What is the function of ic A3100

Sad to say it's likely to be 1 or more transistors in the power amp circuit, although there are other possible causes.
Luckily the repair manual is available (hifiengine.com) and the power amp is built with discrete components, so it should be easily repaired
Most common causes would be an output transistor or dry solder joint(s) due to transistors / resistors getting hot and cooking a solder joint or 2.
Inspect all solder joints carefully with a magnifier, looking for signs of localised heating/burning and/or crysalisation of the solder.
It's normal to replace output transistors as a matched pair even when only one has failed, to minimise distortion. Replacement transistors should of course be as close to the original specs as possible (or better) if genuine parts are not available. The bias will need to be adjusted as per manual (1.5mV emitter to emitter of output transistors).
Good luck.

Hi
Please do not dessolder anything before a thorough test. You should first check the main fuse. If it is blackened the MOSFET switchinhg transistor is probably bad and need to be replaced. The test should then go on thorugh the output line voltage in search of shorted components.
Only when the fuse is clean but open (interrupted) you can replace it and plug in the tv set and test.
Be careful and follow safety instructions on dealing with high voltage section of tv set. High voltage is letal.

I hope this will help you,

Sully

hi zm_16dec,

Right chanel fully dead , output transistor burnedout ,

Without knowing the make and model of your amplifier

all i can advise is to replace the unknown part number of

the transistor.


Look for the working left channel output transistors and

replace the bad transistors in "pair". These may include

other components but check on it as well.


Check the speaker system, especially where that channel

is connected.Inspect speaker wires or cable up to the speaker

itself.


Amplifier wont blow without reason.It could be from the wirings,

speaker or volume settings of the unit.

Thanks for choosing Fixya for assistance!

Make sure you are not set to SAP mode...use mono or stereo.

Check hori output and small blue high voltage capacitor 2k that feeds hori output transistor.
If these componets are OK then replace Both of the STK ICs they are big black ICs and will have PN# on them.example STK392-110.
Mats Electronics has ICs 1-800-628-1118
Encompass Parts Distribution has Free Service Manual for this Model# 57H94 you can print it out online.Go to their website.

Hi,
You need to confirm where is the trouble before replacing any parts.
Test the B+ on the H-out transistor.
No-check the B+ on 160v electrolytic cap.
If No B+ here then the trouble is in the regulator section before the chopper if it has.
Let me know the reading from your ohmmeter.
Thanks for using Fixya.
JDVillanueva

Don't know this particular transistor but most of the B#### transistors were manufactured by Bendix Corporations Semiconductor Division at South Street, Holmdel, New Jersey 07733. I think most if not all were Germanium PNP high power transistors in TO3 cases. It's just possible that some surplus dealer or electronics buff around Holmdel may have one in the junk box. If not look for a replacement with capability of handling the specified channel power output at the supply rail voltage. Gain is probably not too critical.

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

First, locate the horizontal output transistor. This is found very close to, or next to, the horizontal output transformer (also known as the flyback). The flyback should be on an aluminum heat sink, or on the side of the metal chassis. Disconnect or unsolder two of the three legs of the transistor. Measure it with your meter, or plug in the set with the light bulb attached across the fuse.
If the transistor is shorted, or the light bulb doesn’t glow bright anymore, replace the transistor and plug back in. If the light bulb glows bright again, you must replace both the flyback and horizontal output transistor simultaneously. In some cases this will fix the set, but sometimes there are multiple problems with a set.
Go to where the flyback is, and start measuring the diodes and capacitors on the flyback itself. If you don't find any shorts there, it could be a shorted vertical output IC, a shorted sound IC, a shorted disc capacitor in the Hi Voltage/sweep circuit, or in rare cases, a shorted capacitor or tuner.Feel free to ask and post whatever the result of your troubleshooting..


Hope this may help;

Regards,
VOTIT

DON'T FORGET TO RATE

Through my past experience I mwould remove the solder point at the input power B+ line to primary winding FBT. If the HOT has shorted there will be no power.Straight to the point if you know where the HOT is , you can desolder the middle pin or collector of the HOT transistor. If you desolder the pin which result the power led light turn up. That indicates either FBT or HOT has shorted