hello all, my first post ...be gentle.
Im after some help on a dead 4032 PET
here are some details...
I've ordered some sockets for chip removal and ram tested (all soldered) I'm slightly conviced the PSU is outputting wrong ....ive ordered new regs to solve this i hope.
the 12v /5v is too high and the -5 is too low
I've also ordered the PETvet board to help with diagnosis.
mike
RAM 4116 pin1=-6.3v pin8=15.8v Pin9=6.45v Pin16=GND
Video ram - swapped for ZX ram - seems good.
CPU - tested good.
motherboard to monitor
white=0
grn=6.39
white=0
red=5.88
w=0
yell=2.3
AC PSU
BL=13.55
BL=13.55
BLK=0
BWN=12.2
RED=0.44
BWN=12 OR 7 OR 3 (cycles)
CPU pin 8 =6.34v
The monitor occasionally has a light from the centre or a straight line top to bottom about 1mm wide and then fades to black , no beep from the buzzer on the pet.
I think something odd is going on with the PSU but I'm having trouble finding what they should be.
ive done some work since with a new multimeter and the outputs look better , I've list them in a reply below but I'm waiting for moderation? Anyway - Power looks ok , i have changed the CRT controller and now the PET seems to be pulsing like its stuck in a loop ? ....
BLUE/BLUE 16.62-16.64
BRWN/BRWN 18.41-18.42 AC
RAM -4.89, 11.83, 5.06 volts
Video connector now has pulse , voltages are yel:1.53, White 0,Orange 4.58, White 0,green 4.80 (white is ground?)
cpu pin 8 = 5.02v
I video'd the noise that the screen makes , no picture obviously
https://www.youtube.com/watch?v=x6cqniWV4gc
mike.
Im after some help on a dead 4032 PET
here are some details...
I've ordered some sockets for chip removal and ram tested (all soldered) I'm slightly conviced the PSU is outputting wrong ....ive ordered new regs to solve this i hope.
the 12v /5v is too high and the -5 is too low
I've also ordered the PETvet board to help with diagnosis.
mike
RAM 4116 pin1=-6.3v pin8=15.8v Pin9=6.45v Pin16=GND
Video ram - swapped for ZX ram - seems good.
CPU - tested good.
motherboard to monitor
white=0
grn=6.39
white=0
red=5.88
w=0
yell=2.3
AC PSU
BL=13.55
BL=13.55
BLK=0
BWN=12.2
RED=0.44
BWN=12 OR 7 OR 3 (cycles)
CPU pin 8 =6.34v
The monitor occasionally has a light from the centre or a straight line top to bottom about 1mm wide and then fades to black , no beep from the buzzer on the pet.
I think something odd is going on with the PSU but I'm having trouble finding what they should be.
ive done some work since with a new multimeter and the outputs look better , I've list them in a reply below but I'm waiting for moderation? Anyway - Power looks ok , i have changed the CRT controller and now the PET seems to be pulsing like its stuck in a loop ? ....
BLUE/BLUE 16.62-16.64
BRWN/BRWN 18.41-18.42 AC
RAM -4.89, 11.83, 5.06 volts
Video connector now has pulse , voltages are yel:1.53, White 0,Orange 4.58, White 0,green 4.80 (white is ground?)
cpu pin 8 = 5.02v
I video'd the noise that the screen makes , no picture obviously
https://www.youtube.com/watch?v=x6cqniWV4gc
mike.
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