Part 4 – Down and dirty with the drawbars

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On a Hammond it’s the drawbars that sculpt the sound. The number of drawbars per manual varies between the models and on the T series it’s 9 drawbars for the upper manual, 7 for the lower and 1 for the pedals.

Common problems with the drawbars are either the drawbar not working at all or a scratchy sound and a stiff drawbar action. The first problem is usually a very simple fix as the wire connecting to the back of the drawbar can break off very easily. Simply solder it back on. The secondary issue involves quite a bit more work. The temptation is to spray a switch cleaner into the drawbars units as you would for a normal noisy control. Beware – a lot of the later spinet models plus the E and H consoles have plastic parts and these can be seriously damaged by some contact sprays. Some people have reported success with particular De-oxit products which state they are safe for plastics but the long term impact is still not known. Unfortunately the safest route is to remove the drawbars and clean both the bars and the housing. What you will need – flat head and Phillips screwdrivers, a large flat head screwdriver or sockets for loosening the control housings and petroleum jelly. Yep – Vaseline.

To get to the drawbars is not an easy task and is hindered by wire length restrictions. Lift off the wooden top of the organ then remove the metal shroud that covers the circuit boards. Looking from the back of the organ the two boards on the right hand side are the lower and upper manual buss amplifier boards. Amongst all of the wires plugging into these boards are the drawbar connectors. The easiest thing to do is get some tape and mark all of the wires with the pin that they connect to on the boards then unplug them. Don’t forget to indicate which board the wire goes to – UMB or LMB. This may seem a pain but it will save stretched or snapped cables and give easier access to the drawbars. Next thing to do is to remove the bolts that hold the main switch panel assembly. There is one on either side of the panel and once removed you should be able to carefully tilt the whole thing back. This picture shows the panel tilted back and  one set of drawbars already removed.

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There is a small plate holding together the three sets of drawbars and you don’t have to remove it but it does make handling the drawbars easier. Remove the screws holding the drawbars housings to the large back base plate. At this point I would get the tape out and start marking the drawbars – as with the circuit boards indicate lower/upper/pedal and the footage e.g. 16′, 8′ etc. This is now a great time to fix any wiring issues although you can also do this after reassembly. As you can see from the next picture some very dodgy repairs had been carried out with what looks like a poker instead of a soldering iron.

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Now it’s time to remove the drawbars. As you can see from the picture above there is a small screw at the rear of each drawbar that holds the wire and tension spring to the drawbar. Unscrew these and carefully remove the pieces and the drawbar should now slide out from the front of the unit. Get a container and put all of the bits in one place. We’ve now got access to the drawbar housing and what a mess. The housing is usually packed with petroleum jelly which over the years attracts all sorts of gunge. Mine was no exception.

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There’s no easy way around this. Clean it all out, give the drawbar parts a good clean and lightly apply some petroleum jelly. This can take a couple of hours and I used everything from q-tips to soap and water and micro mesh fine abrasive pads. Here’s some nice shiny drawbars:

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I have to admit getting a little confused about putting the drawbar mechanism back together. The following photo of the drawbar assembly with the numbers on was created so that I could ask my good friends on organforum.com in which order it goes together. Here’s the pic and the reply:

drawbarseq-2‘Piece #2 goes in between the contact and the brass base. Be sure that all the pieces are seated down onto the pegs of piece #3 and the pegs fit well into the holes on the brass base of the drawbar assembly before tightening the screw down.’

You could also take a little more notice than I did when pulling it all to pieces. At this point it’s a good opportunity to give everything a good clean and then reassemble the drawbar assemblies – unless your Hammond is in such a mess that you need to strip down the keyboards. Which mine was.

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