Toshiba TV29C90 problem; Image fades to black...

Yes i have some thought but why did you check your speakers for your
problem ? This is confusing. Does it turn on at all or not ? itf the
unit doesn`t turn on then it is not the speakers. What all did you
check on this unit. Did you atleast check for bad solder connections
? I have the schematic but I am not sure if you know how to read it
to undersatnd it to help you to locate your problem. Please give us
some more detail besides just checking speakers.
 
Service manuals are available from Yamaha for about $18, but unless you are
trained or have a lot of experience on these units, they can be a bear for
even a good tech. Could be a leaky backup cap, which have been known to
cause problems on some Yamaha receivers. Needs some real diagnosis. I'd
look for a shop that is a Yamaha ASC or at least does a lot of Yamaha
service.

Speakers would not likely cause intermittent power on. Curious, though, how
did you "check" the speakers?

Leonard

"jw51" <western@webace.com.au> wrote in message
news:1141539005.552320.191660@i39g2000cwa.googlegroups.com...
No power on function, started becoming difficult to turn on over a
couple of days.

Checked speakers(Bose lifestyle) could find no problem.

Am trying to source a service manual for it.

Any ideas?
Click to expand...
 
Thanks Leonard,
I inherited the Model HK 380i from our son and would like to restore it. He
apparently had it worked on by someone who butchered it, but it seems to be
a fine piece of equipment..

I know the 4 power transistors and shorted/open and have ordered the NTE
replacements. A dual 0.33 ohm, 3 watt resistor is missing in one channel
(but present in the other channel... that's how I knew the value) and a
couple of driver transistors are missing. I have no clue as to what kind
they are. I've checked with Harman/Kardon and they don't have service
manuals this old.

Other than that, the FM/AM works up through the discriminator and operates
the dial pointer, which indicates received signal strength.


The maunal would be helpful with the block diagram. I appreciate your offer
and would like to see the manual.

Dan Street

dstreet@nc.rr.com


"Leonard Caillouet" <no@no.com> wrote in message
news:w_zOf.80320$bF.12873@dukeread07...
What is wrong with the unit? I have a .pdf scan of the manual but it does
not have a schematic. If you need the alignments or block diagram only it
might be useful.

Leonard

"Dan Street" <dstreet@nc.rr.com> wrote in message
news:GPrOf.29513$915.17243@southeast.rr.com...
If anyone knows how I can obtain a schematic for a Harman/Kardon Model
HK-380i

receiver, I sure would appreciate your letting me know. It's a solid
state AM/FM

stereo receiver with a 50 watt RMS per channel amplifier, manufactured
around 1982.

Thanks in advance for your help.
Click to expand...
 
Howdy Corey.....No specific help but it sure sounds more like a
mechanical connection that's being influenced by the heat rather than
a circuit problem (inside or outside of the chip). Is the 1451 an SMD?
Was wondering if maybe you could socket it otherwise. Might just be a
case of a little too much heat when soldering if it's seperating inside
the chip perhaps. Looking forward to see what you might find

Gord




imapeppertoo@excite.com wrote:

Bought some old LCD monitors with non-functioning backlights. In
examining the CCFL driver circuit, it appears to be at Texas
Instruments TL1451 PWM regulator chip driving essentially a solid state
tesla coils for the HV/HF output.

Did some checking with my scope and found the 1451 didn't appear to be
switching the output transistors, so I replaced it with a new 1451 chip
and everything works great. I shut the power off and come back 10
minutes later to button up the case and the lights won't turn on again!

To make a long story short, through trial and error, I found that if I
touch any lead of the chip for a few seconds with a soldering iron
(heat it up) the chip works and back lights come on. If it cools off
to room temp, the chip won't work. So now I have two monitors with the
original chips and two monitors with new chips that do the same thing.
I sat down with one chip and could literally touch a lead for 3 seconds
with the soldering iron and get it to function normally, then put a
couple drops of liquid freeze on it and the chip would quit.

Anybody know why my chips work at say 120F, but not at room temp?

Thanks
Corey
Click to expand...
 
Mark D. Zacharias Wrote:
Maybe I can take a pic and e-mail it to you.


Mark Z.
Click to expand...

Email sent, I attached pics of the boards I'm dealing with also.


--
RDC
 
On 5 Mar 2006 07:37:29 -0800, imapeppertoo@excite.com wrote:

Bought some old LCD monitors with non-functioning backlights. In
examining the CCFL driver circuit, it appears to be at Texas
Instruments TL1451 PWM regulator chip driving essentially a solid state
tesla coils for the HV/HF output.

Did some checking with my scope and found the 1451 didn't appear to be
switching the output transistors, so I replaced it with a new 1451 chip
and everything works great. I shut the power off and come back 10
minutes later to button up the case and the lights won't turn on again!

