ddrum 4 SE repair experience

[sofayeti]

Hi all,

I'm a ddrum 4 player since more than twelve years. Recently I obtained a defective ddrum 4 SE with a rack and pads but no hi hat. The unit seemed to be bricked, no reaction from the LEDs when switching on (but humming). I want to share my experience here in case somebody has similar problems.

OK, the first thing was to open the unit. First I noticed that some screws were missing. There were only three left from the eight outer screws total. Moreover, all but one of the nuts holding the pad plug connectors in place were gone.
Now that's a bad sign. It usually means that somebody already tinkered with the unit but wasn't careful enough to retain the screws or too lazy to screw them back in.



This is the main board with the power supply on the left side. Be careful when it is connected to the mains because of lethal voltage levels!
I measured the output voltages on the power regulators (those four three-legged screwed-on components, one has a large heat sink attached). It's best to do this with an oscilloscope to see whether voltages are stable. If there are ripples the microcontrollers might become confused and go on strike. Everything was fine here, though.

One of the first things I usually do with defective devices like this is to literally poke them with a stick, in this case an insulated screwdriver (use the plastic end!). As soon as I touched the EPROM the LEDs flickered. Surely enough, the EPROM seemed to have contact problems, so I unseated it and pushed it back into the socket. Voila, back to life!

I put everything together, plugged in the pads etc. and tried to play. Sounds good, but there were problems on the bass, lower tom, and cymbal 2 channels; the trigger level was way too low, going up two or three bars max where there should have been at least six or seven with trigger level on maximum. A factory reset didn't help. So, it's back to the workbench then.



This is the input board. It's connected to the main board with a flat cable connector that can be disconnected by prying the two latches to the outside. It's held in place tightly with five screws. I don't know who Jonas is but it seems he made sure that everything was ok ;-)



This is what waited for me on the other side. Now this is some case of suboptimal soldering here. Somebody has replaced some of the components marked F1 ... F11 with 22 Ohms resistors, one of them SMD. As you see the plastic plugs of the input jacks have been damaged by the soldering. He also didn't bother to remove the surplus solder flux (the brown stuff) which is something you should always do because it can be corrosive.

The F1 ... F11 components are so called pass-through capacitors used to protect against EMI and other noise. I don't know why the guy replaced them with resistors, and why he chose 22 Ohms. He must obviously have been some kind of semi-pro because he used an SMD device (beginners normally avoid this). Perhaps he suspected the capacitors to be defective but didn't recognize that they were capacitors. Normally these components fail very rarely.

Anyhow, I cleaned up a bit and replaced the resistors with a piece of wire. I'll try to obtain those pass-through capacitors and fix it properly when I've got them.

(continued because of attachment limit)

[sofayeti]

OK, here we go. This is what the board looks now:



When creating wire bridges like this it's best to use as little solder as possible. I didn't bother to remove the remaining flux because it has become very hard already.

Still this couldn't have been the cause for the channel problems because those channels were different. I tried to clean the input jacks like this:



Put some contact cleaner on a q-tip and rub. I personally like Contact 60 or Tuner 600, never use WD40 or similar because they leave an oil film which can cause problems. Be very careful when cleaning potentiometers because the carbon layer can become detached if you use the wrong solvent.

If you look closely maybe you can see the scratches on the inside of the sleeve "hooks". This has probably been done by the previous repair guy as well in an attempt to bend the hooks down to improve contact. I would have done the same because the contacts didn't seem oxidized or dirty. Also, you can see that the threads are partly damaged on some jacks. Another sign that the guy probably wasn't a professional.

All this didn't cure my channel problems, unfortunately, until I noticed that the input board was working fine when it wasn't being pulled down by the weight of the plugs and cables. There seems to be a problem when the board is being bent slightly. Usually this is caused by broken solder or other contact problems, but I could not trace this back to a certain location. Fortunately the fix was easy: put new nuts on the jacks and fix the board tightly in its upper position. Now everything works fine. OK Jonas, we're good :-)

I don't think that this unit will be reliable enough for stage use, though, because the problems may reappear when warm or moved or whatever, but I use it for practicing and home recording only.

This was the first time I opened a ddrum 4, and overall I have to say that the unit looks to be sturdy and of good quality. Fixing should not be a big problem because it's basically 90s technology and even the SMD are easy to solder if you have some experience.

At last, here's a picture of the whole rack:



Enjoy your ddrum and good luck if you try fixing it!

