IBM PCjr doesn't boot

[twistedpneumatic]

Hi guys,

Picked up a non-functional PCjr. Monitor makes continuous buzz tone and a white screen.

Tested:
No output on composite
Reset circuitry seems fine
When reset line is active, tone goes away.
Seems like there isn't too much activity on the address bus, but need an oscilloscope to search further.

Any ideas on where to start digging that isn't replacing the entire motherboard?

 

[twistedpneumatic]

Seems to have a shorted +5V rail intermittently. Putting pressure in the area of the 8088 creates and breaks the short.

 

[twistedpneumatic]

Only shorts when inside the case. Otherwise does as stated above.

 

[erikarn]

sounds very repairable