Nanao MS8-26SU power issue

dave11674

n00b
Joined
Jan 29, 2021
Posts
2
Hi guys
I’m hoping you guys can help me out here with a problematic MS8-26su

Ok to start off
It’s a sega virtua racing
Nanao ms8-26su

First fault when it came into my workshop was
Vertical collapse
Narrowed down to R433 and R.. next to it lol
This brought the image back perfect
While I have a chassis out I usually do a cap kit too
Rules out any other issues.

Ok so the game was fine and running sweet, went for lunch and left it on a soak run.

Came back.. playing blind :-/
Rebooted, came back on but went off less than a minute later.
Reboot got nothing but playing blind.
Now n again the screen would come on but moments later a little click from the chassis as it turned the crt off !!

So I did a few tests

B+ 90v
Adjusted to 92.0vdc as per service manual

Tested x-ray voltage
28v
Service manual says should be 20-24v

Tested resistance with F902 removed to TP
SHOULD READ 2-5kohms
But this reads 6.3kohms

I’m a bit stuck here as if I remove components to test I’m unable to cross ref against any data sheets

Firstly could anyone share a parts list ?
Secondly does anyone know what values these parts are and a suitable replacement I can buy from Farnell’s or eBay
ZD501
D560
D561

Thanks in advance

Dave
 

dave11674

n00b
Joined
Jan 29, 2021
Posts
2
ok update

in regards to my x-ray on this chassis and it shutting the monitor down
i probed into the x-ray circuit
not many parts in this circuit
it runs of pins 3 and 4 of the LOPT depending if you have it normal or wide

so i was advised to test the monitor with a the xray circuit broken....meaning take a resistor out of the circuit...R562, this broke the xray signal into the IC103
this made the monitor stay on for over half hour

so looking at the components in this xray circuit
D560
D561
C560
C563
R560
R561
R565

ALL COMPONENETS TESTED OK OUT OF CIRCUIT !!!!!! lol
so i double checked each component against the schematics....
all but R565 were spot on.
my chassis had a 10K @ R565
schematics said it should be 4.7K !!

so changing this out has the monitor up and running again :)

thanks to all in here and other forums who make up these threads with repair tips

dave
 
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