sci.electronics.repair - 23 new messages in 8 topics - digest

sci.electronics.repair
http://groups.google.com/group/sci.electronics.repair?hl=en

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Today's topics:

==============================================================================
TOPIC: ATX power supply fan noisy.
http://groups.google.com/group/sci.electronics.repair/t/c9cc85470d364e01?hl=en
==============================================================================

== 1 of 9 ==
Date: Fri, Apr 30 2010 9:13 pm
From: UCLAN

Arfa Daily wrote:

>>>If you want long and quiet service, make sure that you get one with roller
>>>bearings, not the cheapo sleeve bearings.
>>>
>>>Arfa
>>
>>Ceramic bearings appear to be even better:
>>http://www.ceramicafans.com/whyceramic.htm
>>
>>- Franc Zabkar
>>--
>>Please remove one 'i' from my address when replying by email.
>
> Haven't had any experience of them yet.

While ball-bearing fans have the longevity edge over cheap sleeve bearing
fans, they aren't necessarily quieter. And newer sleeve bearing designs,
such as Nidec's NBRX sleeve bearing, have made great strides in longevity.

== 2 of 9 ==
Date: Sat, May 1 2010 1:45 pm
From: Ian Jackson

In message
<c1c6ebf7-891b-4fba-9f3d-11d31bc2b5c1@j36g2000prj.googlegroups.com>,
Robert Macy <macy@california.com> writes
>On Apr 28, 10:53 am, "David Farber" <farberbear.uns...@aol.com> wrote:
>> I would like to replace this two-wire, 80mm square, power supply fan. The
>> power supply is used in an AudioReQuest music server and is powered on
>> continuously. The part number is, NMB-MAT 7 followed by a model number of,
>> 3110GL-B4W-B54. 12V DC, 0.30A. I've found a few places online that have them
>> listed but when I call they, don't have them in stock or the price is
>> prohibitively expensive. Is there some generic fan that will replace this
>> and not cost more than the power supply itself?
>>
>> Thanks for your reply.
>> --
>> David Farber
>> David Farber's Service Center
>> L.A., CA
>
>If you caught it in time, you can try relubing the bearins which will
>get you by for a while.
>
>Remove from PC and soak in 30 weight oil, clean up, put back in
>
>I got another 6 months out of mine

My PSU fan seized solid, very solid (nice and quiet, though). The
replacement seemed rather noisy for my tastes. I eventually got the
original fan freed off. [It needed the application of a hot soldering
iron to the end of the spindle.] It ran for 18 months after being well
re-oiled with WD40. It was still going fine when, some time ago, I doing
a spot of once-in-a-while spring cleaning inside the case. So I re-oiled
it again with some '3-in-1' oil. It's still running fine.
--
Ian

== 3 of 9 ==
Date: Sat, May 1 2010 2:44 pm
From: "Michael A. Terrell"

Ian Jackson wrote:
>
> My PSU fan seized solid, very solid (nice and quiet, though). The
> replacement seemed rather noisy for my tastes. I eventually got the
> original fan freed off. [It needed the application of a hot soldering
> iron to the end of the spindle.] It ran for 18 months after being well
> re-oiled with WD40. It was still going fine when, some time ago, I doing
> a spot of once-in-a-while spring cleaning inside the case. So I re-oiled
> it again with some '3-in-1' oil. It's still running fine.

WD40 isn't a lubricant. It was developed for 'Water Displacement',
or in plain english, to spray on ignition wires that got wet.

