Toshiba TV29C90 problem; Image fades to black...

[paragon66x]

Mark - It may take me a day or two to digest your last post - it's
pretty deep for me. I will actually be traveling the next couple of
days for work so it may be a while before I can look into what you
posted. I should be able to reply by the coming weekend. Thanks - John

 

[Andreas Tekman]

JW schrieb:

On 1 Dec 2006 09:33:51 -0800 "tek_user" <bulli_gruen@gmx.net> wrote in
Message id: <1164994431.577125.117250@73g2000cwn.googlegroups.com>:

Hi,

i am owning an Tektronix 2467B. Maybe someone can give me some advice,
please.
The 2467B shows following message:
TEST 04 FAIL 13 (3453)
I have got the complete service manual, but it says something like
"Option Error" ???
(The scope includes Option 10 and 11.)

If i delete the error message by pressing the A/B tigger button, the
device works, but
it has a awful DC-Offset on all channels (which varies with the V/div-
selection).


Best regards from Berlin


You should ask this in sci.electronics.repair. There's a fellow who posts
there who used to work for Tektronix. (sci.electronics.repair added)

Well, we also read here

Looks like a problem in the calibration constants, stored in the NVRAM
A "TEST 04 FAIL 13 " condition means according to my manauls a "bad
checksum in the NVRAM".

If the NVRAM is ok, than this error can be corrected by doing the
calibration procedure (all steps mentioned in the handbook) and storing
the constants in the last step into the NVRAM.

hth, greets from Stuttgart,

Andreas

 

[Andreas Tekman]

Andreas Tekman schrieb:



Ah , sorry, noticed the follow up too late.

Andreas

 

[Andreas Tekman]

Jeff Liebermann schrieb:

I'm apparently the not so proud owner of yet another broken
oscilloscope. This time it's a Tek 2205 with a sick power supply
section.

The eBay guide says that the 2205 is not a very wonderful scope:
http://reviews.ebay.com/Buying-an-Oscilloscope-on-ebay_W0QQugidZ10000000001568756
"Stay away from the 2205, 2225 they were made in the orient,
and have serious quality issues as used scopes."
Oh well. At least it was free.

The outputs of all the various PS voltages are low (not zero). For
example, the 250v line measures about 15VDC. I've checked all the big
caps with an ESR tester and found nothing unusual or suspicious. When
I first inherited the scope, the green pilot light came on but nothing
else. By the time I got it open and started making measurements, the
green pilot light went away. I disconnected all the various power
supply connections (that conveniently run through 0 ohm jumpers) but
the power supply lines still have low output, even with no load. I
have a schematic and service manual.

However, I'm also lazy, have better things to break, and really don't
know why I'm bothering to fix a 20MHz scope. Are there any common or
chronic problems with the 2205 power supply section to check before I
dive into the mess, rip it apart, and probably electrocute myself in
the process?

AFAIR the 2205 has a toroid transformer to set up a low DC of approx.
40 Volts and provides mains isolation. Folowed by a switchmode that
converts the DC into all aother voltages needed in the 2205.

I's d recommend you look for a service manual, and follow the
schematic.In my repairs the following: In the switchmode the usual
suspects: caps, transistors, secondary HV multiplier. I don't know if
bama has one for download, but it is worth a try.

hth,
Andreas

 

[Mark D. Zacharias]

paragon66x wrote:

Mark - It may take me a day or two to digest your last post - it's
pretty deep for me. I will actually be traveling the next couple of
days for work so it may be a while before I can look into what you
posted. I should be able to reply by the coming weekend. Thanks -
John

You can e-mail me direct at:

mzacharias@labolgcbs.net

and reverse the domain name.

Mark Z.

 

[b]

juanato@gmail.com ha escrito:

Need help in changing the RF out channel on my AIWA FX5350. Have
lost
the manual, so can't look up the procedure. (No manual available
online,
as far as I can Google).
A common aiwa procedure is to press both channel buttons on the
VCR
while off, but this takes me none. I have a licensed aiwa clone, the
first line vcr-601 video that employs this feature, turning off the
unit from hand-controler and pressing one of channel keys in the
front panel.

--
(r) Juan Antº Espejo 費用全免 在一個場合
پرسش و پاسخ در خصوص مسائل و مشکلات جنس
P. O. Box 4111
E-14080 CĂłrdoba
Andalucía, ESPAÑA
Fax/Voice answering + 34 940 468 957
USA callers, try FAX 1-602-865-8740

mira aquĂ­, es un foro con mucha gente que saben de esto. Suerte!
http://dudaelectronica.net/phpbb/index.php

B.

