Simple Drum Machine Mods? (early 70s drum box)

[Zoorama]

Hi all,
I'm new to this forum and pretty much an electronics neophyte (I've built one guitar pedal...from a kit).

I have an old Hillwood HR-30 drum machine that I want to modify...It's a great box --has 30 preset rhythms on ten buttons on the row and three buttons for choosing which row you want. BUT: you can select more than one button on each row (up to all 10!) and you can select two or even three rows at once. Which opens up a huge range of possibilities. Especially since speeding up or slowing down the tempo serves to highlight certain sounds over others...

My  main  question for right involves just understanding what kind of modifications are possible for a box like this.

My needs are pretty simple (for right now): I'd like to be able separate the individual drum sounds with their own output and/or volume controls.

How difficult would it be to perform this kind of modification? Is this something I could do myself, or should I look for someone who really knows what he's doing (i.e., pay)? (The box needs a bit of tlc, but it's in pretty good shape for its age --I'm planning on using it onstage though).

Thanks for any help, advice, etc.

[Circuitbenders]

If this machine plugs straight into the mains supply without an adapter i'd advise you to find someone who knows what they are doing to mess with it. You don't want to find out that you really don't know whatyou are doing by killing yourself.

Finding separate outputs is one of those areas where it really helps if you have a schematic or a decent idea of the electronic workings of the circuit. You can often find separate output points by plugging a lead into a guitar amp or similar and then attaching the sleeve connection of the jack at other end of the lead to the ground on the drum machine (i.e. the sleeve connection of the jack sockets on the board). You can then touch various points on the board with tip of the jack plug while the machine is playing. If you find a separate output point you should just hear one sound but bear in mind that analogue sounds like snare drums are usually made up of one or two tones and a burst of white noise. It may be impossible to isolate the entire mixed snare in one go.

I say to use a guitar amp because guitar amps are more likely to be built to cope with any excessive voltages you will inevitably accidently send it using this method. Whatever you do, stay away from the power supply area of the board when probing for outputs'

[Zoorama]

I think my chances of finding a schematic for this box are nil... about all I've found on the net so far is the photo (and the full page of the catalog).

On the other hand, there are a few points on the circuit board that are labeled with instrument names ---that's probably the best place to start with your test method. I can easily rig up a test jack.

Perhaps if I can take a few decent photos of the board that might help too.

I'm definitely leery about monkeying with anything with a power supply! I'm actually hoping to find an electronics expert around here (France) to take the job on.

[Circuitbenders]

On the other hand, there are a few points on the circuit board that are labeled with instrument names ---that's probably the best place to start with your test method. I can easily rig up a test jack.

Well that makes things a lot easier. In that its an analogue machine each labelled area will probably contain the entire circuit for each voice. If you find an output for one voice the layout will probably be roughly the same for all of them at the output stage. Or look for an area where all the labelled areas come together and work backwards from there.

[squidfanny]

Wow, your drum machine is very similar to my roland tr-330. . . You will probably find that the individual drum sounds are clearly marked on the board. Mine is marked 'sd1, sd 4, bd 1, cb 1, etc'. . I can patch these component waves straight off the board. Also there are pots which control decay on the high and low end f the kik drum, there is also tone control and some other functions which could be added.

I am not at all an expert, and I haven't spent much time playing around with my drum machine, but from what I've seen and been told, there is alot you can do with these vintage analogue machines. Just remember that there is alot of power going in to it, and you could easily break it or kill yerself if your not careful...........