Which '3-in-1' oil. That is a brand, not a type.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

== 4 of 9 ==
Date: Sat, May 1 2010 3:00 pm
From: Ian Jackson

In message <JMadnWcTILZFPUHWnZ2dnUVZ_gWdnZ2d@earthlink.com>, Michael A.
Terrell <mike.terrell@earthlink.net> writes
>
>Ian Jackson wrote:
>>
>> My PSU fan seized solid, very solid (nice and quiet, though). The
>> replacement seemed rather noisy for my tastes. I eventually got the
>> original fan freed off. [It needed the application of a hot soldering
>> iron to the end of the spindle.] It ran for 18 months after being well
>> re-oiled with WD40. It was still going fine when, some time ago, I doing
>> a spot of once-in-a-while spring cleaning inside the case. So I re-oiled
>> it again with some '3-in-1' oil. It's still running fine.
>
>
> WD40 isn't a lubricant. It was developed for 'Water Displacement',
>or in plain english, to spray on ignition wires that got wet.
>
Regardless of what it was developed for, WD40 does leave an oily layer.
It penetrates well, and prevents/halts rust. It also serves as a
sort-term lubricant. Despite what the purists might say, it does work
well as a switch cleaner/lubricant.
>
> Which '3-in-1' oil. That is a brand, not a type.
>
It's the type in a small metal tin with a plastic nozzle - the very same
tin I've had on a shelf at the back of the garage for about 40 years. I
haven't a clue what the official grade is, other than its the general
purpose domestic stuff, like you'd use for oiling door hinges and
bicycle chains. And latterly, of course, computer fans.
--
Ian

== 5 of 9 ==
Date: Sat, May 1 2010 4:24 pm
From: "Michael A. Terrell"

Ian Jackson wrote:
>
> In message <JMadnWcTILZFPUHWnZ2dnUVZ_gWdnZ2d@earthlink.com>, Michael A.
> Terrell <mike.terrell@earthlink.net> writes
> >
> >Ian Jackson wrote:
> >>
> >> My PSU fan seized solid, very solid (nice and quiet, though). The
> >> replacement seemed rather noisy for my tastes. I eventually got the
> >> original fan freed off. [It needed the application of a hot soldering
> >> iron to the end of the spindle.] It ran for 18 months after being well
> >> re-oiled with WD40. It was still going fine when, some time ago, I doing
> >> a spot of once-in-a-while spring cleaning inside the case. So I re-oiled
> >> it again with some '3-in-1' oil. It's still running fine.
> >
> >
> > WD40 isn't a lubricant. It was developed for 'Water Displacement',
> >or in plain english, to spray on ignition wires that got wet.
> >
> Regardless of what it was developed for, WD40 does leave an oily layer.
> It penetrates well, and prevents/halts rust. It also serves as a
> sort-term lubricant. Despite what the purists might say, it does work
> well as a switch cleaner/lubricant.

Which dries into a nasty, insulating film over time. I use PTFE to
lube small motors. It Works a lot better than WD40 ever could, and lasts
a lot longer.

<http://www.radioshack.com/product/index.jsp?productId=2102643>

> > Which '3-in-1' oil. That is a brand, not a type.
> >
> It's the type in a small metal tin with a plastic nozzle - the very same
> tin I've had on a shelf at the back of the garage for about 40 years. I
> haven't a clue what the official grade is, other than its the general
> purpose domestic stuff, like you'd use for oiling door hinges and
> bicycle chains. And latterly, of course, computer

'3-in-1' does make an electric motor oil.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

== 6 of 9 ==
Date: Sat, May 1 2010 8:41 pm
From: UCLAN

Michael A. Terrell wrote:

>>> Which '3-in-1' oil. That is a brand, not a type.
>>
>>It's the type in a small metal tin with a plastic nozzle - the very same
>>tin I've had on a shelf at the back of the garage for about 40 years. I
>>haven't a clue what the official grade is, other than its the general
>>purpose domestic stuff, like you'd use for oiling door hinges and
>>bicycle chains. And latterly, of course, computer
>
> '3-in-1' does make an electric motor oil.

