sci.electronics.repair@googlegroups.com

Today's topics:

* Toroidal mains Tx inrush limiter - retrofit - 11 messages, 5 authors
http://groups.google.com/group/sci.electronics.repair/t/da7ba841cd54d76f?hl=en
* Samsung HCN4727 Parts - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/f0cdd12cdd0f43fb?hl=en
* motherboard RAM failures - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/3e25b3ae78058770?hl=en
* ROHDE&SCHWARZ - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/fdb64593c469f06f?hl=en
* Magnavox ZV450MW8A Remote Control Fix? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/c88c8c3007ad7b2b?hl=en
* Backwards electrolytics (again) - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/1ce61685a5164a31?hl=en
* CRT vertical deflection -- bad solder joints? - 6 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/f637b1e686d3f98e?hl=en

==============================================================================
TOPIC: Toroidal mains Tx inrush limiter - retrofit
http://groups.google.com/group/sci.electronics.repair/t/da7ba841cd54d76f?hl=en
==============================================================================

== 1 of 11 ==
Date: Wed, Mar 30 2011 11:12 am
From: Meat Plow

On Wed, 30 Mar 2011 18:52:48 +0100, Mike Tomlinson wrote:

> In article <pan.2011.03.30.16.03.48@lmao.lol.lol>, Meat Plow
> <mhywattt@yahoo.com> writes
>
>>Thought the T mean the size.
>
> T for Time delay :o)

I just thought of something. Ambient temperature does affect current
carrying capability. Maybe this has some influence on Cook's problem?
High ambient temperature over a period of time weakens the fuse material
and after current influx causes the fuse core to 'twitch' many times it
finally breaks. Not unlike a light bulb.

--
Live Fast Die Young, Leave A Pretty Corpse

== 2 of 11 ==
Date: Wed, Mar 30 2011 12:40 pm
From: "Gareth Magennis"

By the way,

What's the antithesis of Occam's razor?

== 3 of 11 ==
Date: Wed, Mar 30 2011 12:53 pm
From: "William Sommerwerck"

Religious superstition?

== 4 of 11 ==
Date: Wed, Mar 30 2011 3:34 pm
From: Stroonz

On Mar 30, 8:22 am, "Phil Allison" <phi...@tpg.com.au> wrote:
> "Nutcase Fucking Kook"

>
>  **You ridiculous, fucking nut case  !!!
>
> ** Fucking stupid.
>

>  **You    ABSOLUTE   DONKEY'S   ASS !!!

>
>    ** Wot a  COLOSSAL  MORON  !!!
>

>  **You fucking stupid ASS !!!!!!!
>
> .....  Phil

I'm sure I'm one of the very few who haven't plonked you yet and can
actually view any of your posts (and realize that by quoting you I am
actually giving you some exposure), but I have to say that you are one
smooth talker Phil. You must be quite the hit with the ladies.

Edwin

== 5 of 11 ==
Date: Wed, Mar 30 2011 5:05 pm
From: "Phil Allison"

"Stroonz"

** Bugger off - IMBECILE

== 6 of 11 ==
Date: Wed, Mar 30 2011 5:13 pm
From: "Phil Allison"

"Mike Tomlinson"

>
> We have a similar problem at work with cryogenic coolers, which are more
> or less like a fridge - a compressor and heat exchanger. Like you say,
> the fuse doesn't blow, just parts cleanly due to inrush surge at switch
> on.

** What absolute crap !!!

The magnetic inush suge of a toroidal tranny plus filter caps charging will
easily SPLAT an undesized "slo blo" or " fast " fuse completely.

> Don't see why not. Or a 1 ohm wirewound resistor which will dissipate
> 3.15W at peak, so use a 5W one

** ROTFL - what difference is 1 ohm gonna make ??

>> will mount on small high temp board and wire into the neutral

>
>>Are polyswitches used in these circumstances , ie not purely "fuse"
>>action or generic name for devices specific for this purpose?
>
> I would say they are unsafe for use on mains, simply because they
> reconnect the current when they heal. If there is an actual fault in
> the equipment rather than the inrush current blowing the fuse and
> disabling the supply permanently, it could lead to a fire.

