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Composite mod Coleco Telstar

RevEng

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#26 Kain3n OFFLINE  

Kain3n

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Posted Fri Jan 20, 2017 8:22 PM

so... i think i should have quit while i was ahead. the TV scoreboard was working with the RF video but picture was a little wavy, that's why I was going to try the composite mod on it too. when I tried it with the Telstar method you could tell it needed it's signal boosted because it was very faint as in the picture above and still wavy. so I think the wavy-nes has nothing to do with the video but decided to finish the composite mod and deal with the wavy later. i managed to find a place local here that sells the transistors and picked it up. and since i had all the parts already i tried to do it as the schematic i originally posted and boom nothing but black screen. i noticed i had damaged the trace leading to pin 4 Vcc (musta pulled on the wire too hard when soldering.) so i unsoldered everything and repaired the trace and tested it with a multimeter to ensure continuity. and tried to hook it up with the original RF connection to test and nothing but static on the screen now. can still hear the ball bouncing but no video i have metered all traces that i touched out for continuity and they are all ok so not sure why no video now...  i am going to try it next with your 4 part way to see if i can hopefully get video. but i need a little clarification on the wiring. i have made a drawing of what i think you meant when you explained it let me knoe if i got it right or if i need to change something before i start. i am gonna throw this thing back together for now until i hear from you thanks :)

IMG_3605.JPG



#27 Kain3n OFFLINE  

Kain3n

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Posted Mon Jan 23, 2017 5:32 PM

hey slydc,So I pulled it out again today and it's not dead. for some reason the RF signal just doesn't work anymore, out of curiosity i hooked it up like the Telstar again and get the same dim picture as before. I tried the circuit from before on it again and blank screen again. redid the circuit completely with new parts in case one was bad and again blank screen. so i pulled out the multimeter and it has the 5vdc going into the collector of the transistor. 90mV going into the base and an output on the emiter of 350mV. so maybe the transitor is no good? i have tried 2 though unless he sold me two bad ones... any ideas? if you could verify the drawing above if thats how you meant for your method I will try that instead but don't want to try it before you check it in case i fry something lol. let me knoe :) thanks



#28 Kain3n OFFLINE  

Kain3n

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Posted Mon Jan 23, 2017 11:12 PM

I had it hooked up like the Telstar no extra parts method again so I could try to figure out why the video is wavy, and I noticed that after few few seconds ( I had just turned it on then off before after seeing bad video) it actually goes clear video but extra wavy and cuts in and out like that so maybe the video mod is fine like this and what ever is causing the wavy video is the problem? i am not sure what to check for the wavy video problem? here is a link for a video i took of the screen

 

any ideas on what to test would be greatly apreciated


Edited by Kain3n, Mon Jan 23, 2017 11:12 PM.


#29 slydc OFFLINE  

slydc

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Posted Wed Jan 25, 2017 2:37 PM

Hi Kain3n,

 

Sorry for the late reply, i'm always running after time (lol). Looks like you're really doing great for someone who doesn't have much

knowledge in soldering and electronics, so thumbs up to you! :thumbsup:

 

This is the first time i'm seeing the "wavy" effect, which is cool in a sense but i think i may have the solution to this problem even

i've never seen it. I can see 3 possible problems that could cuase this, either you connected the SYNC (pin#16 of the AY-3-8500-1)

with all the video feeds (pin #6+9+10+24) or it's a capacitor that is starting to fail or low voltage (are you using batteries ?).

 

For problem #1, here's a quick circuit to see if it's correct the problem:

 

8500vid1.png

 

And if this doesn't solve the problem then try #3: an DC adapter with 9 Volts and between 250 to 500 milliamps

(watch out if it's a positive or negative tip because you could "fry" the game console if polarities are inverted).

 

And if it's still doesn't correct the problem, then it,s a capactor...and the problem will be which one ?

 

Try solutions #3 and 1 and let me know your progress, take care and keep in touch!  :) 

 

--- Sly DC ---



#30 alex_79 OFFLINE  

alex_79

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Posted Sat Jan 28, 2017 8:44 AM

I picked up this pong console at at thrift store yesterday (7 EUR for the console with the detachable rf cable and original box). It's based on the AY-3-8500 chip and came in different variants (and different brands too) with our without the gun and in B/W or color versions.
The one I have has color output and lightgun games (unfortunatley the gun wasn't present).
IMG_0058.JPG IMG_0059.JPG IMG_0062.JPG IMG_0063.JPG IMG_0066.JPG IMG_0052.JPG IMG_0068.JPG IMG_0069.JPG
It worked, but it had a bad solder joint in the RCA connector of the RF modulator, causing an intermittent picture everytime the cable was moved.

