"Trevor Wilson" wrote in message
...
"Alan Rutlidge" wrote in message
...
"Trevor Wilson" wrote in message
...
"TT" wrote in message
...
"Iain Churches" wrote in message
news
"Trevor Wilson" wrote in message
...
Trevor wrote to Atec:
* Your admission that you lied, is duly noted.
* Instead of presenting actual facts, you resort to rancour.
* Your inability to discuss anything logically and coherently is duly
noted.
Trevor instead of all this "duly noting" you could serve
mankind better by writing these ME manuals for
which the world clamours :-)
Iain
Wouldn't it then be like "open source code" for software applications?
Everyone could then see how they work, propose modifications, upgrades,
tweaks etc and then there would be *free* product development.
I would see it as win/win situation for customers and manufacturer
alike. I would envisage that PS and TW would actually get busier and
make more money because of it.
Imagine how many idiots would start tinkering and let the smoke out of
the box or buy relics off fleabay in the hope of repairing them
themselves?
All this "Secret Squirrel" **** is a PITA IMHO. Please keep the cloak
and dagger stuff for mystery novels? ;-)
And from a purely selfish POV a very good product is going to end up
devaluing because no one will want it anymore :-(
Also *IF* the manuals were available surely State (or OS) repairers
could be appointed and even, heavens forbid, actually create demand for
new product and a new manufacturing facility could eventuate.
**Let me re-state the situation:
* Peter Stein is supporting and servicing products he manufactured. I am
servicing and supporting ME and other products.
No argument there Trevor, BUT this requires the non-technical customer to
first find a local tech who is prepared to remove the faulty module, then
the thing has to be sent to FNQ for repair and then replaced by the local
tech.
**Correct.
Let's just for one moment assume not everything goes a planned. A module
suffers some miniscule phyiscal damage on return from PS and as a result
an electrical fault develops.
**What happens if you drive your car over a bumpy road, after taking it to
the local tech? There are a raft of questions, you could ask. OTOH, the ME
modules are well built and, IME (25 years of freighting to Peter, via
Aussie Post) none have ever developed a fault which can be identified as
being attributable to freight damage. Of course, I have an IQ above room
temperature and a good supply of bubble wrap. Pretty much any nong can
pack them correctly.
The local tech fails to visually inspect the
module carefully on re-installation, and at switch on the "smoke gets
out" or it creates another fault. Who accepts responsibility?
**Tell you what: IF that ever occurs, I'll worry about it then. It may
occur, but, in 25 years, it hasn't happened to me. I won't lose sleep
worrying about something which appears to be a very remote possibility.
Who pays for the
damage? This is a legal mindfield and you bloodly well know this. ME
has now been exposed for its lack of support documentation.
**On the contrary. The documentation which comes with the amplifiers is
comprehensive and very helpful. Did you note the flow charts?
No tech in his
right mind is going to swallow up the cost of hours on the phone to PS
when the information could easily be gleaned from a service manual,
thereby minimising any misunderstanding9s).
**I still fail to see what help a schematic would be to a tech. The
modules require carefully matched devices. This is well outside the
capabilities of all but the most well equipped workshops.
So what you are implying is that a transistor tester, capable of reading
current gain and Vbe is beyond the budget or the average electronics tech
and beyond his / her competency to use? Pull the other one Trevor, it's got
bells on it.
* There are others who service and support ME products.
I've asked yopu this question before and you've failed to reveal anyone
else other than PS and your good self.
**Wrong.
Okay, just in case I missed that post, please repeat the information.
Due to the careful matching of semiconductors in all ME products,
servicing the output stages by anyone other than PS (or his appointed
successor/s) is a real bad idea.
Only for those who wish to maintain a monopoly on servicing ME products.
Codswallop TW and you know it. If ME employees (and now PS on his own)
spent part of the production time sitting down with a transistor tester
hand grading semiconductors it deserves to have gone out of business.
And to what tolerances are you suggesting anyhow?
**All transistors in the amplifier stages are matched to within 1% for hFE
and Vbe. The resultant number is written on the top of the output devices.
Oh forgive me Trevor. Just lifted the lid on my ME850 Hi-Cap. Lots of 5%
tolerance parts around the output devices.
Makes perfect sense now. Equip the device with 1% transistors and
surrounding circuitry has 5% components. What a ****ing laugh. Obviously
both you and PS haven't heard that saying - "A chain is only a good as its
weakest link." Also the WW resistors in the output stage have a PTC so the
resistance will change with temperature / power dissipation.
