Atari Jaguar P1 red buttons along with 1,4,7 not working.

[aapuzzo]

I recently purchased a broken Atari Jaguar with the hopes of repairing it.  Originally it wouldn't power but determined it had a stuck power button.  After fixing that with contact cleaner it appeared to just have the typical dirty cartridge slot issue.  I performed a small cleaning of the slot and after 50 tries it worked with Cybermorph and the controller worked as well.  I decided to take it apart and give it a good cleaning to see if I could make it consistently load.  Now I fixed the loading issue but seem to have broken the controller somehow.  The red buttons along with 1,4,7 and maybe * don't work.  I know the controller is good because I have a second Jaguar.  I could have shorted something out on the board because I was plugging the cartidge in with it opened but had the cardboard piece under it.  If I press the red buttons there is some sort of signal because cybermorph will finally get to the gameplay where the dpad works along with some of the number buttons allowing me to change views.    I know the 1,4,7 buttons are out because they don't work in the password screen.

 

What I have done so far.

 

1. Pin 10 on controller port gets 5 volts if a red button is pressed
2. I tried swapping U20, U21, U25 around to see if different buttons would fail.  Same buttons don't work
3. I ordered SN74HCT374DWR & SN74HC244DWR from digikey and swapped U18, U20, U21 & ,U25.  Same buttons don't work.
4. I swapped the player 2 port with player 1 port.
5. I checked the 4.7k resistance   on RP1, RP2, and RP3.  Only one leg comes up with a different resistance because maybe it's in parallel with something else.  This is the same on my now 2nd working Jaguar.
6. Checked continuity between different HC244 & HCT374 chips.  If schematic has same name on pin between chip I checked continuity. 

 

I'm at a complete loss.  Like I said it did work the one time I got it to load before doing a good cleaning.  This is driving me crazy to the point I bought a second Jaguar and was able to fix it.  That one had a blown trace near the DC power port and a completely fried cartridge-in pin in the 104 pin cartridge slot.  Fixed trace and replace the slot and now that one in 100%.  I don't completely understand how this stuff works but I'm good at soldering and checking traces if you tell me what to do.  I don't mind ordering and swapping parts either.

 

Any ideas would be appreciated.

Edited November 29, 2023 by aapuzzo

[Zerosquare]

Given the buttons that don't work, the problem is either on signal JOY1, or the ED1 connection to the data bus on U18. Check the continuity on pin #3 of joypad connector, R108 and U18 pins. There may be a broken trace somewhere.

 

If you have an oscilloscope, you can also check the signal on pin #3 of the joypad connector. You should see regular pulses on it.

[aapuzzo]

3 hours ago, Zerosquare said:

Given the buttons that don't work, the problem is either on signal JOY1, or the ED1 connection to the data bus on U18. Check the continuity on pin #3 of joypad connector, R108 and U18 pins. There may be a broken trace somewhere.

 

If you have an oscilloscope, you can also check the signal on pin #3 of the joypad connector. You should see regular pulses on it.

Tested more and didn't find an issue

 

Joy 1 circuit

Continuity pin 3 to r108 to U18 pin 5 to U21 pin 4

 

ED1 circuit

Continuity from cartridge slot A27  to  U18 pin 4  to  U21 pin 16   to   U25 pin 16 - Can test all the way from the cartridge slot to U25 pin 16

Tested RP6 Pin 2 has 10k ohms and also is passing 5v which is reaching U18 pin 4

 

Any other ideas?

[aapuzzo]

One thing I noticed just now when comparing to my working console  If I measure the voltage coming out of pin 4 on U18 right after pressing power up with Cybermorph it reads ~3.5v and soon after drops to around 1.5v and fluctuates as the demo plays.  The broken console starts at 5v and soon after drops to 3.5 volts fluctuating in that range.  They seem to be doing the same thing on pin 4 with a 1.5v difference.  Pin 5 holds a steady 5v.

[Zerosquare]

Hmmm, weird. Don't have any other idea right now that doesn't require using an oscilloscope, sorry.

[aapuzzo]

18 minutes ago, Zerosquare said:

Hmmm, weird. Don't have any other idea right now that doesn't require using an oscilloscope, sorry.

