Latin/African EPROMs / EPROM expansion issues

[captainjc]

I'm borrowing a friend's Drumulator (with opportunity for permanent trade) with some interesting expansions (and problems).

It has an expansion board with a switch to toggle between 3 different sets of EPROMs. The problem is it has some issues.

It seems to work ok with the factory EPROMs (for some reason I have 2 sets and both work fine), but not for a set of Latin Percussion. However, this Latin set works fine as the only sound set when I take the expansion card out. With the card in, it plays only some of the sounds and some buttons play multiple sounds with one hit. I'm guessing this has something to do with the Latin OS PROM not loading properly?

The card is missing one of the pins that connects to the 5E or EPROM D slot - looks like it broke off. I'm thinking there is a pretty good chance that this is what's causing the problem, but what do I know... not much actually.

In addition, the African Percussion set has pins missing (1 from the OS PROM and 1 each from 2 of the sounds PROMS) and doesn't work... a shame because when i plug the working ones in with the Latin os PROM they sound cool, but they do that thing where multiple sounds play per hit. I'm guessing it's because, since there's more than 1 sound per EPROM, the OS PROM has to tell it where each of the sounds are? So if you use the wrong OS PROM with a soundset, it gets all messed up.

Anyway, this is all a hell of a lot of conjecture on my part, so feel free to correct me if you know better.

Basically, right now, I have a working midi expanded drumulator with Latin Percussion and the factory drum set that I have to open up and swap out to use. Not too bad... but would love to get that stuff fixed.

Does anyone know

a) where I can get the right kind of 28 pin plug to replace the one on the board with the missing pin?

b) if there is some way to repair EPROMs with broken pins? If anyone has the ability to fix or copy them (with the broken pins), I'd be happy to send them out and you can make copies for yourself. I'd pay for any materials of course too.

[captainjc]

This is what the plug on the expansion board looks like. If anyone knows what it's called or where I can get one, please let me know.

[gertie]

you can easily repair the broken eprom by using a bit of soldering iron and a small piece of wire.....i did that for a couple of broken eproms in my drumulator and all sounds are fine now

[captainjc]

I will give that a shot. So you just solder from the missing pin to the board then, bypassing the socket? or do you just try to make the connection in the socket with the wire?

[gertie]

just try to make connection with socket in wire

[captainjc]

Cool. I'll give it a shot. Thanks!

[captainjc]

Ok, so the pins have been fixed (both on the EPROMS and the plug that connects to the board). The screen no longer goes blank in one of the switch positions. However, both the African and Latin sounds still trigger wrong when used in the expansion board. IE You hit one of the buttons and you get a cymbal followed by a drum, or a delay before the sound. For the factory sounds, it works fine.

When they are plugged in directly (without the expansion board) all 3 (Latin, African, Factory) work fine and trigger as they should.

My understanding is that the OS PROM is what tells it where to find the sounds on the other chips. It would seem that the expansion board is somehow using the factory OS PROM only - and only switching between the sounds - even though all 3 OS PROMS are plugged into it. (To connect the expansion board, you have to take out the 4th sound EPROM and the OS PROM so there is no OS PROM left on the main board.)

Anyone have any insights into why this might be? Any ideas for troubleshooting?

[captainjc]

For anyone who may be following this the problem was that I had left 3 of the original eproms in the main board. Once those were removed, it worked perfectly. Pretty sweet!