** Polyswitches all start of with a very low resistane then go high after
some time at high current - mains voltage rated examples do not exist.

... Phil

== 7 of 11 ==
Date: Wed, Mar 30 2011 5:16 pm
From: "Phil Allison"

"Nutcase fucking Kook "
>
> An engineer I know with IBM Hursley has the same problem with large toroid
> Tx on some research kit, he personally was not aware of the phenomenon of
> random remnant magnetisation at switch off, then right/wrong polarity
> mutually coupled across "adds" to the inrush current , until he asked me
> if

** Shame you have totally mis-informed him.

> I knew.

** You know absolutely NOTHING !!

.... Phil

== 8 of 11 ==
Date: Wed, Mar 30 2011 5:18 pm
From: "Phil Allison"

"Mike Tomlinson"

> T for Time delay :o)

** The "T" stamp on fuses stands for the German word " Trage" = lazy.

..... Phil

== 9 of 11 ==
Date: Wed, Mar 30 2011 6:33 pm
From: "Phil Allison"

"Gareth Magennis"

>
> What's the antithesis of Occam's razor?

** Conspiracy theories - cos they always involve many unnecessary,
unsupported and improbable assumptions.

.... Phil

== 10 of 11 ==
Date: Wed, Mar 30 2011 6:46 pm
From: "William Sommerwerck"

> Polyswitches all start of with a very low resistance,
> then go high after some time at high current --
> mains-voltage rated examples do not exist.

Then what causes my bulk eraser to shut off when it overheats -- then come
back when it cools off?

== 11 of 11 ==
Date: Wed, Mar 30 2011 6:51 pm
From: Stroonz

Hehe... I think you and I are the only two folk who can see your
posts Phil. Don't worry, I won't plonk you. There is precious little
else on the web that's as interesting as you. Make sure you come up
with a real zinger for me!!!!

Edwin

==============================================================================
TOPIC: Samsung HCN4727 Parts
http://groups.google.com/group/sci.electronics.repair/t/f0cdd12cdd0f43fb?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Mar 30 2011 11:25 am
From: "Chris F."

I figured as much.... to the trash it goes.

"Chris F." <zappyman@hotmail.com> wrote in message
news:4d8cb39b$0$3988$9a566e8b@news.aliant.net...
> The convergence amp failed again on this set and damaged something on the
> mainboard, so I'm junking this set rather than gamble any more money on
> it. I have the full chassis here, including 3 good CRTs (blue one needs
> the coolant changed). I also bought a new convergence processor board for
> it, I'm asking $50 for that. The rest of it is open to offers.
> If anyone wants parts from this let me know soon, otherwise it is going
> on the trash (except for the convergence processor, I will list that on
> eBay).
>

==============================================================================
TOPIC: motherboard RAM failures
http://groups.google.com/group/sci.electronics.repair/t/3e25b3ae78058770?hl=en
==============================================================================

== 1 of 3 ==
Date: Wed, Mar 30 2011 11:33 am
From: Jeff Liebermann

On Wed, 30 Mar 2011 16:24:32 +0000 (UTC), Meat Plow
<mhywattt@yahoo.com> wrote:

>Jeff here is my current machine:
>
>Corsair XMS3 4GB PC12800 DDR3 Dual Channel 1600Mhz
>AMD Phenom II X4 955 Black Edition AM3
>ASUS M4A78T-E AMD 790GX Socket AM3
>ULTRA LS600 600W ATX POWER SUPPLY

OK. I'm jealous. I know overclocking can be made to work, especially
if the manufacturers of the board and RAM underspecify their maximum
speeds. So far, there's no evidence that the MSI motherboard was
overclocked, so I'm speculating as to the culprit.