 

[george]

Michael

Second appreciation. After your hint on direct connections I found
interlnk and intersvr in dos that allows parallel port connections with
laplink cables. Going to get the cable off of ebay. It does appear
that the parallel port cable (laplink) is not the same as the null
modem that is used on serial connections.

George



Michael Kennedy wrote:

If you happen to be runing windows on this maching, you can use direct cable
connection to connect two computers with a null-modem cable with the serial
ports or the LPT printer ports.

Example
http://kb.iu.edu/data/ahcj.html

 

[Michael Kennedy]

Oh yeah I forgot all about interlnk, that brings back some memories. That
should work for you without too many problems if your good at using dos.

I guess that they have a different name for a null modem parallel cable, but
the concept is just the same as with a serial cable. What is different about
the null modem cable from a regular cable is that the pins are not connected
to the same wires on each end.. For instance pin 1 on one end might be
connected to pin 5 on the other end. This is so that the TX (send) pair goes
to a RX (recieve) pair on the other end just like with a twisted pair
ethernet cable.

- Mike


"george" <gjdbxxxx@adelphia.net> wrote in message
news:1165899973.532911.79280@80g2000cwy.googlegroups.com...

Michael

Second appreciation. After your hint on direct connections I found
interlnk and intersvr in dos that allows parallel port connections with
laplink cables. Going to get the cable off of ebay. It does appear
that the parallel port cable (laplink) is not the same as the null
modem that is used on serial connections.

George



Michael Kennedy wrote:
If you happen to be runing windows on this maching, you can use direct
cable
connection to connect two computers with a null-modem cable with the
serial
ports or the LPT printer ports.

Example
http://kb.iu.edu/data/ahcj.html

 

Scrim wrote:

I finally took the cover off my F520 monitor to see if I can fix its
intermittent blurred picture fault, but, of course, now it won't do it!
Meanwhile, I've noticed something strange and would appreciate some advice:

Included amongst the components on the small PCB mounted on the end of the
CRT are (what look exactly like) four wire ended neon lamps. I don't have
much CRT experience, but still, was surprised to see these. The service
manual refers to them as SG001 to SG301. For example, "SG001 1-519-422-11
SPARK GAP". Anyway, I haven't seen any light up, but they all have very dark
glass envelopes from internal electrode evaporation.
Can anyone:
Tell me what these Neon Bulbs are for?
If there condition indicates a fault (possibly related to the intermittent
blur fault)?
If I can/should replace them with regular neon bulbs?

Thanks,

Scrim

The neons are the backup system. If the main CRT fails, these will
display enough basic characters to enable you to sort it out. Conceived
in the days of DOS, theyre less well suited to modern graphic displays,
but you can reboot into dos and sort your computer from there.

Intermittent blurring is nearly always due to focus voltage variation,
which is nearly always due to arcing somewhere in the focus voltage
line.


NT

 

[Jumpster Jiver]

J.P. wrote:

I have a Ohmite VT4-F varible voltage unit that was taken apart when I
got it. It is wired but just disassembled. It appears the fuse socket
is broken and had no continuity between the front of the fuse under
the cap and the terminal. The fuse has continuity. I would like to
know if someone can tell me how to test this thing to see if it is
good. TIA... J.P.
Replace the fuse holder. Make sure nothing is touching anything else.

Plug it in.

 

[Chris]

J.P. wrote:

I have a Ohmite VT4-F varible voltage unit that was taken apart when I
got it. It is wired but just disassembled. It appears the fuse socket
is broken and had no continuity between the front of the fuse under
the cap and the terminal. The fuse has continuity. I would like to
know if someone can tell me how to test this thing to see if it is
good. TIA... J.P.

The later models had a plastic fuseholder that would crack if its nut
was overtorqued or if the fuseholder was dinged. Try wiggling the back
of the fuseholder (with power off, of course). If you have to replace
it, it's a standard size.

Now, for troubleshooting, unplug, open the front panel, and have the
whole front panel assembly laying on the bench. Just to begin with,
look at the lapped surface of the windings (where it meets the brush)
and look for burn marks or discontinuities. Now turn the control from
0 to 140 and back while feeling the dial and looking at the brush. See
that the dial turns smoothly, and the brush does not catch throughout
the range.

Now use an ohmmeter to look for continuity through the circuit. Black
from the line cord through the fuse and through the VT to L@ and to the
output wire (power off, again).

Having passed so far, get a clean lint-free cloth and some pure alcohol
(NOT 70% rubbing alcohol). Moisten the cloth with the alcohol, and
gently wipe the lapped wire mating surface. (This is a PM procedure
that should be performed periodically -- carbon crumbs from brush wear
are a major killer of VTs.) Let 'er dry.