My favorite "3-in-1" product:

http://www.3inone.com/products/white-lithium-grease/

== 7 of 9 ==
Date: Sat, May 1 2010 8:51 pm
From: "Michael A. Terrell"

UCLAN wrote:
>
> Michael A. Terrell wrote:
>
> >>> Which '3-in-1' oil. That is a brand, not a type.
> >>
> >>It's the type in a small metal tin with a plastic nozzle - the very same
> >>tin I've had on a shelf at the back of the garage for about 40 years. I
> >>haven't a clue what the official grade is, other than its the general
> >>purpose domestic stuff, like you'd use for oiling door hinges and
> >>bicycle chains. And latterly, of course, computer
> >
> > '3-in-1' does make an electric motor oil.
>
> My favorite "3-in-1" product:
>
> http://www.3inone.com/products/white-lithium-grease/

I use lithium grease, but another brand that I can pick up from a car
parts dealer just down the street. I also use PB Blaster and Breakfree.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

== 8 of 9 ==
Date: Sat, May 1 2010 9:09 pm
From: mm

On Wed, 28 Apr 2010 12:08:39 -0700, UCLAN <nomail@thanks.org> wrote:

>David Farber wrote:
>
>> I would like to replace this two-wire, 80mm square, power supply fan. The
>> power supply is used in an AudioReQuest music server and is powered on
>> continuously. The part number is, NMB-MAT 7 followed by a model number of,
>> 3110GL-B4W-B54. 12V DC, 0.30A. I've found a few places online that have them
>> listed but when I call they, don't have them in stock or the price is
>> prohibitively expensive. Is there some generic fan that will replace this
>> and not cost more than the power supply itself?
>
>Any 2-wire, 80mm, 12VDC, 0.30A (approx) will do. Got a Radio Shack nearby?
>http://www.radioshack.com/product/index.jsp?productId=2102826 will do.
>
>Probably cheaper at some place like Frys.

Radio shack has a great webpage in many ways, but one enormous flaw is
that if you click on a link, it might say the part is out of stock,
even when stores have it.

I signed up to get an eamil when their remote A-B switch was back in
stock, and after months I got it, and figured well maybe it's also at
a store now too. So I went in and they had two and the clerk said
they had never been out of them.

He was very confident, and I had gone in the same day I got the email.
It seems unlikely they had in stock items actually shipped for the
same reason they sent me the email. They probably did have them all
along.

So to with the item above. It says it's out of stock, but when I
click on Find it in STores, it gives 10 stores around here that it
seems to say has it. I'd call some stores and see.

P&M

--
Posters should say what U,S. state if any they live in. Why
do so many keep their state as secret as their own name?

IANAL. That is, I am not a lawyer.

== 9 of 9 ==
Date: Sun, May 2 2010 12:34 am
From: Ian Jackson

In message <_IednQW6vL_VJUHWnZ2dnUVZ_jidnZ2d@earthlink.com>, Michael A.
Terrell <mike.terrell@earthlink.net> writes
>
>Ian Jackson wrote:
>>
>> In message <JMadnWcTILZFPUHWnZ2dnUVZ_gWdnZ2d@earthlink.com>, Michael A.
>> Terrell <mike.terrell@earthlink.net> writes
>> >
>> >Ian Jackson wrote:
>> >>
>> >> My PSU fan seized solid, very solid (nice and quiet, though). The
>> >> replacement seemed rather noisy for my tastes. I eventually got the
>> >> original fan freed off. [It needed the application of a hot soldering
>> >> iron to the end of the spindle.] It ran for 18 months after being well
>> >> re-oiled with WD40. It was still going fine when, some time ago, I doing
>> >> a spot of once-in-a-while spring cleaning inside the case. So I re-oiled
>> >> it again with some '3-in-1' oil. It's still running fine.
>> >
>> >
>> > WD40 isn't a lubricant. It was developed for 'Water Displacement',
>> >or in plain english, to spray on ignition wires that got wet.
>> >
>> Regardless of what it was developed for, WD40 does leave an oily layer.
>> It penetrates well, and prevents/halts rust. It also serves as a
>> sort-term lubricant. Despite what the purists might say, it does work
>> well as a switch cleaner/lubricant.
>
>
> Which dries into a nasty, insulating film over time. I use PTFE to
>lube small motors. It Works a lot better than WD40 ever could, and lasts
>a lot longer.
>
><http://www.radioshack.com/product/index.jsp?productId=2102643>
>
>
>> > Which '3-in-1' oil. That is a brand, not a type.
>> >
>> It's the type in a small metal tin with a plastic nozzle - the very same
>> tin I've had on a shelf at the back of the garage for about 40 years. I
>> haven't a clue what the official grade is, other than its the general
>> purpose domestic stuff, like you'd use for oiling door hinges and
>> bicycle chains. And latterly, of course, computer
>
>
> '3-in-1' does make an electric motor oil.
>
Don't get me wrong. I'm not 'recommending' WD40 or 3-in-1 bicycle oil
for lubricating computer fans. It's just that I needed something, and
those were what I had immediately at hand. The sky did not fall, and
continues not to do so.
--
Ian