Not sure if you got to see my other post yet as it's waiting to be approved by a moderator since I'm a new member.  It's regarding the voltages on U16 pin 4 from my working and not working console.  I found a discrepancy.  See post above.  I can buy an oscilloscope and actually was thinking about it for the past 2 weeks.  Have a recommendation?  Do I need 100Hz or will 50 do.  I also want to be able to calibrate all the various cd, dvd, blue ray drive lasers in the difference consoles.

[+Stephen Moss]

Pins 1, 4, 7, * & B are all on the same row strobe so perhaps best to start with the controller as see if we can determine if the problem lies there or with the console.

 

If you are certain all the other buttons work you can eliminate tests 1 & 2 otherwise...

1. Measure the voltage between pins 10 and 20 if U1 you should measure the supply voltage of approximately 5V DC. If that check out move on to Test 2.
2. Measure the voltage between pin 10 if U1 and Diodes D1, D4, D7, D15 & D18, the end without the black line on it should read the same as the supply voltage. If that checks out move on to test 3.
3. All those buttons are on Row 1, find the connector were the controller lead attaches, if memory serves there should be P1 written in the PCB indicting the end with pin1 (pins are numbered sequentially). Row 1 is connected to pin 3 (if all controllers are wired identically it will be the Orange wire) measure between pin 10 of U1 and Pin 3, if you get a static 0V or 5V reading there is a problem, if it reads approximately the same voltage as on pins 12 & 4 of the controller cable connector then it is probably OK.

On 11/30/2023 at 4:20 AM, aapuzzo said:

I can buy an oscilloscope and actually was thinking about it for the past 2 weeks.  Have a recommendation?  Do I need 100Hz or will 50 do.  I also want to be able to calibrate all the various cd, dvd, blue ray drive lasers in the difference consoles.

Oscilloscopes can usually measure signals with frequency in MHz so the only question with regard to frequency is what you can afford vs what you need, for controller issues any oscilloscope should be fast enough to cope with that. But if you want to be able to check out other parts of the Jaguar with it as well then you will need one with a bandwidth of at least 50MHz given the Jaguar' clock frequency because as as minimum it should be twice the frequency of the fastest signal you want to look at otherwise the resulting signal trace may not be a very accurate representation of the actual signal. 

  

[aapuzzo]

Quote

 

Pins 1, 4, 7, * & B are all on the same row strobe so perhaps best to start with the controller as see if we can determine if the problem lies there or with the console.

 

  

My problem definitely is in the console.  I have a second Atari Jaguar I just repaired and it's working 100% with the controller.  It's not the port either as I get continuity through the pins and even swapped the ports.  If you see my post above discussing the voltage differences at U18 pin 4 between my working and not working console.

 

Working console U18 pin 4 testing to ground.

1. 3.5 volts on power up.
2. Once cybermorph loads I see it fluctuating around 1.5v like a signal is going through it.

Broken console U18 pin 4 testing to ground.

 

1. 5v on power up
2. Once cybermorh loads I see the voltage drop to only 3.5v and fluctuate like data is going through it.

As the game plays the demo and switches betweene mines I see definite changes in voltage on both consoles. Just the range they are operating in is different.

Edited November 30, 2023 by aapuzzo
Added quote

[+Stephen Moss]

19 hours ago, aapuzzo said:

My problem definitely is in the console.  I have a second Atari Jaguar I just repaired and it's working 100% with the controller.  It's not the port either as I get continuity through the pins and even swapped the ports.  If you see my post above discussing the voltage differences at U18 pin 4 between my working and not working console.

I found that post (and the topic starter) a little confusing, as most people here trying to repair things have little or no electronics and so may not be correctly or clearly reporting things I find it better to go through things eliminating them one at a time rather then jumping in somewhere random so that I have a clear idea of what is happening.

 

But as the controller is working on another console we can definitely eliminate that. I know how the controller reads work but I can never seem to make sense of it when I look at he schematic.

 

On 11/30/2023 at 3:24 AM, aapuzzo said:

They seem to be doing the same thing on pin 4 with a 1.5v difference.  Pin 5 holds a steady 5v.

So if pin 5 is not going low that should mean the Row 1 strobe line is not going low the and thus causing you button read issue.

There are several possibilities...

