saifbadri wrote on 2020-02-01, 21:59:Thanks got another freind who recommended this on discord. I will test that today. Caps look fine so I hope its just the regulator. I tried applying 5v to the logic inputtaping into ground and 5+ but got the same results. Maybe its a bad eprom...
This won't work if the regulator isn't failed open.
All hail the Great Capacitor Brand Finder
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.
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...
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?
It worked for one day, so polarity was apparently correct.
gdjacobs wrote on 2020-02-01, 22:46: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 is possible. You can erase the EPROM using UV light and reprogram it using a cheap device like the TL866. EPROMs rarely fail electrically, they just develop flipped bits and can be used again after erasing. If you have exactly the same ROM version, you don't even need to erase it.
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.
derSammler wrote on 2020-02-03, 10:37:It worked for one day, so polarity was apparently correct. […]
It worked for one day, so polarity was apparently correct.
gdjacobs wrote on 2020-02-01, 22:46: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 is possible. You can erase the EPROM using UV light and reprogram it using a cheap device like the TL866. EPROMs rarely fail electrically, they just develop flipped bits and can be used again after erasing. If you have exactly the same ROM version, you don't even need to erase it.
Thank you, I found the same rom on ebay so I got one just in case the old one is damaged. I also ordered the reader will see how that goes!
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 became 14...
The data also seems shifted in my file comparing the hex values. Will try burning the attached bin. fingers crossed will fix it! Power supply output seems working on all 5v pins...
DaCiRO wrote on 2018-11-08, 15:34:....I get this on-screen error message: '5ur' or maybe instead of a 5 is a capital S 'Sur'...the manuals do not mention anything about this error message which is rather strange since they mention others, ....this has me puzzled.
Just for the record: I had the same issue on a newly acquired SB-55 and it happens when you try to use a floppy formatted to 1.44 instead of 720k. You have to cover the hole on the lower right hand side of the floppy and format as 720k, that's all .
stalk3r wrote on 2020-06-10, 07:38:DaCiRO wrote on 2018-11-08, 15:34:....I get this on-screen error message: '5ur' or maybe instead of a 5 is a capital S 'Sur'...the manuals do not mention anything about this error message which is rather strange since they mention others, ....this has me puzzled.
Just for the record: I had the same issue on a newly acquired SB-55 and it happens when you try to use a floppy formatted to 1.44 instead of 720k. You have to cover the hole on the lower right hand side of the floppy and format as 720k, that's all .
I had the same issue of the SB-55 saying "Sur" on the display, turns out my floppy disk head was jammed. Opened it up, gave the floppy head a nudge and it started working beautifully.
And I would like to reiterate the above, along with, make sure that you transfer the files using a floppy drive designed for 2DD (double density) disks. Some of the newer 1.44 drives do not natively support 720k DD disks, and if you take a 720k disk and try to format it using "format a:" command, the drive will error out saying Track 0 (zero) is bad, disk unusable. I found that out after spending a whole day trying to get my SB-55 to read a disk ... 😀
I hope this helps someone who's in the same situation as me. Made an account on Vogons just to share this experience 😀 ... by the way, love Vogons, I've been reading stuff on it since the past year an a half, lovely community !