==============================================================================
TOPIC: Oxidisation of Seagate & WDC PCBs
http://groups.google.com/group/sci.electronics.repair/t/2242c6be34042a28?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, May 1 2010 1:15 am
From: Sergey Kubushyn

In sci.electronics.repair Jeff Liebermann <jeffl@cruzio.com> wrote:
> On 30 Apr 2010 23:57:32 GMT, Arno <me@privacy.net> wrote:
>
>>In comp.sys.ibm.pc.hardware.storage Sergey Kubushyn <ksi@koi8.net> wrote:
>>> In sci.electronics.repair Sergey Kubushyn <ksi@koi8.net> wrote:
>>
>>> Just took a brand spanking new WD5000AAKS drive out of sealed bag with
>>> silica gel and all that stuff. The PCB is all _SILVER_ plated, no gold. And
>>> that silver is almost totally black right out of the bag.
>>
>>Not good. Silver really is unsuitable for modern, low voltage,
>>electronics. The last WD disk I bought (a WD5000AADS, 500GB
>>Caviar Green) had mixed gold and silver plating and the
>>silver plating was completely fine, on both sides of the
>>PCB.
>
> I just removed the PCB from a WD200EB-75CSF0 20GB drive. Tin plating
> on both the PCB contacts and the mating pin array going into the HDA
> assembly. No gold or silver.
>
> However, there's one extra item that hasn't entered the discussion.
> There was a sheet of foam something between the PCB and the HDA. In
> this case, it was quite clean and dry, but it wouldn't take much for
> most any liquid to get absorbed by the foam and rot out the board.
> There was a cut-out hole around the connector area, so there was no
> common points of contact, but it was close enough that any volatiles
> would certainly enter the connector area.

20Gb sounds like an old drive. Those were made before this "invention."

My brand spanking new drive was purchased from Amazon 4 days ago and the
manufacturing date is something like a month back. I bought it for a router
I'm building for my recently acquired /28 CIDR IP block on Intel D510MO
Athom board and Intel dual gigabit ethernet adapter (BTW, I highly recommend
that motherboard--it is a small miracle in a huge heap of manure selling
these days.) That means it is _ABSOLUTELY_ the "latest and greatest," not
something dug out of old junk heap. And it is retail.

That means it definitely comes like this right from the manufacturer. I have
serious doubts that it got that tarnished by a mere negligence. They
supposed to have clean rooms there and those drives are packed in airtight
bags. I have a lot of silver plated parts at home in usual zip lock bags and
even without any bags and they don't get this black in years less for a mere
month...