1. The output pin 5 if U18 open circuit
2. The corresponding input pin of U 18 (pin 4) has a problem or
3. The input voltage to pin 4 is not going low enough to trigger an change in output

Given that you have reported that the voltage reading on pin 4 is higher on the faulty that it is on the working Jaguar, then assuming the controller row strobe frequency is the same on both consoles the 3rd item above is where I would start because if the Low voltage is not as low as it should be then the average voltage you would read on the multi-meter would be higher than it should be.

I can only think of two things that would prevent the voltage on pin 4 of U18 going as low as it should be...

1. A faulty output pin that is unable to drive it low enough or
2. Contention on the line, two signals may be trying to control that pin at the same time, one pushing it high while the other tries to push it low, i.e. the outputs of U21 and U25 (or possibly U16 if fitted) being connected to the bus at eh same time.

Unfortunately, you will need an oscilloscope to confirm that suspicion, a logic analyser may also be able to conform that but only if the signal voltage is not going low enough for the logic analyser to register it as a 0.

 

[aapuzzo]

7 hours ago, Stephen Moss said:

I found that post (and the topic starter) a little confusing, as most people here trying to repair things have little or no electronics and so may not be correctly or clearly reporting things I find it better to go through things eliminating them one at a time rather then jumping in somewhere random so that I have a clear idea of what is happening.

 

But as the controller is working on another console we can definitely eliminate that. I know how the controller reads work but I can never seem to make sense of it when I look at he schematic.

 

I love repairing all of the retro consoles and 9 times out of 10 they are just dirty, have a bad laser, bad caps, or a broken trace.  This is the first time I ran into something more complicated and the controller was working when I got my hands on it.  I just cleaned the cartridge slot which now loads more constantly.  The original problems were the power switch wouldn't stay pressed and not loading from being dirty.  I fixed that so it works 95% of the time now and was bummed to find I broke the controller in the process.  I'm starting to wonder if a short is coming from the cartridge slot from my cleaning somehow.

 

7 hours ago, Stephen Moss said:

 

Unfortunately, you will need an oscilloscope to confirm that suspicion, a logic analyser may also be able to conform that but only if the signal voltage is not going low enough for the logic analyser to register it as a 0.

 

  

I just broke down and  bought a Siglent SDS1104X-E and have very little idea how to use it but want to learn.  I think I get the gist that I am looking to first see if there is a signal going across the circuit and second if I see 2 signals causing an issue.  If you tell me where to connect the probes I should be able to test.  I can take pictures of the output and even make a video.  It will be here next Tuesday.  I enjoy fixing all the retro consoles and handhelds for fun and the problems are usually simple like bad caps, blown trace, dirty, or a bad laser where that applies.  All the cd based systems can benefit from the oscilloscope for tweaking the cd lasers rather than just winging it or measuring with a multimeter.  This is the next tool I don't have.  I think it also supports logic testing but may need a special set of digital probes.

Edited December 1, 2023 by aapuzzo
Fixed a typo

[+Stephen Moss]

On 12/1/2023 at 6:41 PM, aapuzzo said:

I'm starting to wonder if a short is coming from the cartridge slot from my cleaning somehow.

First, while there are some electrical that could be done, a simple look with a magnifying glass should tell you that, either shorted solder joints on the underside or bent spring contacts when looking into the cartridge connector from the top.

Second, don't speculate, many things could be causing it and randomly jumping to conclusions and testing things is pointless, you may get lucky but if you do somehow manage to find it that way it could take to many times longer that taking a methodical approach, trying to eliminate different parts of the system at a time.

On 12/1/2023 at 6:41 PM, aapuzzo said:

If you tell me where to connect the probes I should be able to test.  I can take pictures of the output and even make a video.

If you have a cartridge that support two player gaming insert that and test on pins 4 & 17 of U18 simultaneously, I think they should both be the Row1 strobe for each controller port and therefore I would expect the signals to be identical.

The same goes with pins 5 & 16 of U18 which are the corresponding outputs, as most of the semiconductors in the Jag are surface mount you would need a second person to take an image/video as you will probably need both hands to hold the probes onto the pins.

Oops, brain not working will update shortly.

