Info on this pair of A1943/C5200

[RishiGuru]

Hello this is rishiguru. I am a newbie and have very little knowledge about DIY. My friends audio amplifier is broke we have opened the cabinet and found
that a pair of A1943/C5200 is used per channel of the two channel amp.

Now, one of the C5200 is burnt, so below is the image of the other pair(which seems ok).



Can anybody tell the name of the manufacturer & the specs like power output, voltage and current ratings of this pair. The amp is rated 125 watts X 2. the transfo outputs +/-30V to this two pair of transistors. Is the current rating 5A (not quoted on the transfo)?

It also have 4, 4700uF, 50V capacitors used as ripple filters

Also cannot find CKT brand name? Where we can buy this exact pair?

Kindly help. Thanks in advance.

[Bill_P]

2SA1943 and 2SC5200 are Toshiba transistors, also made by Fairchild. DigiKey has them. If you prefer another distributor, a search engine should locate others.

[RishiGuru]

Originally Posted by Bill_P

2SA1943 and 2SC5200 are Toshiba transistors, also made by Fairchild. DigiKey has them. If you prefer another distributor, a search engine should locate others.

thanks. then why this CKT is written? Here is the magnified pic of the above transistors. Are they Toshiba? They do not seem so.

2c95f.jpg at Free Image Hosting

Also having left speakers of CKT brand and Toshiba ones on right can produce different sound signatures in the speakers?

Can any one tell me where I can get this specific pair (Same brand & model)?

[semi932]

Just order 2 each of Toshiba or Fairchild and replace all 4.

Order from Digikey or Mouser and you will not get counterfeit models.

[Tekko]

The reason it broke could well be that those "CKT" marked outputs were fakes.

Amplifiers usually never just fail spontanously one day unless something like a lytic went bad first.

However 30VAC means the rails are at 43VDC and the SOA of these outputs wont allow for more than around 1A if even that, at that voltage = this amp should never see anything less than a 8 ohm load.

If its driving 4 ohm speakers, i'd drill and tap 4 extra holes and double up on the output transistors, or replace them with something beefier like MJL4281 and its companion MJL4302.

[digits]

There are a number of copies which are not fakes, and most likely licenced, I can think of Fairchild for instance. As semi said, you have to get these from a trusted source as the real fakes are everywhere these days.

[AndrewT]

Fairchild do not mark their versions as "Toshiba 2sa1943".
Fairchild's versions cannot be copies, nor fakes, nor counterfeits.

[digits]

Absolutely, I did not mean to leave room for confusion, Fairchild parts will have their own logo and markings... When I deal with some of the smaller suppliers around me, I insist on the Fairchilds as the Toshiba ones they stock are all fake... Tiny die stuck in a giant transistor.

[RishiGuru]

Originally Posted by Tekko

The reason it broke could well be that those "CKT" marked outputs were fakes.

Amplifiers usually never just fail spontanously one day unless something like a lytic went bad first.

However 30VAC means the rails are at 43VDC and the SOA of these outputs wont allow for more than around 1A if even that, at that voltage = this amp should never see anything less than a 8 ohm load.

If its driving 4 ohm speakers, i'd drill and tap 4 extra holes and double up on the output transistors, or replace them with something beefier like MJL4281 and its companion MJL4302.

well the amp is rated:

125W X 2 @ 4ohms
100W X 2 @ 6ohms
80W X 2 @ 8ohms

The transformer is sizebale. From what i heard you need a minimum of 300Va tranfo to pump out 250 watts of power @ 4 ohms. So, i was thinking +/-30V, 5A from the transfo. (ampere not quoted on the transfo)

the transfo have two secondaries +/-30V to the power amps (two sets of the above transistors) & +/-15V to the op amp circuit.

Below is the link to amplifier internal (hope it helps):
http://www.freeimagehosting.net/219d5

The op amps (3 units) are Texas Instruments TL072CP. Are they dual op amps. Just out of natural curiosity is the transfo 300+ VA?

[Tekko]

That amp homemade ? looks kinda like it.