Toshiba TV29C90 problem; Image fades to black...

[bz]

Dick <w6ccd@k7yca.org> wrote in news:1e9nv3h6uskeei64q8i1j94elo7dhijpsl@
4ax.com:

I have a high voltage power supply (Swan 117cx) that may be the cause
of high distortion in the radio it supplies power to. How would I
test for excessive ripple, etc? The voltages are correct.
** Posted from http://www.teranews.com **

If you don't have a scope, look at the AC voltage on the DC lines.
Transmit into a dummy load and see if you get AC on the DC line as you
modulate the rig.

You need to have some idea HOW MUCH ac is allowable. Perhaps the specs of
the rig will help.
In any case, the AC should be MUCH less than the DC voltage.







--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[bz]

Dick <w6ccd@k7yca.org> wrote in news:1e9nv3h6uskeei64q8i1j94elo7dhijpsl@
4ax.com:

I have a high voltage power supply (Swan 117cx) that may be the cause
of high distortion in the radio it supplies power to. How would I
test for excessive ripple, etc? The voltages are correct.
** Posted from http://www.teranews.com **

If you don't have a scope, look at the AC voltage on the DC lines.
Transmit into a dummy load and see if you get AC on the DC line as you
modulate the rig.

You need to have some idea HOW MUCH ac is allowable. Perhaps the specs of
the rig will help.
In any case, the AC should be MUCH less than the DC voltage.







--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[Jim Yanik]

Dick <w6ccd@k7yca.org> wrote in
news:b3inv3hvl12onvq467peg8pjt0mc8eb9n2@4ax.com:

On Tue, 08 Apr 2008 14:18:56 -0400, Bill M <radioexray@geeeemail.com
wrote:

Dick wrote:
I have a high voltage power supply (Swan 117cx) that may be the cause
of high distortion in the radio it supplies power to. How would I
test for excessive ripple, etc? The voltages are correct.

Transmit, receive or both? You can't rule out the PS entirely if its
only on transmit but you have the added possibility of rf getting in via
the mic, etc.

Yep, scope it under load. You can even use a DMM or VTVM set to AC. Of
course you need to know the original specs or a ballpark idea how much
ripple (%-wise) is to be anticipated in order for the readings to be
meaningful.

GL,
Bill
** Posted from http://www.teranews.com **

Thanks Bill. I wanted to use my DVM (Fluke 87), but don't know the
original specs on the power supply. I have been trying to find them
on the Internet.

Dick
** Posted from http://www.teranews.com **

The DC blocking cap on your DMM better be good enough for the AC voltages
you're measuring....

a TEK P6015A HV probe and a scope would measure your HV supply ripple.
Safer,too.

--
Jim Yanik
jyanik
at
kua.net

 

[James Sweet]

"PeterD" <peter2@hipson.net> wrote in message
news:n7unv3pul408ci5si72lickv2hvp6hej5g@4ax.com...

On Tue, 08 Apr 2008 17:17:17 GMT, "James Sweet"
jamessweet@hotmail.com> wrote:



"Dick" <w6ccd@k7yca.org> wrote in message
news:1e9nv3h6uskeei64q8i1j94elo7dhijpsl@4ax.com...
I have a high voltage power supply (Swan 117cx) that may be the cause
of high distortion in the radio it supplies power to. How would I
test for excessive ripple, etc? The voltages are correct.
** Posted from http://www.teranews.com **

Scope it under load.


With a suitable highvoltage probe.

Well that's a given. He didn't specify how high the "high voltage" is, if
it's only a few hundred volts, a normal 10x probe should be fine. Up to a
couple thousand, a simple resistor divider will work ok.

 

[James Sweet]

"Terryc" <newsthreespam-spam@woa.com.au> wrote in message
news:47fc7ca5$0$18363$c30e37c6@pit-reader.telstra.net...

This is something circa 1982. Consisted of a largish, for hand held,
camera and a matching VHS recording pack carried on a shoulder strap. It
ran off a NiCd battery pack. Also came with a mains power station that
could recharge the NiCd pack and distribute the wideo signal

When it was last used, the camera worked, aka image on the sperate CRT in
the hand held bit and on the vcr outlets on recording pack and base
station(?)

