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Info on this pair of A1943/C5200

RishiGuru

Dec 24, 2010
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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).

[url=http://www.freeimagehosting.net/2c95f][img]http://www.freeimagehosting.net/t/2c95f.jpg[/img][/URL]

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.
 

Resqueline

Jul 31, 2009
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2SA1943 = PNP 230V 15A 150W 30MHz TO-264 (TO-3P)
2SC5200 = NPN 230V 15A 150W 30MHz TO-264 (TO-3P)
They seem to be recommended for 100W of output power.
It usually doesn't matter which brand you buy, especially when replacing a complementary pair. Toshiba & ST are common examples of manufacturers for these.
 

RishiGuru

Dec 24, 2010
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2SA1943 = PNP 230V 15A 150W 30MHz TO-264 (TO-3P)
2SC5200 = NPN 230V 15A 150W 30MHz TO-264 (TO-3P)
They seem to be recommended for 100W of output power.
It usually doesn't matter which brand you buy, especially when replacing a complementary pair. Toshiba & ST are common examples of manufacturers for these.

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):


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

Jul 31, 2009
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There are several things you can use to compare & estimate the transformer power with known transformers (& other amplifiers). Keep in mind the mains V & frequency.
1: the primary fuse rating.
2: the physical dimensions of the transformer.
3: the rating of the secondary rectifier diodes.
4: the capacitor bank size (2 x 9400uF).
5: the amplifier module fuse ratings

I would be surprised if the transformer is as powerful as 300VA. They are rarely rated as high as the sum of the output power in audio amplifiers. Google the TL072.
 

RishiGuru

Dec 24, 2010
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Dec 24, 2010
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There are several things you can use to compare & estimate the transformer power with known transformers (& other amplifiers). Keep in mind the mains V & frequency.
1: the primary fuse rating.
2: the physical dimensions of the transformer.
3: the rating of the secondary rectifier diodes.
4: the capacitor bank size (2 x 9400uF).
5: the amplifier module fuse ratings

I would be surprised if the transformer is as powerful as 300VA. They are rarely rated as high as the sum of the output power in audio amplifiers. Google the TL072.

Well here is the info i was able to gather regarding the amp. And yes this CKT A1943/C5200 transistors belong to Taiwan. Do not know the manufacturer yet.

1: the primary fuse rating. :T3AL250V.EI

2: the physical dimensions of the transformer.: Diameter: 11 cm, Height: 6 cm

3: the rating of the secondary rectifier diodes:
i) Secondary +/- 30V --> Diodes used is two pairs of 6A4 MIC, Caps: two pairs of 4700uF, 50V --> goes to power amp
ii) Secondary +/- 15V --> Diodes used is two pairs of "MIC", Caps: two pairs of 1000uF, 25V --> goes to pre amp

4: the amplifier module fuse ratings: Each of these A1943 or C5200 have one T3AL250V.EI fuse. Total 4 fuse for four transistors.

Transformer pics:







Diodes at +/-30V rails:


Internal layout:





Heatsink:


I am very curious to find out the true power output of the amp. Also the VA rating of the toroid.

Thanks in advance:)
 
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RishiGuru

Dec 24, 2010
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Hi, here is the update. My friend have bought the pair of transistors. Also the multimeter.

We will be starting to do our DIY on the amplifier by tommorow.

Also, i got the toroid transformer specs.The transformer is a 5 amp for 30-0-30, and 350 Ma for 15-0-15 winding.

60 X 5 = 300.00 VA [goes to Power amps]
30 X 0.35 = 10.50 VA [goes to Pre amps]
---------------------------
Total = 310.50 VA

Any idea about its true continuous power output per channel for this amp?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Various calculations suggest that 100W per channel into 8 ohms would be most likely.

It appears that the power supply is very conservatively rated -- the output transistors perhaps less so. And that may explain why you're replacing them...

Try not to drive the amplifier into clipping, and avoid speakers which have an input impedance which drops substantially below 8 ohms at frequencies which are likely to have a high power component (i.e approx 500 to 4000Hz)
 
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