Road Kings display issues

Hi guys,

Recently got a Road kings.
MPU had some battery damage right above the holder; and I have the below issue on the displays:
P1 & P2 "y" segments are all on, all the time.

How can I check the cause? If it's located on the MPU or on the display board?

Many thanks in advance for your help!

20210224_181550 (resized).jpg

#2 3 years ago

LAG

Nihonmasa

up?

#3 3 years ago

MCK

I've never had this bad of a problem on a system 11. ...so I don't know if I'll be much help... But:
How far have you gotten on any diagnosis? Have you done a display test? Have you checked for burnt, corroded or cold solder joints on the pins and connectors? check both the mpu and the display boards? I see 00 on display 1--does it score at all when you play a game?
How bad is the corrosion from the batteries and have you done anything to repair the components affected?
Have you checked any repair guides? (I'm not being facetious, it's something I constantly go back to when I have a problem I haven't dealt with, which is often. ).

#4 3 years ago

DEC

GRUMPY

Pinside member

10y 95,050 8,702

OP
Quoted from Nihonmasa:
P1 & P2 "y" segments are all on, all the time.

This is the J segment that is stuck on.

Hook up a logic probe to the CPU. Test SRC 5 pin 3. What do you get?

#5 3 years ago

LAG

Nihonmasa

many thanks to both.
I did check the schematics, reflowed the solder, tried the cables...
Corrosion was not too bad, only component which look damaged was a cap which I replaced.
Neutralized the corrosion with vinegar, and cleaned.

Grumpy: I read 0 in CMOS and 1 in TTL. So I recon it's bad? Do you have an example of a ref I can order to replace it?

#6 3 years ago

DEC

GRUMPY

Pinside member

10y 95,050 8,702

Logic probe should be set to ttl. If you read a high constantly, then you may have to replace the SRC with a new one.

#7 3 years ago

LAG

Nihonmasa

Quoted from GRUMPY:
Logic probe should be set to ttl. If you read a high constantly, then you may have to replace the SRC with a new one.

That's what I feared Would you know the ref? can't manage to find it

#8 3 years ago

TOX

ChrisHibler

Chris' Pinball Repair

Chesterfield, MO

12y 120K 9,996 46

OP
Quoted from Nihonmasa:
That's what I feared Would you know the ref? can't manage to find it

You need a 4.7K bussed 9 pin resistor SIP. The original SRCs are no longer available. They integrated a pull-up resistor and a noise filtering capacitor into the same package. In practice, you won't notice a difference by not having the capacitor in the circuit.

But you really should properly abate the alkaline corrosion which means removing parts, sanding to bare copper, replace parts, conformal coating bare copper. It's tedious but doable on System 11 MPUs. The sooner you abate the damage, the better the chances of success.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#9 3 years ago

LAG

Nihonmasa