23 Feb
2009
23 Feb
'09
2:27 a.m.
Hi
Sounds like capacitors.
Alhough it's a switcher any high voltage/high value capacitors in the
PSU might well need reforming.
Quite often you will see caps with a pair if incised lines on top. This
makes them go pop instead of bang.
You would not want to see a PSU where they have gone bang.
Rod Smallwood
The DEC Collector
-----Original Message-----
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org] On Behalf Of Robert Jarratt
Sent: 21 February 2009 19:17
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: Powering up a 20-year old MicroVAX II
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of Robert Jarratt
Sent: 20 February 2009 22:45
To: cctalk at classiccmp.org
Subject: Powering up a 20-year old MicroVAX II
I have just collected a MicroVAX II which has been in storage and has
not been powered on for 20 years. This is my first machine of such an
age, unfortunately I am not particularly knowledgeable at the
electronics level (I studied circuits academically 25+ years ago and
can solder a bit, but that is as far as it goes). I know I will need
to treat it carefully in order to get it working again. I plan to open
it up and make sure I clear out any debris etc, but
beyond that I need
advice from those with the experience and knowledge
that I lack on how
to go about powering it up carefully.
Thanks
Rob
After removing all the boards and leaving just the disk and tape drive
for load I impetuously decided to try powering it up. I knew the PSU
(model
H7864) was set for 110V and made the switch to 240V (I am in the UK).
When I connected the power cord, after a few moments there was a loud
pop, followed by another before I could pull out the power cord, smoke
rose from the PSU.
This sounded just like when I had once accidentally made a 110/240
mix-up.
The question is, could it be that I had not made the switch to 240
correctly, or could this just be down to the age of the PSU?
Regards
Rob
23 Feb
23 Feb
5:24 a.m.
Rod Smallwood wrote:
Hi
Sounds like capacitors.
Alhough it's a switcher any high voltage/high value capacitors in the
PSU might well need reforming.
Quite often you will see caps with a pair if incised lines on top. This
makes them go pop instead of bang.
You would not want to see a PSU where they have gone bang.
This is the only popped electrolytic I have ever seen, in damn near 30
years of fiddling with electronic stuff:
http://www.gjcp.net/~gordonjcp/blowncap.jpg
Gordon
6:42 a.m.
On Mon, 23 Feb 2009, Gordon JC Pearce wrote:
This is the only popped electrolytic I have ever seen,
in damn near 30 years
of fiddling with electronic stuff:
http://www.gjcp.net/~gordonjcp/blowncap.jpg
I do have tons of such caps, mostly from modern PC mainboards, ATX power
supplies and graphics cards. This is *very* common today due to the high
frequency and high current nature of the designs.
Christian
9:22 a.m.
On Mon, Feb 23, 2009 at 6:42 AM, Christian Corti
<cc at informatik.uni-stuttgart.de> wrote:
On Mon, 23 Feb 2009, Gordon JC Pearce wrote:
Apparently I don't have a picture of it, but my first motherboard died
after a year or so when I was away for a couple days. I came home to
find it powered off; my parents (I was in high school at the time)
said they heard a bang so they hit the surge protector switch. When I
cracked open the case, one of my motherboard electrolytics had blasted
the can right off of itself. The can was laying on the bottom of the
case and there was a pretty spiral of paper hanging from the base of
the cap! The can was pinched at the middle, like somebody grabbed it
with a pair of needle-nose pliers.
Luckily, that has not happened again.
John
--
"I've tried programming Ruby on Rails, following TechCrunch in my RSS
reader, and drinking absinthe. It doesn't work. I'm going back to C,
Hunter S. Thompson, and cheap whiskey." -- Ted Dziuba
This is the only popped electrolytic I have ever seen, in damn near 30
years of fiddling with electronic stuff:
http://www.gjcp.net/~gordonjcp/blowncap.jpg
I do have tons of such caps, mostly from modern PC mainboards, ATX power
supplies and graphics cards. This is *very* common today due to the high
frequency and high current nature of the designs.
