Leslie 145: running 117V motors in series instead of parallel in UK

[omeriah]

Hi

I would like to try powering the motors in my Leslie 145 direct from an IEC cable that supplies 230V by wiring each pair in series. I am in the UK, my motors are marked as 117V; my 145 is marked as a 230V model and the relay coil is 230V. The 230V that switches the relay will still come from the Hammond L100 Fast/Slow switch, and the 145 audio circuitry will still be powered by the 230V that the L100 supplies.

However, in my quest to remove the speed switching CLICK when changing from fast to slow, I would like to ensure that any back emf generated when the fast motors turn off, is not pulsed through the 117V tap of the Leslie mains transformer primary winding. My suspicion is that this is how it is coupling so loudly into the audio circuitry; it is directly appearing in the HT rail. In fact the 0C3 emission visibly shows this when the click occurs. It still shows it when the volume pedal on the Hammond is turned down.

Changing the 3x 100 nF 600V caps made no difference to the click. I am yet to change the relay but I guess that is also on the list of things to try.

My plan then is to run an additional IEC cable into the cabinet whose purpose is to supply power to the motors only. The live connection will be switched via the relay.

So my question is - are there any reasons why running each slow/fast pair of motors in series from a 230V supply, instead of parallel from a 117V supply, is asking for trouble?

Thanks

Tim

[geoelectro]

Clicking in the audio of a 145/147 type Leslie is somewhat common. The caps you described are some of the usual suspects. However, I've found that the clicking more often comes from the AC lines in the Leslie cable switching on and off near the unbalanced signal input. As a test, try pushing the relay on manually with a pencil. See if the click level changes. Also, try it with the Leslie amp volume all the way down. If you can determine the clicking is entering through the input section it may not be the power transformer. The last step would be to pull the 12AU7 and try it. If you find these steps have a significance on the clicking sound then you may have to go in a different direction. Also, a weak filter in the amp can contribute to the switching noise. The last stage which filters the 12AU7 input tube is a typical suspect.
I don't think your idea will hurt anything but I'm not sure it will fix it either. At least I would eliminate all other possibilities first.

Geo

[omeriah]

Thanks Geo, good point about identifying if the click is coupling into the amplifier via the input connection rather than the power supply as i presumed.
The relay has been replaced with a sealed unit so I can't try the pencil test unfortunately...
I'll pull the 12AU7 out and give it a try then report back!

Tim

[tligen]

Hi!

If you want it dead silent, go for solid state relays, like:
http://se.farnell.com/sharp/s202s02f...ate/dp/1618475 (or similar)
One SSR for slow and one for fast
(you'll also need some small components like: 1-2 resistors, 1 capacitor, 1 rectifier)

It's cheap, reliable, silent & safe!
It is also much safer to run only 9V through the half-moon switch

I have a Porta B (L 100P) & Leslie 145 myself, in Sweden, 230V

[omeriah]

After replacing the 145 relay, and trying my idea of feeding the motors from their own 117V supply (separate from the power amp feed) there was still a massive click.

I also replaced the cap on the FAST SLOW switch inside the L100P Hammond that is connected to the 145 - still a click coming from the Leslie.

Then I energised the 145 relay directly from a UK mains socket, switching SLOW to FAST by turning the wall switch on and off. NO CLICK!!!

So it seems that the relay inside the L100P is causing the problem. It even caused a click when I disconnected the Leslie relay from the L100 (when I was doing the above mentioned test and feeding the relay coil from its own source of 230V). So this definitely points to (as Geo pointed out) crosstalk of the L100 relay on/off switching into the unbalanced audio line inside the brown cable.

So now I'd like to find the schematics of the L100P that show the F/S slow switch on the console, the relay inside the base unit and whatever else is involved!

I wonder if running the audio feed in a separate cable will be a solution...

I am going to look inside the base of the L100 and investigate the switching circuits there - I'm guessing the F/S switch activates the relay in the base, which then activates the Leslie relay.

Anyone have any more info on the wiring inside the base of the L100P?

Thanks
Tim

- - - Updated - - -

Also thanks Tligen!
I am happy to go for solid state relays if need be...but when energising the 145 relay from UK mains as I described, there was absolutely 0 click.
So I will see if I can somehow change the relay in the base of the 145 first?
Tim

[Wes]

I'm surprised there is even a relay inside the L100P. Do the UK 147 Leslies use a 230V or 115VAC relay? I guess it doesn't actually matter for the 147. It does for the 251. It would think it should be possible to bypass the relay, provided you have a suitably-rated switch. If that works, and you would like some piece of mind, a solid-state relay could be substituted. They switch at the zero-crossing which is about as quiet as you're going to get.

