So the SD board works as long as the MPU is booting up. Once the displays come on and the MPU has booted the fuse F3 blows. This is when A3J3 connected only.
I also have done the PinWiki ground mods, but for now I have removed the TP1 and TP3 tie in.
I'm told that something is pulling too much current if the fuse does not immediately blow. I have been trying to find what is causing the problem but no luck so far. Any suggestions?
This is the value of the test points after the F3 fuse blows.
TP 1 5V
TP 3 5V
TP 2 195V
TP 4 250V
TP 5 0.67V
I have replaced these parts:
R51 22k ohm 1/2Watt
R52 390 ohm 1/2 Watt
R54 8.2k ohm 1/2 Watt
R55 1.2k ohm 1/2 Watt
R56 82k ohm 1/2 Watt
R35 100k ohm 1 Watt
CR21 1N4004 400PIV 1 amp or better (1N4007, etc.)
VR1 Zener diode 1N5275A 140 volts, 1/2 Watt. Can Sub 1N5275B or NTE 5099A
Q21 2N3584 250volts, 2 amp, TO-66 NPN
Q22&23 2N3440 250 volts 1 amp TO-39 NPN
Q20 LM323K (original 78H05KC or LAS1405)
C27&28 .01 uf 400 vdc metal polyester capacitor