Composite output was working but now isn't...

[khemicals]

Greetings,

I had composite output working on just about any TV I could get my hands on by using the following mod:

http://benheck.com/book/support/Atari2600VidMod.htm

So, when trying to put everything back into the atari case, I decided to follow the recommendation of doing what you can to disconnect the RF unit from the board. Rather than sawing it off, as I just want composite output, I removed the resistors and capacitors right next to the RF unit (The 4 other leads to it were already severed prior to this step, and didn't break its function).

Now, however, the video mod is not working. I am concerned that this could be the cause, but I really doubt it. Those 4 resistors/caps seemed to only be for power regulation to the RF unit, which isn't in use anyways.

I have tested for continuity and proper resistances between the STELLA chip's leads and the leads on the transistor. I have replaced the transistor with a new one, in case I burned it out while resoldering something (the new one was soldered in a way which would not lead me to believe it could have over heated; I also tested it for proper function prior to installation). I have checked for shorts across the various leads/pins. Everything seems to be per the circuit diagram.

The only thing I did notice, however, is that a lead popped off of the atari motherboard while moving the atari around. This led me to believe that perhaps a wire had disconnected, so I retested the circuit again, and found that all seemed well.

Thinking about this wire, I considered some of the other video mods I had tried. And, looking at the board, its most likely that this is the chroma wire, that was connected to the top of R210. So, I looked back at the mod, and noticed that the chroma wire isn't requested/required anywhere.

So, this wire was connected, and has since been removed. Is it possible that by having this connected I did something bad and fried something? Is it possible that the resistors/cap that I removed next to the RF unit could have caused any issues? Any ideas as to what might be wrong/what else to check would be greatly appreciated.

And, the board is not completely dead, because I can hear music when I plug a cart in and power it up...

Thank you,

David

[khemicals]

Also, I did try hooking that wire back up to the R210 spot, and that didn't help...

[zybex]

Without Chroma you can't get colors in your mod...

Always test the modification BEFORE putting back the board in the case.

You can follow this :

http://www.atariware.cl/tableless/hardw ... om=&ucat=2&

(Corrected LINK!)

If you have a sixier, the photo can help to pickup the correct pins.

[khemicals]

Greetings,

So, I tossed the chroma wire to the base of the transistor, as directed in the last comment, but that didn't fix the issue.

So, I poked the wire to the emitter and the collector, and again, no results. Then, I noticed that if I short out the collector and base of the transisor with the chroma wire, I get color output on my older TV and black and white output on my newer TV. This is certainly a step forward, but I know the mod worked before with color on the newer TV. Any ideas as to what could be wrong?

I have tested all the resistances between the pins on the transistor to the pins on the TIA to verify that there is continuity and appropriate resistances, I have also checked to make sure there is a proper voltage drop across the ground/+5V connections.

ideas? Suggestions?

[SpongeBuell]

are you using a heatsink when soldering? Transistors fry pretty easily

[zybex]

Yeah, i have a similar problem when using the 3904.

I use a 2n2222, is more common and you can get a clear image.

About your tv, are you sure the input are composite video? i get b/w image when attach the signal to the DVD input.

you can use a VCR ór DVD to "level" the signal, and send to the TV.

(sorry, i'm not a english man, i write like a dummie)

[SpongeBuell]

(sorry, i'm not a english man, i write like a dummie)

Su ingles no es muy terrible, usted habla mas ingles que yo hablo espanol.

Es posible que su television es poco diferente. En el Norteamerica y Japon, la forma NTSC es que usan. En Europa, usan la forma PAL. No se que ustedes usan en Chile, pero es posible que eso es la problema (o, es posible que su atari es de Europa, supongo.)

Perdon mi espanol

Your English isn't terrible, you probably speak more english than I speak Spanish.

It's possible that your television is a little different. In North America and Japan, the NTSC form is used. In Europe, PAL is used. I'm not sure what you guys use in Chile, but it's possible that that's the problem (or, it's possible that your atari is from Europe, I suppose.)

Pardon my Spanish

[Sparkfist]

The U.S.A, Canada and Japan all use NTSC, pretty much all the rest of the world use PAL. I know that South American countries use a variation of PAL so I dont know how compatiable any coversion of NTSC to PAL or the PAL we know of would work.

Also dont worry about your Engilsh its quite good, dont be overly critical, esspally here.

[zybex]

Well

The U.S.A, Canada and Japan all use NTSC, pretty much all the rest of the world use PAL. I know that South American countries use a variation of PAL so I dont know how compatiable any coversion of NTSC to PAL or the PAL we know of would work.

Chile (my dear country) uses the NTSC standard.

[SpongeBuell]

Also dont worry about your Engilsh its quite good, dont be overly critical, esspally here.

heh, his English is better than some *cough*hotdog*cough* member's

[khemicals]

I must've fried something on the board itself, not the mod. Cause I bought a 'new' atari on ebay, rewired the mod to it, and all is working now.... Fortunately for me the atari I bought was effectively the same model, so didn't even need to drill holes in the case to mount the output jacks, just moved it over to the other atari's case.

Thank you for everyone's help.