I am now trying to run the camera standalone, but think I'm stumped as it
requires certain signals from the recording pack. Both the camera and the
mains station had standby settings, which i suspect responded to a button
on the recording pack. Unfortunately the recording pack has been binned,
but the internal sockets kept for camera and mains station.

Also have been unable to find anything helpful on the internet about this
unit. Even the manual floggers have given up trying to make out they have
manuals.

Basically looking for cluebies to understand it better.

The mains station has a 11 wire plug and when powered on, provides the
following voltages on the following wires
red -18.7V
purple -19.1 V
black 0.0 V
light blue +2.5 V

The camera has an ten wire plug with wire colours matching the first ten
colours of the mainsd station plug.

If the black and red wires and joined to their matching colours on the
camera plug, a relay clicks in the mains station, but voltages alter
significantly.

Red -18.1V to -8.1V
black 0.0V
light blue +2.5V to +7.4V (not connected across)

Seven of the remaining 8 wires on the camera plug then return -1.2V. the
8th(gray) is 0.0V.

But, the power led on the camera is still unlit.

Tried disassembling the camera to see if I could find out where the wires
went internally, but it requires compled board on each side to be removed
and disonnects as the cable entry is really buried underneath the main
camera.

Would like to get the camera working as it has auto iris and auto focus.

T.I.A.

These usually had power supplies available which mated to the camera and
provided composite video and audio out. You might find one of those on ebay
or at a thrift store, but that stuff is getting really old.

 

[GregS]

In article <0n6Lj.1406$Cn4.367@news02.roc.ny>, "Gary L. woodruff" <woodruffrepair@frontiernet.net> wrote:

Howdy, I am new here and am wondering if anyone has a print or can help
me with this repair. Amp came to me with blown output chips. I cross
referenced the obsolete transistors and replaced all 4 outputs. I now
can power up and have a nice clean signal on the left channel. The right
channel is very distorted and attenuated. Any help would be greatly
appreciated.

I would check all input devices driving the outputs and the bias, etc.
Check DC levels.

greg

 

[Arfa Daily]

"Gary L. woodruff" <woodruffrepair@frontiernet.net> wrote in message
news:fp7Lj.1408$Cn4.1109@news02.roc.ny...

Thanks Greg, I have been out of the repair end for a while (25 yrs) so
could you elaborate? I have checked the input signal of the channel and it
looks clean. I do see the distorted output right at the output of the
amplifier board.

Thanks, Gary

With faults like this, a good exercise is often to just compare channels
using a simple ohm meter. With the unit off, and the main PSU filter caps
fully discharged, just hook one lead to ground, and then probe corresponding
points between a working channel, and the one that's bad. If the amp that
you are working on has suffered blown output transistors, I would be looking
for open circuit series resistors in the bases of the output devices. They
are usually low value, and it's very common for them to fail when the
outputs do. Also, check the output transistor emitter resistors carefully.
Although they will usually fail open when the output devices blow, they can
also go high, which can be difficult to spot by just doing a cursory run
over them with your meter. When a nominal 0.02 ohm resistor has risen to 5
ohms, it still looks pretty much like a 'short', unless you check exactly
what the meter is saying, particularly if you are using an analogue one.

Arfa

 

[Mark D. Zacharias]

"Gary L. woodruff" <woodruffrepair@frontiernet.net> wrote in message
news:0n6Lj.1406$Cn4.367@news02.roc.ny...

Howdy, I am new here and am wondering if anyone has a print or can help me
with this repair. Amp came to me with blown output chips. I cross
referenced the obsolete transistors and replaced all 4 outputs. I now can
power up and have a nice clean signal on the left channel. The right
channel is very distorted and attenuated. Any help would be greatly
appreciated.


Gary

Look for an open 220 ohm (surface-mount) resistor across the emitter-base
junction of each of the output transistors.

Be sure to bleed off the power supply voltages first! There are two sets of
higher voltage rails on these. Measure from ALL of the output transistors'
emitters to ground - these units apply B+ to the emitters, not the
collectors.

Mark Z.

