The Mellotron Group

Is there a current source for those big blue Caps in the M400 Power
Supply, 1600 and 2500uF - 40 volt, respectively? I've spent the weekend
trying to track some down, and while I can match the capacitance and
voltage, they don't come anywhere near the size of fitting in the
mounting straps of the originals.
Thanks,
johnb
1407

-----Original Message-----
From: tronbros@aol.com
Sent: Dec 4, 2007 7:55 AM
To: newmellotrongroup@yahoogroups.com
Subject: Re: [newmellotrongroup] Capacitor Source?

In a message dated 04/12/2007 12:11:47 GMT Standard Time, astroboy@cinci.rr.com writes:

Is there a current source for those big blue Caps in the M400 Power
Supply, 1600 and 2500uF - 40 volt, respectively? I've spent the weekend
trying to track some down, and while I can match the capacitance and
voltage, they don't come anywhere near the size of fitting in the
mounting straps of the originals.

John,

 

I know this will be a bitter pill so you had better sit down.  Wait for it...................they don't make the blue ones anymore....................and...............you are going to have to change the straps on the SMS2.  There was no other way to break it to you.  Pour yourself a stiff Frank Stickle and relax.

 

Best, -  Martin

 

 

 

 

Greetings John,Martin and Gang,

 

 

Modern electrolytic capacitors are about 1/3 to 1/5 their original size,

with much improved internal construction over their 1960s-1970s versions.

Due in most part by the huge need for high-quality filter caps used

in computer power-packs.

 

 

Anyway, from tech/eng'g. viewpoint, you can substitute a larger

cap value or higher DC working voltage ,but  NOT the inverse.

Higher capacitance translates to less  AC power-pack ripple.

 

 

I automatically replaced all paper/wax/foil capacitors  on two antique

TV sets and three valve-based radios in the last 1.5 years.

You'll see these fully functional units on forthcoming MONEYPIT pages.

Mellotrons, like other electronic bits of vintage technology WILL

require all caps replaced. 

 

 

You'll have to wrap some tape around the base of replacement caps,

to secure them within the original clamps.   I use paper masking tape,

as the plastic variety sometimes  "slides" when clamed tightly.

 

 

In 2006,  I decided to replace all 40+ yr.old power-pack capacitors within

MK-I #124 "Julia." Result is a stable DC power-source , and much

quieter than before (85% reduction).  KL has clearly heard these results

during our last two MONEYPIT gatherings.

 

 

Hope this helps. Good Luck !     -- Jerry Korb ( at the capacitor  ranch )

 

Rule of thumb. anything from before 1987 need the electrolytics changed especially on psu's.  

Martin,
I'm fighting back tears as I type, but I guess I'll find some way to
soldier on. On the bright side, perhaps I can fashion the old caps
into some kind of...er, trumpet or something.

Do you take your Stickle with or without the coconut?
johnb

PS will you send me an SMS2 so I can change the strap on it?

--- In newmellotrongroup@yahoogroups.com, tronbros@... wrote:

>
> John,
>
> I know this will be a bitter pill so you had better sit down. Wait
for
> it...................they don't make the blue ones
> anymore....................and...............you are going to have
to change the straps on the SMS2. There
> was no other way to break it to you. Pour yourself a stiff Frank
Stickle
> and relax.
>
> Best,
>
> Martin
> ps perhaps a flaccid FS would be more the thing.
>

> You'll have to wrap some tape around the base of replacement
> caps, to secure them within the original clamps. I use paper
> masking tape, as the plastic variety sometimes "slides" when
> clamed tightly.

Or, if you are handy with a saw you could do it like this:

http://pages.plotinka.ru/~cyciron/chinauser.jpg

-joachim

Wouldn't that require some serious toxic-waste-handling protocols and be
decidedly risky to the modifier?

> Or, if you are handy with a saw you could do it like this:
>
> http://pages.plotinka.ru/~cyciron/chinauser.jpg
>

> Wouldn't that require some serious toxic-waste-handling protocols
> and be decidedly risky to the modifier?

Good point. The electrolyte (liquid) within the capacitor is mildly
acidic, so care should be taken when handling.

However, this must not be confused with handling of old electric
utility capacitors which may contain highly toxic PCB (polychlorinated
biphenyls). That's a completely different thing.

Anyhow, the "capacitor surgery" thing wasn't meant to be taken too
seriously. Wouldn't recommend doing such a thing.

-joachim

Good - 'cause though I'm ok with wrapping the cap in tape, I was going
to boil mine on the stove until the can expanded just enough
to fit the old clamp...
johnb
1407


electronglow wrote:

>
> Anyhow, the "capacitor surgery" thing wasn't meant to be taken too
> seriously. Wouldn't recommend doing such a thing.
>
> -joachim
>
>