Sony amps with upc1298v or upc1342v

[euromatlox]

I have been repairing a Sony TA-F170 amp lately, and it seems that the two upc1298v driver ICs are causing about 14v dc voltage into speaker outputs (I bypassed the security chip C1237HA to find out this).

Are these upc1298v or upc1342v chips typical failures for Sony (or other brand) amplifiers ? Do they fail because volume knob is turned too big level ?

I have measured several caps, the main transistors 2SC3855 and 2SA1491, some other driver transistors, but found nothing wrong. Some caps have also been already replaced (just in case).

Voltage from the output of upc1298v into base of 2SC3855 is about 14.6V, and it should be about 0.6v. Several other pins of 'upc' have also overvoltage readings.

I'm not asking any specific help here, just want to know if someone is familiar with the 'upc' chips and Sony amps.

The service manual can be found from elektrotanya.com.

[mohomane]

Re: Sony amps with upc1298v or upc1342v

hi,i had same amp for repairs one upc 1298 was the culprit,even without removing the security i.c.i changed both 1298 chips the amp will work ok even with power output transistors removed but without full power.good luck