[analogorgans] Re: SOS "Expression Pedal not working"
- From: "bh" <lexicon13@xxxxxxxxxxx>
- To: <analogorgans@xxxxxxxxxxxxx>
- Date: Mon, 07 May 2007 17:24:51 -0500
Hi Charles,
Thanks for your reply. I went through my Rodgers Scarborough
750 manual and came upon schematic 1600A (OUTPUT PREAMP) and saw the
following:
ON EXP PEDAL
-----------
| +25 |
| | |
| | | (28) R5/1K LS
| 500 |<---O----O----~~~-----O---- EXPRESSION
| | | ] LAMP
|_____=____| O---- 1460-026
| AFFECTS
| LDR'S 19,43,87,149
=
Yes, Charles, you are right on target. I looked at the OUTPUT PREAMP
and found the (CdS Cells) under a black cover; there are four Cells
which surrounds the lamp. So, I turned on the organ, turned on an 8'
Flute stop, used a pencil to lock in one of the key signals on the GREAT
organ and took a flash-light to the back of the organ and shined it on
the CDS cells where the lamp is located and the organ volume went up and
down as I shined the light on and off the lamp area. Wow, I would have
never thought to have looked there. Let me know if the above specs
relates to the correct lamp that I need and if you have any, please let
me know.
Barry
-----Original Message-----
From: analogorgans-bounce@xxxxxxxxxxxxx
[mailto:analogorgans-bounce@xxxxxxxxxxxxx] On Behalf Of Charles Strack
Sent: Monday, May 07, 2007 3:48 PM
To: analogorgans@xxxxxxxxxxxxx
Subject: [analogorgans] Re: SOS "Expression Pedal not working"
NO--it's probably NOT shorted. Pots have 3
connections: top of the resistor, bottom of the
resistor, and wiper; connect between either top or
bottom and the wiper, and you get a variable
resistance; connect between the top & bottom of the
resistor and you get no variation at all.
Rodgers used the pots to drive a lamp, which was
closely coupled to a light dependant resistor (CdS
Cell) under a black cover. If the lamp burns out, no
variation in volume, so perhaps you've just got a
burned out lamp.
Rodgers used a couple of different style covers and
lamps, but it should be on the output board. It's
probably a #19 or a #24CS lamp, but I don't have the
manual so I can't say for sure. 19's are easy to come
by, but 24CS's are hard to find. If it turns out to be
that one, let me know, as I have a few spares I could
part with.
Charlie Strack
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