Atari - Return of the Jedi - Garbled boot up

[Karnov2017]

Hi everyone, I have recently purchased a holy grail machine for me - a 1985 Atari Return of the Jedi. I am a bit worried though i may have bitten off a bit more than i can chew tho as i haven't got much history with early 80's games & power supplys.

The machine powers up ok, however it will boot to a garbled graphic screen (colored Blocks). Sometimes it will boot OK & I can play a couple of games, but doesn;t really stick. The other issue appear to be that the blue had dropped out of the image, which quite possibly an unrelated chassis issue.

I have checked the fuses and their was one blown which i changed over, which made no difference. I have removed and checked all the Integrated circuits i could & given them a clean/reseat. The only issue i saw with these was a pin leg had broken in 5D. I got excited that this might have been causing the issuue, however it seems unlikely as that particular cheap is a speech chip (i have ordered a new one to replace it).

I am unsure how to check the voltage thoroughly on these older psu's. I watched a John's Arcade video on how to test the unregulated power coming from the power brick (via the 15 pin plug) & all tested within reason. When i checked the test points on the Power/Audio board at the TP points, the -5 & 22V's all seem ok, but had nothing testing at the 12V, would get a small spike of a reading of around.1 or 2 and thats about it. . Unsure if this was the issue or just not used. The 2 VAC36 test points i tested and was only getting 17AC at each point, again not completely sure i tested that correctly, but pretty sure i have.

I have tried to check it on the connector, however get odd results. I have the pinout as below

When i test this with using the black prong in Z/22 to be on the ground, i am getting the below results, which i can't really make sense out of.; I get similar results when i use the GND off the PSU/audio board also.

A/1 = -0.5V
B/2 = 9.1V
D = -6.1V
E = 11.47V


With these readings i must assume i am doing something very wrong as i can't understand how the board can boot at all, even withy the garbled graphics.

I have also gone over both the PSU Driver/Audio board and touched up any vaguely suss solder points, as well as the actual PCB.l Given both a good eye test for not much result.
When the pcb is plugged in, i tested the 2 x +5V points on the pcb and both tested fine (approx 5.1v)

I am a bit confused now at what to try next. Voltages appear to be ok everywhere, except they test a bit crazy at the connector. Is this likely a board or power supply issue. Any assistance anyone can offer would be awesome. Relative novice at this stuff, so crappin bricks that i am going to ruin the machine.

I am in Brisbane Australia & unfortunately we have no real techs you can hire to look at this stuff

 

[Karnov2017]

Also, is there a list of other atati games anywhere that would share the same pinout as ROTJ ? I have friends with a large collection of PCBS, so might be able to borrow a board off them to test it further

 

[jamesv833]

A/1 are the GND for power but Z(switch ground) and 22(sense ground) should be fine to use for voltage measurement.
It looks like your 5v is at 9v and I’m surprised it’s working at all.
I would check the edge connector for burned or tarnished pads especially for the 5v, ground and both sense lines.
There is a potentiometer on the ARII you can try to adjust and get that 5v down to a reasonable level, then I’d try to boot into self test.
Could be a faulty component on the ARII as well, usually a couple resistors burn up.

 

[Karnov2017]

A/1 are the GND for power but Z(switch ground) and 22(sense ground) should be fine to use for voltage measurement.
It looks like your 5v is at 9v and I’m surprised it’s working at all.
I would check the edge connector for burned or tarnished pads especially for the 5v, ground and both sense lines.
There is a potentiometer on the ARII you can try to adjust and get that 5v down to a reasonable level, then I’d try to boot into self test.
Could be a faulty component on the ARII as well, usually a couple resistors burn up.

Thanks for taking the time to reply James, this has been a massive help. I found the power supply adjustment on the ARII as you said. When turned all the way down it goes to 8.4V, no further. I quickly tested the board with the lower voltage and we got a better boot rate from the board, but it would still garbble the graphics after a bit. So i think we are on the right track here & the most likely issue is a faulty resistor on the ARII. I have inspected the board and think i may have found the culprit.

Both resistors at R29 & R7 look compromised in my opinion. I will try to source both & replace & fingers crossed it fixes the issue. I only just picked this game up so i have no idea how long it had been getting run at 9V.... here is hoping that it hasn't damaged the board .

I will report back with results once we have replaced - big thank you for taking the time to respond, its a massive help

 

[jamesv833]

No problem
I wouldn’t power the board without the proper 5v or it could take out more components and make it a pain to repair, I’d get it set to 5v without a load and then bring it up to 5v with the pcb attached once it’s adjustable and stable.
I’m pretty sure those are the two resistors that like to burn up, be sure to install them a little higher so they won’t further damage the board if it happens again.
I’d also order a new 2n3055 as well if it’s the original one on there.
A lot of folks say the ones from Arcadeshop are bad so I’d steer clear of those.
Be sure to inspect the edge connector, some pads may be crispy.

 

[stj]

does this use the AR2 power board?
is the edge connector for the game the original? are any board pads dark or burned?

 

[real]

You should consider using a switch mode power supply for +5V.