---
******************************************************************
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
******************************************************************

==============================================================================
TOPIC: Final version ? Tests for PbF / SnPb solder
http://groups.google.com/group/sci.electronics.repair/t/4f9c32dd044c7c7f?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, May 1 2010 2:54 am
From: "N_Cook"

worked quite well , a sample tube , 45mm long,on a scanner bed, required
disturbing just before the beam passed under. General orange background
colouration due to the tin iodide and the "gold" scintillating flecks from
the lead iodide

http://diverse.4mg.com/lead_iodide.jpg

==============================================================================
TOPIC: Looks similar search engine?
http://groups.google.com/group/sci.electronics.repair/t/6de20fea92c27ebc?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, May 1 2010 2:55 am
From: "N_Cook"

Looking again there are different sizes , but not mutually pluggable and
none have slits or sprung bits and silvered brass seems a bit odd for power
connectors

http://diverse.4mg.com/silvered_pins.jpg

== 2 of 2 ==
Date: Sat, May 1 2010 2:59 am
From: Ron

On 01/05/2010 10:55, N_Cook wrote:
> Looking again there are different sizes , but not mutually pluggable and
> none have slits or sprung bits and silvered brass seems a bit odd for power
> connectors
>
> http://diverse.4mg.com/silvered_pins.jpg
>
>

They look like pins for an Edac or Harting type connector

==============================================================================
TOPIC: Part # of Magnetron for Microwave Oven Emerson MW9107WC
http://groups.google.com/group/sci.electronics.repair/t/f77addde8cb547fd?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, May 1 2010 6:05 am
From: "ian field"

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:hrfufe$fdk$1@reader1.panix.com...
> ian field <gangprobing.alien@ntlworld.com> wrote:
>>
>> "Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
>> news:hrfgmg$ef5$1@reader1.panix.com...
>>> ian field <gangprobing.alien@ntlworld.com> wrote:
>>>>
>>>> "Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
>>>> news:hrf5im$ko7$1@reader1.panix.com...
>>>>> Yimin Rong <yiminrong@yahoo.ca> wrote:
>>>>>> Greetings,
>>>>>>
>>>>>> Can someone tell me the part # of the magnetron for microwave oven
>>>>>> Emerson MW9107WC?
>>>>>>
>>>>>> I know I could probably just take it apart and see for myself, but
>>>>>> would like to determine cost effectiveness of getting a replacement
>>>>>> part and repairing myself, bringing to service technician, or just
>>>>>> getting a new one.
>>>>>
>>>>> How do you know the magnetron is bad, if you haven't even opened the
>>>>> unit
>>>>> yet?
>>>>
>>>> How do you know that you're dead?
>>>>
>>>> You just touched the 4kV terminal.
>>>
>>> just curious, have there been any microwave oven deaths recently?
>>>
>>> I used to hear about them every year or so from trade newsletters, but
>>> considering a microwave oven is throw away item these days, I'm guess
>>> less
>>> people bother to even have them fixed in the first place.
>>
>> Maybe the message is getting through to people just how lethal the HT in
>> a
>> microwave is, or as you say less people bother repairing them.
>>
>> My microwave was found put outside someones door in the flats, when I
>> tested
>> it I found the mains plug wired wrong (live case) it worked fine once the
>> plug had been re-wired and has been since quite a long time ago.
>
> I've noticed they use torx-ish screws on them these days, probably to
> discourage people from opening them, but there's nothing other than the
> standard warnings on them for any electronics you plug in. considering
> they cost $99 these days, I don't see anybody other than people who used
> to actually fix stuff trying to salvage one.

Mine has started to rust at the bottom of the oven compartment so I wave the
leakage meter at it from time to time, meanwhile I rescue any that turn up
in the bin room so there's a fighting chance to cobble something together
when the one I'm using eventually goes phut.

One was in as new condition but missing its dish, that probably works fine
and I have a secret stash of dishes and drive mushrooms.

