I read the rom in my SB55 and compared the file to the attached rom in the begining of this thread. I see a difference 0A string is 15 in the attached bin while its 14 in my bin I read from the eprom. This is consistant with the advice I got which is eprom develop reverse polarity! 1 -> 0 since 15 …

It worked for one day, so polarity was apparently correct. This won't work if the regulator isn't failed open. Exactly. Also, it's quite courageous to just feed 5V in after the voltage regulator without knowing what fault there is. You may even cause more damage this way. But anyway, a failed ROM …

yawetaG wrote on 2020-02-02, 07:59: saifbadri wrote on 2020-01-31, 21:09: Hi, my wife used a 12v DC instead of 9v DC to power our SB-55 and now it has black screen. Reverse voltage or not? No both adapters have Roland's correct polarity. only voltage was different.

I tested today with a multimeter 5v exactly out from the power supply to the logic board. EPROM chip was removed and I notice a tiny stain of oil underneath it and touching one leg, so weird maybe it just died...

Im trying to get a another rom chip. I see a chip with amd 1986 on it. And a bunch of numbers highlighted with red ink. Any idea how we can program the above binary attached to a new chip? Thanks in advance.

Hi, my wife used a 12v DC instead of 9v DC to power our SB-55 and now it has black screen. Normally, the SB-55 can work fine with an input voltage of 12V, as the input voltage is always regulated down to 5V, no matter if you feed in 9V or 12V. But considering it's age, the voltage regulator …

gdjacobs wrote on 2020-02-01, 02:23: Does it function or is there more wrong than the display? No its not working at all. Only gaint sound then the disk stops. Hitting play or clearing it as roland recommended not helping. The power led is off too... Is this a symptom of a bad rom?

Hi, my wife used a 12v DC instead of 9v DC to power our SB-55 and now it has black screen. only a small amber light inside of the disk drive bay (you have to open the disk lever to see it) I was looking at the service manual above (thanks for that btw) and I'm not sure which component I need to take …