 

I could see the problem by removing the top of the metal shield of the modulator, but I couldn't reach it with the soldering iron without first desoldering the entire thing. Once removed, I decided to just replace the innards of the modulator with a simple transistor amplifier and get rid of rf. The modulator had only 2 connections: power (about 6.2V) and the video signal, while the rf shield was soldered to the main board providing ground path. So I just used those same signals and installed the amplifier inside the rf shield (insulated with hot-shrink tube), using the old rca connector as output. (for the amplifier, I used the diagram posted here: http://atariage.com/.../#entry1543881)

 

In that way, once resoldered the modified rf box to the board and closed the case, the console looks completely original, but it now outputs composite video from the rca connector. The audio still uses the internal speaker which can be disabled using one of the switches on the console. The "jailbar" effect you can see in the picture was there even before the mod and it's typical of this console as I saw it on pictures from auctions and other sites showing it running on various TV sets. I don't find it distracting, anyway, as it's steady and uniform across all the screen (and it simulates the grass pretty well in the "soccer" game... :-D )

IMG_0067.JPG


Edited by alex_79, Sat Jan 28, 2017 8:50 AM.


#31 Kain3n OFFLINE  

Kain3n

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Posted 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

post-9166-1214538091_thumb.jpg

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.


Edited by Kain3n, Wed Feb 1, 2017 1:58 AM.


#32 Kain3n OFFLINE  

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Posted 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. 



#33 Kain3n OFFLINE  

Kain3n

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Posted Sat Feb 4, 2017 2:16 AM

here is the pictures of the work i did first picture just shows how the circuit board was originally, interesting how the rf box is on a seperate board connected by wires. last couple is just my splice job on the ac adapter with shrink tubing.

IMG_3608.JPG IMG_3629.JPG IMG_3630.JPG IMG_3631.JPG IMG_3632.JPG



#34 alex_79 OFFLINE  

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Posted Sat Feb 4, 2017 4:00 AM

Nice job!

The problem with the slightly jittery paddles is probably caused by dirty pots. You can try cleaning or replacing them (They should be 1Mohm, linear pots). My unit does that a bit too, altough to a lesser extent (it only happens sometimes and the glitch disappears just by slightly moving the knobs).


Edited by alex_79, Sat Feb 4, 2017 4:00 AM.


#35 slydc OFFLINE  

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Posted Tue Feb 7, 2017 4:23 PM

@alex_79: Very nice job on how you're keeping the "original" look by sending the composite video thru the rf cable.

Quite true the the "grass" effect looks great for the Football/Fusbal (aka Soccer)! =)

 

And you're right for the jittery paddle problem as many old Pong console have this problem which is 95% caused by

dirty pots. Even my Coleco Telstar Alpha does this problem time to time. Buy a can of cleaner/degreaser spray for

electronic parts/contacts, it's usually about $5 and often does miracles. And if a spray cleaner doesn't do the trick

then you'll need to replace the pot(s) which for any AY-3-8500 or TMS1955/1965 are 1MegaOhms variable potentiometers.

 

@Kain3n: Happy to read that you've solved the wavy effect problem!

 

Once i have finished some projects, i will try to A/V mod some other dedicated consoles like the Nintendo TV-Games

and the Coleco Telstar Arcade just to mention a few. I know that ANY game consoles/systems can be A/V modded as

all outputs video signals and are converted to RF signals.

 

--- Sly DC ---



#36 Kain3n OFFLINE  

Kain3n

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Posted Wed Feb 15, 2017 3:15 PM

Thanks guys the dirty pots makes sense and i think is the last electrical contact in there i didn't clean because they looked hard to get open, i just gotta figure out how to get them open i guess... this model doesn't use knobs it has levers and the pots sit sideways instead of facing up and it's actually the physical shape of the pot that holds everything in place in the control pad so if i do have to replace them they would need to be completely identical maybe tonight if not tomorrow i will try to tinker with it and post some pictures of the weird pot/lever control pad setup :)



#37 Kain3n OFFLINE  

Kain3n

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Posted Wed Feb 15, 2017 7:58 PM

Hey guys, so i figured out how to get it open and scrubbed it good with an old toothbrush, que tips and rubbing alcohol. and got it all back together but unfortunately it made no difference, I will seee if I can find some of that cleaner de-greaser you mentioned and see if that makes any difference if not I will have to see if I can find new pots that fit :)

IMG_3651.JPG IMG_3652.JPG IMG_3653.JPG IMG_3654.JPG IMG_3655.JPG


Edited by Kain3n, Wed Feb 15, 2017 7:59 PM.


#38 RahaT OFFLINE  

RahaT

    Combat Commando

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Posted Fri Mar 31, 2017 2:42 PM

I have same Radio Shack scoreboard and same problem with wavy video with a loud sound noise. For noise I can mute TV because pong sound is coming anyway from scoreboard. Only problem is wavy video on my TV screen. I will have to try to do same thing like you Kain3n. You do good job. Thumbs up.



#39 youbecha OFFLINE  

youbecha

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Posted Wed Jul 12, 2017 10:22 AM

I have the Coleco Telstar Colortron which uses the AY-3-8510-1 chip...the 16 pin one. Is this mod possible on this chip? If so what pins? I tried tracing the circuit back from the RF modulator, but I didn't get enough of a signal there to drive a TV...I didn't hook up the oscilloscope yet...if I do what should I look for as a video signal?

