Irem m92 no sound +funky colour problem

[hrvat9]

Looking for the values for :
R202
C205
Edit : just noticed c205 is the brown cap beside it since it has the square on the board; 154J , how do you interpret that ?
They were missing because of corrosion

 

[hrvat9]

Just noticed online that these two aren’t populated (I think on all motherboards). Mine must of just looked like something fell off from the corrosion , since it raised the solder up

 

[rewrite]

154J , how do you interpret that ?

https://www.amazon.com/First-0-15UF-P15-Metallized-Capacitor/dp/B074TCVZ3S

http://www.synthrotek.com/wp-content/uploads/2012/08/Capacitor-Codes.pdf

 

[fuzzbuddy]

M92 cap list (excluding 154J):

C201 1uF 50V
C202 470 uF 25V
C203 220uF 10V
C204 22uF 25V
C209 100uF 25V
C210 1uF 50V
C213 47uF 16V
C215 1uF 50V
C216 1uF 50V
C217 1uF 50V
C218 1uF 50V
C219 1uF 50V
C236 100uF 25V

• R201 – 1KOhm
• R203 – 100KOhm
• R205 – 4.7KOhm
• R208 – 4.7KOhm
• R209 – 2.7KOhm
• R211 – 10KOhm
• R213 – 10KOhm

I appreciate that this doesn't answer your question, but thought this info might be useful at a later date

 

[hrvat9]

Thanks! Got it recapped and now my picture is stable and theres deafening radio silence instead of squealing I also got a funky colour problem

M92 cap list (excluding 154J):

C201 1uF 50V
C202 470 uF 25V
C203 220uF 10V
C204 22uF 25V
C209 100uF 25V
C210 1uF 50V
C213 47uF 16V
C215 1uF 50V
C216 1uF 50V
C217 1uF 50V
C218 1uF 50V
C219 1uF 50V
C236 100uF 25V

• R201 – 1KOhm
• R203 – 100KOhm
• R205 – 4.7KOhm
• R208 – 4.7KOhm
• R209 – 2.7KOhm
• R211 – 10KOhm
• R213 – 10KOhm

I appreciate that this doesn't answer your question, but thought this info might be useful at a later date

 

[hrvat9]

Reseating ics on the b board; one had a pin bent back and not going into the socket (this changed nothing when corrected) and the one mask rom has the ground (?) pin broken clean off. would that mask rom be for sound or for something to do with my colour issue?

 

[nnap]

C-Roms are for GFX tiles, so that would account for graphic issues. Does the problem change when running the board without that mask rom?

 

[hrvat9]

C-Roms are for GFX tiles, so that would account for graphic issues. Does the problem change when running the board without that mask rom?

Good call, yeah It does change similarly but a lot worse with the whiting effect. The grinding pen is coming out first to see if I can reveal this busted leg

 

[hrvat9]

Pin fixed but it didn’t make any difference.
I also noticed this little guy is busted and a pin is gone from this 7474; is that normal on m92s?

 

[hrvat9]

Finally got my other m92 board set back and I confirmed that the sound boards on both work!

Now both of my top boards have a similar problem where the colours are off. Pictures to follow of each board running

 

[hrvat9]

First board set. You don’t see the ram rom test check at the beginning for some reason. You also don’t see the recycle screen after the winners don’t use drugs screen

 

[hrvat9]

Second board set. The ram rom test is visible. The recycle screen is visible but very dark. The irem crests are different colours on both games

 

[ForestOfDreams]

Pin fixed but it didn’t make any difference.
I also noticed this little guy is busted and a pin is gone from this 7474; is that normal on m92s?

I can confirm the IC53 bodge is normal. If you put it back bad things happen with the video. Ask me how I know....lol.

 

[ForestOfDreams]

First board set. You don’t see the ram rom test check at the beginning for some reason. You also don’t see the recycle screen after the winners don’t use drugs screen

You can try re flowing the ga22 or ga21.
My board had an issue with sprites until it warmed up that was completely fixed by re soldering each pin of the ga22 with quality leaded solder and flux.
I don't think hot air will do it, it looked like someone had previously tried.
Its fairly involved unless you are good at soldering but I believe that to be the issue with these chips in general before failure is inadequate solder.