>Built in July 2010. Ran for a month at standard CPU clock.
>Upped 3.2 to 4 ghz in August 2010
>
>Dual boot Mandriva 2010 Power Pack server kernel
># uname -r
>2.6.31.13-server-1mnb

Have you run Prime95 (Win) or MBench (Linux) benchmark to see if you
can kill it? I use that as my QA test for overkill machines.
<http://en.wikipedia.org/wiki/Prime95>
<http://www.mersenne.org/freesoft/>
I've seen stock non-overclocked hang or overheat running this.

>Windows 7 Ultimate.
>
>Zero problems/anomalies. Rarely use the Windows 7 anymore but had
>same stability in Manddriva 2010 and Win 7.
>
>Asus M4A78T-E is the overclocker's choice because of all the
>timing and core syncing features.
>
>http://www.pcstats.com/articleview.cfm?articleID=2379

Nice. One of these days, in my non-existent spare time, I'll build
myself a high end machine. Thanks for the pointers.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 2 of 3 ==
Date: Wed, Mar 30 2011 11:56 am
From: Meat Plow

On Wed, 30 Mar 2011 11:33:49 -0700, Jeff Liebermann wrote:

> On Wed, 30 Mar 2011 16:24:32 +0000 (UTC), Meat Plow <mhywattt@yahoo.com>
> wrote:
>
>>Jeff here is my current machine:
>>
>>Corsair XMS3 4GB PC12800 DDR3 Dual Channel 1600Mhz AMD Phenom II X4 955
>>Black Edition AM3 ASUS M4A78T-E AMD 790GX Socket AM3
>>ULTRA LS600 600W ATX POWER SUPPLY
>
> OK. I'm jealous. I know overclocking can be made to work, especially
> if the manufacturers of the board and RAM underspecify their maximum
> speeds. So far, there's no evidence that the MSI motherboard was
> overclocked, so I'm speculating as to the culprit.
>
>>Built in July 2010. Ran for a month at standard CPU clock. Upped 3.2 to
>>4 ghz in August 2010
>>
>>Dual boot Mandriva 2010 Power Pack server kernel # uname -r
>>2.6.31.13-server-1mnb
>
> Have you run Prime95 (Win) or MBench (Linux) benchmark to see if you can
> kill it? I use that as my QA test for overkill machines.
> <http://en.wikipedia.org/wiki/Prime95>
> <http://www.mersenne.org/freesoft/>
> I've seen stock non-overclocked hang or overheat running this.

I've run several raw digital videos back to back encoding them to DVD
but even at 10x encode rate I can't get the CPU load up to more than 50%.
Not even enough load to speed the CPU fan up past 1800 which is still an
idle speed.

Don't really need to burn anything in or force a failure artificially. I
might do that if there was a problem.

>>Windows 7 Ultimate.
>>
>>Zero problems/anomalies. Rarely use the Windows 7 anymore but had same
>>stability in Manddriva 2010 and Win 7.
>>
>>Asus M4A78T-E is the overclocker's choice because of all the timing and
>>core syncing features.
>>
>>http://www.pcstats.com/articleview.cfm?articleID=2379
>
> Nice. One of these days, in my non-existent spare time, I'll build
> myself a high end machine. Thanks for the pointers.

$500 got all three items. Probably lots cheaper now Already had an Antec
server case. Has a 120mm fan in back and a vent tube the size of the CPU
fan with access to the
side case so the CPU draws its own fresh air in. The tube covers the top
of CPU fan. I thought it was a great idea.

It's a quiet machine also. Rubber mounted hard drives x3. The case has
sound dampening on the sides and a locking cover for the drive bay. I
can't handle a loud PC.

--
Live Fast Die Young, Leave A Pretty Corpse

== 3 of 3 ==
Date: Wed, Mar 30 2011 4:57 pm
From: Jeff Liebermann

On Wed, 30 Mar 2011 18:56:09 +0000 (UTC), Meat Plow
<mhywattt@yahoo.com> wrote:

>I've run several raw digital videos back to back encoding them to DVD
>but even at 10x encode rate I can't get the CPU load up to more than 50%.
>Not even enough load to speed the CPU fan up past 1800 which is still an
>idle speed.

