woensdag 11 december 2019

Roland PM-16 battery replacement

For those who have been involved in electronic drums for some time, it always seems to be the case that when a new piece of gear comes out it can do a little bit more than the last, but still not enough for its resources to be inexhaustible. In other words, you always get to the stage where it just can't do what you want.
Although almost 30 years old, the PM16 is without doubt still close to what percussionists are beginning to realise they need: an extremely flexible triggering system, which has plenty of memory, plenty of programming options and which can be sophisticated when it needs to be, but which can also be set up very quickly.

With its two-stage editing, the PM16 provides just those options. The easier programming stage offers a good introduction to the art of MIDI triggering, but if you find that initial experiments leave you with the desire to go one step beyond, then the Advanced Edit mode means you're not going to end up frustrated or with the need to spend yet more money to upgrade.
Neither does the design of the PM16 limit its applications to drums only. With its switchable trigger inputs it still can prove a useful tool for creative setup's using sensors in DIY installations to trigger sounds in modern DAW's.


With a kid of handpan style interface in mind, using piezo sensors to trigger multiple sounds via MIDI, I pulled my dusty PM-16 off the rack.
One click on the powerbutton revealed that the 9V DC powersupply had died. So off to the stores to get an replacement. Be aware that the polarity is somewhat odd: the plus is on the outside of the connector.
It came alive, but soon I discovered none of the preset patches were kept stored after a power off. The manual stated an internal battery, so that's were the adventure began: replacing the battery.

After googling the internet for an hour it became obvious there's no service manual nowhere. So I was on my own on this one.
The following is my path to replace it. Maybe there are better ways, please let me know. But the following steps may be useful for anyone running into the same issue.

First remove the 7 screws at the bottom side. The large ones can be left alone, these have the purpose to mount the PM-16 on a drumset mounting plate.

Then on the back there are two screws at the left and right side. After this the backplate should come off easily.










When opened you'll see a large shield that covers the place where the battery is located. There is one screw to be removed at the right side.


The shield can be gently folded to the left. I put an heavy object on top of it to keep it in place while working.
Now you can see the battery.
In my case, the battery seems to be fixed mounted in a clip that is soldered on the board! Would this mean that I would have to unmount the entire board?!  Hmm.
I  carefully de-soldered the front pin by using a solder sucker tool and gently lifting the battery up at the front side with a screwdriver while heating the solderjoint. Careful not to scratch the pcb board connections!

This reveals the middel connector which is hard to reach. Desoldering didn't work for me, I think because this joint is groundplated.

So what I did is gently twist the connector until it snapped off, leaving the pin within the pcb hole.
Then I removed a much solder as possible from this pcb joint, but could not remove the remaining pin. A well, doen't matter.





I had ordered a CR2032 battery holder for pcb mounting and had two options for mounting:

1. Solder two wires on the pcb to the battery holder and glue the holder to the backside of the case
2. Mount the new battery on the pcb using some longer legs.

Because of the pcb type holder I choose the latter one. Maybe there are other type of holders that may have been easier to mount in another way. Just depends on what you can get.
 I used two thicker type old cut off legs of a power diode and twisted one of them to match the connectors of the battery holder. Them soldered them partly in and on top of the old holes in the pcb. This way I could ensure to have two solid soldered pins.
It appeard to be quite a good fix and should be shock proof for transport and live performances.

Then cut off the wires at about 8 mm above the pcb, to leave just enough space to be able to solder them to the holder.
Now I could solder the holder on top and flip in the battery.

The last step was to reverse the steps to put the PM-16 together again.




Finaly could turn on the PM-16 again and everything seems still working.
I quickly tested the storage by changing a note number and pressing Write to save it. Then turned the module off and on again. Then looked up the note number and YES, it was perfectly stored and kept in memory. Yey!


Please note that this operation could cause issues with your equipment if not done carefully. I am not responsible for any troubles when following these steps. If you're not sure to do this, please reach out for an experienced person in electronics.

Have a great time with your Roland PM-16 again!   

donderdag 31 januari 2013

A midi to clock trigger interface

Having a lot of old synth stuff around the studio, the question raised: what to do with the gate-triggered arpeggios? Especially the Juno60 one. Although anything can be done with software, using the live knobs is still attractieve. So my nect project is to convert an old midi-cv/gate interface to fetch those midi clock pulses and feed them to the gate output. ...

zaterdag 1 januari 2011

Power supply for battery operated keyboard

"Dad, could you get me some new batteries for my keyboard?" my son asked. The same question as last week and the week before. Time to find a new solution for that power absorbing piece of Hong Kong design. And yes, I've thought about rechargeble ones, but these seem to always get lost somewhere in other electronic toys.


I decided to create a mains powers supply providing the 6 volts and about 150mA needed.
First thing is to design the schematics.

to be continued....