#40 alex_79 OFFLINE  

alex_79

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Posted Thu Jul 13, 2017 3:05 PM

Picked up another cheap pong console at  a thrift store yesterday:
 
This one is from the italian manufacturer RE-EL (Reggiana Elettronica), B&W, based on the AY-3-8500 and doesn't have the lightgun games. There are 3 option switches (angle, speed, bat size) plus power and reset. There's no "serve" button and the ball is always served automatically. The power supply is integrated in the console, so it takes 220V AC directly. There's no option for battery operation and the big compartement on the back is used to hold the controllers and cables when the console is not in use.
IMG_0156.JPG IMG_0159.JPG IMG_0163.JPG IMG_0158.JPG IMG_0160.JPG IMG_0161.JPG
I couldn't tune the channel (All I could get was a very distorted and rolling image, as if the sync signal was missing. So I tried the composite mod (without amplifier, this time I just picked the signals directly from the IC like suggested by slydc in post #4) and it worked, which indicates the problem was in the RF modulator circuit. The mod was very simple, as the 4 video outputs and sync were already connected together on the board and all I had to do was to isolate them from the following rf circuit by desoldering and lifting one lead of a resistor and solder the video cable there. Same for the audio (a cap was the component that I needed to disconnect in this case).
I then desoldered the rf cable and, since the case is almost empty, I secured it to one of the screw post with a zip-tie, so it won't get lost and it will be easy to revert the console in it's original condition if needed (I didn't drill or modified the case in any way). I also replaced the 470 uF cap in the power suply circuit and disassembled and cleaned the two paddle pots (they were so dirty that the games were totally unplayable).
Now it works like a charm!
 


#41 slydc OFFLINE  

slydc

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  • Location:Quebec, Canada

Posted Tue Jul 18, 2017 7:50 AM

I have the Coleco Telstar Colortron which uses the AY-3-8510-1 chip...the 16 pin one. Is this mod possible on this chip? If so what pins? I tried tracing the circuit back from the RF modulator, but I didn't get enough of a signal there to drive a TV...I didn't hook up the oscilloscope yet...if I do what should I look for as a video signal?

 

Hi youbecha,

 

Yes it is possible to mod this chip (same as the AY-3-8512-1) as i did it on my Telstar Colortron (i've made a video on Youtube: ) P.S.: It's just a video showing the games, no info on how to do a mod.

 

So to make a video output on this chip, you can use any of the circuits which "boost" the video signal BUT... you need to invert the video signal

to get a proper signal. Instead of getting the output from the "Emitter" of a transistor, take the output from the "Collector"  as this inverts the signal.

You'll get a video signal but it will be a bit blurry as i still haven't "fine-tuned" or "tweaked" this mod. OH and you'll also need to take the signal directly

from pin #11 and unsolder or cut the parts (resistor & capacitor) before the circuit goes to the RF modulator, as these can generate noises or darken

the signal.

 

BTW, there is only three Pong consoles which have these special "16-pins" chips: The Coleco Telstar Colortron (AY-3-8510-1), the Coleco

Telstar Marksman and the Sears Gunsligner II (both uses the AY-3-8512-1).

 

And here's the pinout of the AY-3-8512-1 made by a Russian fellow: 736c3ffc2e2b.jpg



#42 slydc OFFLINE  

slydc

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  • 126 posts
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Posted Wed Jul 19, 2017 9:40 AM

 

Picked up another cheap pong console at  a thrift store yesterday:
 
This one is from the italian manufacturer RE-EL (Reggiana Elettronica), B&W, based on the AY-3-8500 and doesn't have the lightgun games. There are 3 option switches (angle, speed, bat size) plus power and reset. There's no "serve" button and the ball is always served automatically. The power supply is integrated in the console, so it takes 220V AC directly. There's no option for battery operation and the big compartement on the back is used to hold the controllers and cables when the console is not in use.
I couldn't tune the channel (All I could get was a very distorted and rolling image, as if the sync signal was missing. So I tried the composite mod (without amplifier, this time I just picked the signals directly from the IC like suggested by slydc in post #4) and it worked, which indicates the problem was in the RF modulator circuit. The mod was very simple, as the 4 video outputs and sync were already connected together on the board and all I had to do was to isolate them from the following rf circuit by desoldering and lifting one lead of a resistor and solder the video cable there. Same for the audio (a cap was the component that I needed to disconnect in this case).
I then desoldered the rf cable and, since the case is almost empty, I secured it to one of the screw post with a zip-tie, so it won't get lost and it will be easy to revert the console in it's original condition if needed (I didn't drill or modified the case in any way). I also replaced the 470 uF cap in the power suply circuit and disassembled and cleaned the two paddle pots (they were so dirty that the games were totally unplayable).
Now it works like a charm!
 

 

 

Glad to see i could be of any help! ;)







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