Now, replace the cover, and place the wiper at around the midpoint. I
forget the wire numbers on the front panel of the VT itself, but you
should be able to see there's an L1/Hot/black (from the fuse), and
L2/Neutral/white from the line cord. You've also got a green ground,
which is connected to the chassis, and the output, which goes to the L1
connect on the front output outlet. You should put your meter across
the outlet, and plug it in. You should see about 70V. When you dial
the control from min to max, you should see around 0 to 140V (it will
be a bit high with no load).

If you don't see an output, and you are somewhat adept at working with
line voltage, you can do the above with the case cover open. Just
trace the voltage relative to the white wire/L2. Be careful, as line
voltage is present on all parts inside the box. If the voltage isn't
there, there's an open. Simple. Fixing it, though, can be a problem.

I'd guess your VT winding wire has probably opened up somewhere along
the lapped surface. That's not economical to repair, because you'd
have to first remove the varnish, then strip off the wire, rewind,
revarnish, and relap the windings. In days of yore, Ohmite used to
rewind the larger units, but not any more. Less likely but possible is
lack of contact between the brush and the lapped surface. This happens
from wear, as well as the brush falling out.

If you have a newer one, it's possible you have a Staco variable
transformer inside the unit. If you want, you can still get the Staco
replacement AFAIK -- I believe Staco still sells it. The brush itself
is not replaceable.

Remember, just trace continuity, then the voltage. Where continuity or
the voltage disappears is where it's open. And do be careful -- it's
never a good day to dance the 60 hertz.

Oh, yes -- would you like fries with that? ;-)

Good luck
Chris

 

[Jukka Aho]

tombates@city-net.com wrote:

I hope this is the correct place to ask this question. I notice that
some new stereos come with a USB connection. I am trying to figure out
the purpose of it.

A relative of mine has a Philips MCM530 - a "Micro Hi-Fi System" with a
USB connector on the front panel.

Here's a picture of it:
<http://www.p4c.philips.com/files/m/mcm530_22/mcm530_22_rtp_.jpg>

See here for a brochure:
<http://www.p4c.philips.com/files/m/mcm530_22/mcm530_22_pss_eng.pdf>

And here's the complete user manual:
<http://www.p4c.philips.com/files/m/mcm530_22/mcm530_22_dfu_eng.pdf>

I have visited a number of electronic stores and asked, but I keep
getting different answers.

Whatever functionality the USB connector might have on a given device is
highly dependent on the manufacturer, so you could get different answers
merely because of that.

Is the USB to connect a MP3 player, so you can play the songs from
your MP3 player on your stereo?

I've seen something like that on some other "Micro Hi-Fi System", but
the MCM530 does not support this kind of operation. (The MCM530 has a
USB "B" connector, not the USB "A" connector, so you couldn't connect
MP3 players or USB sticks/keys, anyway.)

Is the USB to connect your computer to your stereo, so you can
use the speakers on your stereo for music being played on your
computer?

That's the primary use for the USB connector on MCM530. You can think of
it as an external sound card - and that's how the MCM530 appears in
Windows. The whole USB functionality - and apparently much of the other
functionality, too - appears to be based on the Micronas UAC 355xB chip:

<http://www.esic.cn/icmanual/icmanual.asp?ic=UAC355xB&id=141312>

The "USB PC Link" is one of the program sources - the other ones being
the 5-disc CD changer, the analog "line in" connectors (2xRCA), and the
FM tuner. As you can see from the above picture, there's a button for
selecting the "USB PC Link" mode on the front panel. There's also a
similar button on the remote.

But there's more to it: the MCM530 also comes with some software - a
custom version of MusicMatch Jukebox, which is a commercial
subscription-based net radio/MP3 jukebox service, disguised as an MP3
player/librarian of sorts:

<http://www.musicmatch.com/>

The fancy thing here is that while the stereo is set into "USB PC Link"
mode, its remote sends commands to the PC. You can control the
MusicMatch application with the MCM530 remote: change tracks, start and
stop playing, pause, etc. The front panel buttons also work in a similar
way.

In addition to the remote control functionality, the MusicMatch
application also sends the name of the artist and the name of the
currently playing song to the VFD display on the front panel of your
stereo - scrolling it there.

The MCM530 also comes with some drivers and software that enable various
"Environment" effects. These are all created by the UAC355xB chip
inside - they're some sort of DSP settings that are uploaded from the
computer to the chip - but for some reason, Philips didn't make them
accessible by any other way than via a computer. (There are a couple of
such presets built-in that work even without a computer, but by
connecting a PC to your MCM530, you'll get lots of more.) These new
effects can be selected both from the PC and from the front panel
buttons.

