> On Mar 16, 2016, at 1:24 PM, Jos Dreesen wrote:
> ...
> Additionally the NiCd never keep charge, if , like me, the drives are only
> fired up once a year...
>
> I am thinking of just adding some wiring to an external battery.
I wonder if it might make sense to replace it by a capacitor. Fo
On 16.03.2016 09:12, Christian Corti wrote:
On Tue, 15 Mar 2016, Paul Koning wrote:
From the various comments, it sounds like NiMH is a useable substitute. On the
other hand, NiCd batteries are still readily available.
Yes, but NiCd cells really don't like being charged only and never dischar
I'd think a stack of supper capacitors would do it.
Dwight
From: cctalk on behalf of Paul Koning
Sent: Wednesday, March 16, 2016 10:32 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: DEC RK05 Emergency Retract Batteries
>
On Tue, 15 Mar 2016, Paul Koning wrote:
From the various comments, it sounds like NiMH is a useable substitute.
On the other hand, NiCd batteries are still readily available.
Yes, but NiCd cells really don't like being charged only and never
discharged. And they tend to crystallise quite badly
> On Mar 15, 2016, at 4:08 PM, Robert Adamson wrote:
>
> Interestingly(?) both my RK05 and RK05J had an assembly of 3, not 4, 2/3rd
> AA NiCd cells for retract, completely decayed of course. I replaced them
> with 3 discrete tagged NiMh AA cells (plenty of headroom)
From the various comments,
Interestingly(?) both my RK05 and RK05J had an assembly of 3, not 4, 2/3rd
AA NiCd cells for retract, completely decayed of course. I replaced them
with 3 discrete tagged NiMh AA cells (plenty of headroom) soldered and
shrinkwrapped. They work fine, lots of retract force. The clip which holds
them
On Mon, 14 Mar 2016, tony duell wrote:
I am told some later drives used the spindle motor as a generator when the
power failed to provide the power for emergency retraction.
Yes, the HP 7905/7906 does this for example.
Christian
> It's now foggy memory, but I'm pretty sure HP 7900A (and 7901) were using
> batteries for emergency head retract.
The 7900 certainly does (there is one to go on my bench when I have some
spare time). In that case it's some AA-size NiCds (not tagged ones) in those
aluminium clip-in holders (Radi
Paul wrote
-
Interesting that they used a battery; I thought the usual mechanism was a
large capacitor, I hadn't seen batteries used for this.
-
It's now foggy memory, but I'm pretty sure HP 7900A (and 7901) were using
batteries for emergency head retract.
The later 7905/7906 - caps.
> On Mar 14, 2016, at 12:55 PM, Christian Corti
> wrote:
>
> On Mon, 14 Mar 2016, Doug Ingraham wrote:
>> The only difference in NiMH and NiCd charging schemes occurs when rapid
>> charging them. When rapid charging both types would use a DV/DT technique
>> coupled with a temperature sensor.
On Mon, 14 Mar 2016, Doug Ingraham wrote:
The only difference in NiMH and NiCd charging schemes occurs when rapid
charging them. When rapid charging both types would use a DV/DT technique
coupled with a temperature sensor. The DV/DT is much smaller for NiMH than
NiCd. So if they went to the ef
On Sun, Mar 13, 2016 at 9:41 AM, Rick Bensene wrote:
> Michael Thompson wrote:
> >
> > The NiCad batteries for emergency head retract are toast. These look like
> > standard 1.2V 2/3AA 400mAh cells. It looks like some cordless phones use
> the
> > same batteries so I can buy an assembled 4.8V bat
On 13/03/2016 15:00, Michael Thompson wrote:
The NiCad batteries for emergency head retract are toast. These look like
standard 1.2V 2/3AA 400mAh cells. It looks like some cordless phones use
the same batteries so I can buy an assembled 4.8V battery pack.
That's what I've always done.
Any ot
Michael Thompson wrote:
>
> The NiCad batteries for emergency head retract are toast. These look like
> standard 1.2V 2/3AA 400mAh cells. It looks like some cordless phones use the
> same batteries so I can buy an assembled 4.8V battery pack.
>
> Any other suggestions for replacement batteries fo
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