sci.electronics.repair@googlegroups.com

Today's topics:

* Asus N7600GS (red dots and lines) - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/f811f0a341e6e63e?hl=en
* Mixing 4 audio channels to 3? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/a9c921002b2ed750?hl=en
* 3mm 1.5V bright LED - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/9857700f8db1631a?hl=en
* home-brew Freon TF substitutes? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/f66a71610e41b61d?hl=en

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TOPIC: Asus N7600GS (red dots and lines)
http://groups.google.com/group/sci.electronics.repair/t/f811f0a341e6e63e?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Oct 27 2011 8:37 pm
From: Franc Zabkar

On Wed, 26 Oct 2011 13:45:08 -0700 (PDT), Jack00 <SPal508596@aol.com>
put finger to keyboard and composed:

>I got this graphics card in my PC and the picture on the monitor
>displays red dots and lines and sometimes goes away but returns
>again. I had to disable the driver for this card as Windows XP wont
>boot in normal mode ie shows a black screen but in safe mode XP boots
>but with red spots and lines and the picture goes purple if you try to
>browse on the internet. Is there any tests I can do with a
>multimeter? Or maybe get hold of a circuit diagram?

Those symptoms are consistent with a fault in the card's RAM. By
switching to a different driver, you are accessing difference areas of
memory. Also, if you select a lower refresh rate, this may mitigate
any timing issue.

Did you check the fan and capacitors on the card?

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

== 2 of 2 ==
Date: Fri, Oct 28 2011 7:45 am
From: Jack00

On Oct 28, 4:37 am, Franc Zabkar <fzab...@iinternode.on.net> wrote:
> On Wed, 26 Oct 2011 13:45:08 -0700 (PDT), Jack00 <SPal508...@aol.com>
> put finger to keyboard and composed:
>
> >I got this graphics card in my PC and the picture on the monitor
> >displays red dots and lines and sometimes goes away but returns
> >again. I had to disable the driver for this card as Windows XP wont
> >boot in normal mode ie shows a black screen but in safe mode XP boots
> >but with red spots and lines and the picture goes purple if you try to
> >browse on the internet. Is there any tests I can do with a
> >multimeter? Or maybe get hold of a circuit diagram?
>
> Those symptoms are consistent with a fault in the card's RAM. By
> switching to a different driver, you are accessing difference areas of
> memory. Also, if you select a lower refresh rate, this may mitigate
> any timing issue.
>
> Did you check the fan and capacitors on the card?
>
> - Franc Zabkar
> --
> Please remove one 'i' from my address when replying by email.

I did check the capacitors and some were high with a capacitor meter
so I replaced them and the card worked for a few days but the symptoms
returned again. The power supply voltages going to the card seem
normal. Are there any tests I can do on the card?

==============================================================================
TOPIC: Mixing 4 audio channels to 3?
http://groups.google.com/group/sci.electronics.repair/t/a9c921002b2ed750?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Oct 28 2011 3:10 am
From: NT

On Oct 27, 5:11 pm, DaveC <inva...@invalid.net> wrote:
> > Or, as is not uncommonly done these days in portable digital players,
> > establish a floating ground for the purpose of providing and signal for the
> > (floating) load, so that the difference between the output and the floating
> > ground can become negative.
>
> Which raises the question I was pondering recently: is it OK to connect 2
> computers' sound cards' grounds together?
>
> The PS for the powered speakers is via "wall wart" (not grounded).
>
> Thanks.

I've yet to have a problem doing it.

NT

==============================================================================
TOPIC: 3mm 1.5V bright LED
http://groups.google.com/group/sci.electronics.repair/t/9857700f8db1631a?hl=en
==============================================================================

== 1 of 2 ==
Date: Fri, Oct 28 2011 3:37 am
From: Man-wai Chang

Is there such a toy?

--
@~@ You have the right to remain silence.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (Fedora 15 i686) Linux 3.0.4
^ ^ 13:36:02 up 11 days 17:42 0 users load average: 0.01 0.02 0.05
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa

== 2 of 2 ==
Date: Fri, Oct 28 2011 1:36 pm
From: "Ian Field"

"Man-wai Chang" <toylet.toylet@gmail.com> wrote in message
news:j8e0kr$ttb$1@dont-email.me...
>
> Is there such a toy?

Yes if you use a 1.5V blocking oscillator.

==============================================================================
TOPIC: home-brew Freon TF substitutes?
http://groups.google.com/group/sci.electronics.repair/t/f66a71610e41b61d?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Oct 28 2011 8:57 am
From: gregz

gregz <zekor@comcast.net> wrote:
> Jim Yanik <jyanik@abuse.gov> wrote:
>> "Arfa Daily" <arfa.daily@ntlworld.com> wrote in
>> news:zL1qq.3343$cH4.2935@newsfe24.ams2:
>>
>>>
>>>
>>> "Jim Yanik" <jyanik@abuse.gov> wrote in message
>>> news:Xns9F8A7A4D7B694jyaniklocalnetcom@216.168.3.44...
>>>> "Arfa Daily" <arfa.daily@ntlworld.com> wrote in
>>>> news:H4Jpq.2929$M61.1622@newsfe09.ams2:
>>>>
>>>>>
>>>>>
>>>>> "Jeff Layman" <JMLayman@invalid.invalid> wrote in message
>>>>> news:j83vnf$cjh$2@news.albasani.net...
>>>>>> On 24/10/2011 13:33, Nomen Nescio wrote:
>>>>>>> I last saw this in the mid 1990s. I knew a warehouse that still
>>>>>>> had some drums hidden away...
>>>>>>> Bloody best cleaner ever. Although some liked Genklene,
>>>>>>> now also banned.
>>>>>>> There are some commercial spray cleaners that claim to be
>>>>>>> almost as good. I would like something in bulk for dipping
>>>>>>> computer boards. Isopropyl alchohol is suggested by some,
>>>>>>> but has 9% water usually.
>>>>>>
>>>>>> Not sure where you are, but isopropyl alcohol is usually available
>>>>>> 99.9% pure, with a negligible water content.
>>>>>>
>>>>>> --
>>>>>>
>>>>>> Jeff
>>>>>
>>>>> I'd go along with that. The stuff specified as 'electronics grade'
>>>>> is typically at least 99.7% to get that rating
>>>>>
>>>>> Arfa
>>>>>
>>>>>
>>>>
>>>> the IPA commonly available at drug stores is usually 90-91%,I
>>>> believe,at least in the US.
>>>>
>>>> --
>>>> Jim Yanik
>>>
>>> Probably the same here, which is why you have to go to an electronic
>>> parts supplier to get the electronics grade one
>>>
>>> Arfa
>>>
>>>
>>
>> I don't know if US parts suppliers even carry IPA in any percentage.
>>
>> besides,after you open your bottle of 99% IPA,it probably absorbs enough
>> moisture from the air to drop it to 91%..... ;-)
>>
>> Hmm,IIRC,Everclear (grain alcohol from a liquor store) is 95% ethanol.
>> I believe it's the highest % of alcohol lawfully sold for drinking
>> purposes.
>
>
> Probably similar to lab grade 95% higher grades cannot be drunk. They used
> to use lab grade to spike the punch. Had some high purity isopropyl. By the
> time the alcohol dries, there is water droplets on boards. Must be dried
> with warm air.
>
> 99% turns to 100% water.
>
> Greg

Adding to the problem, the cooling effect from alcohol evaporation causes
condensation of water vapor.

Greg

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