RGB Mod issues

[Photek1000]

I have installed a Tim Worthington RGB mod to my PAL six switch 2600 but it isn't doing squat, which seeing as I took my time and checked my soldering along the way epicly disappointing.

 

I've not had any advice back yet from the supplier so here I am, are there and methods of diagnostics to work out where the problem lies?

 

Any locations I can stick a meter to test continuity or voltage across various locations.

 

With getting zero output it doesn't really give a starting point, if I got one colour or some sound it would show that maybe it was just a cabling issue to the 8 pin socket, but it does nothing.

 

Prior to fitting I had a composite mod fitted and that worked as expected, so I know that the console did work.

 

Help.........

[+Nathan Strum]

Pictures might help.

[Photek1000]

What pictures would you like, It's the TW RGB mod board and no output.

 

Let me know what bit's would be useful and when I crack it open again I'll post them up.

[+-^CrossBow^-]

Well for starters make sure of two things:

 

Do you have any LED lights that come on when you power on the console from the RGB board? It does have a power LED that comes on when powered up. If you do, that is a good indication that you at least have power going to it. If you don't have a power LED then.

 

1st, check to be sure you do in fact have +5v going to the RGB board.

2nd, check to see if the +5 and GND pad are shorted.

 

Outside of that, make sure you did jumper the proper pads for a PAL console and if you haven't, make sure to at least wire up the extra button even if temporary so that you can try and power the RGB board up in different modes. One is to hold it down as you power on the console to switch between RF and RGB output. If that doesn't work, then I would suggest to at least remove the TIA off the RGB board and pull the RGB board off and insert the TIA back on its own. Then test to see if the Atari is at least still working normally on RF. Unless you removed the RF during the initial composite upgrade? If so... then I might suggest readding in whatever you might have removed and the RF to at least see if you have normal function. 

 

Having said all of this. I've installed about 4 of these RGB boards now, and I actually have had at least 1 just up and die on me after a few min of initially testing it. I was told in short that the RGB boards apparently can burn out and Tim doesn't know why this happens but it does. As a result he sent me a replacement. I installed that replacement using the exact same wires I had before and it came up and worked and still is working as far as I know. So the point is that apparently some of them can have issues that haven't quite been solved yet.

 

@ZeroPage Homebrew's RGB upgraded 2600 also died sometime after it had been used and another tech that looked at it found that +5 and GND had somehow shorted and it was dead. A replacement that was installed took care of it and that 2600 is still working as well. 

 

 

[Photek1000]

Thanks for this, actually gives some method of basic trouble shooting.

 

A power LED is something I didn't know was on the board, do you know it's position?

 

Is there a test pad for the 5V inbound or is just a case of using the pin or leg socket for the TIA?

 

I did check for the 5v \ GND short before I started as I had seen that in one YouTube video regarding the mod and that was clear but I'll check it again.

 

As far as I could tell is was just JP1 that was closed for a PAL console so I have done that one, I haven't added the palette switch for now but I will in case it needs the nudge into RGB mode, I no longer have RF capability but could add the composite mod wiring back in pretty easily to test.

 

Hopefully it's not dead.

[juansolo]

You'll have swapped the regulator out with a little PCB and electrolytic cap as part of the kit. Check that there's power coming into it from the PSU, and 5v coming out. Start there.

[Photek1000]

Awesome cheers, the brain goes fuzzy sometimes with where to start, but yes here would be a good shout, I tested the resistance across the ground pin as per install instructions and checked for any shorts in that area, but I kind of had to bolt it all together and get on with something else (being an adult is a pain sometimes 🤣 ) before testing whilst it was in bits.

 

So I will take it apart and bench test it before putting it together, just need to find the time.

[Photek1000]

Partial success, managed to get 20 minutes to have a poke around and tested the input and output across the VR board and I could see 5V on both sides I am assuming this is correct, everything certainly seems to be 5V on the output side as far as I can see.

 

No led on the board though, so tested again for the short, no short so poked the VR whilst it was on and I can get the LED to flicker occasionally, so when I get some time tomorrow I am going to revisit my soldering on the VR and fingers crossed. 

[Photek1000]

Another small increment forward, decided it's all power related, reflowed the switching power regulator, well a couple of times, soldering issues and had some success.

 

So the on-board LED is it meant to flash on boot and go off or is it meant to stay on?

 

I managed to boot a game or two but after 20 seconds or so the video will skew and go off, so I still think it's power related, it maybe the pads under the power reg but I'm not sure, it might just be this third party PSU, I have a spare at work but a cheapy one that I swapped out because over composite it was very noisy, but I shall try that tomorrow and revisit some of the wiring, but edging forward.

[Photek1000]

Just getting my thoughts out, would a low powered PSU issue cause the problems I’ve got even if I seem to measure 5v across the output of the switching power regulator, whenever I put to meter on the PSU directly I only show a max of about 7.5v but the power switch always measure 5v on both sides of the switch. 

[juansolo]

If it's borderline and can't supply enough current you'll have issues.

[Photek1000]

1 minute ago, juansolo said:

If it's borderline and can't supply enough current you'll have issues.

