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YaBoiiGarfield

2SA1216 + 2SC2922 Substitutions

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Posted (edited)

Hi All, 

 

After searching the internet high and low for an answer, i have to suffice and start a fresh thread.

I've purchased a basket case amp for repair to find it contains blown output transistors, 2SA1216 + 2SC2922, along with a few other surrounding parts etc.

These are not available anymore, so fingers crossed there is a good substitute available.

 

After doing abit of research, it looks like that the 2SA1943 + 2SC5200 would be a close match (and available through RS Components),  but i just wanted to double check, and hopefully learn a thing or two.

Looking at RS at A1943s, there are Toshiba parts and ON Semi parts, the Toshibas have a Ic of 15A, and the ON Semi have a Ic of 17A,  does that difference lean a preference to one part or the other?

 

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Looking at the absolute maximum ratings, they both look similar to me.  my only concern would be the Power dissipation.

 

my understanding of this stuff starts to fade when we get into the nitty gritty.

image.thumb.png.2174d667630e608ce4eb68f19f722f2c.pngimage.png.38e7df7f107176e940927c5f0100698a.png

Is there anything there that stands out that is cause for concern,   to me, the large diffrence in Icbo stands out.

 

I know for a fact that the toshibas a suitable for audio purposes, because that is what was in a C320bee that i repaired a while back.

 

 

Greatly appreciate your input,

Thanks,

Jack

 

 

image.png

Edited by YaBoiiGarfield
delete incorrect pic

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PS; my other question is,

Is it safe to run the amp without the output transistors installed?

I don't have a schematic, and feel like its a good idea to just check the base collector and emitter voltages before i possibly burn up more transistors

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Guest iant
Posted (edited)

nil

Edited by iant

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Posted (edited)

Interesting indeed , very few amplifiers would need transistors with such high voltage needs, or base current. What make and model is the basket case amp.

 

It may well be the transistors were chosen from retired semiconductor lots, where low expenditure came before , what was actually required.

 

 

 

Edited by stereo coffee

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Posted (edited)

Thanks very much Ian, I'll shoot you a pm soon.  + I'll give a donation to SNA

 

It is a Audiolab 8000P , this exact one i sniped of ebay a week or so ago.

I repair amps as a self funding side hobby.

 

Since it wont let me post an ebay link, it is the 8000p that just sold on ebay that is fried.

 

s-l1600.jpg

 

...

 

 

The amp has been repaired before, but who ever did it used a fake transistor,  sigh,  and here we are now.

 

I definitely want to do this right, with no shortcuts.   there are 2 pairs per channel, and only 1 pair are bad,  so ill do the right thing and just drop in the correct parts.

 

 

Greatly Appreciated,

Jack

 

image.png

image.png

Edited by YaBoiiGarfield

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ian changed his mind, so here we are back where i began, looking for substitutions.....

 

The Donation to SNA will definitely still be happening if i can get the correct parts 

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5 minutes ago, YaBoiiGarfield said:

ian changed his mind, so here we are back where i began, looking for substitutions.....

 

The Donation to SNA will definitely still be happening if i can get the correct parts 

make and model of the amp ? will help to advise.

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yeah sorry, i wrote up a post, but for whatever reason it requires admin approval ?

 

It is an Audiolab 8000P, the one that sold on ebay recently

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Posted (edited)

nil

Edited by YaBoiiGarfield

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15 minutes ago, stereo coffee said:

make and model of the amp ? will help to advise.

Audiolab 8000p

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8 minutes ago, YaBoiiGarfield said:

ian changed his mind, so here we are back where i began, looking for substitutions.....

 

The Donation to SNA will definitely still be happening if i can get the correct parts 

The problem arises mainly because Sanken finished production of the MT 200 package in 2018 , relegated to unobtainum, you might be able to get stock from audiolab or gryphon , of the original parts. 