 

[Mark D. Zacharias]

"Gary L. woodruff" <woodruffrepair@frontiernet.net> wrote in message
news:rSuLj.1442$NU2.1353@news01.roc.ny...

Mark, Thanks for the tip. I have not done too much component level repair
in about 20 yrs. I am assuming by surface mount resistor you mean the ones
that are so small I cant see them without magnification (20 yrs means I
now need bifocals)!. If so, any tips for removing and checking such a
small component? (other than don't drop it once removed!)

Thanks much,

Gary

Just measure across the emitter - base junction of each of the involved
output transistors, and you can either trace back and find the bad one, or
just solder a 1/4 watt or smaller flameproof type across the E-B junction of
the transistor that is missing one.

I get them from Pioneer, but not so many these days of course.

Mark Z.

 

[Mark D. Zacharias]

"Gary L. woodruff" <woodruffrepair@frontiernet.net> wrote in message
news:rSuLj.1442$NU2.1353@news01.roc.ny...

Mark, Thanks for the tip. I have not done too much component level repair
in about 20 yrs. I am assuming by surface mount resistor you mean the ones
that are so small I cant see them without magnification (20 yrs means I
now need bifocals)!. If so, any tips for removing and checking such a
small component? (other than don't drop it once removed!)

Thanks much,

Gary

Just measure across the emitter - base junction of each of the involved
output transistors, and you can either trace back and find the bad one, or
just solder a 1/4 watt or smaller flameproof type across the E-B junction of
the transistor that is missing one.

I get them from Pioneer, but not so many these days of course.

Mark Z.

 

[GregS]

In article <fba8bd9e-51c0-4c5e-be41-4bc6ad0fd0b5@8g2000hse.googlegroups.com>, rush14 <rush14@columbus.rr.com> wrote:

I'm wanting to install some solar powered landscape lights but I don't
like the orange colored LEDs or the bluish tint of the so called white
LEDs.

I was thinking of buying some of the solar lights advertised as super
bright white LEDs and replacing the LEDs with what are referred to as
super bright warm white LEDs. The low voltage powered lights are not
an option.

I welcome your thoughts and suggestions.

Thanks,
Rush

This may be a bit off topic but at least I'm not hawking Chinese made
handbags or porno videos.

I'm on the same train. Its just harder to find them and they tend to cost more.
I used some boards from Led Supply that are made to mimic an outdoor
lamp socket. You mount led's to the board. I think its made for 4.
I like using the yellow or orange lamps. they are best for walkways, decks etc.
I should order some neutral or warm whites K2's. These are the biggies.
http://www.ledsupply.com/k2star.php
You can wire these up in series for 12 volt use. I ordered some small whites
from somebody, but they generally run over $1 a piece. I actually bought a pack of 4
at Advance Auto to put in my car. They are made for 12 volts. They actually run a little
too warm with the dropping resistor generating a lot of heat near the LED.

greg

 

[GregS]

In article <ftnvei$e6b$1@usenet01.srv.cis.pitt.edu>, zekfrivo@zekfrivolous.com (GregS) wrote:

In article <fba8bd9e-51c0-4c5e-be41-4bc6ad0fd0b5@8g2000hse.googlegroups.com>,
rush14 <rush14@columbus.rr.com> wrote:
I'm wanting to install some solar powered landscape lights but I don't
like the orange colored LEDs or the bluish tint of the so called white
LEDs.

I was thinking of buying some of the solar lights advertised as super
bright white LEDs and replacing the LEDs with what are referred to as
super bright warm white LEDs. The low voltage powered lights are not
an option.

I welcome your thoughts and suggestions.

Thanks,
Rush

This may be a bit off topic but at least I'm not hawking Chinese made
handbags or porno videos.

I'm on the same train. Its just harder to find them and they tend to cost more.
I used some boards from Led Supply that are made to mimic an outdoor
lamp socket. You mount led's to the board. I think its made for 4.
I like using the yellow or orange lamps. they are best for walkways, decks etc.
I should order some neutral or warm whites K2's. These are the biggies.
http://www.ledsupply.com/k2star.php
You can wire these up in series for 12 volt use. I ordered some small whites
from somebody, but they generally run over $1 a piece. I actually bought a pack
of 4
at Advance Auto to put in my car. They are made for 12 volts. They actually run
a little
too warm with the dropping resistor generating a lot of heat near the LED.

