TEAC A-BX10 MKII integrated amplifier

[Juha]

TEAC A-BX10 MKII integrated amplifier from 1997.

This 100W high end amplifier was designed and manufactured in Denmark by Thule Audio.
Just bought a non-working one from German Ebay.

Anybody heard how this sounds?

Original price GBP 999. Non-working was not expensive.
Only problem seems to be that is is made with miniature surface mounted components.
Let's see, if I can find someone to fix it. This a a power supply problem.
Could be burned IC power regulators.

The trafo on the picture is 250VA 37V.

I'll report later how things turned out.

http://hoone.com/teac2.jpg


http://hoone.com/teac1.jpg

[Firebottle]

There are a lot of fuses in there. Are they all good, if not could give you some clues.

Good luck.

[Juha]

Tested the amplifier.

All fuses are good.

When powering the amp the digital volume control and input selectors seem to work.

The power regulators and big resistors around them get burning hot very fast.

There is some hum from speakers, but no sound.
I guess this indicates that something is shorted/broken drawing big amps from the transformer.

Both channels have 8 expensive looking transistors. Let's hope all of them are not fried.

[Firebottle]

It sounds a bit surprising that no fuses blow if you have shorted transistors.

What are the pert numbers on the transistors? Because they are big doesn't necessarily mean they will be expensive.

[Juha]

The main transistors are Rohm A1633 and C4278.

There is actually four amplifiers.
This is a design where both phases have their own amps.

[Firebottle]

Could be useful to isolate each amplifier in turn by removing the appropriate fuse, maybe only one is faulty?

The transistors are junction transistors, to search for replacements add 2S to the part numbers, i.e. 2SA1633 and 2SC4278.

Cheers