Christian
12:44 p.m.
On Feb 23, 2009, at 6:42 AM, Christian Corti wrote:
Not to mention cheapness in commodity equipment and counterfeit
components. In fact I'd bet real money that these issues are the
culprits far more often than high frequency and high current. There
are components available that are designed to withstand such things,
and they're quite good.
-Dave
--
Dave McGuire
Port Charlotte, FL
This is the
only popped electrolytic I have ever seen, in damn
near 30 years of fiddling with electronic stuff:
http://www.gjcp.net/~gordonjcp/blowncap.jpg
I do have tons of such caps, mostly from modern PC mainboards, ATX
power supplies and graphics cards. This is *very* common today due
to the high frequency and high current nature of the designs. 
1:29 p.m.
Not to mention cheapness in commodity equipment and
counterfeit components.
In fact I'd bet real money that these issues are the culprits far more
often than high frequency and high current. There are components available
that are designed to withstand such things, and they're quite good.
Yes, there was a rash of ultra cheap counterfeit capacitors a while
back, and the problem is still not solved. I would worry more about
them than any caps in a MicroVAX. Those 70s and 80s era caps are
pretty good, and I have only very rarely seen ones go bad (and yes, I
have dealt with piles of them). I would also say that most of the
failures are due not to age and (lack of) reforming issues, but to
seals that leak and let in contaminants. No amount of careful powering
up will repair a capacitor with a bad seal. I am tempted to research
this a little more, talking to capacitor guys and digging up the
reports the military industry has done on the issue, but I fear the
results I find will fall on deaf ears on this list.
So even though I was one of the first people on this list to suggest
reforming old capacitors, I have basically completely reversed my view
on the issue. Now, if the machine is not super old, I will just pretty
much plug in the machine and let it power up. Even if something does
fail, most of the machines I deal with have enough built in protection
that they will just shut down safely.
By the way - counterfeit components are nothing new to the industry.
For example, there were rashes of fake tubes in the 1920s and 50s.
--
Will
1:46 p.m.
In article <e1d20d630902231029h4b85b71bqb508dcca38a026c9 at mail.gmail.com>,
William Donzelli <wdonzelli at gmail.com> writes:
up will repair a capacitor with a bad seal. I am
tempted to research
this a little more, talking to capacitor guys and digging up the
reports the military industry has done on the issue, but I fear the
results I find will fall on deaf ears on this list.
I for one would love to read about this stuff in more detail and I
suspect the "silent majority" would also find it interesting.
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://www.xmission.com/~legalize/book/download/index.html>
Legalize Adulthood! <http://blogs.xmission.com/legalize/>
3:47 p.m.
I for one would love to read about this stuff in more
detail and I
suspect the "silent majority" would also find it interesting.
True, but the "silent majority" does not keep the junk science going -
it is the "loud mouth biased minority" that does.
I will be honest - I probably do not have time for any of this, as the
reports are really rather boring. Who knows, maybe if I bust my leg or
something, I will have lots of time to spend on the subject. I have a
few of the reports in my files (about circuit packaging, not
capacitors), but getting the other reports can be a real hassle. Early
ones are from the OSRD, and later ones from a group I do not remember
right now. They are available from a select few libraries around the
country.
Likewise, it would be fun to run a controlled experiment concerning
e-caps, but once again time is an issue. Frankly, I would like to
spend my time power up machines, rather than trying to convince the
unconvinceable.
--
Will
24 Feb
24 Feb
12:41 a.m.
On Monday 23 February 2009 01:46:42 pm Richard wrote:
In article
<e1d20d630902231029h4b85b71bqb508dcca38a026c9 at mail.gmail.com>,
William Donzelli <wdonzelli at gmail.com> writes:
I will add my expression of interest to this as well.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
up will repair a capacitor with a bad seal. I am
tempted to research
this a little more, talking to capacitor guys and digging up the
reports the military industry has done on the issue, but I fear the
results I find will fall on deaf ears on this list.