Nice, but depending upon how you're running that test, the CPU could
be waiting for HD I/O, which might explain why it's at 50% idle. Try
a CPU and/or RAM only benchmark to see how your overclocking is doing.

>Don't really need to burn anything in or force a failure artificially. I
>might do that if there was a problem.

Awwww.... you're no fun.

>> Nice. One of these days, in my non-existent spare time, I'll build
>> myself a high end machine. Thanks for the pointers.

>$500 got all three items. Probably lots cheaper now Already had an Antec
>server case. Has a 120mm fan in back and a vent tube the size of the CPU
>fan with access to the
>side case so the CPU draws its own fresh air in. The tube covers the top
>of CPU fan. I thought it was a great idea.

I've seen a few boxes with fans like that. They work quite well for
cooling the CPU, but seems to require a 2nd fan to cool the rest of
the system. I've seen video cards that suck almost as much power as
the CPU. $500 for all that is cheap, even with todays prices.

>It's a quiet machine also. Rubber mounted hard drives x3. The case has
>sound dampening on the sides and a locking cover for the drive bay. I
>can't handle a loud PC.

I have the same problem. I *HATE* noisy machines. About 2 years ago,
I went on a noise reduction purge and replaced my office and home
computers with Dell Optiplex 960 and 755 mini-tower machines
respectively. Both use a single 120mm fan for cooling. No other fans
in the box. The fan normally rotates quite slowly, which makes it
very quiet. When I run Bench95 to heat up the CPU, the fan gets quite
noisy. At full speed, it could probably lift the PC off the table.

No shock mounting on the hard disk drives. If there was enough noise
and/or vibration to warrant a shock mount, I would also suspect that
the drive was off balance or ready to blow. Some boxes allow the side
to act as a sounding board for the drive noises, which I guess
justifies sound dampening. I've done as well with stiffeners,
battens, and fiberglass matting on the sides.

Incidentally, I once had a PC (PIII/866) that had no fans. It used
heat pipes, liquid coolant, and a small aquarium pump to move the heat
to outside of the box. Worked nice until I found anti-freeze all over
the carpet.

More recently, I spent some time playing with two "no-fan" ATX power
supplies. This was one
<http://www.fspgroupusa.com/zen-400/p/412.html>
but I don't recall the other model. It had a big copper heat sink
sticking out the back of the machine. I burned myself several times
during testing. Both worked, but with limitations. The Zen-400 would
accumulate heat inside the case, between the top of the case and the
power supply. No air flow in that area would make the top rather hot.
The other would probably scorch anything that came in contact with the
copper heat sink. Meltdown and fire is a small price to pay for a
quiet PC.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

==============================================================================
TOPIC: ROHDE&SCHWARZ
http://groups.google.com/group/sci.electronics.repair/t/fdb64593c469f06f?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Mar 30 2011 11:45 am
From: "Vale"

Does anyone knows where/how find schematics or repair manual for a vintage
receiver ROHDE&SCHWARZ mod EK56/2 ?
I would like overhauling that receiver I love so much!
thanks

==============================================================================
TOPIC: Magnavox ZV450MW8A Remote Control Fix?
http://groups.google.com/group/sci.electronics.repair/t/c88c8c3007ad7b2b?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Mar 30 2011 5:07 pm
From: "Michael A. Terrell"

