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Surprise Visit
John B.


By the time I got to John's house, the Mellotron Mark V was humming away in the corner nicely.  John looked at the fuses on the SMS motor controller and discovered that one of them was burned out.  He replaced it, hit the power switch, and off it went. 

Well, my work was done.  :-)

Ummm...not really.  Mark still had a few issues...
  1. Cracked power switch lens
  2. Dodgy audio section (no reverb, no headphone output)
  3. Unstable pitch
  4. Wobblies (and other keyboard adjustment maladies)
  5. Accordioned, broken, and worn tapes...some oddly installed -->
  6. Bent key retention bar bolts (uhhh...yeah...weird)
  7. Basic maintenance (not much, really)

...but we were able to take care of some of these with more to come later.

Mark is in pretty good shape, with most of the thanks being the Anvil case it was stored in, I'm sure.  The Tolex has some holes, but overall the machine is pretty clean.

The Mark V is basically the chassis of 2 Mellotron M400s sharing a common capstan, motor, and motor controller.  The case is wood covered in Tolex, and small panels held in by screws replace the large panels found in the M400.  If you remove the panel on the right side front (photo above) you will see the bottom of the tape frame, the SMS on the left, and the power supply in the center (behind the tape frame).    This is a smaller power supply than in the M400, and it's a far cry from the behemoth of a power supply (like something out of a science fiction movie) in the Mark I/II.

Also of note is the electronics are more sophisticated in the Mark V than in the M400, adding panning to left and right channels and reverb.  John's Mark V has what may be some custom wiring to two Morley volume pedals.

And, yep, those knobs are usually found on the EMI M400 machines.  Why Mark has a set of them is beyond me!  We do not know if those are from the factory or if someone got creative.

Finally, Mark is a MELLOTRON MARK V, not a Novatron.  The original Mellotron logo is on the front panel, and (as you can see far above) the M400-style serial number tag clearly indicates the manufacturer.


To start working on problem 7, the first thing Your Webmaster did was remove the motor.  That found the cause of the unstable pitch (problem 3):  the nut on the slotted bolt was loose.  After a bit of oil found its way to the bearings, the motor was reinstalled.  The capstan bearings got a little oil, too, for all that you can get oil in there without removing the bearings or tipping the machine on its side anyway.  But given how quiet the machine was running before this, this puppy doesn't have any issues with any bearings.

The tapes were another matter altogether.  I noticed that some ran for 3-4 seconds.  It turns out they'd been accordioned in the past, and the remaining portion was threaded.  The front of one tape was pulled through the frame for a few feet and left dangling.  Many tapes were worn atop the capstan.  Some had crinkles.  What tape start marks we could see weren't lining up all that well to the heads.

  This is one tired set of tapes, and John has plans to replace them.  That'll be the fix for problem 5 on the list.  What's funny is that John had used this set of tapes for years, and it's probably got a little life in it, but some tapes are wearing a bit thin on the capstan.

A Dallas Music Industries box sits in a closet in John's home.    On the cover it says "a. Viola / b. Violins / c. Flute".  Inside are 35 little spools that look like Honeycomb cereal.  Each spool has a tape on it, and most have numbers.  The tapes are labeled "BBHS".  What's on these?  We suspect the tape contents don't match the box's label, so we just don't know...yet.

Being unable to sort out the tapes at the moment, it was time to get the keyboards adjusted.  Several pinch rollers were rather stiff, but the old reliable Merbler Flick came into play and loosened up quite a few.  For the uninitiated, you soak the pinch roller axle in alcohol, then you flick the pinch roller as hard as you can, like snapping your fingers.  Repeat if necessary.  Somehow this can work miracles and loosen up stubborn pinch rollers.  Although some didn't loosen up all the way, all were turning sufficiently in the end.  I sanded off some pinch roller edges and gave the rollers I'd put in alcohol some CAIG Rubber Rejuvenator.

In addition to setting the proper key height and key travel (3/8"), I adjusted several keys on one keyboard the way that I usually do it, and they're very light to play.  I didn't have time to do all the keys, but John had done a decent job of adjusting them over the years, so I adjusted the ones that needed it and let the rest be for the time being.  We can go in and readjust when new tapes arrive, but for now the machine is playing great!  John is quite happy now that there's new life in this old machine.  Problem 4 no more.

Ahh, but now we get to the mystery of problem 6:

My reaction:  !!!?!!?!?!?!??!

In case you didn't notice, the keyboard retention bar (the L-shaped piece of aluminum just left of center) is leaning backward, and the bolts are bent.  BOTH keyboards are like this.  We have no idea why.  Yes, the heavy DX-1 was sitting on top of Mark, but there were no dents on the underside of the lid.  So we're at a loss to explain how the bolts got bent.

The rubber underneath the retention bars was coming out, and the keys were causing a racket when they hit the retention bar, so I turned the retention bars around as a temporary, quick fix (until we get some glue).  I adjusted the keyboard height again, and all was right with the world...

...except the lid wouldn't close anymore.

My reaction:  !!!?!!?!?!?!??!

Could it have been that when they made this the lid didn't fit, so they bent these things so the lid would close...?  I seriously doubt that.  This is going to take a little investigation.

The remaining problems will be sorted out as time goes on---new tapes, maybe some new pinch rollers, keyboard adjustment, getting a look at the audio wiring/reverb, and cleaning scratchy pots.

But for now "Mark" is doing well!  Another successful MONEYPIT adventure.

A Mark V Follow-up Exam

We had a surprise visit in July! -->