Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Chicken or the egg ?

I know this is just a pc ps but I'd like to understand what is going on, or
not going on, even if not repaird.
There are 3 HF transformers and an opto-isolator bridging the HV and LV
sides.
The startup oscillator, on the HV side, is a KA1H0165R whose o/p crosses the
divide to give a Vcc of 12V on the main SMPS controller a KA3511DS, both
datasheets downloaded.
This controller o/p should then cross the divide to drive the HV side main
oscillator to drive the main transformer back to the LV side supply rails.
The SMPS "flag" output pin goes high meaning no-function and no o/p pulses
for either push-pull output of this KA3511.
As the KA3511 monitors over-voltage, and more to this point, under-voltage
of the supply rails , how should it ever get started if it never outputs any
main drive pulses, so no main supply rails.
If i find time today I will run the KA3511 from 12V bench supply and see
what happens .

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



  #2   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 2,770
Default Chicken or the egg ?



N Cook wrote:

There are 3 HF transformers


More likely one transformer and 2 chokes, unless you have a specific reason to
say otherwise.

Graham

  #3   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Chicken or the egg ?

Eeyore wrote in message
...


N Cook wrote:

There are 3 HF transformers


More likely one transformer and 2 chokes, unless you have a specific

reason to
say otherwise.

Graham


Why would chokes bridge the "no man's land" isolation strip between HV and
LV areas ?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



  #4   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 244
Default Chicken or the egg ?

"N Cook" writes:

Eeyore wrote in message
...

N Cook wrote:

There are 3 HF transformers


More likely one transformer and 2 chokes, unless you have a specific
reason to say otherwise.


Why would chokes bridge the "no man's land" isolation strip between HV and
LV areas ?


No, probably transformers instead of opto-isolators (on the feedback
and drive).

Personally, I wouldn't even attempt to do any serious troubleshooting
on a supply of this type unless there was no inexpensive replacement.
I would check the obvious - ESR of e-caps, open high value startup
resistors, and such. But beyond that, these tend to be infinite
frustration sources.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
  #5   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Chicken or the egg ?

Sam Goldwasser wrote in message
...
"N Cook" writes:

Eeyore wrote in message
...

N Cook wrote:

There are 3 HF transformers

More likely one transformer and 2 chokes, unless you have a specific
reason to say otherwise.


Why would chokes bridge the "no man's land" isolation strip between HV

and
LV areas ?


No, probably transformers instead of opto-isolators (on the feedback
and drive).

Personally, I wouldn't even attempt to do any serious troubleshooting
on a supply of this type unless there was no inexpensive replacement.
I would check the obvious - ESR of e-caps, open high value startup
resistors, and such. But beyond that, these tend to be infinite
frustration sources.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above

is
ignored unless my full name AND either lasers or electronics is included

in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.


I don't mind challenges unless someone wants a turnaround repair, which this
is not. Its just practise for some future dedicated complex supply that has
no generic replacement.
I can see the one large and two small HF transformers tied up with the above
process but I wonder what the 4 pin opto device is for, perhaps an overall
on/off killer: when the controller flag is high it locks out the main HV
oscillator from making any blips.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/








  #6   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,569
Default Chicken or the egg ?

On Thu, 4 Oct 2007 09:32:41 +0100, "N Cook" put
finger to keyboard and composed:

I know this is just a pc ps but I'd like to understand what is going on, or
not going on, even if not repaird.
There are 3 HF transformers and an opto-isolator bridging the HV and LV
sides.
The startup oscillator, on the HV side, is a KA1H0165R whose o/p crosses the
divide to give a Vcc of 12V on the main SMPS controller a KA3511DS, both
datasheets downloaded.
This controller o/p should then cross the divide to drive the HV side main
oscillator to drive the main transformer back to the LV side supply rails.
The SMPS "flag" output pin goes high meaning no-function and no o/p pulses
for either push-pull output of this KA3511.
As the KA3511 monitors over-voltage, and more to this point, under-voltage
of the supply rails , how should it ever get started if it never outputs any
main drive pulses, so no main supply rails.
If i find time today I will run the KA3511 from 12V bench supply and see
what happens .


