Dreamcast drive won't work

I've got a Dreamcast here for repair.

symptoms:

1. at power on, fan runs but no picture in tv
2. after i deassembled the whole thing and removed a modchip and reassembled i got picture on tv
3. now everytime i push the lid closed switch , the drive wont spin and the power led dimmed
4. I changed the psu also, now the power led stays, no dimmed led when pushing the lid closed switch
5. still no spinning drive, i switched the drive board, same effect
6. laser still shines red, was at 980 ohms and i turned it to 780 ohms to see if it's just weak, but still no spinning drive

Someone might know?

 

Have you tried swapping the entire GD-ROM assembly? I've seen that sort of problem from a bad spindle motor.

 

Nope, did not switch it yet.

Are those spindle motors common, like used in other cd based systems?
cause i got a lot of spindle motors and rumble motors in my repair parts box.

I always think at last the spindle motor could be broken, cause it will only spin if the laser recognizes the disc correctly.
Funny is, the dreamcast won't boot wihtout the complete drive, even not with the drive board only.
Nowadays consoles will boot even without the whole drive

 

you might want to try and cut the spindle motor wires and give it a small amount of voltage from an external power source , if it doesnt turn its most likely dead

 

what does the BA5986FM on the drive board do actually?
doesn't it do the communication between laser-unit and spindle motor?
I thought of this, cause i had some problems a while ago on a ps3 where the driver was faulty and the drive had like the same problems...

 

It's a multiple channel driver chip - it normally runs both the spindle and sled motors and the focus and tracking coils in the optical pickup assembly - having it drag the power rail down when it's taken out of power save mode is certainly a possible problem, but I had rejected it as a cause because you said you had swapped the GD-ROM controller board.

 

+1 on this

 

yeah I swaped it, but how do i know if the other drive board is working, cause it was loose in my spare parts box.
on a close look of the BA5986FM i can't see anything smoked, black, broken or whatever, but on the cooling pad above on one is a little black.

EDIT:

@ s8n

I did what you mentioned and tested the spindle motor with external current source ( AA battery 1,5V).
Turns out, one spindle motor is faulty.
I also tested the laser unit motor, both work on the laser unit i meassured the laser Ohms.
I downloaded datasheets for the BA5986FM and will meassure if it is faulty, also bought some new spare BA's from Hong Kong.

EDIT2:

I desoldered the BA's on both boards and wait for the new BA's to arrive.

 

It's been a time, but china is not very quick when it comes to shipping times...

I've gotten myself several new BAs , new SPU-3200 16-Pin and 17-Pin laser, just in case

Still running on the same problems after soldering in the new BAs.

Dreamcast powers up and everything, drive spins but very slowly and laser is not shining red.
This behavior is on both drive boards with new BAs and several testet lasers.

Someone got an idea about it?

 

I recently picked up two US units with a zero on the back. I had two Samsung drive assemblies laying around pooped them in an they both work now. I would of prefer to keep the original Yamaha drives but from sitting around in someones basement for to long there is so much corrosion on both the motors to the spindle and drive sled. One unit would shut off as soon as I closed the lid and the other just wouldn't read discs. I'm looking for parts as well. A long time ago I picked up the Samsung drives and two controller boards brand new but I guess these parts are now scarce.

 

Some replacement lasers come with a point bridged so they don't get fried from static electricity in shipment. I'm guessing that's your problem.

 

@ alf717

if you find a source, let me know
what I have are both Samsung drive boards.

if I had another unmodded Dreamcast to test out if the problem is from the drive boards...

I have only several modded Dreamcasts and dont want to disassemble them anymore.


@ billcosbymon

you mean ESD bridge, they are desoldered.


EDIT:

I managed to do some more testing.
disassembled a modded Dreamcast and took out a working drive, put it into the Dreamcast I've been testing on and what do I see, the working drive behave like all the other ones, like a faulty one.
So it isn't the drive at all !
the mainboard is not modded at all, so I must look whats wrong there, could be the bios or flash...

 

Try cleaning where the ribbon and the rom cables connect to the logic board. Sounds like a bad connection especially if the laser lights up

 

found the problem and I can't believe that a drive is acting faulty because of this problem...

its the psu !

power lines are not stable. i replaced all caps, still the same problem.
if i place a blue led ( 3-3,3V) on the 3,3v line and power on, it takes a little time till it lights up and then its flashing, not lighting up continously...
if i place a led on the 5V line, the 12V line drops down to about 7V.

i don't know what exactly is going on here.

 

It's rather hard to diagnose and repair switching power supply. A quick way is to unplug and remove it. With a meter set to ohms, check each v pin with respect to ground. It should be around 100 ohms. If it's fluctuating, very low, or very high check that rail for bad component.

You did put the new caps in the correct way? A backward polarized cap will throw a fit.

 

There is this pic that shows what voltages should be. Not sure if this is the same on a 220v power supply though, but if you have a good one, you can measure it and compare:
http://www.ultimateconsoleguides.com/Power.gif

 

@ wilycat

yes everything in the correct way soldered in.
for correct readings in ohms for components, i would have to desolder every component...

@ mickcris

the voltages are all fine and there, but like i said, its not stable, i can see this behavior with a led attached to the 3,3v line and its pulsating.
i have repaired Sega Saturn psus before, must be one of the pwm switches i guess...

 

You could connect the led and start tracing back. You may be able to tell what component is causing it by measuring before and after everything on that line.