Without a circuit diagram it isn't hard to guess that there are low value
(0.51 ohm) resistors in each leg of the emitter circuits of the output
devices. Matching or no matching (within reason), the currents flowing in
the emitter circuits will be effectively shared between parallel output
devices in this type of circuit configuation. It's no rocket science
secret. The technique is commonly used by nearly every competent class A/B
SS output stage.
Read the Cherry and Hooper book on amplifier design. Published in the early
70's it's essential reading for anyone contemplating SS amplifier design.
My God it even mentions the V-FET and MOSFETS.
As for ME output device matching. By that I assume all the MJ15026 devices
in any one channel would have the same "batch test" number and likewise all
the MJ15024 devices would have their own?
This is just the same sort of
snake oil bull**** Perreaux used to peddle and it has turned out to be
bull****.
**I am unaware that Perreaux claimed such a thing. I'll take your word for
it. How would you suggest that I prove it to you that Peter does match his
devices?
I'm not saying PS doesn't attempt to match his devices within reason. Just
I think 1% matching is overkill and it is unnessecary if one selects an
output device with reasonably tight specifications to begin with.
* Supplying schematics to anyone calling themselves a 'tech', in the
case of ME, may be a very bad idea. Techs who are unable to perform even
basic fault-finding, can end up doing far more damage to the amplifier.
Fully agree there TW, but if they don't know what they are doing and the
smoke geats out than surely they need to accept they ****ed up.
**Indeed they do.
I get this problem with idiots who think they know all about PCs, except
it's the OS that gets out of wack and the system crashes. No physical or
electrical damage but the loss of data can be just as, if not more
costly.
* In the case of most ME models, the output stages are modular in
format. This makes removal and replacement a quick, simple exercise.
Peter Stein (and his appointed successors) can effect service to those
output modules and the modules posted back, safely, inexpensively and
easily. Freighting amplifiers around the nation is not required. All
that is required, is a competent tech.
As I wrote earlier in this post. 3rd party liability issues if something
goes wrong.
**When I see such an instance, I'll let you know. I won't hold my breath.
Unfortunately it is commonplace and not just in the electronics industy.
Perhaps TT can add some value to the problems one has with transmissions
which are re-built by and then installed by 3rd parties.
Let's say the re-build wasn't up to spec. The transmission tech instals the
re-built box under good faith the work on the innards is okay.
The customer drives the car for a day or two and returns it claiming the box
is faulty. The tech diagnoses the box is faulty, takes the transmission off
and returns it to the re-builder only to have the blame shifted back to the
tech with a claim of faulty installation. The installing tech says he did
nothing wrong, the re-builder claims likewise. See the problem? In the end
the only one getting shafted here is the customer.
Who are the appointed successors?
**Myself and David on the mid NSW coast.
David who? the David of David and Golliath fame? :P
* I have seen many ME amplifiers which have been worked on by
incompetent techs. The result is not pretty, nor cheap to rectify.
Same here, but not nessecarily limited to ME.
**Indeed. However, in one instance, the resulting mess cost the client
$1,200.00 in fried output devices. For some reason, the tech removed all
the outputs. It wasn't necessary, since they were undamaged. He did not
secure them to the heat sink properly. The whole lot went up. On
examination, I suggested that the customer approach the manager of the hi
fi store he purcahsed the amp from and request the $1,200.00 be refunded
to him. He got his money.
* Poorly serviced ME amplifiers reflect badly on the product's
reputation.
All the more reason to have full service documentation available to
eliminate the guesswork.:P
A competent tech would heed to the documentation oan follow the service
recommendation strategies.
If it says match Q25 to a certain gain range before replacing, this can
easily be done by any qualified service tech.
**To secure a full set of matched output devices for an ME850 would
require approximately 10,000 transistors, in order to obtain suitable
numbers of matched devices. Same deal with the preamps. In fact, I once
met a guy who claimed to have built an ME preamp, after Peter provided him
with schematics. I challenged him on the point, knowing that it was
impossible. Then, he dropped the bombshell. He spent $1,500.00 on
transistors, to build what was then a $1,000.00 preamp.
The products reputation can't be harmed except (maybe) if it is ME580
Hi-Cap as this the is ONLY ME product still in production.
ALL the other ME amplifiers haven't rolled of the production line in
years so in essence there is no reputation to protect.
**The reputation is still there. Peter cares about his customers and he
cares about the products which are in the market.
Trevor Wilson