PeterD wrote:
>
> On 3/29/2011 8:25 AM, Michael A. Terrell wrote:
> >
> > PeterD wrote:
> >>
> >> On 3/28/2011 1:56 PM, Michael A. Terrell wrote:
> >>>
> >>> Guv Bob wrote:
> >>>>
> >>>> I have had this DVD/VCR combo unit for over 3 years now, and would like to find out if anyone has found a 3rd party remote control that can be used with it, or if the factory has a remote with upgraded software.
> >>>>
> >>>> The device is top quality and the manual is excellent, but the remote is so complicated and non-intuitive that if you don't use it every day, you have to go back to the manual, even after this long time.
> >>>>
> >>>> The manual does leave out some basic steps -- like how to set the record speed (which they call "mode"). I'm fairly good with electronics (servicing industrial electronics is my business) and took me a good year before I could make basic settings without looking it up.
> >>>>
> >>>> Most of the features can't be done from the device and must be done via the remote control which is cryptic. It has way too many buttons, even for a combo unity, and has tiny labels that can't be read in a darkened room. If you hit a wrong button, sometimes it is impossible to figure out how to return the device to normal use without digging out the manual again. My manual is well worn and has many notes scribbled in it now.
> >>>>
> >>>> One problem is that when you are using the timer, you have to turn the device off and on with a button other than the ON/OFF button. If your lovely wife comes in and used ON/OFF, it disables the timer, and must be reset again with the special non-ON/OFF button.
> >>>>
> >>>> It is a real shame that such a fine device from a good manufacturer has such a poor user interface. A better designed remote would completely change the usability.
> >>>
> >>>
> >>> Wrong newsgroup. This is a test equipment newsgroup. You want
> >>> news:sci.electronics.repair.
> >>>
> >>>
> >>
> >> Michael... Careful you posted your reply to the wrong groups too!<g>
> >
> >
> > No. I added the proper group.
> >
> >
>
> I had to read that twice before I realized what you meant... <g> So you
> added SER to help the OP out. Sure left me confused!

Get used to it. It will happen more and more as you age. :(

--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

==============================================================================
TOPIC: Backwards electrolytics (again)
http://groups.google.com/group/sci.electronics.repair/t/1ce61685a5164a31?hl=en
==============================================================================

== 1 of 2 ==
Date: Wed, Mar 30 2011 5:09 pm
From: Jeff Liebermann

It's another day in capacitor hell. About 2 months ago, I replaced
the bulging caps in a Dell Optiplex GX-520, but inserted them
backwards.
<http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>
Today, I have an irate customer with a Dell XPS-200 that I sold him.
Same problem, again:
<http://802.11junk.com/jeffl/crud/xps200-bad-caps.jpg>
I had replaced 11 caps on this board, all of them backwards. It's
difficult to see on the photo, but the white silkscreened arrow is "+"
instead of the usual "-" . Now, I get to check all the other Dell
machines, where I probably inserted the caps backwards.
<http://802.11junk.com/jeffl/crud/For-Sale-PC.jpg>
Maybe I should find something else to do for a while? Grumble...

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

== 2 of 2 ==
Date: Wed, Mar 30 2011 5:56 pm
From: "Shaun"

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:utg7p6dkggh8mvhr8mub58svj828s83vk5@4ax.com...
> It's another day in capacitor hell. About 2 months ago, I replaced
> the bulging caps in a Dell Optiplex GX-520, but inserted them
> backwards.
> <http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>
> Today, I have an irate customer with a Dell XPS-200 that I sold him.
> Same problem, again:
> <http://802.11junk.com/jeffl/crud/xps200-bad-caps.jpg>
> I had replaced 11 caps on this board, all of them backwards. It's
> difficult to see on the photo, but the white silkscreened arrow is "+"
> instead of the usual "-" . Now, I get to check all the other Dell
> machines, where I probably inserted the caps backwards.
> <http://802.11junk.com/jeffl/crud/For-Sale-PC.jpg>
> Maybe I should find something else to do for a while? Grumble...
>
>
>
> --
> # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
> # 831-336-2558
> # http://802.11junk.com jeffl@cruzio.com
> # http://www.LearnByDestroying.com AE6KS
>

You IDIOT!!!

