Music & Gear

Battery replacement on Korg M1R

Sonntag, Juni 15th, 2008

My M1R came up with a „battery low“ warning just a few months after I did the replacement on the TX802. Possibly these oldies start a conversation on their sicknesses each night after the boss has gone to sleep. The CR2032 button cell is sitting in a socket, so there is not much to tell about the exercise itself, but it was still an opportunity to take photos of the innards.


Battery replacement on Yamaha TX802

Sonntag, Juni 8th, 2008

My TX802 started behaving like it was broken: strange characters on the display and strange sounds. Not even a factory reset and a following sysex dump helped to remedy this situation. Although there was no „battery low“ warning, I first replaced the 20 years old battery before going on with error search. It turned out, that this was a good decision; everything is fine now and the box is back fully operational. As you can see on the photos, it is fairly straightforward to open the housing and reach both sides of the mainboard. The new battery holder did not fit exactly into the soldering holes, but I found a decent workaround by twisting the pins a bit and underlaying the holder with hot glue.


Hammond B250 repair and cap replacement

Sonntag, Oktober 14th, 2007

Recently, after having visited the Tasten-Festival at Herdecke, I felt inspired to sit down on my Hammond B250 and move my fingers. This sadly happens seldom enough, and so the organ hadn’t then been powered on for months. And although the B250 is a quite reliable oldie in my experience (just one repair within the past 10 years, a voltage regulator on the PSU had to be replaced), it now came up with a dead „G“ pedal tone.

So I first checked the pedal unit and then opened up the B250 and found a broken connector on the bass tone generator board. The pin just broke in pieces after being unclipped and pulled out of the housing (see red circles on image). With an appropriate replacement part this was quickly fixed. But there was another thing that soon concerned me much more: Electrolytic capacitors with green corroded pins.

Approximately 80 percent of all caps on the B250’s PCBs showed more or less visible signs of aging and deterioration. I started to replace a few caps on the bass tone generator board, measured their ESR and capacity values and – to my surprise – couldn’t detect any problems. »Dude«, you may say now, »it is too obvious that these caps have to be replaced«. You are right, but the organ still plays and a complete swap would mean a total of 98 caps. »Replace them immediately. They will soon lose capacity and the leaking acid will irreparably damage the PCBs «, an expert told me after I sent him a photo. Ok, I’m persuaded, this is a case of „bad caps alert“.

While removing and „recaping“ the panel PBCs I took the opportunity to refurbish the drawbars. Although my B250 lives in a smoke-free environment and a deep cleaning was not necessary, it was still a good idea to remove the dry old grease and lubricate it with fresh „white“ lithium based grease. See this excellent Hammond Service page for instructions and tips.

All in all it took two workdays to complete this operation. Below is a photo of my B250 after wakening up, and I think the organ looks happy now. The overall sound is a bit more bright and substantial, due to the all new coupling capacitors. It also smells like a new one ;-) .


JX-8P reloaded (2)

Samstag, April 15th, 2006

Before going into work with JX I cleaned the keyboard in the last few days. The keys were sticky and smeary from nicotine and dirt, so I put them all into denture cleaner over night and on the next day brushed them with dish liquid.

A small plastic strip on the bottom side of the keyboard must be removed to get the keys out. It puzzles me that Roland glued the strip instead of choosing a solution that would be faster to recover at service. One also has to manually (un-)clip 61 springs with a pliers, one for each key. Compared to the Yamaha keyboard on the Korg 01/W this is cumbersome.

Having the best opportunity, I checked the aftertouch sensor for proper operation. As you may read on analog.no or synthzone.com, early JXs may suffer from oxidation on the metal films of the sensor. With not having the sound engine operational yet, I measured the resistance changing on pressure and, to my feeling, didn’t find any anormalities (equally somewhere below 20kΩ along the sensor).


JX-8P reloaded

Montag, April 10th, 2006

Yesterday I fetched this classic piece of gear out of my cellar.

I am guilty. The cellar is wet and mouldy and a hostile environment for electronic equipment, but I closed my eyes and left poor JX vegetating there for the past ten years. A wedding musician gave it to me after it was worn and broken from heavy use. I remember that I tried to repair it but wasn’t successful in the end.

Dear JX, I promise to make up for your sufferings. To be continued.