for both at the same time and I found some!

http://www.ampslab.com/trans_2sa1492.htm

Not too bad of a price either, it's cheaper than the NTE pair, though not quite as good as the Toshiba pair.

Although, I'm not even sure these are the correct transistors for the amp now because as I posted in the Solid State forum, I found that each transistor looks like it was aftermarket modified. Unless someone had to replace all the transistors, I'm guessing they put these in because they thought they'd be better.

AndrewT 18th November 2005 05:46 PM

Hi,
try comparing specs for these;-
2sa1294, 2sa1302, 2sa1386 (only160V), 2sa1943, 2sa1962 and their complements.

Why do you need to replace the originals? Do you want to consider selecting something that can take a bit more abuse or add extra devices in parallel?

All of these 130W/150W plastic semis are not very robust and suffer terrible SOAR at elevated voltages. I would keep the supply rails below +-55Volts or be prepared to use multiple outputs.

jacco vermeulen 18th November 2005 07:08 PM

Re: Which replacement transistor for Sanken C3856/A1492?
 
Quote:

Originally posted by rkc7
(2S)C3586 and (2S)A1492
2SC3856.
The S1000 is 300/8 and 1000 in 8 bridged.
Can not imagine these were the original devices for such a high power amplifier.
I'd go for the 1943/5200 combo.

rkc7 18th November 2005 09:15 PM

Yeah, I was wondering why a pro amp would be using Sankens, plus there were only 5 pairs per channel, which is supposed to put out 500w into 4 ohms.... that's another reason why I believe these are not the original transistors.

Would the MJL21193/MJL21194 be a good bet for original parts?

AndrewT 19th November 2005 07:50 AM

Hi,
I guessing that your transformer is about 50Vac giving PSU voltages of +-74Vdc.
MJL21193/4 would be an excellent choice and 5pairs at those voltages can drive 4ohms reactive load at 60degree phase angle.

These transistors are about 5 times slower than the Sankens you have taken out but can cope with about twice the power I would expect the gain to be a bit lower which will load the drivers.
In both these respects the 21193/4 may well be better than the unknown originals.

rkc7 21st November 2005 04:32 AM

Yeah, the output sounds about right, it has 100v filter caps. I'll go ahead with the MJLs, but now I have some other parts needing replacement....

there are the drivers (?) 2SA1659A and 2SC4370A. It looks like these may have been put in along with the Sankens, are they appropriate for this amount of power? There are one each that were heatsinked and 2 3470s and 1 1659 not heatsinked. One of the 1659s (heatsinked) was bad in channel damaged worst.

http://www.datasheetarchive.com/semi...ecsheet=127411

http://www.datasheetarchive.com/semi...ecsheet=138011

Also, there is a unknown zener diode that I can only make out Z10M (I think) on it that need replaced. Can't find anything about it anywhere.


If anyone would like to buy the Sankens I have, I don't need them. I have 6 pairs (2SA1492/2SC3856), 3 individual 2SA1492 and 1 2SC3856. The pairs were the ones there were matched in the circuit, whether they actually do "match" I have no idea. All same transistors have the same code ("8N P" for the 1492, "80 P" for the 3856)

rkc7 1st December 2005 10:00 PM

I was able to contact Samson and get a schematic for the amp. It turns out that the Sankens ARE original parts.

What would need to be done to use the MJL parts instead of the Sankens? The Sankens I believe are rated for 100w and the MJLs are 200w. I'm assuming I wouldn't need 5 of each transistor per channel like with the Sankens. Or if I did decide to fill all the spots, would I need to change any other parts to accomodate?

AndrewT 3rd December 2005 11:25 AM

Hi,
now that you have confirmed that the Sankens are the original fitment then it appears you are proposing to fit a non equivalent substitute.

As I see it you are losing both speed and gain in return for power. I would expect this to have some effect on performance.

I do not know if this would be audible but the concensus on this forum is generally that fitting faster outputs can improve the sound provided the amp is refettled to remain stable. You are going in the opposite direction.

I would expect the stabilty components will need to be reselected to optimise the circuit.

Any protection circuit will be completely wrong for the new outputs. Even farther astray if you change the number of output pairs.


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