==============================================================================
TOPIC: CRT vertical deflection -- bad solder joints?
http://groups.google.com/group/sci.electronics.repair/t/f637b1e686d3f98e?hl=en
==============================================================================

== 1 of 6 ==
Date: Wed, Mar 30 2011 5:28 pm
From: "Arfa Daily"

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:imu10l$dit$1@dont-email.me...
>>> This is a common problem in servicing. As an EE, I want to know
>>> exactly why something isn't working correctly. But I learned a long
>>> time ago that it's more important to simply get the damned thing
>>> fixed. If that means shotgunning likely components, so be it.
>
>> Shotgunning is, IMHO, very bad practice, and often leads to the
>> creation of more problems than it fixes. I am actually quite surprised
>> that you would advocate doing this, William.
>
> I don't understand how shotgunning can /create/ problems, as long as the
> replaced components are correct replacements. Unless you mean the customer
> might get upset.
>
> As an experienced service technician, you know that the cause of a given
> problem is not always obvious, even after extensive troubleshooting. The
> customer is paying for your time, often more than what the parts cost. Why
> burn up the customer's money when replacing a half-dozen parts is likely
> to
> fix the thing?
>
>

Every component that is replaced, increases the potential margin for error
by the person replacing it. I have had many items cross my bench over the
years, which have been 'elsewhere' first, and have seen wrong values fitted,
caps in backwards, diodes in backwards, damaged print and so on, amongst the
many components that have have obviously been shotgunned, as evidenced by
the flux all over their joints. I have also seen unsuitable substitutes
fitted, where technicians have had insufficient understanding of the
requirements of a circuit's design, and have just put in 'what came to hand'
in order to complete their shotgun.

Very occasionally, it is necessary to replace a block of components, when a
fault is particularly obscure, but I would never recommend it as an
acceptable procedure to anyone who wasn't hugely experienced in the field of
service work, and particularly in the case of a simple problem such as the
OP has with his TV's field scanning, and which would be easily diagnosed
with the use of appropriate test equipment.

Arfa

== 2 of 6 ==
Date: Wed, Mar 30 2011 5:37 pm
From: "Arfa Daily"

"Mark Zacharias" <mark_zacharias@sbcglobal.net> wrote in message
news:4d932454$0$31449$c3e8da3$c14f6927@news.astraweb.com...
> "Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
> news:Pyvkp.993$KZ7.136@newsfe08.ams2...
>>
>>
>> "William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
>> news:imsmrd$5nf$1@dont-email.me...
>>> Hello? Instead of fussing over it, why not replace all the electrolytics
>>> "in
>>> the vicinity" while the bad-looking solder joints are being re-done?
>>>
>>> This is a common problem in servicing. As an EE, I want to know exactly
>>> why
>>> something isn't working correctly. But I learned a long time ago that
>>> it's
>>> more important to simply get the damned thing fixed. If that means
>>> shotgunning likely components, so be it.
>>>
>>>
>>
>> Shotgunning is, IMHO, very bad practice, and often leads to the creation
>> of more problems than it fixes. I am actually quite surprised that you
>> would advocate doing this, William.
>>
>> Arfa
>
>
> I have seen sets (notably Toshiba and Mitsubishi) where shotgunning was
> advisable in addition to replacing whichever single cap might have been
> causing your issue.
>
> Mark Z.

Occasionally, this is true, but only - for me at least - if the manufacturer
has recommended a block of components to be replaced, on the grounds that
some or all of the additional ones, may have been unacceptably stressed or
damaged, by the primary failure. In these cases, the manufacturer or his
spares agent usually supplies 'service kits' of all the necessary
components. Often the case with switch mode power supplies.

As in, for instance

http://www.ohmsupplies.co.uk/

Arfa

== 3 of 6 ==
Date: Wed, Mar 30 2011 5:46 pm
From: "Arfa Daily"

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:imvm1k$cqb$1@dont-email.me...
>>> But I learned a long time ago that it's more important to simply
>>> get the damned thing fixed. If that means shotgunning likely
>>> components, so be it.
>
>> Would you be happy for a car mechanic to shotgun a fault on
>> your car, with you paying for his time and all the parts he is
>> unnecessarily fitting?
>
> Yes, if an initial /conscientious/ troubleshoot didn't reveal the problem.
> I'd rather pay for parts than time.
>
> Of course, you can't draw an exact parallel between cars and electronic
> equipment. It's easier to "see" what is wrong with mechanical devices, but
> car parts tend to be more-expensive than electronic parts.
>
>

