Gulbransen Rialto K: what may I have broken?

[pedropol]

Hello,

My Rialto K was 80% functional. Some of the keys were not active immediately when pressed and others were out of tune, but it was globally in good condition for its old age. Last week, I decided to open it to clean the dust and take pictures, in preparation for a project repairing it. So I removed the back and front panels, the top and the horse shoe panel with the console lights. I cleaned it gently with tissues to remove the accumulated dust. I unclipped the pedal board and I clean the mud and the mould. And then I took a few pictures of the various components of the organ (uploaded on my gallery). I found two screws that probably a previous technician had forgotten and I screwed them where they were missing on the top of the chassis of the Main generator and the Voice networks.

Feeling that it was enough for a first contact with the internal of my organ, I fixed the various panels back in position and I plugged it to the power. I switched it on to check that everything was back to normal. Argh! I've broken something and now the pedal is not working. When I switch on one of the pedal tongues (Tuba 16', Bourdon 16', Gedeckt 16', Dulciana 16', Flute 8' or Cello 8'), I can ear a constant sound and I can use the accompaniment manual. Even with no tongue/stop activated, the lower manual is enabled. This happens also when the Pedal Sustain tongue is pressed alone...

In Jan Girardo's Rialto K service manual, there is a reference to a "cipher" sound, in the Omega section:

Notice that a shorted or leaky diode will cause a note to sound constantly when a percussion piston is depressed. The constant sound is commonly referred to as a "cipher". A cipher may also be caused by a shorted or leaky Omega capacitor. However, if it is a capacitor, it will not be controllable by any of the Omega pistons, nor will any of the stop tablets effect such a cipher.

The symptoms seems similar to what is described. How can I confirm that the constant sound problem is generated by a broken Omega capacitor? I did not touch that part of the organ when I tried to dust clean it... And how can I find which one?

Also is there any relation between that cipher and the now dumb pedal?

Now my Rialto is 40% functional! That's not a good start for a repair project...

Thanks for any guidance and encouragement.
--
Pierre

[indianajo]

See the other post about silences caused by switches in phone jacks to speakers.
Also, moving wires around may have broken solder connections on those custom bits you pointed out.
You've got the manual. Omega capacitor doesn't mean anything to me, but sustain capacitors do. Little *******s often cause ciphers past 20 years of age. Look in the manual for an electrolytic capacitor connected in parallel with the pedal switch. there will be an ellipsis because there is usually one for every pedal or key switch.
I test the things with a calender. One suspicious actor, out they all go. Buy the 10000 hour service life variety, unlike pro TV repairmen, you DON'T want to do this again in 5 years. You don't get paid to repeat work.
If you dlon't know how to solder, start with the ones in the power amp. Dodgy soldering on those big ones, they are not so sensitive and a cold joint will be pretty obvious because you killed the sound, also the DC voltage will be on the wire, but not the cap terminal.
See this for what I think about overaged electrolytic caps (the ones with + on one end). http://www.organforum.com/forums/sho...146#post280146
The instructions about oxidized connectors stopping low energy sound signals applies to an organ of the Rialto K age, also. Rialto K's are also prone to norton op amp failures. they still sell norton op amps but nobody designs with them anymore. They are triangles with a + and - input on the left on the schematic diagram. I think the expert on here replaced 2 or 3 of them in his K.
have fun with this. Nice organ, but one has never showed up around here.