 

Update: 05/12/2030 08.28 GMT

Scopes generally ship with the probes set to x1 and the channel attenuation set to x1, the trigger set to Ch1 and the channel coupling set to AC, check that and set the channel coupling on both channels to DC.

Move both traces down 1 (ideally 2) full screen divisions so they overlap, set the volts per division (vertical scale) for both Channels to 2V and the time base (horizontal scale) to 1mS per division.

 

As far as we know all the other row strobes are unaffected to to start connect the Ch1 probe to pin 1 of the controller connector all thing being equal you should get a signal just over 2 whole divisions in amplitude, adjust the time base to that you see the negative going row strobe pulse (go from high to low (where the second channel trace is)) and back again at least 3 times.

All things being equal if the second controller is being read connect the Ch2 probe to 1 pin of the the second controller port, if they are being read simultaneously you should get two identical overlapping traces, of one is being read and then the other both traces should be approximately identical for amplitude and pulse width but will not be overlapping. That will establish that you have the scope setup correctly and provide a baseline of what you should be getting. If you can take a photo for reference.

Are the traces overlapping or is the Ch2 pulse occurring at a different time to that on Ch1?

 

Now repeat on pin 3 of the controller ports to see if the Row1 strobe of both controller ports are not working or just one of them.    

 

 

[aapuzzo]

On 12/4/2023 at 4:10 AM, Stephen Moss said:

Update: 05/12/2030 08.28 GMT

Scopes generally ship with the probes set to x1 and the channel attenuation set to x1, the trigger set to Ch1 and the channel coupling set to AC, check that and set the channel coupling on both channels to DC.

Move both traces down 1 (ideally 2) full screen divisions so they overlap, set the volts per division (vertical scale) for both Channels to 2V and the time base (horizontal scale) to 1mS per division.

 

As far as we know all the other row strobes are unaffected to to start connect the Ch1 probe to pin 1 of the controller connector all thing being equal you should get a signal just over 2 whole divisions in amplitude, adjust the time base to that you see the negative going row strobe pulse (go from high to low (where the second channel trace is)) and back again at least 3 times.

All things being equal if the second controller is being read connect the Ch2 probe to 1 pin of the the second controller port, if they are being read simultaneously you should get two identical overlapping traces, of one is being read and then the other both traces should be approximately identical for amplitude and pulse width but will not be overlapping. That will establish that you have the scope setup correctly and provide a baseline of what you should be getting. If you can take a photo for reference.

Are the traces overlapping or is the Ch2 pulse occurring at a different time to that on Ch1?

 

Now repeat on pin 3 of the controller ports to see if the Row1 strobe of both controller ports are not working or just one of them.    

 

 

I just got my Oscilloscope and I'm not an expert more like a kid playing with a new toy but it seems to confirm there is no pulse on pin 3 of player 1.  I had to try with Tempest to get pulses on player 2. 

 

Broken Console using Tempest

Player 1 & 2 pin 1 seem to pulse above the more solid line

Player 1 & 2 pin 2-4 pulse low except for pin 3 of player 1 which has no activity besides a solid line.

 

Working console using Tempest

Player 1 & 2 pin 1 seem to pulse above the more solid line

Player 1 & 2 pin 2-4 pulse below the more solid line

 

I will try and get screenshots once I figure out how to use the capture functions of the oscilloscope but this may be the information you were looking for.

 

[aapuzzo]

Ok I attached pictures now.  Disregard my previous post as I have a fact wrong about pin 1 player one.  It looks like only player 2 pin 1 goes from low to high.

 

Yellow Trace = Player 1 Pin 1

Blue Trace = Player 2 Pin 1

 

As you can see in the picture they seem to overlap timing wise.  I provided one zoomed in picture so it shows what both traces are doing.  They pulse at the same time and seem almost like an inverse of each other.

 

Player 1 Pin 1  -  Pulses from High to low

Player 2 Pin 1  -  Pulses from low to high

 

Player 1 Pin 2 & 4 = Pulses high to low

Player 1 Pin 3 = Base line is at same level as pin 2 & 4 but doesn't pulse.  I think this means it registers the same 5 volts but isn't transmitting a signal.  Volt meter shows 5v like pins 2&4.

 

Player 2 Pins 2 - 4 = Pulse High to low.