If it's a typical ATX PSU, then one transformer is part of the +5VSB
supply, a second drives the oscillator/chopper, and the third supplies
the secondaries. The optoisolator may provide voltage feedback for the
+5VSB rail, or it may be part of a protection circuit that shuts down
the oscillator.

See http://www.pavouk.org/hw/en_atxps.html.

Otherwise, if you have an AT PSU, then AFAIK the PWM controller on the
secondary side gets its supply rail from the very first "kick" of the
main oscillator and then "bootstraps" itself into regulation.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
  #7   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Chicken or the egg ?

Franc Zabkar wrote in message
...
On Thu, 4 Oct 2007 09:32:41 +0100, "N Cook" put
finger to keyboard and composed:

I know this is just a pc ps but I'd like to understand what is going on,

or
not going on, even if not repaird.
There are 3 HF transformers and an opto-isolator bridging the HV and LV
sides.
The startup oscillator, on the HV side, is a KA1H0165R whose o/p crosses

the
divide to give a Vcc of 12V on the main SMPS controller a KA3511DS, both
datasheets downloaded.
This controller o/p should then cross the divide to drive the HV side

main
oscillator to drive the main transformer back to the LV side supply

rails.
The SMPS "flag" output pin goes high meaning no-function and no o/p

pulses
for either push-pull output of this KA3511.
As the KA3511 monitors over-voltage, and more to this point,

under-voltage
of the supply rails , how should it ever get started if it never outputs

any
main drive pulses, so no main supply rails.
If i find time today I will run the KA3511 from 12V bench supply and see
what happens .


If it's a typical ATX PSU, then one transformer is part of the +5VSB
supply, a second drives the oscillator/chopper, and the third supplies
the secondaries. The optoisolator may provide voltage feedback for the
+5VSB rail, or it may be part of a protection circuit that shuts down
the oscillator.

See http://www.pavouk.org/hw/en_atxps.html.

Otherwise, if you have an AT PSU, then AFAIK the PWM controller on the
secondary side gets its supply rail from the very first "kick" of the
main oscillator and then "bootstraps" itself into regulation.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.


Didn't get around to powering from 12V dc but did trace a bit of the tracks.
The opto would seem to link, DC fashion, from the 3.3V rail back to the
feedback pin of the low power startup IC to shut that one down.
This IC, with the reservoir caps, will keep the main smps IC running for 10
seconds after removing the mains supply (in the present unfunctional as a ps
state)

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




  #8   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 244
Default Chicken or the egg ?

"N Cook" writes:

Sam Goldwasser wrote in message
...
"N Cook" writes:

Eeyore wrote in message
...

N Cook wrote:

There are 3 HF transformers

More likely one transformer and 2 chokes, unless you have a specific
reason to say otherwise.

Why would chokes bridge the "no man's land" isolation strip between HV

and
LV areas ?


No, probably transformers instead of opto-isolators (on the feedback
and drive).

Personally, I wouldn't even attempt to do any serious troubleshooting
on a supply of this type unless there was no inexpensive replacement.
I would check the obvious - ESR of e-caps, open high value startup
resistors, and such. But beyond that, these tend to be infinite
frustration sources.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/


I don't mind challenges unless someone wants a turnaround repair, which this
is not. Its just practise for some future dedicated complex supply that has
no generic replacement.
I can see the one large and two small HF transformers tied up with the above
process but I wonder what the 4 pin opto device is for, perhaps an overall
on/off killer: when the controller flag is high it locks out the main HV
oscillator from making any blips.


Could be, since the transformers can't provide DC coupling.

The problem is that with no schematic or service manual, there can be
so many dead ends and confusion that the experience IMO may not transfer
to other areas. It's not clear that the knowledge gained is worth the
hair lost.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Chicken Wire Fasteners Stormin Mormon Home Repair 27 April 29th 07 04:35 AM
JVC HR A630 VCR chicken or the egg ? n cook Electronics Repair 2 August 20th 06 02:10 PM
DONE OT proper way to kill a chicken Gunner Metalworking 13 May 18th 06 01:16 AM
Chicken coop Alain Hermans Woodworking 4 March 30th 05 02:01 AM
Where to start? Addition (Chicken/Egg) snapperhead Home Repair 5 December 29th 04 06:11 PM


All times are GMT +1. The time now is 02:29 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"