2600 UAV help needed

[unixdude]

Hi, all.

 

I picked up a new, dead Vader 2600 recently, and after playing with it I was able to get a snowy RF picture.  I decided to drop a UAV into it, first, to see if it would fix this 2600, and second, because I haven't done the UAV mod yet and didn't want to screw up my otherwise good Woody.  The video is beautiful, but it has some issues with vertical hold.  The audio is completely nonexistent, but I do have audio via RF, so I know the unit's audio works.  For my install, I chopped the connectors off of one end of an unused AV cable, and I have soldered that directly in.  I have checked my soldering, and the connection between the RCA L/R audio pins is good to the 4th pin from the left on the RF modulator (I'm not doing the stereo mod, at least not yet).  I know the AV cable ground line is good because video works.

 

Any ideas what I should look at to get these issues sorted?

 

Also, this is a Rev 16 board, so I need to pull a resistor... need to find that and get it done.  But the results even now are really good.

 

I would take a picture of the RF right now, but I can't get that to work at all anymore.  No wonder this guy thought it was dead -- the RF is dead.

 

Edited to add: Yes I have read several other postings on 2600 UAV mods -- there's one from just 2 months ago, and I was following the excellent diagram in the original post there.  Unfortunately my audio doesn't work.

 

Edited March 28, 2021 by unixdude

[+DrVenkman]

Skip the RF modulator connection for your audio. Dig up the schematics and pull the audio from the resistors on the TIA AUD0/AUD1 pin outputs. 

[unixdude]

Sure, I saw that on the stereo mod option on the linked article.  One reason I didn't do it is because I didn't want to have to mess with inline resistors.  Will I need an inline resistor for this audio if I go straight to the TIA?

[unixdude]

Well, I figured I'd try it anyway, so I soldered audio to AUD0 (pin 13 on the TIA), with no resistor.  I do get audio, but in order to hear it, I have to turn my amp up to 11.

 

Also, I pulled R234, so here's another pic of that -- note that the colors are washed out as compared to when R234 was installed; maybe these colors are more accurate, but I thought the other colors were correct.

 

That's a pretty amazing "before & after" set right there, I think.  And yes, you can barely see it, but that's Space Invaders in the RF shot as well.

 

 

Edited March 28, 2021 by unixdude

[unixdude]

So, basically, it's working great, with minor issues to fix:

- color is washed out

- vertical hold is a little flaky (image jumps up and down on the TV)

- audio amp has to be turned way up in order to hear it

 

Anybody have any thoughts on those 3 issues?  As a reminder, this is a rev16 2600, with a Rev.D. UAV from TBA.

[unixdude]

And, after more research, it looks like I need the audio companion board.  Fortunately those are pretty cheap at TBA.  

[+DrVenkman]

14 minutes ago, unixdude said:

it looks like I need the audio companion board.

Not unless you just want to buy one. As I said, you can pull the audio straight from the resistors where the TIA audio pins come out, before they run to the RF modulator.

As for your color issues, be sure to remove the saturation boosting resistor for a Rev 16 or later board. If you've already done that, then you may need to tweak your TV's settings; the UAV's outputs are basically at the reference levels per the NTSC/PAL specs for colorburst. 

[unixdude]

Thanks, yeah, I was looking at a schematic now, in the FSM.  I was trying to figure out where to tap, and I don't know enough about electronics to know where to tap.  Maybe on the modulator side of R207 or R209 (FSM PDF page 12).  Is that what you were thinking?

[+DrVenkman]

I did a UAV install in my own 4-switch Rev 14 boards - I don't know if the resistor designations are consistent between all the board revisions. Just ping out the connections to the TIA audio pins. If you want the same levels, take the signal your audio connection from the other side of the resistors where the signals are summed. If you think that's too low, then either take the signals from the TIA side of each resistor and tie them together yourself, or solder new, lower-value resistors to the TIA side.

 

[unixdude]

Well, that audio issue might be a 1 delta 10 tango error here... I just reconnected my modded 2600 to take before & after pics again (before using my other, unmodified RF-only 2600; after using the UAV-modded one that was dead when I bought it)... and I have audio at normal volume.  I'm not complaining, just surprised.

 

So, I have now successfully UAV-modded a left-for-dead 2600, and I did the same thing with a left-for-dead 5200.  Fun!

Edited April 6, 2021 by unixdude

[hizzy]

On 3/28/2021 at 1:53 PM, unixdude said:

So, basically, it's working great, with minor issues to fix:

- color is washed out

- vertical hold is a little flaky (image jumps up and down on the TV)

- audio amp has to be turned way up in order to hear it

 

Anybody have any thoughts on those 3 issues?  As a reminder, this is a rev16 2600, with a Rev.D. UAV from TBA.

The vertical hold thing is related to scanlines. New TV's are more particular about the number of scanline on screen compared to analog TV's. There's no fix for this, sadly.