 

So what are the next steps?  I would say just pin 3 isn't transmitting data but I will wait for advice.

 

×

 

 

[Zerosquare]

Check pins 4 and 5 of U18. Do you get pulses on those?

[+Stephen Moss]

5 hours ago, aapuzzo said:

As you can see in the picture they seem to overlap timing wise.  I provided one zoomed in picture so it shows what both traces are doing.  They pulse at the same time and seem almost like an inverse of each other.

 

Player 1 Pin 1  -  Pulses from High to low

Player 2 Pin 1  -  Pulses from low to high

They are many ways the controller read could be programmed, the pulse width of the blue trace is wider then that of the yellow so unless you were monitoring the wrong point the fact that they are so different is disappointing as it would make comparisons easier.

The fact  that is appears to be mostly low is odd as well, perhaps check that channel display setting to see it if is set to inverted.

 

For next test I would compare the signal on pins 4 & 17 of U18  and then the test suggested by @Zerosquare 

[aapuzzo]

3 hours ago, Stephen Moss said:

 

 

 

They are many ways the controller read could be programmed, the pulse width of the blue trace is wider then that of the yellow so unless you were monitoring the wrong point the fact that they are so different is disappointing as it would make comparisons easier.

The fact  that is appears to be mostly low is odd as well, perhaps check that channel display setting to see it if is set to inverted.

 

For next test I would compare the signal on pins 4 & 17 of U18  and then the test suggested by @Zerosquare 

I don't think the channels are inverted but I will do more reading up on my scope this afternoon.

 

U18 Pin 5 is a steady signal.

U18 Pin 4 & 17 look similar and I can't zoom in on a solid square pulse.  

 

Don't forget if you want me to I can compare to a working Jaguar.

 

U18 pin4

4

 

U18 Pin5

 

 

U18 Pin17

 

Edited December 7, 2023 by aapuzzo

[Zerosquare]

Hmmm. Usually I'd tell you symptoms point to U18 being bad, but since you already did so with no change, it must be something else.

It can't be the ED1 signal, because it's also used by the ROM, so if it were defective your Jaguar wouldn't even boot.

It can't be the JOYCSL signals either, otherwise none of the buttons would be working.

 

At that point, I'd check to see if pin 3 on the joystick connector is not shorted to any of the other pins.

[aapuzzo]

20 hours ago, Stephen Moss said:

They are many ways the controller read could be programmed, the pulse width of the blue trace is wider then that of the yellow so unless you were monitoring the wrong point the fact that they are so different is disappointing as it would make comparisons easier.

The fact  that is appears to be mostly low is odd as well, perhaps check that channel display setting to see it if is set to inverted.

 

For next test I would compare the signal on pins 4 & 17 of U18  and then the test suggested by @Zerosquare 

 

5 hours ago, Zerosquare said:

Hmmm. Usually I'd tell you symptoms point to U18 being bad, but since you already did so with no change, it must be something else.

It can't be the ED1 signal, because it's also used by the ROM, so if it were defective your Jaguar wouldn't even boot.

It can't be the JOYCSL signals either, otherwise none of the buttons would be working.

 

At that point, I'd check to see if pin 3 on the joystick connector is not shorted to any of the other pins.

I tried swapping u18 again with a new chip from retrosix that is specified for Jaguar just to safe.  I could swap 20,21,25 with the chips that came from there now as well.  I don't see any shorts from pin 3 to U18.  I checked the traces around 18 while it was removed again.  I also swapped the resistor it flows through on its way to U18 around with another.  Is there any other components that can be bad because I don't mind getting new parts and swapping them?  I don't think it's a broken trace because it was working before cleaning the cartridge slot.  I could have temporarily shorted/grounded something or had moisture still in the slot when I powered it on causing damage to something.  This is driving me crazy.  I just want to know what it is at this point for learning.

Edited December 8, 2023 by aapuzzo

[+Stephen Moss]

17 hours ago, aapuzzo said:

U18 Pin 5 is a steady signal.

U18 Pin 4 & 17 look similar and I can't zoom in on a solid square pulse.  

