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keesan
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Electronics
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Sep 22 21:25 UTC 1998 |
The item for discussing anything with tubes or transistors.
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| 203 responses total. |
keesan
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response 1 of 203:
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Sep 22 21:27 UTC 1998 |
We have two dead CD players, one small walkman type (Sony) and one that is
part of a large stereo system (Sharp). They do nothing. The rest of the
stereo system works fine. What should we check out first? The stereo system
gets fixed first as it has been purchased, as is, by one of kiwanis best
customers, who comes in once and a while and spends a hundred dollars without
arguing or even testing out the equipment, and we want to be nice and surprise
him with a working CD player. He will be back Saturday.
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n8nxf
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response 2 of 203:
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Sep 23 10:11 UTC 1998 |
The optical needle. Specifically the laser in the optical needle. Radio
Shack use to sell a little plastic disc that would give off visible light
when it was illuminated by inferred light. Handy for checking the laser
in the CD player. Last time I looked into the price for a new one,
however, I was shocked. Close to $100. (An audiophile would consider
that cheap for a good cartridge though. Also, optical needle is just my
term for it. A more techie term would be optical reader or laser
assembly.)
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keesan
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response 3 of 203:
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Sep 23 17:54 UTC 1998 |
We had one that needed the unit replaced, not worth it. I was wondering if
it might be some simple reason why nothing was moving or lighting up. We will
check tomorrow and report back. Another problem is a combination stereo in
which, if you put the selector switch to 'tape', you get a very loud buzz,
without even pressing play. I stopped the buzz somehow by pressing a few
buttons on the tape player, but it started again. Two wires touching and
causing an AC hum somewhere? But how would the selector switch and the record
button both affect it?
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keesan
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response 4 of 203:
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Nov 27 16:48 UTC 1998 |
U\I think the above problem was a loose screw that needed removing.
Yesterday we fixed a 'bad channel amp' (someone else's guess) by cleaning all
the controls on the amp, the equalizer, and the tape player. And we fixed
the rewind by cleaning the rubber tire (on a VCR we had fixed the rewind by
cleaning the part the rubber tire moved against, since the FF worked and REW
did not and they used the same tire which hit different parts). Jim
discovered you can fix VU meters by untaping them and opening them up and
cleaning them to unstick the needles. And he replaced a burnt-out bulb with
one of a different voltage plus a resistor, after testing different resistors
to get the right voltage. Anyone want a really nice five-component stereo
system from around 1980, a Project One with athe aluminum slab fronts, perfect
condition (apart from the nonmatching bulb and one missing capstan cover)?
On sale at Kiwanis Dec 4 and 5 for $300, plus some nice speakers. Accutronics
helped us price it and suggested the bad channel problem might be solved by
a good cleaning, they saved us all a lot of time. Multiple causes for the
same symptom, our 'boss' was going to start by changing fuses. I have
convinced him to write down the symptoms that he notices, rather than guessing
at the causes. The last two 'bad belts' tape decks were not bad belts - one
had a worn out capstan (design flaw) and the other has a bent erase head.
Spray cleaning TV tuners helps with reception.
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keesan
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response 5 of 203:
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Nov 29 20:41 UTC 1998 |
The most recent non-working tape players were both missing their
clutches (springs) and the piece that the clutch went against. In one case
a piece had been taped on the outside but two others were missing, and in
another case the two pieces in question were rattling around inside, one of
them was cracked and had come off freeing the other - fixed with a soldering
iron. The first case will require figuring out what is missing, which we plan
to do by taking apart another GE boombox which has a working tape player and
a dead radio. At the very least we can combine parts. We now have parts from
five dead SONY CD players, all with different problems. One camein with a
piece of hte loading tray taped to the outside. Nice of the people who donate
their dead equipment to let us know what is broken in it. Tonight may be a
CD-player puzzle session - match up the parts until you get a whole.
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keesan
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response 6 of 203:
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Nov 30 17:52 UTC 1998 |
Jim fixed the latest CD player by replacing part of the loading tray that had
been taped to the back of the cube. He can't imagine how it came out, but
he drilled a small hole in it and managed to reattach it. The cube was quite
difficult to get open, because SONY designs things that way - you need a
special long screwdriver (he ground down a long rod into a screwdriver).
Please donate any broken stereo equipment to Kiwanis (thanks Davel).
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rcurl
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response 7 of 203:
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Nov 30 18:26 UTC 1998 |
Do you want an old TV that has lost one of its colors (green)?
