Atari STe 1040 - Joystick fault

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Atari STe 1040 - Joystick fault

Postby fattonytm » Wed Nov 07, 2018 10:00 pm

Well I have a joystick fault on my Atari STe 1040! I have a Cheetah 125+ which initially seemed to work but after 5 minutes of playing the fire buttons stop working. Checked all the contacts in the joystick, cleaned the contacts but still the same issue, 5 minutes of full function then the fire buttons stop working.

I know dry solder joints are an issue but this doesn't seem to replicate dry solder joints, but does seem to identify a capacitor or logic ontroller fault. Anyone experienced the same problem and know what component(s) to replace? I'd assume it would be the logic controller/capcitors located under the keyboard PCB?

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Re: Atari STe 1040 - Joystick fault

Postby Greenious » Thu Nov 08, 2018 8:52 am

The keyword here is "5 minutes", is it really like exactly 5 mins or is it random?

You always resolder the mouse/joystick ports whenever you open up the keyboard because of the wear and tear these ports are subjected to, not so much that they were badly soldered from the beginning... after some use, a loose contact is more or less guaranteed.

Other than the mouse/joystick port needing resoldering the keyboard is in my experience very resilient.

https://www.dev-docs.org/docs/ got a Mega ST schematic "Atari Mega ST2/ST4 Schematic (Rev 9, C100166)", page 8 & 9 contain a schematic of the keyboard (the same is used on all st/ste/tt/f030).

as you can see, the signals from the joystick port pass through a line filter, then have a 10k Ohm pull-up resistor, and after that the mouse/firebuttons are connected straight to the IKBD. Obviously reseating socketed chips never hurts.
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Re: Atari STe 1040 - Joystick fault

Postby fattonytm » Fri Nov 09, 2018 12:36 pm

I will reflow the solder once I have it all apart as you just mentioned, it doesn't hurt to do this.

Regarding the time it takes for the fire button to stop working is probably around 5 minutes, its not that random as its happened everytime, to a point where I can predict when its about to conk out. The fire buttons will intermittently operate but requires 10-20 clicks before I get a trigger. Once I power down and re-initiate the STe, it seems to work again for another 5 minutes, 2 games were tested. The cable plugging into the Atari is fixed using blu-tak (stops movement of the 9-pin connector which caused issues with my mouse originally but this is probably the cable).

It feels like a logic controller fault just because of the way it acts, similar to a floating gate, but the link you've provided will help me perform a proper diagnostic on this. It does seem like an unusual problem!

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Re: Atari STe 1040 - Joystick fault

Postby mpattonm » Fri Nov 09, 2018 3:51 pm

I would check the voltage levels on ACIA chip with oscilloscope. It may be the power supply is failing to cover increased consumption of system under load, causing voltage drop below operational levels. This scenario is yet more probable, if the PSU and mainboard have not been recapped yet.

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Re: Atari STe 1040 - Joystick fault

Postby fattonytm » Tue Nov 13, 2018 10:40 am

Excellent suggestions guys, thank you! Regarding voltage levels...I think there's something iffy going on when the STe will stop loading games and black screen now and again, I just took it as bad floppy disks or a dirty floppy drive head (how much innuendo can you make from that!) I will look into these as soon as I take the STe apart, now its getting the time to do it!

Just out of interest, any idea on the number of caps which would be replaced within the PSU? or is it wise to do the motherboard as well? I've performed a re-cap on Spectrums so its no big deal :coffe:

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Re: Atari STe 1040 - Joystick fault

Postby mpattonm » Tue Nov 13, 2018 8:40 pm

Look here for the motherboard part: https://centuriontech.eu/product/1040ste-recap-set/
As regards to PSU, it depends on what model you have in.

PS: The recap might not go as easy as on Speccy.

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Re: Atari STe 1040 - Joystick fault

Postby dlfrsilver » Wed Nov 14, 2018 9:56 am

fattonytm wrote:I will reflow the solder once I have it all apart as you just mentioned, it doesn't hurt to do this.

Regarding the time it takes for the fire button to stop working is probably around 5 minutes, its not that random as its happened everytime, to a point where I can predict when its about to conk out. The fire buttons will intermittently operate but requires 10-20 clicks before I get a trigger. Once I power down and re-initiate the STe, it seems to work again for another 5 minutes, 2 games were tested. The cable plugging into the Atari is fixed using blu-tak (stops movement of the 9-pin connector which caused issues with my mouse originally but this is probably the cable).

It feels like a logic controller fault just because of the way it acts, similar to a floating gate, but the link you've provided will help me perform a proper diagnostic on this. It does seem like an unusual problem!


It's 98% sure that it's due to the solders of the joystick port(s). Most ST users had this problem. After a good reflown, everything will be back :)
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Re: Atari STe 1040 - Joystick fault

Postby fattonytm » Wed Nov 14, 2018 3:00 pm

Well after much umming and arring I realised that standing still in a crowded city whilst doing this was just strange.

My plan is to have this computer open only one more time and just try and sort everything out. Other than caps and interface solder joints, are there other components that are typical with the Atari STe to wear out after use? I know this is super vague and probably impossible to actually pin-point

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Re: Atari STe 1040 - Joystick fault

Postby hencox » Wed Nov 14, 2018 3:32 pm

I recognize your problems vaguely from when I had similar problems many years ago. The mouse on my falcon would work normally directly after power on but after a few minutes it would start to get more and more unresponsive until it was completely dead. I think I tried resoldering the Dsub9-connectors on the keyboard PCB but it didn't help. Eventually I disassembled the falcon and inspected the motherboard PCB and found a small bubble in the circuit board near the Dsub9 mouse/joystick-connectors (on the bottom side I think). It looked like a trace inside the PCB had heated up and got burnt off or at least was in a very bad shape. I remember that it was quite clear between which pins this trace was connected, so I soldered a short insulated wire between them and then the mouse started to work all the time again :) This could be something to have a look into as well.

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Re: Atari STe 1040 - Joystick fault

Postby Greenious » Wed Nov 14, 2018 3:57 pm

I can't really say there are any other "common" faults. Proper storage and regular reseating of the socketed components is usually all that is needed.

Maybe replacing the CPU for a HCMOS version, since it seems to eradicate the "faulty DMA" that has people riled up every once in a while.
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Re: Atari STe 1040 - Joystick fault

Postby fattonytm » Thu Nov 15, 2018 11:06 pm

Right, so I still haven't had the opportunity to strip down the STe and have a jolly good nose. However, after playing Leisure Suit Larry 3 for 20 minutes with no trouble at all something peculiar happened which I will assume is related to this joystick fault. No matter what key I pressed on the keyboard, it would type out random characters, or add spaces or backspace. Came out of the game and tested in the TOS environment, created a new folder and typed a folder name, but even if I kept pressing the same key (in this case L and backspace) it would add random numbers, characters, backspace, space and Enter.

After all the suggestions from all you guys, would it be logical to say the issue is probably a supply voltage issue or U1 6301 IC fault?

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Re: Atari STe 1040 - Joystick fault

Postby Greenious » Fri Nov 16, 2018 7:27 am

All inputs via the keyboard depends on pull-up resistors. When a key/joystick button is pressed, or mouse/joystick is moved, atleast one input to the IKBD is grounded, which tells it what happened.

I'd check the Vcc supply to the resistor arrays.
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