Help needed Output Transistors blown - diyAudio
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Old 14th February 2007, 10:12 AM   #1
Rossy is offline Rossy  United Kingdom
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Default Help needed Output Transistors blown

Hi can anyone help me please?
i have a Non branded Amp called Pro-240
4 Transistors have blown
and 1 resistor
the numbers on the transistors are A940
only info i can get is this
A490 C2073
TO-220 PNP

http://216.239.59.104/search?q=cache...df/To-220/A940(TO-220).pdf%3FPHPSESSID%3D597428d6d3003a87c0d6ecd0718 50b87+transistor+A940&hl=en&ct=clnk&cd=1&gl=uk&lr= lang_en

i am strugeling to get this in the UK or find an equivilant

please help

Thanks
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Old 14th February 2007, 10:28 AM   #2
Bone is offline Bone  United Kingdom
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What's the power output of this amp and do you have the circuit?

This is an odd transistor ( The full part no is 2SA940 ) for a power amplifier it looks like its supposed to drive a TV or Monitor. Full data sheet at: http://pdf1.alldatasheet.com/datashe...EC/2SA940.html


The C2073 which I assume is the NPN complementary part - again full part no is 2SC2073 data at: http://pdf1.alldatasheet.com/datashe...C/2SC2073.html

This may help you find replacements

Tony.
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Old 14th February 2007, 10:32 AM   #3
Netlist is offline Netlist  Belgium
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A970 is in fact 2SA970. You could substitute it with MJE15031 which is easily available and a very reliable device.

/Hugo
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Old 14th February 2007, 11:21 AM   #4
Rossy is offline Rossy  United Kingdom
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Hi thanks for reply
i do have the PCB out and can post a picture of the circuit
the other numbers on the Transistors that have blown are as follows
There is a Italic F at the top am assuming thats the brand
then in a embosed circle (U) then 537
then underneath A940

this is all the info i have on the amp
PA DJ Amplifier - "PRO 240" 480 Watt

Art Nr: AW1248244



480 Watts power!

High performance amplifier with 19” width, 2HE

High power and fidelity paired with a convincing design!

Fits in every system as easy as winking (19” standardised)

Ideal for monitoring, PA use, parties etc.



Stable 19” steel-body, 2HE

Powerful 2x106W RMS at 8 Ohm

Frequency 20-45.000Hz

Distortion factor >0,3%

Signal-to-noise ratio 80dB

Separated mixer for volume left/right

Peak and Protection LEDs

Front-sided on/off switch

Back-sided high-performance ventilator

Input over 6,3mm jack

Speaker output with golden 4mm screw plug terminal, PA cable or Jack

Safety switch (short-circuit-resistant)

Dimensions B x H x T: 485 x 95 x 270 mm

Weight 9 kg
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Old 14th February 2007, 11:21 AM   #5
Rossy is offline Rossy  United Kingdom
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Quote:
Originally posted by Netlist
A970 is in fact 2SA970. You could substitute it with MJE15031 which is easily available and a very reliable device.

/Hugo


Hi it was A940
but thanks for help

thanks
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Old 14th February 2007, 11:21 AM   #6
Rossy is offline Rossy  United Kingdom
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Think ive found them what luck

http://cgi.ebay.co.uk/2SC2073-TOSHIB...QQcmdZViewItem
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Old 14th February 2007, 11:21 AM   #7
Rossy is offline Rossy  United Kingdom
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Hi the 2SC2073 is NPN like you say but the original is PNP will this matter?
thanks
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Old 14th February 2007, 11:28 AM   #8
Netlist is offline Netlist  Belgium
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Quote:
Originally posted by Rossy
Hi it was A940
This of course was a typo.

Quote:
Originally posted by Rossy
Hi the 2SC2073 is NPN like you say but the original is PNP will this matter?
thanks
You need to replace NPN with NPN and PNP with PNP.
So, previous posts is still valid. You can replace 2SA940 with MJE15031.

If the amp doesn’t contain 2SC2073, you need not to bother.
If it has, MJE15030 is a good substitute.

/Hugo
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Old 14th February 2007, 11:44 AM   #9
Rossy is offline Rossy  United Kingdom
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Hi thanks for that
there is a few variations in teh data sheet but with MJE15031 as the Mhz is 30 but on my A940 it is 4 will these mater

thanks
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Old 14th February 2007, 11:52 AM   #10
Netlist is offline Netlist  Belgium
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It could be that the amp will oscillate and you will need a scope to watch if it does. A schematic would be real handy but I'm afraid you will not have that.
As for now, try posting a clean picture of the amps inners, concentrate on the output stage.

/Hugo
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