I'm not at all sure you would say that if one of the incorrectly fitted
parts was the EMU, for example. This, and many of the expensive sensors on
engines nowadays, are usually 'bonded' parts, and once the box has been
opened, the supplier will not accept it back, which leaves you paying for
it, when it was not required. A while ago, I had just this problem with my
local garage, who replaced a cartload of parts and sensors on my engine, for
an idle problem that ultimately turned out to be due to a split in the PCV
hose. I argued with them long and hard about having to pay for parts that
had been shotgunned due to the fact that the guy doing the job had not
correctly diagnosed the problem. I eventually had to settle for a reduced
labour bill to offset the unnecessary parts cost, which they were determined
were staying on the engine, and that I was going to be paying for (at retail
price, just to make it worse)

Arfa

== 4 of 6 ==
Date: Wed, Mar 30 2011 5:50 pm
From: "Arfa Daily"

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:imvpdu$p1l$1@dont-email.me...
>>> Would you be happy for a car mechanic to shotgun a fault on your
>>> car, with you paying for his time and all the parts he is unnecessarily
>>> fitting?
>
>> It's commonly done. Had a girlfriend a few years back who took her car
>> in because it was overheating. They called with the estimate (of many
>> hundreds of dollars), saying they had determined that it needed a new
>> radiator, new water pump, new thermostat, and new hoses.
>
>> I went down there and asked them how they had determined the radiator
>> fault, and they claimed to have pressure-tested it. A 15-second look
>> under the hood confirmed my suspicion that they had not.
>
>> I took the car and replaced the thermostat -- $12 and 1/2 hour -- and it
>> served her for several more years.
>
>> The shop in question is consistently voted winner of the annual
>> "Reader's Poll" in our local rag.
>
>> Oddly, I don't think they operate that way solely to cheat the customer
>> financially. I think they're more driven by not wanting any return
>> complaints. That's why the "Readers" like them -- "they fixed it right
>> the first time!!"
>
> There's also the possibility that a comprehensive makes it possible to
> offer
> a "lifetime" warranty on the repair.
>
>
>> I drove around town for the next 3 months with a giant sign in my back
>> window:
>> "Richard's Auto: As Crooked As the Day is Long."
>> I got a lot of stories from people who saw the sign, about their own bad
>> experiences there.
>
> It goes without saying that if a service shop claims that lots of things
> need fixing, it's probably not telling the truth.
>
> Thirty years ago I worked part-time -- at $6/hour -- for Chestnut Hill
> Audio
> in Philadelphia. The owner said to me "You're not as fast as the other
> people I use -- but nothing you repair comes back."
>
> I had a holy horror of callbacks. It costs the business money, and it
> makes
> the business and the service tech look bad.
>
> By the way, I never shotgunned anything I repaired there, because nothing
> seemed to need it.
>
>

Which is precisely what I'm saying. Yes, there are some items - notably
switch mode power supplies - where it is often prudent, or even recommended
by the manufacturer, to replace a whole raft of parts, but for most general
repairs, the cause of the problem should be correctly diagnosed, and the
(usually) one faulty component replaced.

Arfa

== 5 of 6 ==
Date: Wed, Mar 30 2011 5:55 pm
From: "Arfa Daily"