[chuychayote]

Hello sofayeti, thanks for the post. Wow great job bringing that baby back to life. Did you happen to have to replace an input jack? I think my hihat jack may have gone bad. goNna redo all my troubleshooting before i try or take it in for repair, but thought i'd ask. I have a lil soldering experience as i have resoldered all the triggers in the other cymbals and pads, but not sure if i should try this job or how difficult it might be. I opened the hihat and both triggers seem to be intact, as well as the xlr jack. A new stereo cable did not do the trick either. Ok thanks in advance for any info you can share.

[sofayeti]

Hi,
I didn't have to replace an input jack and I think that if you don't find an exact replacement type you shouldn't attempt to do this because you might have a lot of trouble getting the thing to fit.
Also, I believe that input jacks fail very rarely. Worst case is something has broken off, so that's when you need to replace them. The common contact problems might be cured by cleaning and bending the hooks back into position.

The first thing I'd do in your situation is check whether your hihat is definitely working and it's really a channel problem. You cannot be sure by looking at the triggers, you need to measure them or make experiments. Try connecting your hihat to another working cymbal channel; you should at least hear something (I haven't tried this). You can also connect a known working cymbal pad to the hihat channel, that should at least cause some triggering; if it doesn't you can assume that something is wrong with your hihat channel. I'll try it when I'm back home tonight.

If the hihat (and cable) are definitely ok then only I'd check the ddrum channel. First try gently to push the plug up and down, maybe it's just a contact problem with the jack. You can also open the unit and connect crocodile clips from the cable plug to the jack's contacts. A bit tricky with the hihat double tip plug, so if possible use a separate jack and bridge the wires over to the ddrum jack. Only if it works then and plugging in directly fails would I think of replacing the input jack because it can really be a hassle and you need some experience to get it right (the soldering is not so much of an issue here, rather the "unsoldering").

If the pad is ok and bridging over the jack doesn't cause triggering then the problem is somewhere in a later stage. Soldering skills won't help you here so in that case it's probably best to take it to a repair shop.

[sofayeti]

OK, I have checked it. A cymbal pad triggers the hihat channel and vice versa.

[chuy75]

Hello, and thanks again for the info. I rechecked everything again and found two issues. One was an id10t error(me) as i forgot the simplest check of the hihat input sensitivity knob, which i must have accidentally turned way down. Still had issues, so i reopened the hihat pad and the hihat edge trigger had indeed become unsoldered. So i resoldered and viola, good as new. Another question though. I recently acquired another dd4 brain v1.20. It seems to work fine but also has a humming sound coming from the machine(not through the audio outputs though). Did you fix yours or is it still humming? Should i even be concerned about it? Also, any dd4s os can be upgraded to 1.5 right? Thanks again for your help.

[sofayeti]

Hi, good that you could fix the problem. About the humming, it's probably the transformer (the blue box in the first picture). That's usually nothing to worry about (the vibration is caused by the 50 or 60 hertz line frequency) so if it's not too loud just live with it. I can't even here mine hum when the case is closed. Try to isolate the brain from any resonating surface which might amplify the hum.
One problem that might arise from this is that the transformer solder dots might develop cracks causing dropouts. In that case you can simply resolder the dots. If you're really concerned you can stick some foam or so in between the transformer and the case but don't overdo it because of heat dissipation problems.
Another cause might be the large silver capacitors on the top left. In my box they were fixed in place with some plastic strap. Maybe check if that's still ok.
Such capacitors are also likely to fail after 15 or 20 years or so. In case of problems it's wise to replace them if they are too old.
Anyway, I'd just ignore it. As drummers get older they also tend to hear less and less ambient noises ;-)

[chuy75]

Awesome, thanks again for all the help. I'll perform those checks when I open it for the upgrade. Until then I'll just ignore it!

[Jack uk]

I've had exactly the same problem. Nearly sent it off for repair. Did you come to any reliable solution in the end? I'm having to tension certain inputs upwards to get the right signal to the brain .. regards
Relentlesshuman@gmail

[sofayeti]

Hi Jack, sorry, I'm out of the loop, what's your problem exactly?

If you have to pull up the inputs probably the solder joints have cracked. Can you solder? If yes you can fix it yourself (see the pics above), otherwise have it done by a professional.

I fixed my unit back in 2014 but I haven't played much on it because I use my old one for practicing... so I don't really know whether it's still working or not ;-)