==============================================================================
TOPIC: Conductive grease?
http://groups.google.com/group/sci.electronics.repair/t/f7650663e358dd69?hl=en
==============================================================================

== 1 of 4 ==
Date: Sat, May 1 2010 6:20 am
From: "N_Cook"

That age-old problem of conflicting requirements.
Someone's cherished domestic amp from 1983 uses slideway ribbons from the
front panel to pcb mounted slide switches. I last saw this amp 5 years ago,
loss of some function switch function.
Same problem this time. Then it was a build up of black copper sulphide/
silver sulhphide? forming a black insulated layer , eventually too tough for
the sliding phosphor bronze contacts to break through. The structure of the
switch with 1mm gaps between the static contacts means it needs lubricant to
overcome the sliding contacts slipping in and out of these gaps or I imagine
they are likely to buckle and jam. Sliding contacts seem fine, they retract
fully on removing from the static pins, no distortion. No trace of
corrossion this time, good to see that worked, but the lubricant I used
probably did the same as the original sulphide and blocked contact ,
thickening over time perhaps. Previously I cleaned out all the corrossion
and ex-lubricant goo and then used a mixture of silicone paste and graphite,
only signal levels, so not too concerned about stray graphite conductive
paths, >100Kohm or so. Anyone else any ideas?
I was thinking this time to totally clean out , rotate contacts 180 degrees
and use a liberal amount of graphite only in the recesses as a dry
lubricant. Then when switch is resoldered into place surrounding the whole
switch with a membrane to keep the graphite inside. Or much the same as
before (5 years is not too bad any way) but less silicone grease in the mix
proportion. Too little grease and it will not stick to the contacts. A
different sort of grease perhaps with the graphite .
The conflicts are
Keep corrossion at bay
lubricate sliding contacts
retain electrical conductivity in static posistions
sliding contact pressures cannot be increased or they would score into the
silver plating or jam and then buckle
long term material stability

== 2 of 4 ==
Date: Sat, May 1 2010 6:31 am
From: "William Sommerwerck"

Complex problem, which I don't fully understand. But I'll respond anyway...

Why isn't a reducing agent -- such as TarnX -- sufficient to remove the
sulphides? And once removed, wouldn't the sliders return to their original
state, with or without a bit of lubricant?

You needn't reply. I'm just asking questions to provoke thought.

== 3 of 4 ==
Date: Sat, May 1 2010 9:39 am
From: "N_Cook"

William Sommerwerck <grizzledgeezer@comcast.net> wrote in message
news:hrhaf7$5f7$1@news.eternal-september.org...
> Complex problem, which I don't fully understand. But I'll respond
anyway...
>
> Why isn't a reducing agent -- such as TarnX -- sufficient to remove the
> sulphides? And once removed, wouldn't the sliders return to their original
> state, with or without a bit of lubricant?
>
> You needn't reply. I'm just asking questions to provoke thought.
>
>

Normally the gaps between the dual-in-line pins 2x13 here would only have
0.2mm or so spacing to maintain electrical isolation and unobstruced slide
action but these ones have large gaps and consequently have more requirement
of lubrication I would have thought.
The stop/go resistance to movement is much more than normal "wave-band
change" multiway multipole slide switches

== 4 of 4 ==
Date: Sat, May 1 2010 10:09 am
From: "N_Cook"

I just thought of another factor in the conflict. You could do away with
lubricant if you filed in the gaps but then there would be no cleaning of
the sliding contacts on each slide movement.

==============================================================================
TOPIC: PSU eval. # n3252w View Sonic, Model vs11335-1m
http://groups.google.com/group/sci.electronics.repair/t/309ceaf8a98ba4e8?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, May 1 2010 10:25 am
From: "ctops.legal"

This PSU looks new, being there is no service manual to d/l that I can
access (other than the scam sites), the power light comes on after
hard reset then blinks green, bad PSU right ?, well looking at the
main board (2006) the general continuity testing turns out ok, the
specs are as follows:
PSU outputs: 12 pin output to main board, and 10 pin output to video.
PSU has no part# that corresponds to any posts here or in Google
groups, I can clearly see the scratch marks where the PSU has been
replaced and/or looked at by the face plate, I don't want to purchase
an replacement PSU to find out it's some other problem that's not
feasible within the client's budget to find I can't return the PSU for
a refund.
Any suggestions would be appreciated, also I suspect a problem with
the inverter based on the "power on response" which is very similar to
a PSU failure.
Description, press power LCD try to start then goes off and the green
power light blinks green.
Please email me directly I will compliment my findings to this forum.