"whit3rd" <whit3rd@gmail.com> wrote in message
news:a40cc351-8a75-4797-a32b-b5837a7caadb@glegroupsg2000goo.googlegroups.com...
> On Monday, March 28, 2011 5:51:41 PM UTC-7, Arfa Daily wrote:
>> "whit3rd" <whi...@gmail.com> wrote in message
>> news:157d392f-817a-4788-b72b-5198c68bb1af@glegroupsg2000goo.googlegroups.com...
>> > On Monday, March 28, 2011 4:15:45 AM UTC-7, Mike Tomlinson wrote:
>> >> In article
>> >> <fa3b18fc-cf26-4f79-8899-e45f302cb1e6@l14g2000pre.googlegroup
>> >> s.com>, Sean Hamilton <sean...@gmail.com> writes
>> >>
>> >> >Is it likely that bad solder joints would cause vertical foldover in
>> >> >a
>> >> >mid-90s CRT television?
>> >>
>> >> Yes, but it's more likely to be a bad cap.
>> >
>> >> Visual inspection is not enough. You need an ESR meter.
>> >
>> > Maybe not; the ESR issues crop up mainly in high-performance
>> > low voltage power supplies
>
>> I think you are missing the point of what he was saying regarding ESR.
>> This
>> parameter is a valid test of the 'goodness' of any electrolytic
>> capacitor,
>
> A test, yes; but not a complete test. The ESR of a 10uF capacitor can be
> good, but it won't do the work of a 100 uF capacitor. A combination
> of ESR and capacitor-meter testing is better, and a test at the
> frequency of interest for ripple reduction is better still.
>
> I wouldn't bother with any of that parameter testing, though.
> If you suspect the 10-year-old capacitor, replace it. You'd possibly have
> to
> desolder to test it anyhow, spend the eighty-five cents to put in a new
> one.

I hear what you're saying, and it does, on paper at least, have some
validity. However, my comments are based purely on many many years'
experience of doing service work on electronic equipment, from all walks of
life from consumer through industrial, and on a daily basis. I replace bad
electrolytic caps all the time. Several items every week will require bad
caps finding and replacing, and in just about every single case, the ESR
meter tells the story. In fact, it is probably the most useful test
instrument to live on my bench, and has paid for itself many times over.

Whilst I accept that electrolytics *do* fall in value, I find it actually
quite rare. Almost always, if a cap has fallen in value, its ESR will also
be out of the window. In my experience though, the reverse is often not
true. Having found a bad cap with my ESR meter, I do occasionally check the
value on my digital C meter, and for the most part, find it to be well
within tolerance.

As to having to remove caps to test them, again this is rare, and quite
impractical on complex switchers which may have many electrolytics, and more
than one that is faulty. I don't know if you are personally involved in
commercial service work, but in today's economic climate, and with the low
value of much equipment, the name of the game is quick and accurate
diagnosis of a problem, and minimising additional costs of time and
materials. I have never been an advocate of 'shotgunning' faults by
replacing components which may or may not be faulty. I have had many items
pass across my bench over the years which have come from other service
outfits who have replaced components 'willy-nilly' that they suspected to be
faulty, but without ever getting to the bottom of the original problem, and
having compounded that original fault in their efforts. I have had caps
fitted backwards, diodes and transistors fitted backwards, wrong value
resistors fitted, print damage and so on. So personally, I like to have a
bit more than a suspicion that a component is faulty, before replacing it.
In the case of electrolytics, my ESR meter, for the most part, does that for
me. In saying that, however, I think that I should also say that I fully
accept that the use of an ESR meter is as much black magic as science and,
although it is a useful instrument when used by its instruction manual, for
the professional user, there is also a considerable amount of interpretation
and 'feel' involved. In 'casual' hands, an ESR meter may be little better
than a multimeter for finding bad caps ...

One place where it can fool you is where an electrolytic has gone short
circuit - fairly rare these days, but does happen. In that case, the ESR
meter will of course, give a nice low reading that will, initially at least,
fool you into thinking that the cap is (probably) good.

Arfa

== 6 of 6 ==
Date: Wed, Mar 30 2011 6:47 pm
From: "William Sommerwerck"

> Every component that is replaced, increases the potential margin for error
> by the person replacing it. I have had many items cross my bench over the
> years, which have been 'elsewhere' first, and have seen wrong values
fitted,
> caps in backwards, diodes in backwards, damaged print and so on, amongst
the
> many components that have have obviously been shotgunned, as evidenced by
> the flux all over their joints. I have also seen unsuitable substitutes
> fitted, where technicians have had insufficient understanding of the
> requirements of a circuit's design, and have just put in 'what came to
hand'
> in order to complete their shotgun.

Yes, but you and I don't make such mistakes.

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