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Marshall mg100fx 2sc and 2sa main power transistors getting too hot.The heatsink fun operate normaly.But their is no output sounds.Is their a posible problem on the emiter and differential transistors?

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SOURCE: Pioneer SA 9800 Ampliffier Output transistor going off frequently

I assume these are the complimentary pair that drive the speakers. On one of the speaker. You know I think you have a short in the speaker that it drives. Speaker can fuction even if there was a problem with it. I think what happened is when the original transistors shorted out it overloaded the speaker, but not to a point where it is burnt. There is nothing that can overload a power transistor except the speakers, I design a lot of amplifiers, the base input can overload it if you put dc in there, but that would make a the sound all distorted, I assume the sound seem fine. Solution is try connecting a known good speaker and I bet it wont burn out anymore. Even if the speaker look fine don't trust it.

Posted on Jun 30, 2009

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1 Answer

The type of audio power and the number on onkyo A917 amplifier


Hi
Usually there are 2 transistors for each channel, if you don't know the numbers on the transistors.
there is another way to get as close as possible to have equal or similar to the same type of transistors (NPN/PNP)
example: 2SA is PNP transistor.
there are (2SA/2SC) transistors and there are (2SB/2SD)
complementary transistors
1: you have to know the supply voltage for the transistors
2: choose transistors that it is equal to the current and voltage that suits the supply voltage.
follow this link to find suitable transistors.
be aware and be careful that there other parts you need to check on the power amplifier circuit, resistors,capacitors and drivers etc...
I would suggest (2SD1047/2SB817)

http://www.smcelectronics.com/DOWNLOADS/COMPTRANS.PDF
Good luck
Hope this helps

Jun 25, 2016 | Onkyo Audio Players & Recorders

1 Answer

Was watching one day and the screen went completely blank. Now when you plug the TV in and/or turn it on you can hear it kind of "power up" but nothing comes on the screen. I have been told its...


Heatsink? Nonsense. Almost any heatsink is no more than a hunk of metal.

There is a likely shorted transistor on the main power board (possibly the Horizontal Output Transistor, HOT). They are very inexpensive to buy (about $5) but tricky (and dangerous) to replace if you are not familiar with electronics.

There are A LOT of wires, cables and connector in this TV that need to be undone to get the main power board out.

I love this TV and was able to fix mine in an evening... but I've 20years experience in electronics.

Jan 08, 2011 | Pioneer SD-P50A5-K 50" Rear Projection...

2 Answers

I have a Sony Model KV-HF21N80 and the problem is the horizontal output d2578, if change this it will runs normal and I tried to operate for how many hours but the problem is the next day if I will turn on...


I assume this is the exact replacement transistor? If it is not then use the original part with no substitutes. Next be sure the transistor has heatsink compound applied and is securely tightened to the heatsink. You say the B+ is normal, but does it remain "normal"? I would monitor the B+ also at power up to be sure it is being regulated. Another critical issue is the drive signal at the base of the HOT. If you have a o-scope & schematic check this carefully not only for amplitude, but wave shape & timing. This determines the on/off time of the HOT. Check components in the base circuit (there are only a few) as perhaps they were damaged when the HOT originally failed. If you have a high voltage meter make sure the voltage is within spec. the retrace tuning cap. in the collector may have changed value allowing excessive amplitude of the pulse. One final thought, after running the set for a time is the HOT excessively warm. It should be slightly hot, but not to the point of burning your finger. If it is too hot I would be suspicious of the drive signal, and or heatsinking.

Nov 25, 2009 | Sony Televison & Video

2 Answers

Having power issue. Comes on first time,turn


Sounds like improper speaker installation causing the amp outputs to overheat and thermal protection to kick in.

Aug 11, 2009 | KLH R5100 Receiver

2 Answers

Pioneer SA 9800 Ampliffier Output transistor going off frequently


I assume these are the complimentary pair that drive the speakers. On one of the speaker. You know I think you have a short in the speaker that it drives. Speaker can fuction even if there was a problem with it. I think what happened is when the original transistors shorted out it overloaded the speaker, but not to a point where it is burnt. There is nothing that can overload a power transistor except the speakers, I design a lot of amplifiers, the base input can overload it if you put dc in there, but that would make a the sound all distorted, I assume the sound seem fine. Solution is try connecting a known good speaker and I bet it wont burn out anymore. Even if the speaker look fine don't trust it.

Jun 30, 2009 | Lasonic TRC-931 Cassette Boombox

1 Answer

I have a teac a717 amp which is blowing both 5A fuses.


Thanks for the clarification. From the fuse behavior and feeding the amp into another amp (generally a no-no) it almost certainly is in the output section. If the amp used output transistors (numbered something like Axxxx/Cxxxx where xxxx=0000-9999) there will be some white three-legged low value (.47 ohm or less) resistors that are probably open. FYI the full part numbers for the transistors would be 2SA/2SC so a part marked C3281 would need a 2SC3281. B+D Enterprises (Google them) has most Japanese semiconductors and they have never sold me a fake transistor.

For more repair tips check out www.audiokarma.org

Dec 27, 2008 | Audio Players & Recorders

1 Answer

Power On + red LED turns on + but final relay (click) don't come so no sound


Your audio output transistors are shorted and your unit is staying in "protect " mode to protect your speakers from 40 to 60 volts that is being sent at them from the shorted outputs. If you can use a meter you won't need the schematic MOST likely because the outputs are USUALLY the only parts that short out. The output transistors( or chip ) are mounted to the large, finned heatsink. The #'s on the transistors start with "2SA-" and "2SC-" followed by numbers. There are two output transistors per channel. If your unit uses an IC for audio output then the # on the IC will be "STK-" followed by numbers. These parts are available from tritronicsinc.com. Good Luck!

barneyluc

Oct 17, 2008 | Denon PMA-2000R 2-Channel Amplifier

1 Answer

Hi I have a kenwood Krf-v609od receiver


Hi Rodney,

Have a look at the following. 1. Check your supply to the frnt panel. You ma have some power there but also look for a Resistor that will mesure open, and look for a Reulator. This will be fitted to a heatsink, not a big one though. If there is no heatsink look for the transistor on the main heatsink starting with la78XX. The last 2 dig should give you the power it is letting through. for expl: LA7812 will be a 12V+ regulator. A LA7912 will be a 12V- regulator. If nothing is found on the front panel check for this on the main bord. Once you get this right you will see that your fron panel will switch on and the controler will also switch.

Now for your heatsink that is still warming up. Disconnect your power to the main Transistors. You can do this by desoldering all resistors that is going to all the transistors. Your supply is going hi and your transistors is getting hot.

I know all the above is much but try it.

Jun 01, 2008 | Audio Players & Recorders

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