Vintage Synth Explorer Forums

Hello all,

I have a Microwave I (rev. B I believe but it still has some characteristics of rev. A, green led w/black letters, board layout of rev. B but uses Curtis CEM 3389). Unit was functioning fine and had version 1.25 factory eproms installed. I bought version 2.0, off ebay from Vintage Planet and installed them.

I was distracted when I installed them and I installed them incorrectly. I installed them in the correct L and H position but the wrong orientation. Powered up the unit and the display was black. I opened it up and realized my mistake and switched the orientation (indentation of the eprom chip oriented the same way as the previous eproms). Put it back together and powered it up with no results. took it apart and realized the fuse had blown.

I replaced the fuse and at the same time put in a new battery. By the way, the fuse which was in there appeared to be a slow-blow, I replaced it with a fast-blow fuse which I assumed would be safer for the synth - any issue with this?

Now the unit powers up, but all I get is a row of black boxes across the top of the display and a drone of what sounds like a mish-mash of audio waves coming out the audio ports.

I am unable to start up the unit in service mode (by holding down Mode button on startup). No response from any buttons on the unit or using the rotary dial.

I attempted to load some sysex data and also midi files which I found on Waldorf archive pages with no success (I tried factory.mid . I don't seem to have any midi communication.

I also don't posses any original ROM/RAM cards as I bought this unit new, so I haven't been able to try to "initialize or reboot" the system with a card installed.

Maybe someone has had similar issues and could help or could point me to another forum or resource for troubleshooting this issue. I've searched this forum and the internet and not been able to find any solutions or documentation to resolve this. Saw some previous posting with somewhat similar issue but no solution to the problem (and it was about 5 yrs. old...)

thanks for any info!

dan

P.S., I'm in northern california, in the event that I have to resort to taking it to a shop and anyone knows a good waldorf tech.

Unfortunately you probably fried the EPROMs. My experience with 27xx EPROMs has been that damage is inevitable if you plug them in backwards. Have you tried reinstalling the factory EPROMs to see if it boots up?

As for the fuse, if it works with a standard fuse of the same amperage, no worries. However, you may find that sometimes it blows the fuse at power on. If that starts happening. go back to the slow-blow.

Thanks for the reply Cornutt,

I'm afraid you are probably correct - what a bonehead move... I did replace the original v1.25 eproms and loaded factory patches back in and everything is functioning normal. I'll try to order some new eproms and not make the same mistake twice...