434 Concerto - Write In Issues - Even Numbers Won't Play

[bjmoody85]

Hello All, I recently acquired a 434 Concerto that my uncle had in storage for several years. I finally got the mechanism running, but now I'm having an issue with selections. All of the A and B selections work, the buttons lock down, and the write in finds them with no issue. But if I select odd numbers on C-K, the buttons lock down as they should, but the write in just spins until I cut power. I've cleaned and degreased the wobble plate and all of the contacts twice now. The second time I even burnished them gently with a wire wheel on my dremel until they were shiny. I've cleaned all of the connections with contact cleaner as well, but no luck.  I took the buttons out last night and sprayed more contact cleaner and actuated them up and down several times to try and clean them without taking them apart. If I take them apart I'm afraid I'll never get it all back together. Does anyone have any additional ideas? I've read all of the FAQ's and searched the site, but I've not found any discussions that listed a resolution. I don't doubt that it's not making good connection somewhere, but I can't think of anything else to clean lol. Any help would be appreciated. 

[jukenorman]

When you say you cleaned the wobble plate, do you mean the write-in circuit board (service manual, page 14)? It's almost certainly going to be that or the pushbutton switches. Contact cleaner can be very hit or miss! You can carefully wash the switches with a mild detergent solution, rinse and blow dry (or leave in the sun!). This has been covered before (a search should find it), you should protect vulnerable item from moisture like the latch solenoid.

Norman.

[bjmoody85]

Yes, I cleaned the write in circuit board. I will try the buttons again. Any issues putting them in an ultrasonic cleaner as long as I don’t get the solenoid wet? That seems to me to be the best way to get everything with a light scrubbing afterward with a brush. I’ll have to find my small rifle brushes to get in the small spaces without taking things apart.

[jukenorman]

I honestly don't know whether an ultrasonic cleaner would be successful, it might be? Ron Rich's guidance for switch banks is in the thread on contacts in the FAQ above and it's pretty much what I do and I know of others also doing that - so let's say it's tried and tested!

Norman.

[bjmoody85]

I actually went ahead and gave the ultrasonic cleaner a shot yesterday. I got the one from harbor freight because they had it on sale. I used Simple Green mixed 50/50 with distilled water and turned the heater on. That water got very hot! I was impressed how hot that machine heated the water. It really helped with the cleaning. I ran them for about 30 minutes each taking care not to get the solenoid wet. (I put it in a gallon sized zip lock bag). I disassembled enough to get the boards off the frame, but didn’t desolder any connections and washed them one at a time. If you wanted to desolder connections it would all fit at the same time. They cleaned up great! I got it back together enough to test the C selections and they all work. Then jumped to K and they all worked as well. I have to get new selection label plates before I can fully reassemble, so I’ll report back if I run into any more issues. But I think all is good and I can move on to the amp. One word of caution…. If you don’t desolder, be very careful with the connections to the switches when moving the boards around. I tried to be as careful as possible, but I still broke two connections on the lock switches and had to solder them back together.