Digest for sci.electronics.repair@googlegroups.com - 5 updates in 3 topics

9:45 AM Penedão
Robin Ingenthron <ingenthron@gmail.com>: Oct 04 01:26PM -0700

Thanks John-Del. That is similar to the instructions we got from the Ghana Africa guy who makes these. I was hoping that the Alibaba link ( finder.com.cn/Products/Details/LCDPower.htm ) will work.
 
Here is a link to a Powerpoint done in Ghana by the USA apprentices we sent to work under Master Technician Karim Zakaria.
https://docs.google.com/presentation/d/1nxPz3F66ngYVHUVwjtSDPP51EafaqhwHCM9LG0Qs2vQ/edit?usp=sharing
John-Del <ohger1s@gmail.com>: Oct 05 09:35AM -0700

On Wednesday, October 4, 2017 at 4:26:03 PM UTC-4, Robin Ingenthron wrote:
> Thanks John-Del. That is similar to the instructions we got from the Ghana Africa guy who makes these. I was hoping that the Alibaba link ( finder.com.cn/Products/Details/LCDPower.htm ) will work.
 
> Here is a link to a Powerpoint done in Ghana by the USA apprentices we sent to work under Master Technician Karim Zakaria.
> https://docs.google.com/presentation/d/1nxPz3F66ngYVHUVwjtSDPP51EafaqhwHCM9LG0Qs2vQ/edit?usp=sharing
 
 
This is a lot more complicated than sourcing an LED supply and connecting it to the existing LED array inside the screen.
 
If you want to source a universal supply to run existing LEDs, you must be sure that it can run independently from the donor's original main board. Very few power supplies will turn on the back lights without a pwm adj/brightness signal from the main board to set LED drive current.
 
One that I can think of that will run independently from a TV main board is this power supply included in recent certain RCA and ProScan TVs (possibly others):
 
http://www.shopjimmy.com/rca-re46hq1301-power-supply-unit.htm
 
This supply will run and output LED drive with only AC supplied. The on command can be enabled by using a 470 ohm resistor between the power supply's standby line (pin 8) and the on/off line (pin 9) of CON2 to turn the power supply on. You'll need to do the same between pin 8 of CON2 and pin 3 of CON4 to power up the LEDs. This will enable the backlights with no input to the "adj" line although the output of the supply will be reduced (which is a good thing to ensure LED longevity).
 
The first problem is that this supply needs a balanced load on the LED outputs, so you'll need to divide the LED strips into equal pairs. If the donor TV has an odd amount of LED strips, this may trigger LED shutdown (some do, some don't). You may have to rewire the strips in order to present two identical loads to the two output terminals of the LED output on the power supply (CON5) Another problem is that TV power supplies adjust it's LED voltage output in order to regulate to a specific current, and so some LED strings might require more voltage to reach the required run current than this particular supply is capable of.
 
The point I'm trying to make is that you aren't going to be able to teach trained monkeys to do this job if you intend to make these signs in quantity. The workers will need to possess a working understanding of electronics and basic design. Almost every job will be a custom one as there is an almost infinite number of LED TV designs in the market. If the assembler manages to get it running but doesn't monitor run current, the sign may fail within minutes or hours.
 
It would be far easier to buy LEDs on flexible ribbons, buy the controller that is used with these types of LED ribbons, and install these inside the screen. You can even program color changes and brightness as well as remote control of on/off with these:
 
http://www.ebay.com/itm/5050-RGB-LED-Strip-Decorative-Light-Tape-Ribbon-with-44keys-IR-Remote-Controller-/162535694280?var=461540370055&hash=item25d7e1dfc8:m:mw_r_9Ul6iUCkrWlmvnaFqA
 
If the LEDs you install have an uneven appearance on the TV screen, you can pop the lens' off the donor LED strips and carefully glue them over the dead center of the new LED.
Hugo <f6ceedb9c75b52f7fcc0a55cf0cfbf5d_1059@example.com>: Oct 05 03:37AM

responding to
http://www.electrondepot.com/repair/icepower-200asc-amp-module-165648-.htm ,
Hugo wrote:
 
> Hola, el condensador es de 2,2pf 2kv y poner un fusible de 3,15a y a
> funcio
> nar.
 
Hi and thanks for info. I've been looking at this on and off for a long time!
With my very limited but growing (mostly iPhone and Mac logic board)
electronics knowledge I'm still rather unsure of what to do to fix the amp.
 
So avoid SMD - Use something like a single layer ceramic through hole?
600v to 2kv from looking through the thread
2.2pf or whatever pf can fit for component size?
A fuse 3.15amp so the cap doesn't keep blowing or maybe the 3 resistors in
series after the cap... - something leaded and I'm lost on voltage here, 250v?
 
perhaps this cap -
http://au.rs-online.com/web/p/ceramic-single-layer-capacitors/8312929/
with this fuse -
http://au.rs-online.com/web/p/non-resettable-wire-ended-fuses/8951678/
 
Any help would be super appreciated, I'm in dire need of BASS!!!
Peter Easthope <petereasthope@gmail.com>: Oct 04 10:53AM -0700

> connect the camera to an NTSC monitor and see what happens?
 
Thanks for the reply.
 
A Sony Trinitron CVM-1270 is available here. I haven't found specs
for it but the manual for the PVM-1353MD and PVM-1953MD is at
https://docs.sony.com/release//PVM1353MD.PDF. On page 13 "Color system
NTSC, PAL". Haven't found anything about switching. Appears these
monitors recognize NTSC and PAL and switch automatically.
 
When the JVC TK-1070U camera is connected to the Sony CVM-1270
monitor, it produces an image. Nothing yet convinces me that the
camera output is NTSC or NTSC-J recognizeable by the Hauppauge card.
 
Can NTSC and PAL be distinguished reliably with an oscilloscope?
Instructions on a Web page? I havn't found anything specific.
 
Thanks, ... Peter E.
"pfjw@aol.com" <pfjw@aol.com>: Oct 04 11:10AM -0700

On Wednesday, October 4, 2017 at 1:53:19 PM UTC-4, Peter Easthope wrote:
 
> https://docs.sony.com/release//PVM1353MD.PDF. On page 13 "Color system
> NTSC, PAL". Haven't found anything about switching. Appears these
> monitors recognize NTSC and PAL and switch automatically.
 
We are presently using a 30" Sony that switches between NTSC, PAL, SECAM, et.al. as needed. So, this does not surprise me. Also between 100, 120, 220 & 240, 50/60 HZ.
 
Peter Wieck
Melrose Park, PA
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