PDP 11 gear finally moved
mhs.stein at gmail.com
Tue Jul 21 22:52:19 CDT 2015
----- Original Message -----
From: "Tothwolf" <tothwolf at concentric.net>
To: "General Discussion: On-Topic and Off-Topic
Posts" <cctalk at classiccmp.org>
Sent: Tuesday, July 21, 2015 9:46 PM
Subject: Re: PDP 11 gear finally moved
> On Tue, 21 Jul 2015, Mike Stein wrote:
>> FWIW I'm certainly not about to spend 100s of
>> dollars, not to mention time spent in sourcing
>> and replacing, to replace the caps in systems
> 100s? Where are you sourcing your components
> from? The typical board I rebuild has a
> component cost of about $20 or less. Smaller
> switchmode PSUs with a bunch of 10-18mm radials
> might be closer to $35-50. Larger PSUs /might/
> cost closer to $100 if they have several large
> screw terminal capacitors in them. All things
> considered, that isn't very much money in
> today's dollars, and considering the full
> replacement cost of some of these boards (if
> they are even available), those preventive
> maintenance costs are an absolute bargain,
> /especially/ if you are doing the work yourself
> on your own time.
Maybe it isn't much money in your world,
especially when someone else is paying. I just
priced the main power supply caps in one of my
Cromemco systems and it comes to ~ $120 (and all
special order of course); if I replaced all the
caps in all my (working) systems as you and a few
others are suggesting across the board regardless
of the system, condition etc., it would easily
exceed $2000 if I could even find suitable
replacements. And what about those prone to
explode tantalums while we're at it...
If you're recapping 20-year old or newer circuit
boards for customers as you apparently are then it
does indeed often make sense to replace all the
aluminum electrolytics, especially if the board
has problems or there's visual evidence of
failure, but let those of us with older,
well-working systems use our _judgement_ whether
to replace or not. OK?
To each his own...
>> that are running perfectly "just in case"...
> How do you -know- they are "running perfectly"?
They reliably do what they're supposed to do.
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