Roland JC77 chorus switch

[TarheelTechinTraining]

Hey folks I'm new to this forum and I'm trying to find a replacement switch for a JC77 . The chorus selector switch s**t the bed, insides broke up. When I called Roland they said the part is no longer available but it seems to me the switch is the same as a JC120. Any help would be great,Greg.

[Enzo]

Photo?

The switch I have in mind looks a lot like the switches used in old Pioneer stereo receivers. I might even have a few.

[grooveunit]

There's several revisions of the JC77, mine is early with the aluminum barrel knob on the switch, and Roland had it as of two years ago. Maybe yours is later- they checked the serial number for you?

[TarheelTechinTraining]

Thanks for the replies. Here is a pic of what left of the switch.
If either of you fellas have an extra I'd be more than happy to buy it off ya just PM me,Greg

[Enzo]

Oh my. Well I had the right mechanical type visually, but I was imagining a simple SPDT, yours is clearly a multisection switch.

[Mark Black]

Looks like the big parts are still there - sure you can't repair/rebuild it? I don't see the detent ball & spring but that is not insurmountable. How about the sliding contacts?

[TarheelTechinTraining]

Not possible the toggle to slide teeth are broken along with one side of the detent spring/ball socket. I was thinking of wiring in a DPDT switch, something generic but I'm stumped at how to wire it to pcb. Here is the schematic maybe someone can point out the easiest way to wire it in. Roland JC-77 Jazz Chorus (84) Schematic.pdfThanks again for the feedback,Greg

[52 Bill]

I was thinking of wiring in a DPDT switch, something generic

According to the schematic the switch needs to be a 3 pole 3 throw.

[oc disorder]

Hi Greg

As Bill 52 said the switch shown in the diagram is a triple pole triple throw switch ...ie 3 separate identical switches in the one package
each capable of three choices.
If you look at the schematic down the bottom centre there are 3 sections to switch one, S1a near the chorus footswitch socket,
S1b near the depth control and S1c near the rate control.
The picture you provided of your broken switch looks different to the earlier ones found in JC 120's.
The ones I remember had an extension to the rear of the main metal housing and look longer than yours.
Their part number was SLT-143N and made by TMS Japan who I cannot find on the web.
The Roland JC-60 although a mono power amp model had a smaller toggle/lever switch for vib/ch and
only a used double pole triple throw switch in that position part no ESC 3653.
So on the circuit board it had 4 connections per switch section i.e. one for the selection "lever" and the 3 contacts it could connect to.
I am mentioning this as there are a lot of variations from the published/available schematics so you need to check if your switch
had a total of 8 solder points or 12 which is what your provided schematic shows.
Of course ignore the physical solder connections that are mechanically holding the metal frame of the switch in place.
The Roland JC 50 also had only a double pole triple throw switch but was a slider type , part No SSM-023-00.

The easiest way to get it working without destroying the front panel would be to hard wire the switches to one pre-set ,
say manual depth and manual rate and wire the footswitch socket to turn it off and on with a footswitch.

So to do that hard wire the connection between the wiper of the chorus depth control to R154 a 100k resistor (S1b)
also hard wire the connection between the wiper of the rate control and R166 a 1 meg resistor (S1c).

At this point the chorus will be permanently on unless you join the tip switch contact in the chorus footswitch to ground connection.
Then by inserting a plain ole on/off footswitch jackplug into the chorus footswitch socket that will disconnect ground from the tip
and the chorus will work until you press the footswitch which will turn it off again as Q21 fet mutes the chorus output signal.

You could instead of rewiring the f/s socket put a small on/off toggle on the front panel and wire it as S1a ie run it between R96 a 270k
resistor and ground or connection 26 (at ch. f/s) to ground.

If you need more help I would suggest you obtain the full Roland JC-77 service notes either from Roland or here

Roland JC-77 Service Notes, Analog Alley Manuals for $12.95.

That way you can get the exact part number for the switch and try Roland service & spare parts in different countries as they don't
contact each other re old stock.

Also you could post the track layout which would make it easier to guide you via this forum to re-wiring your switch.

I don't know of any triple throw-triple pole toggle or lever switch that is available as a replacement but a rotary wafer switch would work although it would spoil the front panel.

[TarheelTechinTraining]

OC thanks so much I didn't even see the third connection.I think I'll use your idea of hard wiring the switch to manual and use the footswitch to turn it off, though I don't have the footswitch but that's an easy fix. Once again thanks to all this is a great forum !!