Mellotronists

--- In Mellotronists@yahoogroups.com, john barrick <astroboy@...> 
wrote:
>
> I'm wanting to remove the end boards from the frame so I can get a 
> really good polishing job done on the aluminum, and I was 
wondering if 
> there are any issues with remounting them - or should they simply 
> re-attach and that's it.
> 
> Also, what are the specs on the resistor for magnetization 
prevention 
> that you need to put on the preamp lead from the headblock, and do 
you 
> simply solder it across the leads of the jack?
> 
> Thanks,
> john barrick
>


  Hi Again, Dealing with second question, resistor recommended is 
40k, but do not presume you are going to leave it on there.  First 
let's look at the reason for this.  On your headblock are 35 tape 
heads.  That is there are 35 coils able to store energy. Assuming 
you are demagging headblock removed from machine, a good practice, 
the coils can pick up a residual static charge.  Think of them if 
you will as capacitors.  So before you plug heads into preamp, they 
need to be drained.  This is what the resistor does, but you can do 
the same thing by shorting out the lead at headblock and the head 
receptacle on preamp with same results.  If you have run new ground 
wires from frame to preamp and again at power supply, and replaced 
coax from heads to preamp then to power supply, you should not have 
any continuity issues.  Again make sure all your connections are 
clean and tight.  This is the 'ounce of prevention" part.

As far as removing wooden sides, and strictly my opinion only, if 
there were no misalignment issues with framework, I would leave it 
alone and work around it. I would have to believe these frames were 
jigged when originally assembled, which is why I believe the parts 
that were riveted were done for a reason, and if you remove them, 
you may not get same symmetry when reassembled without taking a lot 
of measurements. I'm sure others have done frame rebuilds with 
success, but unless you had issues with warped rails to begin with, 
go with "play it safe" on this one.  Be careful,  Doug