Someone has schematic for 4D0 <Romulus> drives as i have many hdd with no power in pcb , or someone could tell me what are most of the problems in these kind of pcbs .

Thanks

Hi,

Could be the motor combo (SH6770), or the 3.3V regulator transistor, or something else
I would give it 3.3V to the proper point, check the clock signal at the crystal, if it is OK, then pull up the -POR line and see if there is any activity on the RAM address and data lines.
if these are OK, most probably the motor combo is damaged.
But of course these are only raw guidelines, there could be anything else causing the problem.
regards,
pepe

Thanks for reply .

One more thing i need to ask u is there any fuse on this hdd ?

Hi,

I don't think so.

pepe

no fuse in harddisk friend

There are fuses on pcbs on some hdds but i was not sure about this hdd .
Thanks for reply

Rameeze check L201, 202 203 &204 by power connector Q502 has 5v on 1 leg (closest to IDE connector)& 3.3 on other. U 503, 504, & 505 need to be good for motor to work. Rest is the same for the schematic you have. If you want me to give you some readings post what you need I have a few working drives so I can check.

_________________
I think ST is a sub company of Lucas

I will chk these points and give u update
thanks for help