All in all, being able to control your MP3 archive (and a net radio
service) with the remote, and being able to view the names of the tunes
on the VFD display are pretty neat features, but the downsides are:

- The remote control functionality and the song-name-on-
the-VFD-display functionality will only work with the
MusicMatch Jukebox application. If you prefer some other
player, you won't get those features. There's no
programming information available, so other media players
can't implement any support for the same features (unless
someone reverse-engineeres the drivers and their API.)

- I havent been able to get the USB connector to work in
Linux at all. The MCM530 is recognized as a USB audio
device, but it remains silent even if you try to play back
music on it. (Maybe that's just me; I haven't been doing
any extensive testing.)

- In the end, it's only a USB connector, with the 5 meter
limitation. An Ethernet connector would have been much
more useful since then you could stream music to your
stereo over the home network, without needing a computer
nearby.

- Placing the USB connector on the front panel does not make
any sense since the connector (in this case) isn't intended
for removable devices. It should be relocated on the back
panel.

* * *

Other manufacturers and devices might have a completely different idea
about what a USB-connector-on-a-stereo should do, so don't take this as
any kind of general guideline.

--
znark

 

[Jim Yanik]

beemererik@bellsouth.net wrote in
news:1165947495.260412.246950@79g2000cws.googlegroups.com:

One attenuator in my TDS744 is damaged. Can anyone tell me where I
might find a replacement or have it repaired.

Thanks.

www.tek.com,IF they still support it.
Otherwise,you may have to cannabalize another broken TDS744.

the entire TDS series of scopes were intended for module exchange service
only,unless TEK does the repair. That's Beaverton or DC Service centers.

--
Jim Yanik
jyanik
at
kua.net

 

[Homer J Simpson]

"Scrim" <nospam@nospam.com> wrote in message
news:Qxzfh.64620$Pk.18615@fe2.news.blueyonder.co.uk...

Included amongst the components on the small PCB mounted on the end of the
CRT are (what look exactly like) four wire ended neon lamps. I don't have
much CRT experience, but still, was surprised to see these. The service
manual refers to them as SG001 to SG301. For example, "SG001 1-519-422-11
SPARK GAP". Anyway, I haven't seen any light up, but they all have very
dark glass envelopes from internal electrode evaporation.
Can anyone:
Tell me what these Neon Bulbs are for?

They are spark gaps.

 

Homer J Simpson wrote:

"Scrim" <nospam@nospam.com> wrote in message
news:Qxzfh.64620$Pk.18615@fe2.news.blueyonder.co.uk...

Included amongst the components on the small PCB mounted on the end of the
CRT are (what look exactly like) four wire ended neon lamps. I don't have
much CRT experience, but still, was surprised to see these. The service
manual refers to them as SG001 to SG301. For example, "SG001 1-519-422-11
SPARK GAP". Anyway, I haven't seen any light up, but they all have very
dark glass envelopes from internal electrode evaporation.
Can anyone:
Tell me what these Neon Bulbs are for?

They are spark gaps.

Seems a bit strange they all have darkened glass.


NT

 

[Stephen Cowell]

"N Cook" <diverse8@gazeta.pl> wrote in message
news:elonuu$7ja$1@inews.gazeta.pl...

Could a Crate BV120H valve amp really blow 4x 12 inch 16 ohm speaker box ?
Amp as received was set for 16 ohm output, I measured the speaker box
impedance at 13 ohm, or so, before connecting up just to be sure.
Very feeble and distorted sound. No signs of the reported burning smell,
output matching transformer primaries at about 50 ohm seemed ok and
secondaries not open circuit in the amp so turned to the speakers. The amp
o/p switch setting was set for 4 ohms instead of 16 ohms but as I measured
16 ohms I assumed a switch problem.

It sounds like the speakers were blown before this exercise
started... what you did (with no loud noise) should not have
blown any speakers... *maybe* the amp could suffer, but
not the speakers.
__
Steve
..

 

[N Cook]

Stephen Cowell <scowell@sbcglobal.net> wrote in message
news:uGTfh.5176$Gr2.696@newssvr21.news.prodigy.net...

"N Cook" <diverse8@gazeta.pl> wrote in message
news:elonuu$7ja$1@inews.gazeta.pl...
Could a Crate BV120H valve amp really blow 4x 12 inch 16 ohm speaker box
?
Amp as received was set for 16 ohm output, I measured the speaker box
impedance at 13 ohm, or so, before connecting up just to be sure.
Very feeble and distorted sound. No signs of the reported burning smell,
output matching transformer primaries at about 50 ohm seemed ok and
secondaries not open circuit in the amp so turned to the speakers. The
amp
o/p switch setting was set for 4 ohms instead of 16 ohms but as I
measured
16 ohms I assumed a switch problem.

