Untested Atari 2600 jr - working or not?

[hyvax]

Hello everyone (since I'm new here) and... straight to the point

 

I got a dirt cheap Atari 2600 Junior (without PSU, joysticks and cartridges), have none technical experience with that console (besides playing it as a little kid, I guess that does not count in that case ). I put a mono jack plug on a 9V 600mA PSU, got some old quickshot joysticks (working fine, tested on my c64) and since i got some free parts lying around and eproms i made a 512in1 cart for it (http://rdemming.home.xs4all.nl/Atari/MultiCart2600/) (cart untested, since i dont have another working 2600).

 

After plugging 2600 jr to TV (without a cartridge) i get at random: orange screen, black screen, color stripes, sometimes mixed with sound - is it normal behaviour? Should 2600 jr display anything on the screen without cartridge inserted? If yes, shoud it be constant, what should it be?

 

When I instert the cart i made into the slot and power on the console the randomness is gone, i allways get the same screen, depends on the game chosen by hex encoder setting it changes colours and stripe-patterns , can assume it may be a game screen but it more looks like a stripe-mess than a game - also, pressing buttons or wiggling joysticks do nothing, nothing changes on the screen.

 

I have checked the voltage regulator, around 10V in and 5,12 out, not overheating - looks OK to me, i checked the cartridge contact with the cartridge port - also OK, all pins with fine contact. I guess for next step i will have to get a working cartridge to test it further, really hard to test things when they both are questionable (home brew cart and untested console). Depens on what will be Your suggestions, if this symptoms speaks for a faulty chip or something I may just get another tested 2600 dont know Yet...

 

Looking for advice, thanks!

Edited November 4, 2014 by hyvax

[hyvax]

Can't edit my above post so making another - small update:

 

replaced 2200uF cap (C26) tho old one was busted, unfortunately that didn't help much, also checked on cpu, tia and riot ICs - none of them is getting hot. Some photos:

 

Without cartridge (at random):

 

 

With cartridge:

 

[alex_79]

The "without cartridge" screens you posted are correct. The 2600 doesn't have a bios and without a cartridge the registers for audio and video are in a random state which results in the random vertical stripes and sounds you experienced.

I suggest to double check your cart, as wrong or missing connection in an address or data line might cause that kind of problems. Also inspect the cart port of the console for missing or bent pins and, if you didn't already, try cleaning the pins with a contact cleaner.


I built an eprom cart for the 2600 in the past and it had the same problems as yours. I fixed it by replacing the inverter circuit on the "A12" line with an inverter IC (74ls04). The problem was probably due to the fact that I didn't used the exact same part number for the transistor and, beacuse of my limited experience in electronics, replacing it with an IC was simplier for me than calculating the right resistor values to use with the different transistor.

[bleki]

To give my 5cents ..since i had almost the same problems with my atari clone. try changing ALL of capacitors on board , usualy they don't seem to leak , just get dry and doesn't work anymore.

Since it's RF connection i guess you have some capacitors around RF connector or maybe even in it under the shielding.

well i might be wrong ... but it doesn't hurt, also i guess the problem could be with PSU i have read somewhere that different carts draw different power from psu so the strain on volta regulator is bigger with cart and if the component is old it breaks on a strain , also try psu with more amps ..since custom made cartridge could draw more amps

[hyvax]

Thanks guys for all your suggestions. What I did so far:

 

1) Replaced all remaining electrolytic caps (4x 4,7uF)

2) Tried with a different PSU (1000mA)

3) Built a simplified version of 512in1 cart on a breadboard using one m27c801 and a 7406 on A12 (since i couldnt find a spare 74ls04, will try to look for one today and test with it as well just to be 100% sure)

 

still no luck

 

Anyway, I'm not going to give up yet will try to get an confirmed-working cart somehow and test with it. Good to hear that 2600 seems to act as it should without a cart, I really hope its working fine. Any more advice appreciated!

[Osgeld]

Ill mail you a confirmed working cart if you are in the USA (local store sells them 2 for a dollar, so no biggie)

Edited November 9, 2014 by Osgeld

[hyvax]

Ill mail you a confirmed working cart if you are in the USA (local store sells them 2 for a dollar, so no biggie)

 

Thanks for that! ...but I'm from Europe , anyway - yesterday I bought a confirmed working cart (Berzerk, for around 4$ shipping included). Should be here soon, so will report then if it was the case or not

[hyvax]

Good news! 2600 is working perfectly fine with the original game cartridge. Looks like I screwed something up with that home brew cart, will have to take a closer look at it, but now... Berzerk time!