Out of tune hammond?

[harmony head]

Hey all..

I have a Hammond 18150k (not a model i know a lot about.. i'm no expert either). It's like a stage hammond, has 2 manuals and bass pedals but is 'portable'. It's not a valve thing or anything. I've had it for 15 years and love it to death.

However, a weird thing has started happening. All the C notes are sharp about 10 cents. Every other key is perfect, but the Cs are all out.

Any ideas how to fix thing? Like i said, i'm no expert, and finding someone here in Sydney is harder than you'd think, so any advice would be appreciated.

Or do i just ditch it and search for a new old hammond?

HH

[Howard Jones]

I'm not familiar with the circuit details of this model, but if all the Cs have gone out together, I imagine that this would imply that there is a single oscillator producing top C and that the other Cs are produced by divider circuits. Hence, the master C oscillator drifts and all Cs drift with it.

I expect that either Dave Peach at Peach Audio (Coogee) or Warren McAlister at Phase Enginering (Dee Why) might have circuit drawings/ service manual.

[Howard Jones]

It has also been suggested to me that Owen Reynolds may be knowledgable on these. I believe he works out of Continuumusic.

Depending on the age of your Hammond, it may use tone wheels driven by electric motors rather than oscillator circuits. It will still come down to one C oscillator throwing all the others out.

[Linear]

Depending on the age of your Hammond, it may use tone wheels driven by electric motors rather than oscillator circuits. It will still come down to one C oscillator throwing all the others out.

Not likely.

If the thing is using tonewheels, then it would be impossible for one note to be out of tune to the other notes, because all of the tonewheels are driven at the same rotational speed by an AC motor with the number of teeth on each tonewheel determining the pitch of the note.

You can hear this by holding several keys of a tonewheel organ down, then switching it off. You can hear the tonewheel (and hence pitch) spin down at exactly the same rate from all keys. Tonewheel Hammonds, for all their shortcomings, have extremely stable intonation because of this very fact.

So I would say that the Hammond you have is not a tonewheel Hammond, and that one of the oscillator chips is on it's way out. Happened to a friend of mine's CX80. You should be able to find a replacement somewhere on the internot.

Chris

[rick]

there is a company whos name remains a mystery to me that buys sells and services hammonds on the central coast

they appear in the trading place from time to time with a hammond wanted add


your hammond is not a tonewheel one

so its more like the osc circuits are drifting, which could be anything but i would bet your electro caps are shot and resistors values have changed over time in general its time it had a service

OR you could be really lucky and there could be an internal "tune" trimpot
on each note which just needs a spray and a tweek.
if its only all the the Cs for my money i would be finding a tech and getting it fixed.

[harmony head]

OK.. i just opened it all up and investigated. Lots of cables, circuit boards, caps etc. Unfortunately, after much searching, i've found no master tuning thing for the individual keys, though there is one for the whole thing.

I'm dreading having to take this somewhere for a service...

HH

[mark rachelle]

SOUL-AMP ENGINEERING. Location: MELBOURNE, VIC Australia, Contact: Simon Tregear soulamp@alphalink.com.au 61 03 95780639 61 03 95780639

[headman]

If you are serious about a Hammond, You can have one of my L100's for probably the cost of fixing your non tonewheel model. Contact me via the forum if this is an option.

tony heads