Leslie 710 - Rotates on SLOW setting, but stops working on FAST?!?

[gdmorgan]

A friend and I tried had to go deep into a Leslie 710 case to fix a loose weight inside the bass rotor drum. Everything went well with the reassembly, until we fired up the speaker, only to find that now the upper horn and bass rotor will rotate on SLOW setting, but not on FAST anymore!!! On FAST setting, both the upper horn and bass rotor just STOP completely!!! So we think we may have loosened some electrical connection, or the slow/fast switch isn't working, or something. Before we tried this fix, the Leslie was rotating on both SLOW and FAST, just serious vibration on the FAST setting. Any suggestions on how to fix? Thanks in advance for any suggestions! We're almost finished restoring this Leslie!

Here is my previous post explaining the fix we performed on the vibrating bass rotor:
http://www.organforum.com/forums/sho...g-up-my-rhythm!

[jdoc]

follow the wires back from the fast (big) motors to the chassis, look for loose connections, otherwise could be a failed relay and bad timing for your repair

[Momboc]

I think you are exactly right when you say that you have loosened some electrical connection or the slow/fast switch isn't working anymore (actually the slow switch must be working).

Go here and download the Model 710 service manual. Go to page 36 and read the section on motor controls.

http://www.captain-foldback.com/Lesl...ie_manuals.htm

Go here to get the schematic diagram

http://www.captain-foldback.com/Lesl...schematics.htm


You will see that the 710 will brake (i.e. stop) both rotors when both pins 6 and 7 of the input plug are not connected. When Pin 7 (Slow Motor Control) is connected to Pin 1 (Ground) via the 'slow' switch the 710 will run the rotors at Chorale speed. When Pin 6 (Fast Motor Control) is connected to Pin 1 (Ground) via the 'fast' switch then the 710 will run the motors at Tremolo speed.

I suggest that you check the connection between Pin 6, the 'fast' switch and ground (pin 1) to make sure that the fast switch is properly grounding (the fast motor control) pin 6.

[picothinker]

You might unplug the fast motors, and verify you have 110vac when the tremolo setting is selected. Any cheapie DMM set for AC/auto can tell you that quickly.

If you do have power there, can you see if the fast motor itself is turning? The fast/slow motors could need adjustment; make sure the shaft moves/retracts on the tire properly.

If you don't have power to the motors, look at the relays/switching.

[gdmorgan]

Momboc et all,

Thanks for the replies. If you could, can you provide a little more insight on how to "check" the connection between pin 6 and pin 1? Is it as easy as visual inspection - or do I need a multi-meter for this?

I'm going to try these solutions shortly and post back. Thanks,

gdmorgan

[Momboc]

Momboc et all,

Thanks for the replies. If you could, can you provide a little more insight on how to "check" the connection between pin 6 and pin 1? Is it as easy as visual inspection - or do I need a multi-meter for this?

I'm going to try these solutions shortly and post back. Thanks,

gdmorgan

Remove the 9 pin the cable from the Leslie and set the switch to slow and measure (with a multimeter set to measure resistance) if you get a short circuit between Pins 7 and 1 (which you should) on the cable end socket that normally plugs onto the Leslie amp. Then switch to fast and see if you get a short circuit between Pins 6 and 1 (which you may not if there is a problem). Also visually check the cable ends plug and socket and the plug on the Leslie to see if there are damaged pins or broken wires etc

[dunderola]

Had a funny thing recently with a "homemade soldstate relay thing" its a 234 volts motorleslie..worked fine on fast, worked on slow but with serious vibration..turn out to be one of the relays(thyristor/triac)thing..that when "on"let 230 volt thru but when "off" then it let only half wave of ac thru resulting given fast motor halfwave 115 volt at the same time it gave the slow motor 230 volts. couldnt measure it on the relays it self but had to do it on the fly..
Isnt it the same kinda switching in theese? like the 760?