I for one would love to read about this stuff in more detail and I
suspect the "silent majority" would also find it interesting. 
23 Feb
23 Feb
2:30 p.m.
Date: Mon, 23 Feb 2009 13:29:26 -0500
From: wdonzelli at gmail.com
To: cctalk at classiccmp.org
Subject: Re: Powering up a 20-year old MicroVAX II
I am tempted to research this a little more, talking to capacitor
guys and digging up the reports the military industry has done on
the issue, but I fear the results I find will fall on deaf ears
on this list.
--
Will
You might be surprised how many people read without chiming in.
But if it helps, there are posters on this list of whom I read
almost everything. You're one of them. I learn every day something
new from this list, sometimes technical, somtimes historical.
Both equally interesting (IMHO).
- Henk, PA8PDP.
5:57 p.m.
Henk Gooijen wrote:
*Ding*
That is me chiming it - Yes, all messages are read, and some are even
remembered -
You never know how useful somebody's random data actually is.
So, Please feel free to post your findings, the ears here are not deaf,
it is just the mouth that is often silent.
:-)
--
Doug Jackson, I-RAP, MAIPM, MIEEE
Principal Information Security Consultant
EWA-AUSTRALIA
PO Box 6308 O'Connor ACT 2602
Level 1, 214 Northbourne Ave, Braddon ACT 2612
Tel: +61 (0)2 6230 6833
Fax: +61 (0)2 6230 5833
Mob: +61 (0)414 986 878
http://www.ewa-australia.com
============================================
IMPORTANT: This email remains the property of Electronic Warfare
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in accordance with the Privacy Act 1988 (Cth).
============================================
Date: Mon, 23
Feb 2009 13:29:26 -0500
From: wdonzelli at gmail.com
To: cctalk at classiccmp.org
Subject: Re: Powering up a 20-year old MicroVAX II
I am tempted to research this a little more, talking to capacitor
guys and digging up the reports the military industry has done on
the issue, but I fear the results I find will fall on deaf ears
on this list.
--
Will
You might be surprised how many people read without chiming in.
But if it helps, there are posters on this list of whom I read
almost everything. You're one of them. I learn every day something
new from this list, sometimes technical, somtimes historical.
Both equally interesting (IMHO).
- Henk, PA8PDP.
24 Feb
24 Feb
2:17 a.m.
On Feb 23, 2009, at 1:29 PM, William Donzelli wrote:
Yup:
http://deep-blue.ro/tmp/chinese%20capacitor.jpg
Frightening, isn't it?
Not to
mention cheapness in commodity equipment and counterfeit
components.
In fact I'd bet real money that these issues are the culprits far
more
often than high frequency and high current. There are components
available
that are designed to withstand such things, and they're quite good.
Yes, there was a rash of ultra cheap counterfeit capacitors a while
back, and the problem is still not solved. 
I would worry more about
them than any caps in a MicroVAX. Those 70s and 80s era caps are
pretty good, and I have only very rarely seen ones go bad (and yes, I
have dealt with piles of them). I would also say that most of the
failures are due not to age and (lack of) reforming issues, but to
seals that leak and let in contaminants. No amount of careful powering
up will repair a capacitor with a bad seal. I am tempted to research
this a little more, talking to capacitor guys and digging up the
reports the military industry has done on the issue, but I fear the
results I find will fall on deaf ears on this list.
Not these ears! Research away; I'm interested. We're not ALL
curmudgeons.
-Dave
--
Dave McGuire
Port Charlotte, FL
9:16 a.m.
On Tue, 24 Feb 2009, Dave McGuire wrote:
That's the most insane thing I think I've ever seen. I'd heard about the
dodgy formula that was causing caps to burst some years ago, but never
this kind of thing... Wow. Thanks for the pic Dave.
g.
--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
Yes, there was
a rash of ultra cheap counterfeit capacitors a while
back, and the problem is still not solved.
Yup:
http://deep-blue.ro/tmp/chinese%20capacitor.jpg
9:21 a.m.
