Sony hb 75p freezes | MSX Resource Center (Page 2/2)

Paragon (1426)

16-11-2020, 11:03

only -12v is on this board check on pins of C8 47µf 16v

on the 2 litle board you have the regulator for 5v and 12v
for 5v check on pins of C6 47µf 16v
for 12v check on pins of C7 47µf 16v

By AndreV

Expert (102)

16-11-2020, 21:01

Thanks all for a crash course electrician, learned much. much appreciated.

By sdsnatcher73

Paragon (1351)

17-11-2020, 07:11

So you fixed it? What was the cause and remedy in the end?

By AndreV

Expert (102)

17-11-2020, 08:33

sdsnatcher73 wrote:

So you fixed it? What was the cause and remedy in the end?

No not yet, maybe i can't fix it, but i can try and now have someting to check, i seen also a repair clip on youtube where the ram chips where faulty, The msx was not verry expensive, I could have known sometings wrong with it. The fun is to get it working again.

By Briqunullus

Champion (261)

17-11-2020, 09:44

Don't go down the route of lifting components too hastily. Only do so if you are told explicitly. Otherwise you may end up swapping more and more components without any progress. It's a nice puzzle though.

By AndreV

Expert (102)

17-11-2020, 10:50

The guy in the repair video mentioned that also, cos the pcb is made of paper not fiberglas, and a real pain to repair and not pulling the copper traces. And like you said its a puzzle, i hope i can solve it, and not still learned something.

https://www.youtube.com/watch?v=SknAQpC26oo

https://www.youtube.com/watch?v=OSoKJ3F56wQ

By AndreV

Expert (102)

26-11-2020, 15:25

I did a little expirement.

with the fan on it runs perfectly, it runs as long as i wanted,With the fan off after 10 minutes it resets and freezes so i think that the ram chips get to hot and it resets. thats a bummer I'd rather replace a capacitor than ram chips.

By AndreV

Expert (102)

11-12-2020, 21:43

Read some specs from the 4116 dram used for the vram, and they can't run hotter then 70 C and 6 of the vram run within 10 minutes to that temperature, other 2 stay at 50 C, ordered 8 4116 dram (still waiting). first gonna install the ic sockets. new 4116 vram ic's. I hope that it solves the issue.

By AndreV

Expert (102)

27-12-2020, 16:29

Removed the 4116 chips, which almost took the whole day. now I have to install the ic sockets and insert the new 4116 chips, and hopefully the hb 75p will be fixed.