 

[stj]

nothing wrong with the AR2 other than the active feedback that needs to be bypassed.
atari's real problem was the shit crimp-pin edge connectors they used that burned the power tracks on the gameboard.
contrary to what you may read, that is NOT caused by the AR2 feedback circuit - it's because the contacts arent rated for the current.
this problem effects every fucking game they made with an edge connector from stuff like pong all the way through to return of the jedi.
then they got wise to it and stuff like blasteroids,xybots and so-on used different connectors

 

[Karnov2017]

No problem
I wouldn’t power the board without the proper 5v or it could take out more components and make it a pain to repair, I’d get it set to 5v without a load and then bring it up to 5v with the pcb attached once it’s adjustable and stable.
I’m pretty sure those are the two resistors that like to burn up, be sure to install them a little higher so they won’t further damage the board if it happens again.
I’d also order a new 2n3055 as well if it’s the original one on there.
A lot of folks say the ones from Arcadeshop are bad so I’d steer clear of those.
Be sure to inspect the edge connector, some pads may be crispy.

Thanks for this advice, we have done some more work on this today.

When we inspected the board we noticed some resistors that looked unhealthy & have replaced the resistors at R7 & R29. After we did this the 9 volt dropped down to 3.5V which was great, however the 10V went up to 12V. These were tested on the connector. We then tried to increase the Voltage using the adjustment on the board, but this is no longer altering the Voltage readings and appears to be non responsive. This was responsive prior to the resistor changes (but would only drop the 9V @ the 5V to 8.4V).

We also replaced the 2n3055 as you suggested. Unsure how to test if this was successful or not.

We then replaced a Capacitor @ C1 as this also had some burn rings in it that looked suss. This made no difference to any results

We have tested voltage on on the actual boards TP & the -5V + the +22V all tested ok. the +12V still read as zero, but unsure if that is used on this board. I am a little confused at why the TP are all fine on the board, yet at the connector the readings are out. There is likely an obvious explanation to this, but my lack of experience is probably showing out.

Is there anything else we should be looking at here? The project is proving productive in that we are using new techniques we hadn't previously to test Resistor & Capacitors etc - but we are unfortunately no closer to solving the problem . Any advice would be really appreciated.

 

[jamesv833]

I think the 10v is unregulated so I wouldn’t be surprised to see 12v.
Ok you replaced R29 and looking online it seems the other that likes to fail is R30 so I’d check that one it could be a bad or possibly the LM305 or TIP32.
Did you make sure to install the mica/silicone insulator under the 2n3055?
Here is a link to a page that shows the circuit and also explains a modification a lot of folks like to do regarding the sense lines.
https://bitslicer.tripod.com/ar_sense_mod.htm

 

[stj]

you have to bypass the sense line feedback circuit or the shitty edge connector causes the 5v to rise until it blows chips!!!

 

[Karnov2017]

Hi everyone

Thanks for all the direction here, we are following all these instructions and learning a hell of a lot.

After re-checking the Resistors we swapped on the ARII, we realized where we stuffed up. We replaced the resistors using the PCB R7 & R29 components, not that of the ARII! We fortunately never plugged the PCB into the ARII after we did this - we have now swapped both over to the correct resistors and our voltage issues have been resolved.

We now have 5.25V @ the 5v, -5.4V @ the -5V & 11.9V @10.3V on the connector. When testing the TP points on the PCB, we are getting 5.3V roughly at both points.

When i test on the PCB Pads with the connector plugged in, i am getting 5.1V, -5.2V & 8.4V@the 10.3. Not sure if its interesting or not, but the 10.3V is showing closer to 12 at the actual connector, but drops to 8.4V on the actual PCB at the same point when plugged in - so about a 3.2V variation. Unsure if this is a clue or normal

Unfortunately though, we are still getting a garbled boot up. If anything we appear to be having far less success at getting the game to boot., we get a garbled screen everytime. When we had the board working at 8.4V last time we actually had some success with the game booting up. We are starting to wonder if there is damage on the board, however why it seemed to work better running at a high Voltage is a but unknown to us. On the PCB, what would be the most likely cause to the below boot up screen? Is there anything else we should be trying?

Below is an image to the game pads too, can't really see any noticeable burn marks.

Thank you to everyone helping, we are learning heaps. Despite the game not working still we are pretty stoked we managed to get the Voltages right again,

 

[Karnov2017]

you have to bypass the sense line feedback circuit or the shitty edge connector causes the 5v to rise until it blows chips!!!

Not exactly sure what you mean by this. Is this the mod at r29&30 i heard about where you replace the resistor with a metal wire?

 

[stj]

yes, and no.
you should link the tracks on the back of the power connector with thick copper wire
that way you also turn the sense cables into extra power cables so the current goes through more edge connector pins

and judging from the sanding marks on the gameboard power tracks - you need to replace the edge connector too.

 

[Karnov2017]

Just an update on this, we have decided to park the project until we can get someone more experienced to work on the board for us. With it being so valuable the risk of damage is just too great for us to persist with the repair. Was hoping once the 5V was fixed we would have been all good, but clearly more going wrong than that. Will update once we get some progress hopefully in the near future.

Thanks to those who reached out to assist, we were able to fix the ARII based on that advice at least