Stereo Power Amplifier Philips type 22AH578/00

3/12/2001 4:18:37 AMSeb

Hello...

I need technical informations for this amplifier :

High Fidelity Laboratories Power Amplifier
PHILIPS Type 22AH578/00

There are 16 transistors TO-3... One of them is failing... On the transistor is written :

Toshiba 355-1
0 .827

Nobody knows this type of transistor... So help me if u can... What sort of transistor is that ?!? Somebody know where I can found it ?!?...

thx bye !

3/20/2001 10:58:05 AMJohn McPherson

Hi,
Pull out one of the good transistors, and determine if it is NPN, or PNP.

If you know what the "B" voltage in the final stage is; you may have to install the bad transistor temporarily to do this- check the good channel however.

While checking the "B" voltage, check the bias voltage at the base of the corresponding transistor that is on the good channel. Inn other words, note where in the circuit the bad transistor is located, and on the good channel, measure the base voltage.

If your "B" voltage is between about 60 and 80 volts, It may work for lower voltages too. NTE 28, or NTE 29 are likely to be suitable replacements.

If your "B" voltage is lower than that, NTE121 is like a suitable replacement if it is a PNP type.

Otherwise, with the known voltages for the "B" voltage, and the base voltage, you can find a close match by looking at the specs for a replacement, and find one that is close, yet still greater in voltage ratings, and you should see satisfactory results.

One note- For the best results, and reliability, just replace all of the transistors at the one time, otherwise you may hear noise in one channel, better sound reproduction in one channel, etc.

: Hello...

: I need technical informations for this amplifier :

: High Fidelity Laboratories Power Amplifier
: PHILIPS Type 22AH578/00

: There are 16 transistors TO-3... One of them is failing... On the transistor is written :

: Toshiba 355-1
: 0 .827

: Nobody knows this type of transistor... So help me if u can... What sort of transistor is that ?!? Somebody know where I can found it ?!?...

: thx bye !