Curt

PSU--> http://img100.imageshack.us/i/dscn0178q.jpg/

== 2 of 2 ==
Date: Sat, May 1 2010 1:59 pm
From: Grant

On Sat, 1 May 2010 10:25:34 -0700 (PDT), "ctops.legal" <ctops.legal@gmail.com> wrote:

>This PSU looks new, being there is no service manual to d/l that I can
>access (other than the scam sites), the power light comes on after
>hard reset then blinks green, bad PSU right ?, well looking at the
>main board (2006) the general continuity testing turns out ok, the
>specs are as follows:
>PSU outputs: 12 pin output to main board, and 10 pin output to video.
>PSU has no part# that corresponds to any posts here or in Google
>groups, I can clearly see the scratch marks where the PSU has been
>replaced and/or looked at by the face plate, I don't want to purchase
>an replacement PSU to find out it's some other problem that's not
>feasible within the client's budget to find I can't return the PSU for
>a refund.
>Any suggestions would be appreciated, also I suspect a problem with
>the inverter based on the "power on response" which is very similar to
>a PSU failure.
>Description, press power LCD try to start then goes off and the green
>power light blinks green.

I recently rescued a faulty LCD with similar problem, would turn off
after very short time. Symptoms like bad caps in power supply, except
this monitor ran off an external 12V power brick and nothing looked
busted around the power board.

After much searching I found info on a Russian site which suggested
changing the capacitor across backlight inverter xformer primary as
it had lost capacitance. So I replaced both caps (dual inverter
board for four CCFL tubes) and the thing worked!

Replaced 2 x dark red 220nF 250V with 220nF 630VDC or 275VAC polycarbonate
mains rated cap. Had to mount the caps off-board as they were much larger
than the originals, but there was plenty of horizontal space around the
inverter board.

What started out looking like a power supply problem was in fact over
on the backlight inverter board.

Worth a try?

Grant.
--
http://bugs.id.au/

==============================================================================
TOPIC: LCD Desktop Monitor Fading to White, then Black
http://groups.google.com/group/sci.electronics.repair/t/2c04885c7b46754a?hl=en
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== 1 of 3 ==
Date: Sun, May 2 2010 12:05 am
From: saber850

Hi,

My LCD desktop monitor has been exhibiting a problem for over 1 year.
It is out of warranty and I would like to fix it.

The problem is that the monitor displays the picture, and then
gradually fades to white, and then gradually fades to black.

The monitor does not exhibit the problem all the time. It comes and
goes. I do not have a procedure which triggers the problem; it seems
to be random. Sometimes it will behave this way for only a few
minutes, while other times it will behave like this for weeks.

I do not do anything to trigger the problem, other than have the
monitor powered on.

I have two of these monitors. I bought both monitors at the same time.
Both monitors are connected to the same video card (nVidia) via a DVI
connection. Only one of the monitors exhibits the problem--the other
continues to function properly. When the monitor exhibits the
problem, I can swap the DVI cables and the other monitor continues to
function properly. So I do not believe the problem is my video card or
computer.

I do not know of a method to get the monitor out of this problem
state. I've tried cycling the power to the monitor, and I've tried
rebooting the computer. Neither method fixes the problem. The only
thing I can do is wait for it to fix itself. But eventually, it
malfunctions again.