I would like to thank Sindi and Jim for the electronic recycling
'industry" they have created at Kiwanis, partly in the name of Grex. The
earlier and much smaller effort to rehabilitate old computers and make
them available to the clients of non-profit charitable organizations died
because of the administrative problems of finding the equipment, storing
and repairing it, and matching the equipment to the clients. Sindi and Jim
have solved some of those problems by having a place to store and work on
the equipment, and having both collection and distribution functions that
are built into the Kiwanis business. But it only works because Sindi and
Jim, and others donating their time to help, repair the equipment and
manage the inventory. This is not formally a Grex charitable function, but
I think Grex can claim some relation to its origins and volunteer support.
This kind of public service is exactly what I have long thought Grex
should foster and support.
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keesan
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response 8 of 203:
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Nov 30 23:01 UTC 1998 |
Grex members have been among the best customers, and Bruin is now going to
be listing our more interesting items in classified.
Thanks Rane, but I think you offerred us this TV before. Make that 'please
donate any possibly fixable stereo equipment to Kiwanis'. Jim can handle
mechanical problems, esp. tape players, but we cannot deal with broken picture
tubes, parts have to cost less than we can sell a working unit for.
Grex volunteers now include Bruin, Kentn, Tpryan, and Jimmy2 dropped by one
Saturday but we have not heard from him again. There is always something to
help with, if nothing else you can make an inventory of software and hardware
and post in on grex, this would take quite a lot of time.
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keesan
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response 9 of 203:
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Dec 2 01:20 UTC 1998 |
We are trying to fix a 17" NEC Multisynch monitor that is drawn in at the left
side and after a few minutes goes off, and eventually on again. I suggested
a voltage regulator, what else could it be?
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scg
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response 10 of 203:
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Dec 2 05:05 UTC 1998 |
NECs have pretty long warrantys, last I checked. You might want to call NEC
and see if it's still covered.
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keesan
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response 11 of 203:
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Dec 2 18:40 UTC 1998 |
We are not the original owners, does that matter? We have no papers.
Another puzzler: two CD players that power up and light the power on light
but not most of the rest of the display, the door open/close works, the
loading motor works, but they do not play. Jim measured voltage, about 9 V
to the motor connector when it is unplugged, but no voltage to the motor.
Play, FF, REW, memory, etc. do not seem to do anything. ??? The machines
have three separate motors, or at least the one we looked inside did.
Some problem with a chip, or a dirty contact, or a component?
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scg
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response 12 of 203:
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Dec 3 02:18 UTC 1998 |
Call NEC and ask. Sometimes being the original owner, or having original
paperwork, matters. Sometimes it doesn't. The worst they can do is say no.
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n8nxf
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response 13 of 203:
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Dec 3 10:41 UTC 1998 |
Those things use a little dedicated CPU that writes to the display and
controls the motors, solinoids, laser and reads the buttons to see what
the operator wants to do. Look for breaks in any of these communication
paths. The CPU may also be partly defective, internally crippled, making
it incapable of doing all it should. If the laser mechanism is defective,
that too may render the remainder of the unit inoperative. (The little
lense assembly should move up and down, attempting to focus the laser on
the CD, when the CD is inserted.)
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keesan
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response 14 of 203:
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Dec 3 16:55 UTC 1998 |
Klaus, if we give up would you like five CD players in which the motor does
not spin when you insert the disk? We will try following your suggestions.
The very helpful owner of Accutronics said that all sorts of causes could
produce similar symptoms and to give up soon. We tried switching laser
mechanisms between three and a half Sony models. It could be a slow motor,
a spot on the motor, a spindle at the wrong height, a switch....
The little lens assembly does move up and down, but is there something that
happens before that? Should it spin before focussing? Does it spin whether
or not there is a disk in there? Does it spin when the door closes even
before we push play (it does not for us) and if so, are there any limit
switches controlling that step, or sensors, that need to be actuated before
the next step? It goes from door close to focus, no spin. One machine will
start to spin and then stop, repeatedly, Jim thinks it is looking for a disk.
We made a nice plastic door cover for an Akai tape deck from a diskette case.
We have only given up on four tape decks so far, they are easier than CDs.
One has a bent-out-of-shape erase head that pinches the tape, and it needs
the asimuth adjusted. What does that mean? Jim cannot explain. He thinks
he can figure out how to adjust the asimuth. Is the asimuth an angle?
Marathon cleanup and organizing session tonight at Kiwanis before tomorrow's
sale, anyone who wants to stop buy for early purchases call 665-2211 after
around 6 or 7, we have one appointment for a turntable already.
