MAC A1706 NO POWER

[NConstantinou]

GOOD MORNING ALL
I HAVE THE ABOVE BOARD AND DRAWS 20V 0.087AMPS.
PPBUS_G3H I GET 13.05V.
I NOTICED L7960 IN DIODE MODE I GET 0.0001 ON PIN 2 WHICH GOES TO CPU. ALSO U7800 IS GETTING HOT.
FOCUSING ON L7960 PIN 2 GOES TO C7964 WHICH SEEMS OK AND THEN DIRECTLY TO CPU.
IS THE PROBLEM ON CPU OR U7800!

THANKS

[Harryrepair]

Gia sou, 0.00 seems low for the cpu. Check in resistance mode (OHM MODE)

[NConstantinou]

Gia sou Harry, the resistance is very low 0.4 OHMS

[Harryrepair]

indeed the resistance seems low. Try to inject into cpu and check the heat development

[NConstantinou]

i have injected 0.7v and 1.2 amp on coil 7960 but nothing gets hot. if i increase amps the the red light from power supply goes off.
any other suggestions.

thanks

[mon2]

Is the heatsink on the CPU off?

[NConstantinou]

the heatsink on the cpu was off

[mon2]

Meter in resistance mode. Touch your meter probes together. What is the resistance in ohms? Then measure the resistance to ground again of L7960. What is the measurement?

[NConstantinou]

in both cases resistance is 0 OHMS

[mon2]

I would suspect that your CPU is dead but wait on other comments.

For giggles, lift up one leg of L7960. Then measure again. Which side is with the 0 ohms to ground? Maybe with some luck, it is the low side of the internal mosfet inside of U7960.

[NConstantinou]

Hi Mon2. How is Windsor!
the problem is on pin 2 on L7960. on pin 1 of L7960 i do have resistance.
what i have done i disolder pin 1 of L7960 and i inject voltage but nothing got warm.
if i connect pin 1 of L7960 then U7800 gets HOT

[mon2]

Hey Windsor is exponentially declining. Junkies everywhere - have had multiple attempts to break into our business.

When you lift up L7960 - what is the resistance to ground on pin #1? Pin #2?

[NConstantinou]

Pin 1 is 6.93k and pin 2 0. Junkies are everywhere today. we have a lot coming from African countries. unfortunately we work for them

[mon2]

To me, the CPU is dead. What used to be our downtown library is now a shelter for the homeless. Scared to even go downtown anymore. Personal pizza @ Terra Cotta down the street from your former place has increased from $12 to around $20. Pizza is outstanding but we reserve to eat it only on the '2 for Tuesday' deal - still a ~$100 investment. New owners there and also Shin Shin. Next time I am in the area, will try to take a few pics to update you.

[NConstantinou]

Thanks a lot for the brief info. it seems that the same story is everywhere. Here also in a few years will be minority and yesy at night you are afraid to go downdown because of these people BUT is missed WINDSOR.