These I'm referring to are bluish whites.

greg

 

[James Sweet]

"GregS" <zekfrivo@zekfrivolous.com> wrote in message
news:ftnvei$e6b$1@usenet01.srv.cis.pitt.edu...

In article
fba8bd9e-51c0-4c5e-be41-4bc6ad0fd0b5@8g2000hse.googlegroups.com>, rush14
rush14@columbus.rr.com> wrote:
I'm wanting to install some solar powered landscape lights but I don't
like the orange colored LEDs or the bluish tint of the so called white
LEDs.

I was thinking of buying some of the solar lights advertised as super
bright white LEDs and replacing the LEDs with what are referred to as
super bright warm white LEDs. The low voltage powered lights are not
an option.

I welcome your thoughts and suggestions.

Thanks,
Rush

Sure, just get the type with white LEDs, and replace the LEDs with the warm
white type.

 

[James Sweet]

"GregS" <zekfrivo@zekfrivolous.com> wrote in message
news:ftnvei$e6b$1@usenet01.srv.cis.pitt.edu...

In article
fba8bd9e-51c0-4c5e-be41-4bc6ad0fd0b5@8g2000hse.googlegroups.com>, rush14
rush14@columbus.rr.com> wrote:
I'm wanting to install some solar powered landscape lights but I don't
like the orange colored LEDs or the bluish tint of the so called white
LEDs.

I was thinking of buying some of the solar lights advertised as super
bright white LEDs and replacing the LEDs with what are referred to as
super bright warm white LEDs. The low voltage powered lights are not
an option.

I welcome your thoughts and suggestions.

Thanks,
Rush

Sure, just get the type with white LEDs, and replace the LEDs with the warm
white type.

 

[GregS]

In article <fc825465-18f3-4e23-98ed-00af4aaba56d@f36g2000hsa.googlegroups.com>, z <gzuckier@snail-mail.net> wrote:

On Apr 11, 10:55=A0am, rush14 <rus...@columbus.rr.com> wrote:
I'm wanting to install some solar powered landscape lights but I don't
like the orange colored LEDs or the bluish tint of the so called white
LEDs.

I was thinking of buying some of the solar lights advertised as super
bright white LEDs and replacing the LEDs with what are referred to as
super bright warm white LEDs. =A0The low voltage powered lights are not
an option.

I welcome your thoughts and suggestions.

Thanks,
Rush

This may be a bit off topic but at least I'm not hawking Chinese made
handbags or porno videos.

replace the batteries with high capacity ones too, while you're doing
the surgery. the stock batteries are ridiculous.

In places where there is little sun, like Pittsburgh, it doesn't much
matter on battery type. The problem with most of the lamps
is their build quality. You have to waterproff them, and use silicon
grease to coat the batteries and contacts. I bought some really good
floods at Harbor Freight, but that design is no longer available. I ordered some
warm whites from LED Supply. 4000 Neutral white and 3000 warm light. I don't know the temp
of the 5 mm I bought.

greg

 

[Spamm Trappe]

On Fri, 11 Apr 2008 14:26:12 -0500, cuhulin@webtv.net wrote:

Many years ago, I read in a book or magazine, the little short guy had
something to do with inventing or improving something to do with
refrigeration.What was it?

Whatever it was, it probably had *nothing* to do with _sci.electronics.repair_.

 

[Spamm Trappe]

On Fri, 11 Apr 2008 14:26:12 -0500, cuhulin@webtv.net wrote:

Many years ago, I read in a book or magazine, the little short guy had
something to do with inventing or improving something to do with
refrigeration.What was it?

Whatever it was, it probably had *nothing* to do with _sci.electronics.repair_.

 

[Rheilly Phoull]

"rockinnomo" <hlbucklin@verizon.net> wrote in message
news:985e8812-c3ce-47ab-a362-8179bd548e48@q27g2000prf.googlegroups.com...

