please see embedded comments below.
Dick
-----Original Message-----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Thursday, October 28, 1999 4:23 PM
Subject: Re: HELP! ( totally OT) - Hitachi Monitor problem
>> >Well, I know I don't have the service data for this one. And it's
>> >somewhat unusual for such problems ot be related ot the pincushion
>> >circuitry -- more often it's related to the hsync stuff -- the PLL (if
it
>> >uses one) isn't locking, something like that.
>> >
>> Having attempted to locate a source of service data for this beastie for
>> over four months, during which time it sat on the floor of my already
>> overcrowded computer room, where I, mobility-handicapped as I am, had to
>> step around it, I decided to look at the adjustments. This fault came
about
>> VERY gradually, having been noticeable during the warmup phase for a
couple
>> of years, but until more recently, when the duration of this problem grew
to
>> over half an hour, I figured that it might be in some way related to the
>> aging process.
>
>THis really does sound like a failing electrolytic capacitor. I've had
>them behave oddly when cold, or behave oddly when warm or...
>
>>
>> Like most CRT's it has several hundred electrolytic cap's, and I'm loath
to
>> remove them all so they can be tested, though it may come down to that.
I
>> bought this thing in late '93 and it was manufactured in '91, so I have
to
>> assume it's aged a bit.
>
>Somtimes you can check the ESR with the capacitor in-circuit. The main
>exception is when it's shunted by an inductor or another low DC
>resistance path IIRC.
>
>I don't own an ESR meter yet, but it's certainly on my list of things to
>get/build. From what I've heard they're a great time-saver for doing
repairs.
>
>> It's surprising that one can't easily order service documents for these
>> monitors, but I guess it's my inability to understand how business is
done
>> these days.
>
>Hey _I'm_ the one that flames about not being able to get service
>information for everything I own. Last time I ranted on about this you
>pointed out a number of good reasons why such information might not be
>available.
>
It's like getting the service manual for a car of the same vintage, except
that when a car is this old, it's just starting to cause little problems and
the third-party repair manuals are available everywhere. In the electronics
business, there have never been really decent repair manuals from 3rd
parties, except maybe for TV's, of which I've never had one break.
Unfortunately, as the prices of these commodities drop, the level of
expectation to which the vendors respond drops as well. These days, you can
get a really decent 20" monitor for $400 or less. When it breaks, it's
unlikely you'll get anyone to fix it for less than the price of a new one.
If you want a schematic of a 7-year-old TV set, I doubt it's readily
available either. I've never had a monitor repaired successfully by a
"professional" working at an "authorized" repair center. I sent in a very
nice NEC monitor which had some wierd malfunction in the power management
hardware which caused it to drop out at random times, then refuse to come on
again for weeks at a time. The service center couldn't fix that. The
monitor cost $879 new, and was still in warranty, as it turned out (they
give you a 2-year warranty and perform no outgoing inspection, apparently)
so when I phoned the NEC people, they sent me a new one via FedEx, and
really didn't demand even that I return the old one. I had a similar
experience with a DELL monitor with the same problem, except that the
monitor wasn't mine. The problem was the same, and the response was the
same. A new monitor over night, no demand for the original one. I guess
the shipping cost is too high to warrant repairing them.
>
>Although it's hard to imagine anything particularly clever/unusual in a
>standard colour monitor. Most monitors that I've worked on use pretty
>much standard circuitry.
>
That's what puzzles me about the color displays I have sitting about. There
aren't many that look even remotely similar beyond the most superficial
observation. Not one has a flyback transformer, and all the
current-generation multisync types use some encapsulated device about 4x6x1"
or so to effect the power management functions.
>
>More likely, the company is worried that you'll either hurt yourself or
>damage the unit if you have a go at fixing it. No, I'm not happy about
>this -- IMHO if I pull the cover and fiddle around then it's _my_
>responsibility if I do damage to the unit or to myself. And I'm more
>likely to do such damage _without_ a service manual (people who know me
>know full well that the lack of a service manual is not a reason for me
>not to dive into something). But trying to explain this to the company is
>generally a waste of time.
>
In view of the fact they don't want the broken/defective ones back, that
must be their logic.
>-tony
>
Received on Thu Oct 28 1999 - 20:08:02 BST