That was my fault, I forgot that it is part of the main data bus and to therefore mention that you would need to use an external trigger input (or use a third channel to trigger off) so that the trace would start during a controller read. Perhaps get a high density 15 way D connector and solder wires to pins 9 (GND) and 1 to 4 (Controller Row strobes), plug it into the controller port then you could connect your trigger signal to say pin 1 (set trigger for falling/negative edge) and being able to clip the scope probe onto the wires leaves you hand frees.

Although for Tempest getting it to trigger on the right controller read would be a bit hit and miss as if memory serves it does something like 7 Row 0 reads (to catch Rotary changes) to ever 1 full controller read which make things a little more difficult tricky.

 

25 minutes ago, aapuzzo said:

I could swap 20,21,25 with the chips that came from there now as well.

It it your choice but I would advise against randomly changing parts as every time you perform solder/de-solder operation on the PCB you risk damaging it, the pads to surface mount device as quite small and can easily broken off if you are not careful so you might end up increasing your problems.

 

17 hours ago, aapuzzo said:

U18 Pin 4 & 17 look similar and I can't zoom in on a solid square pulse.  

 

Don't forget if you want me to I can compare to a working Jaguar.

They maybe similar in shape but what about amplitude, as one of your early posts indicated a higher voltage reading on a DVM compared to a working Jag I was think that comparison may show something up.

The problem with comparing to a working Jag is that you often need to compare the exact same signals and capturing them at the same moment is tricky, you could try to use a controller read at the trigger to synchronise but you still cant be 100% certain you care comparing like for like signals, i.e. both are on the 1000th controller read.

 

5 hours ago, Zerosquare said:

It can't be the ED1 signal, because it's also used by the ROM, so if it were defective your Jaguar wouldn't even boot.

Generally speaking I would agree, however it is possible that say a bad solder joint in a layer change somewhere after the connection to the ROM/RAM/Cartridge port but before the connection to U18 is resulting in the signal being capacity coupled rather than electrical connected so you get signal but it cannot sink any current and so Pin 4 of U18 is not being electrically pulled down hence no change in the corresponding output pin.

 

I may be worth trying a comparison of Pins 2 & 18 of U26 and Pin 2 of U26 with Pin 4 of U18. I think the signals should be the same so it does not matter where the trigger point is, but you could used a controller Rows strobe anyway. Signals my be identical but signal voltage may not to take a close look at that.

May also be worth connecting a 560 Ohm between pin 4 of U18 and GND just to see if that gets Pin 5 to go low, if it does that could support my capacitively rather then electrically coupled signal hypothesis.    

[aapuzzo]

I finally have some information that may lead to the resolution.

 

I attached the 560 ohm resistor between pin 4 of U18 and ground. This caused pin 5 on U18 to read millivolts or no reading I can't tell.  I decided to test the controller while the resistor is attached and the red buttons function in cybermorh as intended.

 

Numbers 1 ,3, 6 function as 3,6,9 instead of doing nothing.

 

That has to be useful data.  What should I try next?

Edited December 11, 2023 by aapuzzo

[+Stephen Moss]

10 hours ago, aapuzzo said:

Numbers 1 ,3, 6 function as 3,6,9 instead of doing nothing.

I would not worry too much about that the having the resistor there is likely to cause some odd results as it is always trying to pull the input low. But I do feel that the fact the resistor made pin 5 of U18 go low adds support my earlier capacitively coupled signal hypothesis, as I would otherwise have suspected U18 if you had not already changed it.

Therefore I would remove the resistor and perform the signal comparisons I mentioned in my previous post, namely...

On 12/8/2023 at 8:56 AM, Stephen Moss said:

I may be worth trying a comparison of Pins 2 & 18 of U26 and Pin 2 of U26 with Pin 4 of U18. I think the signals should be the same so it does not matter where the trigger point is, but you could used a controller Rows strobe anyway. Signals my be identical but signal voltage may not to take a close look at that.

It would be interesting to see if there is a visible difference in the signals, if there is that would be the way to try and locate where the problem may lie, particularly if it is where a track layer change occurs between components, because it it lies with a solder joint on a component the pressure of putting the probes on a component leg to measure the signal can temporarily reconnect the signal.

 

Alternatively, you could try re-soldering every pin shown as connected to signal ED1, if the problem lies with a solder joint on a component instead that could solve the problem.  Start with U21 and U25 first then work back.

