On 02/05/2014 03:21 PM, Dave McGuire wrote:
On 02/05/2014 03:14 PM, Ian McLaughlin wrote:
Mine's a cheap Chinese DT-9935 - $140. Free shipping from most Ebay vendors.
I do like HP gear, but the 4276A is a bit steep for me :)
I got it broken for even less than that and fixed it. =) I love doing
that...learn a lot in the process too!
(not to gloat, of course...just sharing the fun..)
--
Dave McGuire, AK4HZ
New Kensington, PA
On 02/05/2014 03:14 PM, Ian McLaughlin wrote:
Mine's a cheap Chinese DT-9935 - $140. Free shipping from most Ebay vendors.
I do like HP gear, but the 4276A is a bit steep for me :)
I got it broken for even less than that and fixed it. =) I love doing
that...learn a lot in the process too!
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
Mine's a cheap Chinese DT-9935 - $140. Free shipping from most Ebay vendors.
I do like HP gear, but the 4276A is a bit steep for me :)
Ian
On Feb 5, 2014, at 12:10 PM, Dave McGuire <mcguire at neurotica.com> wrote:
On 02/05/2014 03:08 PM, Ian McLaughlin wrote:
The best tool for repairing switching supplies (or monitors, for that
matter) - an ESR meter. Out of all of the test gear I've purchased
over the years, this one probably gets the most use! They use such a
low voltage, you can usually use them in-circuit without having to
desolder the component off the board before testing. Only takes a
few minutes to go through a power supply and identify the suspect
electrolytics.
Agreed 100%. I use an HP 4276A for exactly that.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
---
Filter service subscribers can train this email as spam or not-spam here: http://my.email-as.net/spamham/cgi-bin/learn.pl?messageid=9394905A8EA111E39…
On 02/05/2014 03:08 PM, Ian McLaughlin wrote:
The best tool for repairing switching supplies (or monitors, for that
matter) - an ESR meter. Out of all of the test gear I've purchased
over the years, this one probably gets the most use! They use such a
low voltage, you can usually use them in-circuit without having to
desolder the component off the board before testing. Only takes a
few minutes to go through a power supply and identify the suspect
electrolytics.
Agreed 100%. I use an HP 4276A for exactly that.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
The best tool for repairing switching supplies (or monitors, for that matter) - an ESR meter. Out of all of the test gear I've purchased over the years, this one probably gets the most use! They use such a low voltage, you can usually use them in-circuit without having to desolder the component off the board before testing. Only takes a few minutes to go through a power supply and identify the suspect electrolytics.
Ian
On Feb 5, 2014, at 12:05 PM, Dave McGuire <mcguire at neurotica.com> wrote:
On 02/05/2014 04:17 AM, Mark Wickens wrote:
Fans would click for a second and then kick right back off. It
stopped doing that until I removed all the drives. Plugged 'em back
in after opening the PSU to look for obvious faults and found none.
Everything is working fine now...Strange.
I had a hard disk taken out by a power spike. I also had firmware
corruption that required reflashing the EEPROM, but I don't remember if
that was related to the PSU. They draw 30 watts when switched 'off' so
it's definitely worth turning them off when not in use.
Twitching fans might indicate over-current protection kicking in.
If it's a repetitive twitching, it's probably the error amplifier or
the voltage divider feeding it. (those will be difficult to test
individually unless they're discretes, of course)
One other thing I've seen recently with older switching power supplies
is the output capacitors' ESR going up due to age, causing their time
constant to exceed that of the regulation loop...creating, you guessed
it, an oscillator.
I know one thing however - switched mode PSU experts are few and far
between!
This is painfully true. I *design* the damn things and I shy away
from working on them most of the time. Direct AC-driven ones are RIGHT
OUT in my book.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
---
Filter service subscribers can train this email as spam or not-spam here: http://my.email-as.net/spamham/cgi-bin/learn.pl?messageid=EA9D86968EA011E39…
On 02/05/2014 04:17 AM, Mark Wickens wrote:
Fans would click for a second and then kick right back off. It
stopped doing that until I removed all the drives. Plugged 'em back
in after opening the PSU to look for obvious faults and found none.
Everything is working fine now...Strange.
I had a hard disk taken out by a power spike. I also had firmware
corruption that required reflashing the EEPROM, but I don't remember if
that was related to the PSU. They draw 30 watts when switched 'off' so
it's definitely worth turning them off when not in use.
Twitching fans might indicate over-current protection kicking in.
If it's a repetitive twitching, it's probably the error amplifier or
the voltage divider feeding it. (those will be difficult to test
individually unless they're discretes, of course)
One other thing I've seen recently with older switching power supplies
is the output capacitors' ESR going up due to age, causing their time
constant to exceed that of the regulation loop...creating, you guessed
it, an oscillator.
I know one thing however - switched mode PSU experts are few and far
between!
This is painfully true. I *design* the damn things and I shy away
from working on them most of the time. Direct AC-driven ones are RIGHT
OUT in my book.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
On 05/02/2014 08:00, Cory Smelosky wrote:
On Wed, 5 Feb 2014, Google wrote:
On 5 Feb 2014, at 05:26, Cory Smelosky <b4 at gewt.net> wrote:
So, my VAXstation 4000/60 shut off and I had difficulty getting it to turn back on. Seems like a not-to-abnormal situation, right? PSU's getting old or overheating protection kicked in? That's not the weird part!
