Philips-Magnavox chassis 25X601 00 AA

[Reece]

In checking over the devices suggested in the Sams power supply troubleshooting section, I find one transistor "iffy." It's Q462, identified as "8V source," and marked 554-3 and marked under that the Motorola batwing symbol and 617. I can't find it or a cross for it anywhere. Anyone know of one?

[Zenith26kc20]

I HOPE I found the correct notes...
C432 opens, killing Q402 and R432. It can also kill R435 which will give a small picture after the repairs are thought to be done. Q403 also can fail and I think it caused the set not to turn off. The regulator does not usually fail but Q400 will fail if high voltage rises too high from C432 opening. This sets regulator IC is actually a driver for the true regulator (Q400). Pin 2 of the regulator is pulled down to 17 volts when the set is off and rises to 133 when on. Kind of a twisted power supply but it works!
A shorted HOT will kill Q400.
Be careful with vertical electrolytics also, they will open and kill the vertical out IC.
I'm pretty sure these are the correct notes on this set. It applies to many of the Magnavox chassis out there. The first sign of failure on this sets power supply is a scrambled picture when C432 starts to open. Keep playing and R432 will start to overheat. Keep going and the fun begins!
Never had any flyback issues on this one.
Otherwise very reliable sets.

[Dangler]

Originally Posted by Reece

In checking over the devices suggested in the Sams power supply troubleshooting section, I find one transistor "iffy." It's Q462, identified as "8V source," and marked 554-3 and marked under that the Motorola batwing symbol and 617. I can't find it or a cross for it anywhere. Anyone know of one?

According to the NTE web site, it crosses to an NTE 399. I really don't know if that is correct or not. It lists two 554-3's. The first is an RCA part and the second is a NAP (North American Philips). You might check it out and see for yourself.

I got the regulators and fuse out in the mail yesterday, so you should have them by Thursday.

[Reece]

Thanks, Dave. Yeah, I saw the NTE cross, but don't think they are right. They don't jibe with the functions. The RCA is a big IC, and the other sounds like it ought to be right, I'm guessing NAP is North American Philips, but it doesn't ring true per the description. And can't find the Motorola reference anywhere. This is just a little three-legged xsistor.