Gene Buckle wrote:
On Tue, 24 Feb 2009, Dave McGuire wrote:
That's the most insane thing I think I've ever seen. I'd heard about
the dodgy formula that was causing caps to burst some years ago, but
never this kind of thing... Wow. Thanks for the pic Dave.
Is there any verification behind it, though?
Gordon
Yes,
there was a rash of ultra cheap counterfeit capacitors a while
back, and the problem is still not solved.
Yup:
http://deep-blue.ro/tmp/chinese%20capacitor.jpg
9:33 a.m.
Dave McGuire wrote:
...
Yeah, but did you think to open the 2200 uF cap inside? It probably
contained a 680uf cap, and so on, like Russian dolls.
More insidious than the much less than rated capacitance is the fact the
inner one is rated to 35V and the outer one is rated at 50V. So rather
than just having extra ripple in your power supply, you end up with a
blown cap.
Yes, there was
a rash of ultra cheap counterfeit capacitors a while
back, and the problem is still not solved.
Yup:
http://deep-blue.ro/tmp/chinese%20capacitor.jpg
Frightening, isn't it? 
10:09 a.m.
On Tue, 24 Feb 2009 08:33:48 -0600, Jim Battle wrote:
More insidious than the much less than rated
capacitance is the fact the
inner one is rated to 35V and the outer one is rated at 50V. So rather
than just having extra ripple in your power supply, you end up with a
blown cap.
Most applications using a 6800mf cap are filtering 5~24v supply voltages.
35wv will work just fine.
My question would be ....
Did the solder monkey who made this, get the polarity correct ?
That could assist in the generation of a small Bang !
I think that the cap pictured represents a lot of labor just to recyclea little
electrolitic:-)
I expect the 2200uf came from some computer scrap we ship back for recycleing.
The other Bob
3:41 p.m.
On Tue, Feb 24, 2009 at 02:17:30AM -0500, Dave McGuire wrote:
On Feb 23, 2009, at 1:29 PM, William Donzelli wrote:
Yup:
http://deep-blue.ro/tmp/chinese%20capacitor.jpg
Frightening, isn't it?
More along the lines of "WTF?" - that kind of effort is actually worth
doing and pays off? Previously I was just aware of the trouble that was
caused by an imcompetently stolen electrolyte formula, which caused
electrolytic capacitors to die by the truckload.
Thanks for the image.
*shakes_head*
Regards,
Alex.
--
"Opportunity is missed by most people because it is dressed in overalls and
looks like work." -- Thomas A. Edison
Not to
mention cheapness in commodity equipment and counterfeit
components.
In fact I'd bet real money that these issues are the culprits far
more
often than high frequency and high current. There are components
available
that are designed to withstand such things, and they're quite good.
Yes, there was a rash of ultra cheap counterfeit capacitors a while
back, and the problem is still not solved.
23 Feb
23 Feb
11:55 p.m.
On Monday 23 February 2009 05:24:32 am Gordon JC Pearce wrote:
Rod Smallwood wrote:
I was given a flatscreen a while back and after opening it up I saw a whole
*bunch* of them that looked like that...
I'm undecided yet whether I'm going to just change the ones that are bulging
out the top like that or swap them *all*, which is going to end up being
rather more extensive.
I suspect that lack of a surge protector was probably a good diagnosis for
this user. :-)
I have another one from the same source that uses an external power supply
that's dead. A replacement is at hand, so I'll probably "fix" that one
first.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Hi
Sounds like capacitors.
Alhough it's a switcher any high voltage/high value capacitors in the
PSU might well need reforming.
Quite often you will see caps with a pair if incised lines on top. This
makes them go pop instead of bang.
You would not want to see a PSU where they have gone bang.
This is the only popped electrolytic I have ever seen, in damn near 30
years of fiddling with electronic stuff:
http://www.gjcp.net/~gordonjcp/blowncap.jpg
Gordon
5623
days inactive
5624
days old
18 comments
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