No signal light sixer

[Shea]

Hi im posting to this part of the forum because i dont know where else to post this but im very inexperienced when it comes to the world of electronics so i decided to buy a broken atari at my local pawn shop to get my foot into the door. When the atari is powered on and brought to the proper channels (we used both an old and new tv for this) it will display no information at all and will simply cease to do anything having no signal be the only thing on the tv. I have used both those old tacky rf boxes along with a rf to coax (i think thats what theyre called) cables to find any signal but still nothing.

 

I have tried some basic multimeter tests on voltage regulators like Q 200 and Q 201 and the main one ontop with the heat sink along with the compacitors and all of them seem to be in proper order so i have not been able to find any conclusive diagnostics.

 

The few things i have not tried have been testing both the riot and TIA chip with an oscilloscope for possible flaws or to see if they arent sending data anymore, cleaning the cartridge slot with alchahol to see if the lack of a connection was the problem, and trying to open the god forsaken RF modulator box thing for any possible flaws but those are things im am worried about doing due to potential damages.

 

Theres also cleaning the 2600 but i dont want to put in the effort until i found some actually leads and i am also very lazy and dont have isopropyl alchahol

I have come here to seak any pointers like grounds on the 2600 or possibly some missed thing that i did not notice if you have any guidance at all or questions about my light sixer please reply i am all ears (assuming i figure out how to reply on a forum of course).

 

 

Edited July 22 by Shea

[CPUWIZ]

First thing I would try, pull the TIA and see if the contacts are corroded.  Sometimes simply removing and re-inserting the TIA will give you a hint, if it doesn't just start working magically.  Even if it does work, I would clean the "legs".

 

You can repeat this for the other socketed chips and none of that involves soldering or special knowledge.  Just make sure to keep the orientation of the chips, in the position you found them in (a notch or dot indicates the direction).

[Pitfall Harry]

@Shea  In the 4th picture of your posted sequence, the upper left corner of the PCB shows a big fat circuit trace that appears to have been corroded away.  You may want to check that for continuity and solder a shunt wire across it if it fails.

 

 

-Ben

[CPUWIZ]

12 minutes ago, Pitfall Harry said:

@Shea  In the 4th picture of your posted sequence, the upper left corner of the PCB shows a big fat circuit trace that appears to have been corroded away.  You may want to check that for continuity and solder a shunt wire across it if it fails.

 

 

-Ben

 

Looks like calcium deposit from water exposure to me, but you could be right!  Alcohol wipe will tell.

[Stephen Moss]

4 hours ago, Shea said:

When the atari is powered on and brought to the proper channels (we used both an old and new tv for this) it will display no information at all and will simply cease to do anything having no signal be the only thing on the tv.

By no signal do you meant a Black screen or static (Snow)? A black screen suggests the unit is powering up but no running (i.e. no clock or a reset pin not being pulled high)/TIA not producing any video output.

Whereas static suggest a possible lack of power somewhere which could just be to the RF modulator, the TIA or more system wide, or perhapse less likely the RF frequency is off from what it should be so you need to tune to a different channel.

4 hours ago, Shea said:

I have tried some basic multimeter tests on voltage regulators like Q 200 and Q 201

Those are transistors, not voltage regulators, the only voltage regualtor is the heatsinked 7805.

 

Do you get the 5V supply voltage when you measure across the GND and Supply pins of the TIA, RIOT and 6507?

Do you get the 5V supply when you measure across the GND and overscored RES pins of the RIOT and 6507?

Do you get a voltage other than 0 or 5 in the XTAL pin of the TIA and any pins on the TIA, RIOT and 6507 that start with a circle with a line through it ( ø ) that would suggest the clokc is gettign to where it should as a multimeter cannot accuratly measure a clock voltage, may be able to measure the clock frequency rather than voltage if your miltimeter has that function up to at least 4MHz.

[Shea]

11 hours ago, Pitfall Harry said:

@Shea  In the 4th picture of your posted sequence, the upper left corner of the PCB shows a big fat circuit trace that appears to have been corroded away.  You may want to check that for continuity and solder a shunt wire across it if it fails.

 

 

-Ben

I just did a continuity test between these two and i got continuity so it seems that the corroded debris dosent matter to this 

[Shea]

7 hours ago, Stephen Moss said:

By no signal do you meant a Black screen or static (Snow)? A black screen suggests the unit is powering up but no running (i.e. no clock or a reset pin not being pulled high)/TIA not producing any video output.

Whereas static suggest a possible lack of power somewhere which could just be to the RF modulator, the TIA or more system wide, or perhapse less likely the RF frequency is off from what it should be so you need to tune to a different channel.

Those are transistors, not voltage regulators, the only voltage regualtor is the heatsinked 7805.

 

Do you get the 5V supply voltage when you measure across the GND and Supply pins of the TIA, RIOT and 6507?

Do you get the 5V supply when you measure across the GND and overscored RES pins of the RIOT and 6507?

Do you get a voltage other than 0 or 5 in the XTAL pin of the TIA and any pins on the TIA, RIOT and 6507 that start with a circle with a line through it ( ø ) that would suggest the clokc is gettign to where it should as a multimeter cannot accuratly measure a clock voltage, may be able to measure the clock frequency rather than voltage if your miltimeter has that function up to at least 4MHz.

I can only answer the first part for now as the atari produces nothing with the modern tv saying no signal so i assume it has something to do with chips not producing something

 

I have screwed around abit with the tia chip and have found that im getting readings of 5 volts with one of the pins reading 9v but i havent done too much research into that chip yet so im going to try what cpu wiz was talking about then do more research and follow your recommendations 

 

 

Edited July 22 by Shea