Hi John, thanks for the welcome message, I can see there is nice people here like you said. I already downloaded the manual you mentioned but it's not the one for repairing the 5200.
CPUWIZ, couldn't find any info about that part either, anyway I added it to the compatible list.
I couldn´t find those memory parts in some electronic shops I called, but I found some 256Kx1 DRAMs in a 286 MOBO, so I replace the fused drams with this ones grounding their not used address inputs (pins 1,9 not used in 16Kx1 drams).
The replacement parts are TMM41256CP-10, featuring 100ns RAS access time, 50ns for CAS, and 100-220ns for cycle times (100 for page mode). I suppose it should work with this ones.
Anyway, now there is no heat on memories but the screen stills black for every game except Defender, where shows up on the rigth of the screen a vertical white line. On power on some random inverted horizontal lines appears over the vertical one, but after a little while this jumping random lines tends to be less and finaly they vanish leaving only the vertical white one on the screen.
If anyone has an open unit and feels like testing some VDC values, I measure this (those in parenthesis are from the schematics for the four ports in this site)
Q1: 4.02 V (4.3) - 3.45 (3.5) - 1.42 (1.2)
Q2: 4.02 V (4.3) - 3.44 (3.5) - 0.92 (1)
Q7 (emisor): 9.4 (14)
This last one is quite far from the value in the schematics.
For the three test points over U8 on the board (left to right): 3.93 - 4.92 - 0.36
From the regulators inside the unit: 9.3 and 4.94 V (side pins)
I'm using a regulated power supply at 11.5 V - 10.6 V when 5200 powered on (it can handle three amps).
Now I'm really stuck, any clues?
Should I post this in the hardware forum?
Thanks,
Zinok