I posted this a while back and am still needing help so here it is
again. PLEASE E mail me directly hlbucklin@verizon.net

My electronics tech is having trouble fixing an SAE Two amplifier
model A-14. It has no audio output. If he shorts across a relay the
audio works fine. He has a good service manual but can't track down
what the problem is. Does anyone know what the problem may be
specifically? It was repaired for the same problem by another tech
and
the repair didn't last long. I do know that 4 ohm speakers are a no-
no. He's testing with headphones. Sure would appreciate some help
here. Please eMail me at hlbuck...@verizon.net.
Harvey

Phil has given you good advice.

--
Cheers ............. Rheilly

 

[Arfa Daily]

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:TYGdnXEfprc0aGLanZ2dnUVZ_qiinZ2d@earthlink.com...

EricM wrote:

I have replaced two old Federal/ITT selenium rectifiers in an
amplifier power supply with new silicon diodes; the original part
numbers are 103H4AX1 and 104B1AX1. I can't find any reference to
either part on the web - anywhere - ITT can't even provide
information. Since one of the legs of the circuit supplies the plate
voltage (600V) I used 600V 10A diodes (NTE5815HC) to be safe. Problem
is, there is a time-delay relay that closes to engage the 600V
circuit, and without it attached to the amp; all tube supplies,
biasing voltage, etc. are normal. If hooked up, once the relay closes
- the main power fuse blows. I'm guessing I need a dropping resistor,
but it would be nice to have the original data on the selenium parts
to be able to figure out the value. The 600V and the -38V biasing
voltage are derived from the same part of the power transformer. The
-38 side works, but the 600V side reads upwards of 927 volts without a
load. Using a Variac, the plate voltages were above 600V at about 70
percent. Is there a way to find the original specs on these selenium
parts? Any leads would be greatly appreciated!


If the DC voltage is 600 volts you need higher voltage diodes. That
is a PIV rating, not an RMS rating like they used on Selenium
Rectifiers. As a minimum you need 600 * 1+1.414 PIV. That is 600 for
the voltage across the capacitor, and 600*1.414 (848.4) volts when the
AC line reverses polarity, for a total of 1448.4 volts. That assumes
your line voltage never exceeds the rated transformer input, no spikes
from motors or other heavy loads, no lightning induced surges. As a
MINIMUM, I would use three 1000 PIV diodes in series to replace each
section of the original rectifier.

So would I, along with 10 watt wirewound resistors with a starting value of
say 1k

Arfa

 

[Arfa Daily]

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:TYGdnXEfprc0aGLanZ2dnUVZ_qiinZ2d@earthlink.com...

EricM wrote:

I have replaced two old Federal/ITT selenium rectifiers in an
amplifier power supply with new silicon diodes; the original part
numbers are 103H4AX1 and 104B1AX1. I can't find any reference to
either part on the web - anywhere - ITT can't even provide
information. Since one of the legs of the circuit supplies the plate
voltage (600V) I used 600V 10A diodes (NTE5815HC) to be safe. Problem
is, there is a time-delay relay that closes to engage the 600V
circuit, and without it attached to the amp; all tube supplies,
biasing voltage, etc. are normal. If hooked up, once the relay closes
- the main power fuse blows. I'm guessing I need a dropping resistor,
but it would be nice to have the original data on the selenium parts
to be able to figure out the value. The 600V and the -38V biasing
voltage are derived from the same part of the power transformer. The
-38 side works, but the 600V side reads upwards of 927 volts without a
load. Using a Variac, the plate voltages were above 600V at about 70
percent. Is there a way to find the original specs on these selenium
parts? Any leads would be greatly appreciated!


If the DC voltage is 600 volts you need higher voltage diodes. That
is a PIV rating, not an RMS rating like they used on Selenium
Rectifiers. As a minimum you need 600 * 1+1.414 PIV. That is 600 for
the voltage across the capacitor, and 600*1.414 (848.4) volts when the
AC line reverses polarity, for a total of 1448.4 volts. That assumes
your line voltage never exceeds the rated transformer input, no spikes
from motors or other heavy loads, no lightning induced surges. As a
MINIMUM, I would use three 1000 PIV diodes in series to replace each
section of the original rectifier.

So would I, along with 10 watt wirewound resistors with a starting value of
say 1k

Arfa