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Member Since 14 Jan 2017
OFFLINE Last Active May 5 2019 12:47 PM

#3687468 Composite mod Coleco Telstar

Posted by Kain3n on Sat Feb 4, 2017 2:10 AM

OK update. so I tried the circuit with the 2.2k and 3.3k resistors as seen above and blank screen again. and then tried replacing the elecrolytic capacitors and no change. and then i finally solved it! well 98% solved it lol. as you said Sly DC it wasn't getting enough power. i tried my volt meter on the telstar adapter out of curiostiy and it was actually putting out slightly higher than 9v even though it was rated for 9v (meter showed 12 but the tv scoreboard was at 8.9v... my meter probably sucks lol) so i tried another adapter and BAM! crystal clear. the paddles how ever are just slightly glitchy on the screen i tried the testar adapter and same thing but it doesn't stop this pong unit from being fully playable now so might just leave it as is unless you have an idea what i can check. here is a video of the display now not the paddles glitching slightly. 

#3684985 Composite mod Coleco Telstar

Posted by Kain3n on Wed Feb 1, 2017 1:54 AM

First time I have seen a color pong unit! neat!. I am also going to use your hollowing of the RF box to use the RCA connector and keep the unit looking original from the outside alex_79 so thanks for the tip, that is... if I ever get this thing to work properly lol. and Sly DC Thanks for getting back to me, I know you are a busy man and appreciate the help when ever you are able to give it  :) so where my progress currently stands. The video above that I took yes all pins 6,9,10,and 24 are all tied together and going directly to the output. I have tried the circuit with all the extra parts that I originally asked about and get no display at all on the TV so I re-did the circuit again with another set of pieces in case something was defective and same result blank screen. I have now tried the circuit you drew up for me and same result just blank screen on the TV. I also tried it with the 75 ohm resistor and also no luck. only way I get any display at all is with all pins tied together and going directly out. I am using an AC adapter. I took 2 Adapters i grabbed from the local thrift store (one with a tip the fits the console and one with the right voltage(9v 350mA)) and spliced the tip onto the 9v plug making sure it was a positive tip to match the circuit board. checked with my meter and it is putting out 9v so low power or incorrect tip polarity shouldn't be the issue. looks like alex_79 used this circuit for the Atari for his pong unit


maybe I will pick up some 2.2k and 3.3k resistors (worst case I can use them on my Atari 2600 and 7800 if I mod those later) and try this circuit out next, I am thinking i'll still get the same blank screen results though. this pong unit and transistor circuits don't seem to like each other so far. I read somewhere that electrolytic capacitors are more likely to fail than ceramic ones? there are two 220uf 16v axial electrolytic capacitors on the circuit board right next to the power input so I will try replacing those next as well. the rest of the capacitors are ceramic ones so will leave them alone for now untill i try these other two things.