Wes

[tligen]

"So now I'd like to find the schematics of the L100P that show the F/S slow switch on the console, the relay inside the base unit and whatever else is involved!"

There is no relay in L100P for the Leslie-switching, just a switch
Run a separate half-moon instead, so you can have a three-way if you want, slow-off-fast (you can buy a telecaster or strat 3-way switch and put in any case)
My rig is the same as your, and silent, because I know what I'm doing!
Zero crossing switching is the answer, you cant get that with mechanical relays
You will never ever get silent (motor) switching with relays
You can reduce it slightly with smart wiring and and some capacitors

I also run it from the power amp output from L100 to the Leslie in the load-mode

I have one cable for switching and one for audio, probably better, but main reason, it's easier if you wanna use Leslie and organ separate

I checked my old orders, here is the place I bought from (cheaper)
http://www.tme.eu/se/details/s202s02...er-ssr/sharp/#

Search the forum for links to schematics for Porta B, L100P
I got mine from here some years ago, If you can't find I'll send you tomorrow


Here's more than you need:
www.tle.se/album/Porta_B_manual.zip

[jimmywilliams]

Maybe I am not following something ... but ... If the L100P is anything like a Porta-B , and I think it is the European version of the Porta-B more or less, then is not wired for a 145. Older ones have two 6-pin sockets for a 122 type - a completely different switching mechanism than the 145 and would cause damage to a 145. Newer ones have one 6-pin 122 type and a 9-pin socket (like my porta-B but again not sure if the L100P had a similar revision). I have never heard of a stock portaB/L100P being wired for a 145 type. So please let us know exactly how you have the 145 hooked up to the L100P. Do you have an add on kit? The rocker switch would work with the factory stock hookups.

[omeriah]

Many many thanks for all your contributions so far!

So please let us know exactly how you have the 145 hooked up to the L100P. Do you have an add on kit? The rocker switch would work with the factory stock hookups.

I will go to the studio and investigate more and draw out the present state of the switching that is going on in the L100P and its connection to the 145.
For the moment I can offer this picture, which shows the offending relay that is causing the click in the Leslie speakers.
As mentioned previously, the click still occurs when I disconnect wires 2 and 5 at the Leslie end on the 6 pin connector.
The picture seems to show 110V from the transformer energising the relay via an RC arrangement. The brown wires go off to the 6 pin sockets.
I will draw out the circuits and report back.
I can also confirm that when the FAST SLOW switch is activated on the console, that this relay shown activates, and that 230V is also passed onto the 145
Tim

[omeriah]

I haven't been back to where the Hammond /Leslie is located yet, however until then, could I ask some beginner's questions?

The attached picture shows where the speed is controlled from on the Hammond, which controls a relay inside the base unit and also the relay in the Leslie.

It was mentioned above that the L100P should not have a relay, but there is one inside the one that I am working on. For those L100Ps which dont have a relay, is the switching to the Leslie 145 achieved by running 230 V via the switch in the attached photo, which then feeds pins 2 and 5 of the 6 pin connector?

I have found a system diagram of the Porta B organ which shows how the various signals are connected to the 32 pin connector that mates the top and bottom units. Is this the same pinout at is used on the L100P? Or is there a different convention on another system diagram? I couldnt fine any pinouts in the L100 service manual.

Sorry if these questions appear dumb.

Thanks
Tim

[jimmywilliams]

omeriah,
It seems to me that the Leslie 145 hookup in your L100P is a custom job with a power transformer and relay.

If you look at a schematic for a porta-B (not the L100) you will see there is a wiring diagram for a 6-pin Leslie socket - however the stock hookup is for a 122, not a 145. In the portaB this connection is in the bottom part. You will notice on the stock diagram that a 122 hookup is very different - the audio signal first goes through a transformer which splits the signal into opposite phases making a balanced audio signal, and also a fairly high DC footage is superimposed on the balanced audio lines via the transformer to switch speeds in the 122 Leslie. The 145 works totally different. The audio signal is unbalanced (single ended) and the switching voltage is 120vAC carried on different pins (2 and 5).

There is no stock wiring for a 145 in these organs that I am aware of, and no you will not find such a diagram in any porta-B schematics.

Now assuming that everything is wired correctly in this custom hookup we can further troubleshoot - however we would need to understand completely how it is wired now. That will be the first step.