To make a long story short, through trial and error, I found that if I
touch any lead of the chip for a few seconds with a soldering iron
(heat it up) the chip works and back lights come on. If it cools off
to room temp, the chip won't work. So now I have two monitors with the
original chips and two monitors with new chips that do the same thing.
I sat down with one chip and could literally touch a lead for 3 seconds
with the soldering iron and get it to function normally, then put a
couple drops of liquid freeze on it and the chip would quit.

Anybody know why my chips work at say 120F, but not at room temp?

Thanks
Corey
Click to expand...
Do you have some electrolytic caps near the chip?
 
"Damir" <nop@nop.hr> wrote in message
news:v72m021i7b4o5vestiku80057d1p1jkjuo@4ax.com...
On 5 Mar 2006 07:37:29 -0800, imapeppertoo@excite.com wrote:

Do you have some electrolytic caps near the chip?
Click to expand...
That's exactly what I was going to ask. I'll bet the heat from the IC is
simply being conducted to nearby faulty electrolytic caps.

Dave
 
Free download and you don't have to prove you know what you are doing.

http://manuals.harman.com/hk/Service%20Manual/hk380i%20sm.pdf




Dan Street wrote:
If anyone knows how I can obtain a schematic for a Harman/Kardon Model
HK-380i

receiver, I sure would appreciate your letting me know. It's a solid state
AM/FM

stereo receiver with a 50 watt RMS per channel amplifier, manufactured
around 1982.

Thanks in advance for your help.
Click to expand...
 
Gord - Thanks for the input. I guess at this point I would be willing
to consider anything. The 1451 is a 16-SOP package, so it is surface
mount and pretty tiny!. I took a look at my soldering under a 40x
microscope...it looked acceptable, but who knows!

Damir - Yes there are a couple of electrolytics near the chip. I put a
scan of the board up at:

http://coreyonline.tripod.com/CCFLdriver.jpg

C1 is 100uf, 25V and C2 is 10uF, 25V. These are really the only two
electrolytics on the board. There is a filter cap (blue) for each HV
output and then some surface mounts scattered on the board.
 
Gord - Thanks for the input. I guess at this point I would be willing
to consider anything. The 1451 is a 16-SOP package, so it is surface
mount and pretty tiny!. I took a look at my soldering under a 40x
microscope...it looked acceptable, but who knows!

Damir - Yes there are a couple of electrolytics near the chip. I put a
scan of the board up at:

http://coreyonline.tripod.com/CCFLdriver.jpg

C1 is 100uf, 25V and C2 is 10uF, 25V. These are really the only two
electrolytics on the board. There is a filter cap (blue) for each HV
output and then some surface mounts scattered on the board.
 
Gord - Thanks for the input. I guess at this point I would be willing
to consider anything. The 1451 is a 16-SOP package, so it is surface
mount and pretty tiny!. I took a look at my soldering under a 40x
microscope...it looked acceptable, but who knows!

Damir - Yes there are a couple of electrolytics near the chip. I put a
scan of the board up at:

http://coreyonline.tripod.com/CCFLdriver.jpg

C1 is 100uf, 25V and C2 is 10uF, 25V. These are really the only two
electrolytics on the board. There is a filter cap (blue) for each HV
output and then some surface mounts scattered on the board.
 
On 5 Mar 2006 08:52:03 -0800, imapeppertoo@excite.com wrote:

Gord - Thanks for the input. I guess at this point I would be willing
to consider anything. The 1451 is a 16-SOP package, so it is surface
mount and pretty tiny!. I took a look at my soldering under a 40x
microscope...it looked acceptable, but who knows!

Damir - Yes there are a couple of electrolytics near the chip. I put a
scan of the board up at:

http://coreyonline.tripod.com/CCFLdriver.jpg

C1 is 100uf, 25V and C2 is 10uF, 25V. These are really the only two
electrolytics on the board. There is a filter cap (blue) for each HV
output and then some surface mounts scattered on the board.
Click to expand...
Check or replace C2.
 
On Sun, 5 Mar 2006 15:21:32 +0200, "Bert"
<lijbertv_at_xsinet_dot_co_dot_za> wrote:

December around the 21st last year I did have a question on charging a
rechargeable alkaline AA battery.

Hope this will help someone sometime.

And the number of spontaneous exploding charging cells is still
zero, I guess ?

No exploding cells, do check every hour or so that the voltage on the
battery stays below 1.7 volt and the battery is still cool to touch.
Remember it is a rechargeable AA alkaline cell.
Click to expand...
My apologies.
I missed the part about the cell being 'rechargable Alkaline'.

--
Kind regards,
Gerard Bok
 
Get an estimate. Likely not too expensive to repair.

Leonard

"Kath" <kathg5@netzero.net> wrote in message
news:1141600031.190675.162360@u72g2000cwu.googlegroups.com...
Hello, I don't know if I should just buy a new TV or have this one
fixed. I realize it is 9 years old. May I have some advice?
Everything works but then the picture starts moving up vertically until
it just disappears altogether and the screen is dark. This happens
gradually as if something is squeezing the picture upwards but the
sound is just fine. Shall I have it repaired? I would appreciate some
opinions on this. Many thanks!