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n8nxf
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response 15 of 203:
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Dec 4 11:37 UTC 1998 |
It has been my experience that the disc will not start spinning unless
the laser is able to focus on the the disk. I have only fiddled with a
few CD players but my experience suggest that faulty laser mechanisms
are pretty common and very expensive to replace. Thank you for the offer
but I will pass on the broken CD offer. My kids may like them to take
apart, however.
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keesan
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response 16 of 203:
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Dec 4 23:36 UTC 1998 |
I got a library book that also implicated the laser focus mechanism, and a
customer today said they often get bumped out o position. Jim says he sees
the focus going up and down (in and out), did not know it had to focus before
spinning. We will follow the flowchart in the book on focus problems.
Another book sayape buildup may be responsible for poor (very faint)
record, which many of our boomboxes have. Where is this dirt? We cleaned
the heads themselves.
How does the focussing work on a disk that is not moving? What is
normal. (I will try reading the book about how they work, that is Jim's very
last resort).
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n8nxf
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response 17 of 203:
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Dec 7 11:02 UTC 1998 |
I've not heard of sayape. Could be that the record head needs to be
demagnetized. They use to sell head demagnetizers at Radio Shack and
such. The disc on a CD does not have to be spinning for the player
to optimized the level of the return signal. Radio Shack also use to
sell a little plastic paddle that would glow when exposed to IR. Since
CD players use IR lasers, I suspect you could use one to see if the
laser is still lasing. There is little to wack out of alignment in a
laser assembly so I doubt that is the problem. I could be very wrong,
however. I have not worked on them much.
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keesan
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response 18 of 203:
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Dec 7 15:26 UTC 1998 |
sayape - says tape (with garbage from a bad phone line, looked okay when I
typed it). I think Jim has a demagnetizer, if that is the same as a
degausser, if this works we have a customer for our dual tape deck, who is
coming back Sat for his computer, thanks.
How does one repair a non-lasing laser? We have no parts budget.
One of these CD players plays intermittently, would that be some component
going bad?
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n8nxf
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response 19 of 203:
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Dec 8 11:31 UTC 1998 |
Yes, the laser diode. The ones I've seen are glued into the optical
assembly which consist of the laser, a nifty prism, a lens or two,
the optical sensor that receives the reflected light from the laser
and the coil driven lens that moves up and down. I once tried to take
one apart but the epoxy holding the laser in is really good stuff and
would not let loose with reasonable amounts of heat. The laser is only
about $5 but the optical assembly starts at about $60. The one I tried
to fix was $98.
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keesan
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response 20 of 203:
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Dec 8 17:56 UTC 1998 |
We are selling working CD decks for under $60, now we have seven dead ones.
One portable came in with a broken nylon gear which Jim may try to melt back
together. They are pretty flimsily made.
Trying to fix a non-recording dual tape deck which does not erase or
record, the book said to clean the R/P switch, so we will take it apart and
spray it, but there is absolutely no erase or record. (The boomboxes had
erase and faint record). May be something electronic (transistor?).
Jim will enjoy taking apart an optical assembly when we have time.
There are three spares removed from dead boomboxes to learn on. Why can't
they use better diodes?
We also have a receiver that takes 16 ohm speakers, and Stereo Shoppe
agreed that putting a resistor in seires with the speaker (4 ohm would be
enough) would protect the amp but diminish the volume of the sound. We may
add this to the receiver, not the speakers. 10W 4 ohm? More than 10 W will
destroy the speakers anyway.
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n8nxf
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response 21 of 203:
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Dec 9 12:17 UTC 1998 |
It should be fine with an 8 ohm speaker too. I came across an interesting
site yesterday: http://www.howstuffworks.com The even explain how a CD
player works.
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rcurl
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response 22 of 203:
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Dec 9 17:54 UTC 1998 |
HSW is indeed a nice site. Thanks! I looked up how GPS works and it did
a very lay explanation but then provided a link to the professional pages.
However, there is some bug on it, at least for Netscape 4.0 on my Mac.
Each time I chose a link, my system froze for 2 minutes or more before
responding (two tries on topic links and one to respond to a "How did you
get here" inquiry).
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keesan
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response 23 of 203:
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Dec 9 20:13 UTC 1998 |
Thanks, I just translated a bunch of words having to do with cars, this could
have made it more understadable (but Jim helped convert 'propulsion on four
points' to 'four wheel drive'). Right now I have to learn a lot in a hurry
about how things are made into tablets, that must also be on the web somewhere
(but I do have Remington's Pharmaceutical Sciences).
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n8nxf
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response 24 of 203:
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Dec 10 12:33 UTC 1998 |
Rane, I had the same problem. I found that if I clicked on the text
browser button, on the top left corner of the page, it was active much
faster.
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