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It's probably something to do with the Midi mod so have a look around for anything suspicious, wires/broken tracks etc.

It's very rare that you get problems with an Eprom, they are very tough. If you can read them with a programmer then UV erase them, then re-program them any problems will show up. Having said all this however, static is an enemy of us all. It depends how safe you are in this respect as to what possibilities may arise during troubleshooting.

It is much more likely that another IC is damaged/has been damaged by static or other reason/age etc, the main cause possibly being problems created during the installation of the Midi mod. EEproms (Eproms that aren't ceramic with a little erase window) can develop problems over time as they are erased/programmed with much lower voltages.I would not expect an OB to have these types installed.

I don't have any OB series synths. If there is a back-up memory system involved, then a big candidate for suspicion are the memory chips involved as any hint of static while checking the battery or replacing it is liable to damage the memory chips. I would look here first for problems if it was me.

From: Doug <dmeek@...>
To: oberheim@yahoogroups.com
Sent: Wednesday, 28 November 2012, 14:09
Subject: [oberheim] Re: OB-Xa Diagnostic EPROM needed

Yes, my best guess is that it is a bad EPROM. Unfortunately I don't have
the image files for the MIDI version. I have image files for the
original so I tried to remove the MIDI board and put in the original
EPROMs. There was no flickering but no sound either. I'm not sure
if i need to change anything else to revert it to original non-MIDI.

So a set of image files for the MIDI version would be useful too.

Doug

> Posted by: "Paulo Palmieri" paulopalmieri@... souldream70
> Date: Tue Nov 27, 2012 11:58 am ((PST))
>
> I don ´t have the eprom but have an OB-Xa with the same problem.
> In my case the buttons are working but the leds are flickering too and after 20 minutes they light off...
> I suppose that this could be an Eprom problem
>
> Paulo
>
>
>
> ----- Original Message -----
> From: doug1052365
> To: oberheim@yahoogroups.com
> Sent: Tuesday, November 27, 2012 5:43 PM
> Subject: [oberheim] OB-Xa Diagnostic EPROM needed
>
>
>
> I'm trying to repair this OB-Xa w/JL Cooper MIDI.
> Has no sound, all LEDs are flickering, buttons don't change anything.
> The power supply is OK. It seems the CPU is not booting up.
> Does anyone have an image of the Diagnostic EPROM
>
> Thanks
>
> Doug
>
>
>
>
>
>
>
> Messages in this topic (2)
>
>
>
>
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1434 Re: [oberheim] Re: OB-Xa Diagnostic EPROM needed