Kath

PS Wouldn't you know it, it is working right now but I'll bet it goes
by Oscar time.
Click to expand...
 
Take it to a tech who has experience with these units. Other than cleaning
the outer lens, I would not recommend a novice trying to take apart the
light path to clean it thoroughly.

Leonard

"Andy & Kim" <Andy@akmt.demon.co.uk> wrote in message
news:dufgqi$p78$1$8302bc10@news.demon.co.uk...
Hi, can anybody advise me of how i clean the optics on my Sanyo projector
that has been sat in the roof space of a smoky club without a housing. I
now have a housing and would like to get it clean before reinstallation.

Thanks
Click to expand...
 
imapeppertoo@excite.com wrote:

Bought some old LCD monitors with non-functioning backlights. In
examining the CCFL driver circuit, it appears to be at Texas
Instruments TL1451 PWM regulator chip driving essentially a solid state
tesla coils for the HV/HF output.

Did some checking with my scope and found the 1451 didn't appear to be
switching the output transistors, so I replaced it with a new 1451 chip
and everything works great. I shut the power off and come back 10
minutes later to button up the case and the lights won't turn on again!

To make a long story short, through trial and error, I found that if I
touch any lead of the chip for a few seconds with a soldering iron
(heat it up) the chip works and back lights come on. If it cools off
to room temp, the chip won't work. So now I have two monitors with the
original chips and two monitors with new chips that do the same thing.
I sat down with one chip and could literally touch a lead for 3 seconds
with the soldering iron and get it to function normally, then put a
couple drops of liquid freeze on it and the chip would quit.

Anybody know why my chips work at say 120F, but not at room temp?

Thanks
Corey

seems strange, always thought the 1451 was a dual generic op-amp?
Click to expand...
anyways, i would test the by pass cap at the Vcc, Vee area.
and other components in that area for solder cracks.
could even be the driver transistor that is just around the
area.


--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
 
Jamie wrote:

imapeppertoo@excite.com wrote:

Bought some old LCD monitors with non-functioning backlights. In
examining the CCFL driver circuit, it appears to be at Texas
Instruments TL1451 PWM regulator chip driving essentially a solid state
tesla coils for the HV/HF output.

Did some checking with my scope and found the 1451 didn't appear to be
switching the output transistors, so I replaced it with a new 1451 chip
and everything works great. I shut the power off and come back 10
minutes later to button up the case and the lights won't turn on again!

To make a long story short, through trial and error, I found that if I
touch any lead of the chip for a few seconds with a soldering iron
(heat it up) the chip works and back lights come on. If it cools off
to room temp, the chip won't work. So now I have two monitors with the
original chips and two monitors with new chips that do the same thing.
I sat down with one chip and could literally touch a lead for 3 seconds
with the soldering iron and get it to function normally, then put a
couple drops of liquid freeze on it and the chip would quit.

Anybody know why my chips work at say 120F, but not at room temp?

Thanks
Corey

seems strange, always thought the 1451 was a dual generic op-amp?
anyways, i would test the by pass cap at the Vcc, Vee area.
and other components in that area for solder cracks.
could even be the driver transistor that is just around the
area.


excuse me. it was the 1458 i was thinking of :))
Click to expand...


--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
 
dkuhajda@locl.net wrote:
Absolutely, unplug it to reset the system control. With all the
different manifestations of the Gemstar circuit in an RCA, many odd
problems are easily fixed with a simple unplugging to reset any
software glitches.

Beyond that troubleshooting by a qualified technician will be required.
Click to expand...
WHAT A PIECE OF SHIT WHO THE FUCK WOULD BUILT A TV THAT NEEDS TO BE
UNPLUGGED AND PLUGGED BACK IN TO WORK
 
"trm54321" <trm54321@hotmail.com> wrote in message
news:6dam0219h5vbn43bk9qf3ri83ehepog1bp@4ax.com...
Thanks, I contacted four suppliers today with two replying and no luck
so far...
This machine is pretty old...
I've added a search on eBay also and may have to wait until one shows
up also...
Cheers Dave

On Sun, 05 Mar 2006 09:53:37 -0800, JR North <jasonrnorth@bigfoot.com
wrote:

There are 3 machines on Ebay, but no manuals- now. I have found several
service manuals for my vintage Technics audio equipment on Ebay for a
few bucks each. Most of the service manuals are sold by volume sellers,
who list many different ones. You could try contacting some of them, and
see if they have one laying around. For instance:

http://stores.ebay.com/jchas555

JR

trm54321 wrote:

This is an older Beta machine I'm trying to repair that doesn't rewind
anymore.
Any suggestions and does anyone have a service manual for this vintage
deck?
Cheers Dave
*** Free account sponsored by SecureIX.com ***
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Click to expand...

The reel belt and idler tire(s) need to be replaced.

Mark Z.
 
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