 

As for substitutes, looking at the schematic for the 8000p, the  1216 and 2922 are not the output devices, rather are part of a much lower current pre driver stage. Also audiolab are cagey to say the least as to the voltage rail, which at 100 watts rated output is likely 55 volts on each rail  The output transistors are Q130 and Q129 which are not revealed as to their manufacturers part, perhaps MJ15004 and MJ15003

 

There appears no need for such high current, in this driver stage as it runs into a resistive L pad divider, so BD140 pair for the PNP  and BD139 for NPN should be  good IMO 

 

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4 minutes ago, stereo coffee said:

looking at the schematic for the 8000p

hmm,  how did you find a schematic? after searching around to no avail, I emailed them directly, and he got back to me and just said "Audiolab do not support the 8000p anymore", i wrote about that in the post that hasnt been approved yet, maybe soon it will be up.

 

5 minutes ago, stereo coffee said:

1216 and 2922 are not the output devices, rather are part of a much lower current pre driver stage

'current pre driver stage',  rightio, that is beyond my understanding [for now], definitely need to read up on that.

 

13 minutes ago, stereo coffee said:

The output transistors are Q130 and Q129

I searched around my amp and couldn't not find those part numbers ,  it only goes up to Q128. 

18 minutes ago, stereo coffee said:

The output transistors are Q130 and Q129 which are not revealed as to their manufacturers part

which may because they dont exist???

 

 

I wouldnt mind having a peep that that schematic your looking at now,  considering i couldnt find one anywhere for the amp.  

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2 minutes ago, YaBoiiGarfield said:

hmm,  how did you find a schematic? after searching around to no avail, I emailed them directly, and he got back to me and just said "Audiolab do not support the 8000p anymore", i wrote about that in the post that hasnt been approved yet, maybe soon it will be up.

 

'current pre driver stage',  rightio, that is beyond my understanding [for now], definitely need to read up on that.

 

I searched around my amp and couldn't not find those part numbers ,  it only goes up to Q128. 

which may because they dont exist???

 

 

I wouldnt mind having a peep that that schematic your looking at now,  considering i couldnt find one anywhere for the amp.  

Its at hiFi Engine     https://www.hifiengine.com/manual_library/audiolab/8000p.shtml

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5 minutes ago, stereo coffee said:

Looking at the schematic, its a funny one indeed , the output stage has a zobel at R149 and C113, and I was wrong the output transistors are the ones you are trying to source, whereas Q130 and Q129 are part of a different part of the circuit.

 

I would therefore try and change to have TO3 devices which will be made forever ( well nearly ) and MJ15004 for PNP pair and MJ15003 for NPN might be good choices. it will need a few hardware changes, but nothing too drastic.

 

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12 minutes ago, stereo coffee said:

ahhhh,   i saw that when i first started this expedition but couldn't make sence of it and disregarded it for an earlier model,  now i take a second gander it is falling into place.  silly me.   bit of a light bulb moment there. 

 

enough of me making a fool of myself on a public forum,  i'm going to get some sleep and battle on tomorrow,  thanks for your time.

You've definitely helped me get over a learning barrier and i am grateful indeed for the guidance. 

 

...

 

5 minutes ago, stereo coffee said:

I would therefore try and change to have TO3 devices which will be made forever ( well nearly ) and MJ15004 for PNP pair and MJ15003 for NPN might be good choices. it will need a few hardware changes, but nothing too drastic.

Rightio sounds good,  hardware changes are a non issue.  I'll let you know how i get on with the repair.

 

Thanks mate,

Jack

 

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Have you tried B&D Enterprise in the US as they have the 2SA1216  2SC2922 in stock in pairs.

These guys are reputable sellers of hard to source parts.

Steve.

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Posted (edited)

Both types may still available from Wagner Electronic Services in Ashfield, NSW. They also do a very reliable mail order or over the counter. I am a customer and have no other affiliation 

 

https://www.wagneronline.com.au/catalogue/

 

 

WES has moved to Summer Hill - sorry

Edited by phred505
correction

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