Jumpering The Shark (CEM3360 and MN3007/3101 content)

[spacelordmother]

I just grabbed a mid-80's Roland HP-5500 electric piano. Not my image -- the one I have is in pretty rough shape:



Sounds ok, but is huge and I don't have a need for it. BUTTTT it has a stereo chorus and trem effects section that I do have a need for. Had a thought "wouldn't it be cool if the effects were on their own board I could just pull out of there." Guess what:




annnnd it has a CEM3360 chip and 1 each MN3007 and MN3101. Now I'm really intent on getting them out and passing the rest of the piano on for free. I unplugged all the wiring harnesses to see if if would still work without, but unfortunately not. What I am hoping to figure out is a way to make the connections needed so that it will still work without. I wouldn't feel right scrapping the entire piano for the sake of a board, but who knows what road I will go down. Those chips are too valuable/cool to let rot. No luck finding the service manual so far other than an ebay auction.

I tried to compare the board to images of CE-2 (period correct) for similarities, but it didn't seem to match up. Any ideas on what these chorus/trem circuits might be? I doubt they aren't recycled from something else.

More board images from an ebay auction:

NSFW: show

[fever606]

JC-120 perhaps?

[crochambeau]

One half of a CE-300?

Once you apply correct power, you're probably also going to need to emulate any panel controls to complete functionality (I've no experience with this unit, so forgive me if I'm pointing out the obvious).

[spacelordmother]

Both good ideas to check out, thanks!

Panel controls for the chorus and trem? Currently they only have on/off and rate for the trem. First step is extricating it, but would then look to adding depth/rate/vibrato to chorus and maybe slow/fast to trem. (I tend to get wayyyy ahead of myself)

Croc -- if you were to tackle a project like this (pull board and jumper/recreate connections to maintain piano) where would you start looking?

[Strange Tales]

First step would be to find a schematic for this. Quick google search didn't bring anything up though.

[spacelordmother]

First step would be to find a schematic for this. Quick google search didn't bring anything up though.

In a perfect world.

All I can find is this auction for the service manual, so at least I know it exists:
http://www.ebay.com/itm/Original-ROLAND-Service-Notes-HP-5500-5600-Keyboard-/371879411751

[Strange Tales]

Here is a link to the Owner's Manual:
http://cdn.roland.com/assets/media/pdf/ ... 600_OM.pdf

[crochambeau]

Croc -- if you were to tackle a project like this (pull board and jumper/recreate connections to maintain piano) where would you start looking?

I'd figure out what ground is and clamp a multimeter lead to it, power the keyboard up (with your effects board removed) and record what DC power is on which pins.
AC voltage readings can point to signal input (if it's not fairly clear by looking at the board), effects output will hopefully be easy to decipher.
Unplug the unit (from the wall) and try to trace which wire loom goes to the on/off & rate controls, otherwise you're looking at spending some time with the loom looking for continuity and resistance changes when those controls are adjusted. Once you've got a road map on that jumper/recreate it on the effects board, since those controls serve no purpose on the piano, it might be easier to just pull them and use the original equipment (depends on how crazy the cabinet makers were).
I'd guess anything like "bypass" is done on the effects board, so its removal has killed the piano? I'd just connect the signal input and output wires (you have at this point established at the effects board) on the piano and treat yourself to a well deserved beverage!

[spacelordmother]

Nice, will poke and around and see what I see!

Yes -- unplugging the board killed the piano. I tried to see the effect of each harness removed one at a time in thinking one of them would be the issue, but having any of them out killed the output. Strange.

Looking forward to that beverage...

[eatyourguitar]

what he said. you need the entire rig to build your own documentation for panel controls, power supply, remote switching, ideal signal volume in and out. the easiest way (there is no easy way) is to remove the panel controls one by one and shorten the harness. then test each pot as you go with a 3 inch single pot 3 wire harness. after you get all that you can label the power wires (write down voltages and polarity) and remote switching lines (check voltages!). then you can check the remaining wires to find the signal in and out. process of elimination. then you can take it to the bench and connect your bench supply or some simple diy bipolar supply. it should be possible to get a working stand alone effect unit and a working "sans effect" organ. if done by a skilled technician with all parts and tools in stock I would say maybe 10 to 40 hours total for the two jobs. anyone else maybe 40 to 80 hours with a chance of oh fuck.

P.S. you may have a remote switching that is grounding the transistor in a two transistor flip flop. this is tricky. it will float from ground or short to ground but under no circumstance would you get a +5v to control a relay. check for +5v switching anyway. you never know.

[spacelordmother]

Project has been delayed as we had a large storm and water came through the garage ceiling. The piano didn't get too wet and I cleaned it up, but wanted to give it a bunch of time to dry out before powering it up again. Effects board has been pulled and brought inside for safe keeping.

Sounds a little (a lot) over my head! Not really sure this is something that I should attempt, and even if I did it would take me forever. Again, don't want to ruin the piano, but it's also hard to give it away knowing it has expensive parts inside...