Sanyo 14" Color - Blows 355ma fuse

[MonitorGuru]

Hopefully Ken can help with this one   I just picked up a Nintendo game with a 14" Sanyo monitor in it.

When received it did not power up, but there was 100 volts out to the monitor and proper DC volts to the game board.  The seller said it didnt work.

A quick look showed the mini fuse, 355ma DC one was blown, but the 4 Amp AC one was okay.

I replaced the fuse and plugged it in (into the 100va output of the nintendo transformer).  There was a typical thump of a monitor coming on/degaussing, then after it had been on at least a second but before 4 seconds (didn't count exactly), a flash was seen in the 355ma fuse and it was blown.  

No sound of anode voltage crackle or anything.  About 10 seconds after it blew, there was about 80 volts across the fuse and decreasing at about 2 volts a second. a minute later there was no voltage left.

Any ideas where to even begin looking on this one?  

Note: The picture tube has some light etching, but in the lower center there appears to be a slightly darker "blob" showing in the phosphor.  Not a typical shot-tube where the neck is busted open and tons of particles blew onto/off the phosphor directly in the center, but rather a completely consitent colored dark blob that is noticable in the right angle but it's not dead center, it's offset.  

Could this have been a blown tube as well? would that cause the screen coloring if it was a tiny slow leak from an edge of the neck ? Would this blow the low amp DC fuse if connected?


Thanks in advance Ken!  I can post to RCVAC if you think others may have seen this problem too.

[Ken Layton]

If you suspect the tube, look closely for cracks particularly in the neck.

I think your blown fuse is from a shorted horiz output transistor or bum flyback.