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Old 14 August 2015, 18:35   #301
John Man
 
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Oh, and just one other thing I noticed the other day and would like to show you all.

I own a "big" Panasonic CRT TV and when I went through the owner's manual instructions, on the page relating to audio/video connections there is a warning note specifically stating "do not connect to this device a computer with a TTL output of 5V".

Now, is that a coincidence or what?

Sorry for picture quality and language but it translates to exactly what I have written above.








So, this seems to backup and reinforce the idea that care should be taken when making connections involving certain types of signal and amplitude on TV's.

Fortunately, I don't remember ever connecting the Amiga to this TV and hopefully will not try to find out what happens untill I take proper precautions by making a cable with the 330ohm resistor.

Last edited by John Man; 14 August 2015 at 20:45.
 
Old 23 August 2015, 19:54   #302
John Man
 
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Quote:
Originally Posted by Stedy View Post

..., something I missed, is the DC offset of the Amiga video signal. Black level is about 600mV, it should be 0-50mV. This has an easy fix, on each of the RGB signals, add a 220uF capacitor, + end to the Amiga output. This will AC couple the video, with minimal droop...

Ian
Would this also apply to an Amiga 500?
 
Old 19 November 2019, 09:05   #303
fpmpaolo
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Hello people, can I use a 150ohm instead of a 75ohm at pin 23 (SCART 16)?
"The BLANK signal (pin 16 of the SCART) is fed from +5V via a 75 ohm resistor, which together with the 75 ohm terminator in the TV, creates a voltage of 2.5V, adequate to RGB input mode."
Image says 47 to 270ohm acceptable range of values.
I couldn't find a 75ohm resistor at work.
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Old 29 January 2020, 05:37   #304
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Quote:
Originally Posted by fpmpaolo View Post
Hello people, can I use a 150ohm instead of a 75ohm at pin 23 (SCART 16)?
"The BLANK signal (pin 16 of the SCART) is fed from +5V via a 75 ohm resistor, which together with the 75 ohm terminator in the TV, creates a voltage of 2.5V, adequate to RGB input mode."
Image says 47 to 270ohm acceptable range of values.
I couldn't find a 75ohm resistor at work.

hello using 150 ohm it will result in 1.67V, while using 220 ohm (which I do recommend) it will be 1.27V
200 ohm is more compatible with asian TV models/brands
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Old 07 April 2020, 11:00   #305
stevew
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Hi,

I bought an Amiga SCART cable from ebay, the cable works on my Panasonic G20 LCD TV from 2010 (although picture cropped on left slightly), and it works perfectly on my 21" Samsung LCD TV from 2017, no cropping and picture quality on both TV is excellent. Its made up of 9 cores + 1 ground wire, so the only ground wires connected are SCART pin 17 ---> Amiga pin 17 and SCART pin 18 ---> Amiga pin 19, and it has a 470ohm resistor on CYSNC (SCART pin 20) and a 180ohm resistor on BLANK (SCART pin 16)

I bought a 5m fully wired SCART to SCART and cut it in half, added a cut down db25 connector and the resistors as above. Plugged it into the Samsung LCD TV, works fine, no issues, great picture quality, plugged it into Panasonic and I get an issue with the picture jumps about every few seconds like it has not got a lock,sometimes when it jumps it flashes black.

I measured voltage with a mm, as my cable is 20 core with smaller wire gauge so resistance is slightly higher.

ebay cable measurements
CSYNC (470ohm resistor) - 0.484v
BLANK (180ohm resistor) - 1.430v

My cable
CSYNC (470ohm resistor) - 0.469v
BLANK (180ohm resistor) - 1.377v

Tried different resistors no difference on Panasonic
CSYNC (390ohm resistor) - 0.538v
BLANK (100ohm resistor) - 1.960v

I disconnected the 12v supply for SWITCH to see if that was causing interference, no difference on the Panasonic TV.

Wondering if anyone could assist here as to what the issue could be and what I should try next?

Thanks
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