How much current should it be supplying? I have measured voltage across the output but not current.

[juansolo]

Should be marked on the PSU (in A or mA). I would normally recommend a Meanwell GS15A-2P1J. Not sure if you can get them there. 9v and more than enough power at 1.6A (you'll have to graft a different end onto it).

 

7.5v coming out of your PSU seems low...

Edited December 12, 2022 by juansolo

[Photek1000]

I have brought everything into work so I can have a play in peace later, but from recollection the "better" PSU is a new but transformer style and is labelled at 9v 500mA and the cheapy light electronic version is 9v 1000mA as per the labels.

 

I shall stick my meter across them both again and test, then test in the console again, see what happens.

I'm in the UK and the Meanwell is available so could be an option further down the line if required.

[juansolo]

9v and 1A should be plenty. 500mA might be a little low. Can't remember off the top of my head what an original PSU was but it's probably an unregulated supply in that region. The Meanwell is a high quality modern supply that is overkill, but any problems you had beyond that wouldn't be from the power supply. I personally wouldn't trust any cheapo wall-warts of Chinese origin. Sure some can be alright, but a lot of them really aren't good.

 

When it comes to fault finding I always start with power, and that means using a known good PSU that's well up to the job in hand. Start from there, then make sure you've a nice solid 5v coming out of the reg, then make sure that makes it to the ICs as a nice solid 5v (or 3.3v, whatever it is they require).

[juansolo]

18 minutes ago, Photek1000 said:

I'm in the UK

If all else fails, if you're in the area you could bring it over. Or send it to us to take a look at.

Edited December 12, 2022 by juansolo

[Photek1000]

Just now, juansolo said:

If all else fails, if you're in the area you could bring it over. Or send it to us to take a look at.

Thanks for the offer, but I'm a fair way south from Wakefield.

Yeah the first PSU I got was a cheapy Chinese thing with no weight to it and with the composite mod it was noisy as hell, so I bought a transformer based one but that is only claiming 500mA on the sticker, but I shall test it.

 

I feel I'm getting close and that it is all power related, some probing and some testing and we'll get there, eventually.

 

All I can say is that in the brief moments I saw an image was that it was very good indeed, so this will be worth it in the end.

[marauder666]

The stock 500ma transformer based PSU can power a RGB modded console, but only if its fitted with the supplied switching regulator.  The original linear regulator only works with the RGB mod with a better (more output) psu.

 

There's loads of crappy PSUs around, stick to name brands in the UK, Meanwell, Strontronics, you'll only need to swap the connector over from old PSU.

This all assumes its a PSU issue.

 

[Photek1000]

Thanks for the advice, I have fitted the Switching regulator but I'm not convinced on the juice coming out of the PSU, it is a copy of the original transformer style but still aftermarket.

 

Some testing later and we'll see.

[+-^CrossBow^-]

I can confirm that the stock US PSU is able to power an RGB upgraded 2600 without issue. But it does require installing the small switching regulator that is provided in the kit. A stock 2600 I want to say takes about 400mA to run and after 40 years, those linear regulators and other components could start to require a little more current with less being provided over time. The original VR was only rated for the 500mA of the PSU as well. With the switching regulator installed, it should only require about 320mA with the RGB in place. And that is with using something like a Pluscart that will require more juice to run vs a stock cartridge.

 

As for the LED on the RGB board, I can't recall if it stays on or not? I can tell you that the 7.5v input from the PSU you are using is marginal for the system and likely to cause some color and sync issues. I know when I was much younger, I used to use one of those voltage adjustable PSUs and always thought it was funny how at 7.5v the games would start to go into crazy rainbow colors. 

 

I also highly advise the use of the 220µf cap that comes with that switching regulator also be installed. It doesn't impact the RGB output at all, but if you happen to still have the RF connected and plan to use it, it will cause interference with the video output unless you have that cap across the input and gnd of the regulator.

 

[Photek1000]

So I think I’ve solved the riddle. 
 

I believe my install was sound and fine, all installed correctly including the replacement switching power regulator and the issue was all supply side. 
 

so testing with the cheap as chips Chinese PSU I get a stable output and can play for more than a few seconds, it’s still noisy but it works. The so called better transformer PSU just isn’t kicking out enough juice as far as I can test and drops the signal, you can actually see on the OSSC the sync disappear on the lcd. 
 

so I have ordered a “fingers crossed” good PSU from the same place I got the mod from, time will tell. 
 

I think my old 8 Pin SCART may have a bit of a loose connection for some colour reproduction occasionally, but it’s all looking good for now. 
 

if I get a chance later I’ll hook it up at home and take some pictures. 
 

Thanks for everyone’s help, it’s been good to have a sounding board for fault tracing process. 

[Photek1000]

So the new PSU arrived yesterday and that looks to have been the biggest culprit in my woes, I think if I had a decent PSU in the first place I would have have any problems to troubleshoot and it was a good install.

Anyway, now noise free and providing enough juice to give no sync issues on the output to the OSSC it's time for a couple of photos.

Thanks for all the help.

 

               

Edited December 17, 2022 by Photek1000