[sdiy] Cheetah MS800 replacing NiCd Varta Mempac

Richie Burnett rburnett at richieburnett.co.uk
Fri Jun 4 17:57:18 CEST 2021


Thanks.  Sadly no luck now though.  NiCd seems to be outlawed in most places 
now :-(

-Richie,



-----Original Message----- 
From: Joel B
Sent: Thursday, June 3, 2021 4:51 PM
To: Mike Bryant
Cc: Richie Burnett ; synth-diy mailing list
Subject: Re: [sdiy] Cheetah MS800 replacing NiCd Varta Mempac


Not sure if still possible but I was able to find a company selling 
replacement nicads that looked like they matched the spec of my cheetah MS6 
back in 2016… didn’t want to remove the charging system:

This is from my receipt:

3.6V 110MAH NICD
Item# NIC0010
https://interstatebatteries.com/


Worked for me.

Joel

Sent from my iPhone

On Jun 3, 2021, at 8:10 AM, Mike Bryant <mbryant at futurehorizons.com> wrote:



I've always dropped in NiMH into NiCad slots okay.  But that's no 
guarantee.  As you say not getting rid of the old one is a far worse 
scenario.

-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Richie 
Burnett
Sent: 03 June 2021 15:30
To: synth-diy mailing list
Subject: [sdiy] Cheetah MS800 replacing NiCd Varta Mempac

Hi all,

I'm currently servicing a Cheetah MS800 digital wavetable synth and want to 
change the old NiCd Varta Mempac to a brand new NiMH Varta Mempac before 
putting it up for sale.

The old blue NiCd battery hasn't started to leak yet, and is still holding 
it's charge but I know that old NiCd Mempacs are regarded as a ticking 
time-bomb in equipment of this age (>.<)  I wouldn't feel comfortable 
selling it without addressing this issue first.

The existing 100mA 3.6V NiCd trickle charges from the 5V supply rail through 
a 1k resistor when the unit is powered up.  Should I be looking at changing 
this trickle charge current when changing the battery type to the 150mA 3.6V 
NiMH replacement?

I did a search online and found very little solid information about this.
Everything from "The NiMH Mempacs are a drop in replacement" to "you need to 
decrease the trickle charge current because NiMH is less tolerant of being 
overcharged"  The trickle charge current already seems low to me.

I would be interested to hear your thoughts!

-Richie,


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