A video of the problem occurring is available here:
http://www.youtube.com/watch?v=W7YpFZVRjcE

Best regards,
Nick

== 2 of 3 ==
Date: Sun, May 2 2010 12:21 am
From: "N_Cook"

saber850 <saber850@yahoo.com> wrote in message
news:2468c376-1884-4039-af3a-55c41cedb3c6@k29g2000yqh.googlegroups.com...
> Hi,
>
> My LCD desktop monitor has been exhibiting a problem for over 1 year.
> It is out of warranty and I would like to fix it.
>
> The problem is that the monitor displays the picture, and then
> gradually fades to white, and then gradually fades to black.
>
> The monitor does not exhibit the problem all the time. It comes and
> goes. I do not have a procedure which triggers the problem; it seems
> to be random. Sometimes it will behave this way for only a few
> minutes, while other times it will behave like this for weeks.
>
> I do not do anything to trigger the problem, other than have the
> monitor powered on.
>
> I have two of these monitors. I bought both monitors at the same time.
> Both monitors are connected to the same video card (nVidia) via a DVI
> connection. Only one of the monitors exhibits the problem--the other
> continues to function properly. When the monitor exhibits the
> problem, I can swap the DVI cables and the other monitor continues to
> function properly. So I do not believe the problem is my video card or
> computer.
>
> I do not know of a method to get the monitor out of this problem
> state. I've tried cycling the power to the monitor, and I've tried
> rebooting the computer. Neither method fixes the problem. The only
> thing I can do is wait for it to fix itself. But eventually, it
> malfunctions again.
>
> A video of the problem occurring is available here:
> http://www.youtube.com/watch?v=W7YpFZVRjcE
>
>
> Best regards,
> Nick

Can you observe discrete jumps in the fade, ie stepped.
Is it a backlight problem? if so perhaps find the brightness control line to
the inverter and break there and add your own subcircuit perhaps. First
monitor that line as maybe a fault inside the inverter chip

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://diverse.4mg.com/index.htm

== 3 of 3 ==
Date: Sun, May 2 2010 12:25 am
From: saber850

On May 2, 3:21 am, "N_Cook" <dive...@tcp.co.uk> wrote:
> saber850 <saber...@yahoo.com> wrote in message
>
> news:2468c376-1884-4039-af3a-55c41cedb3c6@k29g2000yqh.googlegroups.com...
>
>
>
> > Hi,
>
> > My LCD desktop monitor has been exhibiting a problem for over 1 year.
> > It is out of warranty and I would like to fix it.
>
> > The problem is that the monitor displays the picture, and then
> > gradually fades to white, and then gradually fades to black.
>
> > The monitor does not exhibit the problem all the time. It comes and
> > goes. I do not have a procedure which triggers the problem; it seems
> > to be random. Sometimes it will behave this way for only a few
> > minutes, while other times it will behave like this for weeks.
>
> > I do not do anything to trigger the problem, other than have the
> > monitor powered on.
>
> > I have two of these monitors. I bought both monitors at the same time.
> > Both monitors are connected to the same video card (nVidia) via a DVI
> > connection. Only one of the monitors exhibits the problem--the other
> > continues to function properly. When the monitor exhibits the
> > problem, I can swap the DVI cables and the other monitor continues to
> > function properly. So I do not believe the problem is my video card or
> > computer.
>
> > I do not know of a method to get the monitor out of this problem
> > state. I've tried cycling the power to the monitor, and I've tried
> > rebooting the computer. Neither method fixes the problem. The only
> > thing I can do is wait for it to fix itself. But eventually, it
> > malfunctions again.
>
> > A video of the problem occurring is available here:
> >http://www.youtube.com/watch?v=W7YpFZVRjcE
>
> > Best regards,
> > Nick
>
> Can you observe discrete jumps in the fade, ie stepped.
> Is it a backlight problem? if so perhaps find the brightness control line to
> the inverter and break there and add your own subcircuit perhaps. First
> monitor that line as maybe a fault inside the inverter chip
>
> --
> Diverse Devices, Southampton, England
> electronic hints and repair briefs , schematics/manuals list onhttp://diverse.4mg.com/index.htm

Thanks for the quick response. I do not observe discrete jumps in the
fading--it seems very smooth to me.

I do not know if it is a backlight problem; how can I tell?

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