It sounds like the speakers were blown before this exercise
started... what you did (with no loud noise) should not have
blown any speakers... *maybe* the amp could suffer, but
not the speakers.
__
Steve
.

Reasonably easy to cleanly remove one of the cones.
If a next time, to cleanly remove the dust skirt I will make a small hole
and pull with a sickle probe to cleanly remove that section.
No sign of burning on the voice coil so I could count the number of turns in
both layers if I was to rewind another. But the cardboard core that this
coil was on has broken up completely . Not knowing how to do precision
origami , looks like the end of that one.

If there is power for power no audio difference between a 16 and 4 ohm
speaker, is there an advantage to protecting amps or speakers to opt for 2
pairs of parallel 16 ohm for 4 ohms overall or 2 seriesed 4 ohms in parallel
with same for 4 ohms. For 16 ohm setting for the last one of 4 4 ohm in
series then if 1 goes o/c then that would protect the others

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

Hi :

I have some technical PDF for gdm-w900 and similar. If you need I could
send to you (I think it's the same monitor).

I wish you can repair it.

If you finally decide not to repair it I would ask you about the
possibility to buy you one of the internal circuits from this monitor,
the D Mount or D Block circuit (Deflection circuit). My monitor still
works but I have a problem with this circuit and it's burning fast.

Please tell me if you want the PDF files.

Best regards,

Francesc

On 12 nov, 05:41, had...@gmail.com wrote:

I recently acquired a Sun GDM-90w10 (rebadged Sony w900) 24" widescreen
crt. It is very old (manufactured Dec '97), but it was in remarkably
good condition and worked beautifully.

Tonight I returned home and switched it on, to find that while it made
the clicking noises that it usually makes as it starts up, it didn't
come on. Instead of the tube powering up with the typical "bong" noise,
it made an extra click noise, and the green light switched off, to be
replaced by the light next to it blinking orange. This LED has a symbol
that appears to be a crossed out lightbulb.

When I bought the monitor, there were no manuals for it, and the best I
could find on the internet was a <a
href="http://www.sunshack.org/data/sh/2.0/infoserver.central/data/syshbk/De...">spec
sheet</a>, so I have been unable to find what this flashing LED means.

I do not believe that there should be anything physically broken in the
monitor, as (to my knowledge) it hasn't been moved since I used it last
week, but I can't be sure.

Did my monitor just meet it's inevitable end and wear out? Can anyone
help? Is all hope lost?

 

[Jim Land]

"wg" &lt;gerstlwilhelm@t-online.de&gt; wrote in news:1166015271.694942.141910@
79g2000cws.googlegroups.com:

Hi all
I search for keithley 485 the schematics. Maybe someone can me help
Willi

http://www.keithley.com/support/data?asset=975

 

[Scrim]

"Andy Cuffe" &lt;acuffe@gmail.com&gt; wrote in message
news:89k0o21l64e8kevsecp8o8chjo8mj4ep8r@4ax.com...

On 12 Dec 2006 21:42:43 -0800, meow2222@care2.com wrote:

Homer J Simpson wrote:
"Scrim" &lt;nospam@nospam.com&gt; wrote in message
news:Qxzfh.64620$Pk.18615@fe2.news.blueyonder.co.uk...

Included amongst the components on the small PCB mounted on the end of
the
CRT are (what look exactly like) four wire ended neon lamps. I don't
have
much CRT experience, but still, was surprised to see these. The
service
manual refers to them as SG001 to SG301. For example, "SG001
1-519-422-11
SPARK GAP". Anyway, I haven't seen any light up, but they all have
very
dark glass envelopes from internal electrode evaporation.
Can anyone:
Tell me what these Neon Bulbs are for?

They are spark gaps.

Seems a bit strange they all have darkened glass.


NT

Those have darkened glass even when they are new.

I've seen a LOT of flat CRT Sony monitors with bad CRTs that cause
arcing and loss, or change of focus.
Andy Cuffe

acuffe@gmail.com

Hi Andy,
Thanks a lot for the info about the 'Neon' spark gaps having a dark coating
from new. I wouldn't have considered that possibility.
The intermittent blur seems to have stopped for now, but I always got the
impression it was worse in cold weather. My hope was that if it turned out
to be the tube I might help it with a bit of carefully placed thermal
insulation.

Scrim