[aapuzzo]

23 hours ago, Stephen Moss said:

I would not worry too much about that the having the resistor there is likely to cause some odd results as it is always trying to pull the input low. But I do feel that the fact the resistor made pin 5 of U18 go low adds support my earlier capacitively coupled signal hypothesis, as I would otherwise have suspected U18 if you had not already changed it.

Therefore I would remove the resistor and perform the signal comparisons I mentioned in my previous post, namely...

It would be interesting to see if there is a visible difference in the signals, if there is that would be the way to try and locate where the problem may lie, particularly if it is where a track layer change occurs between components, because it it lies with a solder joint on a component the pressure of putting the probes on a component leg to measure the signal can temporarily reconnect the signal.

 

Alternatively, you could try re-soldering every pin shown as connected to signal ED1, if the problem lies with a solder joint on a component instead that could solve the problem.  Start with U21 and U25 first then work back.

I am going to try both of your suggestions above later today but I quickly hooked up the scope and tested pin 3 while adding and removing the resistor.  I can see the voltage drop at pin 3 when doing that but still no pulse.  For my own knowledge what chip/device adds the pulse at pin 3 that is missing?  That may help my brain troubleshoot.

Edited December 12, 2023 by aapuzzo

[aapuzzo]

On 12/8/2023 at 3:56 AM, Stephen Moss said:

I may be worth trying a comparison of Pins 2 & 18 of U26 and Pin 2 of U26 with Pin 4 of U18. I think the signals should be the same so it does not matter where the trigger point is, but you could used a controller Rows strobe anyway. Signals my be identical but signal voltage may not to take a close look at that.

May also be worth connecting a 560 Ohm between pin 4 of U18 and GND just to see if that gets Pin 5 to go low, if it does that could support my capacitively rather then electrically coupled signal hypothesis.    

Posting pins as a reference 

 

U26 Pin 2 = D0

U26 Pin 18 = ED0

U26 Pin 17 = ED1

U18 pin 4 = ED1

U25 pin 17 = ED1

U35 pin 14 = ED1

 

 

 

Are pins 2 & pin 18 on U26 the correct pins I should be comparing because pin 18 looks like it is ED0 and not ED1?  Regardless I did measure/compare them and the voltages are different with Pin 2 being about 1 volt lower than pin 18 on U26.  Just as a reminder my working console did average a volt lower on U18 pin 4

 

I compared the voltage and signal between the ED1 pins U18 pin 4, U21 pin 16, U25 pin 16, U35 pin 14 and they all look identical.  Same voltage and similar but hard to read pattern.  The traces on scope look to overlap perfectly.

 

I did test continuity on the ED1 pins to make sure I was measuring correct connecting pins.

 

In addition I measured the resistance between pin 4 of U18 and the various ED1 points all the way to the top of the cartridge slot A27.  At most I get 1.1 ohms which is similar to ED0 measuring from U18 pin 3 to A23 on the cartridge slot.

 

Where does the pulse on player 1 pin 3 get generated?

Edited December 12, 2023 by aapuzzo
Added a note on continuity.

[aapuzzo]

Just figured out where the issue is!!  I think U26 was bad.  I swapped it with U22 since it had the same part number and now 1,3,6 and the red buttons are working and only button 8 seems to be not working.  I haven't validated all my new solder joins are good yet as I just removed and replaced the ICs with heat and haven't touched all of the pins with new solder.  However the joints looked good before so I wouldn't be surprised if U26 was bad.  I'm going to try and source a replacement chip for U26 and U22.

 

I figured what the hell it was the only thing in the chain besides the BIOS chip and resistor packs I haven't replaced. 

 

Edited post with this part number from Digikey.  Should have them later this week.

 

https://www.digikey.com/en/products/detail/texas-instruments/SN74AC245DWR/276702?s=N4IgTCBcDaKHAEBlAcgdgCwEEDCY0FYARAdQCU4QBdAXyA

 

I will say I have no idea why only 8 doesn't work when the other things on the row and column are working.

 

 

Edited December 12, 2023 by aapuzzo
Edited for part info

[+cubanismo]

Are you certain 8 works on the "good" port or other Jaguar you had?