It may have overheated, I do know power switches can get flakey in VS4000s but the symptoms tend to be it won't turn OFF not on't turn ON but I guess if the switch is not contacting correctly it could be that too. the switch isn't, as far as I can tell, directly controlling the current, it is in some kind of latch circuit that unlatches when you flick it to 'OFF'. I think it's an early 'soft-power' implementation.
I moved the UPS further away. Very possible it got bumped and got too close to the UPS.
Full explanation:
http://dectec.info/vaxstation-4000-power-switch-issues-and-cleaning/
Thanks!
Also talk to Mark Wickens, he's had a few issues with 4000/90 PSUs.
When I rebooted the system...it had decided it was suddenly /2015/ and all the licenses expired. I've heard of systems resetting to the past when something happens...but NEVER the future!
That is odd, but Mark W remarked on my blog about one PSU failing and spiking his 4000/90 so badly it fried several parts, it's possible it could have upskittled the TOY clock?
Fans would click for a second and then kick right back off. It stopped doing that until I removed all the drives. Plugged 'em back in after opening the PSU to look for obvious faults and found none. Everything is working fine now...Strange.
I had a hard disk taken out by a power spike. I also had firmware corruption that required reflashing the EEPROM, but I don't remember if that was related to the PSU. They draw 30 watts when switched 'off' so it's definitely worth turning them off when not in use.
Twitching fans might indicate over-current protection kicking in.
I know one thing however - switched mode PSU experts are few and far between!
Mark
--
http://www.wickensonline.co.ukhttp://hecnet.euhttp://declegacy.org.ukhttp://retrochallenge.nethttps://twitter.com/urbancamo
On Wed, 5 Feb 2014, Google wrote:
On 5 Feb 2014, at 05:26, Cory Smelosky <b4 at gewt.net> wrote:
So, my VAXstation 4000/60 shut off and I had difficulty getting it to turn back on. Seems like a not-to-abnormal situation, right? PSU's getting old or overheating protection kicked in? That's not the weird part!
It may have overheated, I do know power switches can get flakey in VS4000s but the symptoms tend to be it won't turn OFF not on't turn ON but I guess if the switch is not contacting correctly it could be that too. the switch isn't, as far as I can tell, directly controlling the current, it is in some kind of latch circuit that unlatches when you flick it to 'OFF'. I think it's an early 'soft-power' implementation.
I moved the UPS further away. Very possible it got bumped and got too close to the UPS.
Full explanation:
http://dectec.info/vaxstation-4000-power-switch-issues-and-cleaning/
Thanks!
Also talk to Mark Wickens, he's had a few issues with 4000/90 PSUs.
When I rebooted the system...it had decided it was suddenly /2015/ and all the licenses expired. I've heard of systems resetting to the past when something happens...but NEVER the future!
That is odd, but Mark W remarked on my blog about one PSU failing and spiking his 4000/90 so badly it fried several parts, it's possible it could have upskittled the TOY clock?
Fans would click for a second and then kick right back off. It stopped doing that until I removed all the drives. Plugged 'em back in after opening the PSU to look for obvious faults and found none. Everything is working fine now...Strange.
--
Cory Smelosky
http://gewt.net Personal stuff
http://gimme-sympathy.org Projects
On 5 Feb 2014, at 05:26, Cory Smelosky <b4 at gewt.net> wrote:
So, my VAXstation 4000/60 shut off and I had difficulty getting it to turn back on. Seems like a not-to-abnormal situation, right? PSU's getting old or overheating protection kicked in? That's not the weird part!
It may have overheated, I do know power switches can get flakey in VS4000s but the symptoms tend to be it won't turn OFF not on't turn ON but I guess if the switch is not contacting correctly it could be that too. the switch isn't, as far as I can tell, directly controlling the current, it is in some kind of latch circuit that unlatches when you flick it to 'OFF'. I think it's an early 'soft-power' implementation.
Full explanation:
http://dectec.info/vaxstation-4000-power-switch-issues-and-cleaning/
Also talk to Mark Wickens, he's had a few issues with 4000/90 PSUs.
When I rebooted the system...it had decided it was suddenly /2015/ and all the licenses expired. I've heard of systems resetting to the past when something happens...but NEVER the future!
That is odd, but Mark W remarked on my blog about one PSU failing and spiking his 4000/90 so badly it fried several parts, it's possible it could have upskittled the TOY clock?
--
Mark Benson
http://DECtec.info
Twitter: @DECtecInfo
HECnet: STAR69::MARK
Online Resource & Mailing List for DEC Enthusiasts.
So, my VAXstation 4000/60 shut off and I had difficulty getting it to turn back on. Seems like a not-to-abnormal situation, right? PSU's getting old or overheating protection kicked in? That's not the weird part!
When I rebooted the system...it had decided it was suddenly /2015/ and all the licenses expired. I've heard of systems resetting to the past when something happens...but NEVER the future!
--
Cory Smelosky
http://gewt.net Personal stuff
http://gimme-sympathy.org Projects
