From swalker@phoenix.cs.uga.edu Mon Jan 23 10:18:02 1995 Date: Sun, 22 Jan 1995 13:57:26 -0500 (EST) From: "Stewart S. Walker" To: ana Subject: cleaning the 909!! After the 808 man suggested buying tuner cleaner and lubricant from radio shack, I did so that afternoon. I took it home and was ready to attack my scratchy pots. I started out on my dunlop Crybaby (a wah pedal from my guitar days) because I figured if I messed up, then it wouldn't matter. But The cleaner worked very well. No more loud pops or scratches. So, next, having had some experience, I decided to look at my 909 which has noisy instrument volume knobs. I'll lay it out in detail because I think this is a common 909 problem. Besides I don't like my instruments to work against me in any way. 1. The first thing you have to do is pull off every knob on the front panel including volume and tempo. This is difficult to do with your fingers, so its better to use pliers. I didn't have to grab hard enough to leave teeth marks in the knobs. Now would be a good time to clean the face, I did this just because it looked like hell, but now it's very shiny. I just used soap and water. 2. Unscrew the bottom from the 8 perimeter screws, leaving alone the feet, as they do not connect to the chassis. 3. Underneath the bottom plate there is a metal box on top of screw-in posts. I managed to strip one of the screws completely while trying to unscrew the top screws. So finally, I decided to use my angled pliers to grab the post and wiggle it in order to loosen the screw, finally with the help of my needle nose pliers, I managed to remove the screw. After this, just twist out the posts. 4. There are about 8 or 9 screws holding down the voice PCB, of which some are hidden, It's important to do this completely because if you are pulling on the circuit board while it's still atttached, you can break it, which I have done before. Anyway, once you remove the screws, the PCB should seem pretty loose. 5. After removing the screws, and putting them safely back into my toolbox, I looked at the numerous amount of ribbon cables holding on to the voice board, and got worried. Sometimes I am not so good at putting equipment back together, so this time, for the first time, I made a list of all of the ribbon connectors and wrote down approximately where they are on the PCB. I undid them all, which was a mistake since you only need to take out the ones at the other side of the module from the voice jacks, then you can just flip the board over and have full access to the potentiometers. Anyway, they are tightly connected and your fingers will hurt when you are done removing them. Mine did because I'm always afraid of bending the male connectors. I thought the operation was too fragile to use pliers. A little wiggle is helpful. 6. Once you are able to flip the board over, you have full access to the potentiometers. Thanks to Roland, the knobs are so open, that it's easy to get the spray into them, of course it's easy for dirt to get into them as well, and that's why I had this problem in the first place. You can use just a little bit of lubricant, but the button is hard to control to get just a little out. So inevitably I got some on the circuit board. It bubbles on the circuit board. At first I thought it was eating away the board but the stuff is supposed to be safe on plastic. So I assume the cold temperature it came out at just caused the stuff to boil. Radio Shack had two kinds of cleaner the day I went. One was TV tuner cleaner and lubricant and one was Color TV tuner cleaner and lubricant which was the same as the first except it had fragrance and dye. I don't know why it had this. So this is a wordy description of how to do it but I wanted to show some people that it is not too difficult. So, maybe this will be good as a reference. If anybody has any suggestions, I'd like to hear them. Stewart