Amiga 600 rev. 1.5 port 2 joystick up-left issue

Dahman · 07 October 2015, 12:51

Seems to be an known issue but no one have a solution. In my Amiga 600 rev 1.5, my joystick in port 2 is acting up. Basically, when I press up, it registers up-left with high frequency. I use a a604n, but the issue persists even without it. I tested voltage on U34 and it was 4.92, so no point of changing PSU, nevertheless I tested it anyway on three different ones (brick, light, homemade pcs). There is not damage on the board, no capacitor leaked, etc. Do you know anyone who had that problem and managed to fix it?

demolition · 07 October 2015, 13:04

Still have the same issue in one of my 600s while the other one is fine. I never found a fix for it though, so I would also like to know more about this if anyone has some insight.

amigoun · 07 October 2015, 13:04

I had the same problem in the past on 2 of my mobos (were rev 1.5 also) but only when A603 / A604 was connected. As I did not managed to find any solution, I had to buy another mobo that finaly worked fine.

demolition · 07 October 2015, 13:25

Just to recap what I know about the issue so far (what Dahman probably have read elsewhere):

My A600 with the issue is a Rev 2, while the other, Rev. 1.5, does not show the symptoms (I'm guessing revision is not relevant).

A low 5V line will make the issue worse. Thus adding expansions like additional memory, Indivision, accelerators etc. can make it worse or 'tip it over the edge' so it starts showing the symptoms. Increasing the PSU 5V line to etc. 5.2V if possible might be a fix for some to compensate for the voltage drop.

Heat might affect the issue. In mine it seems to become worse after a little while.

A full recap did not improve this issue. I also added significant additional decoupling capacitors to the 5V line beneath the CPU, at the expansion port and beneath the floppy power header. Also no improvement.

It seems to me like it could be a timing issue since the two signals are multiplexed together by U34 in time slots controlled by CCKQ_A and one signal is leaking into the other when decoded. Maybe messing with the RC values of E128 could help since it will change the timing of the CCKQ_A signal. Or perhaps the problem is internally in Denise. I am not sure which clock signal Denise is using to separate the signals, but it is not connected to CCKQ_A. I am guessing CCK. I am adding sockets to one of my 600 board, so could then test various Denise chips to see if it follows the IC. It could also be U34 or E371. My best guess would be to tweak E371 and/or E128 to see if this changes the issue. I have not had time to do this yet though (too many projects

).

Edit: I have not heard about anyone having this issue on other Amiga models, so it would be nice to know if it only happens on the 600. If it is A600 only, that might also give clues as to finding the culprit.

FOL · 07 October 2015, 15:55

Quote:

Originally Posted by amigoun

I had the same problem in the past on 2 of my mobos (were rev 1.5 also) but only when A603 / A604 was connected. As I did not managed to find any solution, I had to buy another mobo that finaly worked fine.

I have seen this issue before and it was a dirty edge connector.
Very wierd. This is what the original OP described, when we were contacted (guessing its the same person).

Happening without A604n, could be cap leakage. Audio circuit is aweful for leaking caps. just above joy ports and edge connector.
Ive had cap leakage cause a simular issue, in the past. However normal issue is taking 1 hour + to turn on.

Lord Aga · 07 October 2015, 16:19

Yup, also had this problem. My was rev 2D. Never managed to solve it. It died completely after a while.

Daedalus · 07 October 2015, 16:32

Have you measured the voltage of the "up" line in the joystick or inside the port (pin 1)? it should be pretty much 0 when you press up. Also, left (pin 3) should be close to 5V and not change when you press up. Also, check for any cracked joints or foreign material around the multiplexer chip (U34) and Denise. There are a number of pull-up resistors and such involved. It's possible the chip itself if faulty or has a bad input - a high frequency signal like that can be caused in these cases. If you have a scope, check out the clock and output lines of U34 and see if the signals coincide.

demolition · 07 October 2015, 16:45

I have tried adding an extra pull up on the left signal to make the pull up twice as strong (half resistance). No effect.

My board was very clean since it went through the dishwasher as part of the recapping. Using a continuity checker there did not seem to be any shorts between up/left. I have not checked the signals on a scope yet though. I do find it curious that everybody seems to have the problem with up/left and never with down/right.

Daedalus · 07 October 2015, 16:59

Yep, and having looked at the multiplexer, the multiplexed signals are up+down, not up+left as would give an issue. Still suspicious of the multiplexer though, would need to give it a look with a scope to get a better idea...

demolition · 07 October 2015, 17:12

On my schematic, pins 1A and 1B on U34 is connected to pins 1/3 which is FORWARD and LEFT. 2A and 2B goes to BACK and RIGHT, so it is indeed FORWARD and LEFT which is multiplexed together.

Daedalus · 07 October 2015, 20:37

Apologies, you're right - pins 2 and 3 cross over and I didn't spot that during my brief look earlier. That does sound more like a malfunctioning multiplexer then, though it could still be Denise.

amigoun · 08 October 2015, 13:04

Quote:

Originally Posted by FOL

I have seen this issue before and it was a dirty edge connector. Very wierd. This is what the original OP described, when we were contacted (guessing its the same person).

That was not my case, I also cleaned the connector but did not help.
But I believe I was the first who experienced the problem some 5 years ago. You kindly exchanged my A603 and I had some mails exchanged with Jens, but he did not know either what could be causing the problem.

Dahman · 08 October 2015, 19:03

This must be the biggest mystery in Amiga 600 world :P Later this month I should have an opportunity to test another A604n. It's just a bummer that such a fine piece of machine has such a game breaking glitch. Any former commodore engineers on board?

fgh · 08 October 2015, 20:40

I had the joystick stuck up/left on my r1.5. It was fixed by changing the U34 as already suggested above.

Here are some troubleshooting tips I got from one of the gurus:
U34 (74LS157) is most likely, or components between U34 and port.
It is 99% guaranteed if joystick signals in input side of U34 are correct. Use DMM to check them.
It can't be problem in output side of U34 because it would also affect the mouse port. (joystick in mouse port would also have exact same problem)

demolition · 08 October 2015, 22:39

Maybe I should try to replace U34 to see if it can solve the problem.

I don't remember if the problem exists on both joy ports, but the mouse pointer 'jitters' when it should be still, so I figured that was related to the joystick problem. I need to pull the 600 out and revisit this problem.

Dahman · 09 October 2015, 14:05

Quote:

Originally Posted by demolition

Maybe I should try to replace U34 to see if it can solve the problem.

I don't remember if the problem exists on both joy ports, but the mouse pointer 'jitters' when it should be still, so I figured that was related to the joystick problem. I need to pull the 600 out and revisit this problem.

it only affects port 2, port 1 joystick is fine. Are u34 available to buy? demolition, let us know if replacing worked for yours

demolition · 09 October 2015, 14:59

Quote:

Originally Posted by Dahman

it only affects port 2, port 1 joystick is fine. Are u34 available to buy? demolition, let us know if replacing worked for yours

I think this should be the one:
http://www.ebay.com/itm/74LS157D-SMD...item1c33e514af

amigoun · 07 July 2016, 23:59

I seem to be very lucky on this issue

The third 1.5 mobo I got has this issue (occurs only when A604n connected). That particular mobo was already recapped. I am very curious if anyone will some day solve this.

demolition · 08 July 2016, 00:18

I can add that I did try to replace U34 with a new IC and it didn't fix it.

Spacemonkey · 10 September 2016, 16:31

Hi

I have the same problem on my Amiga 600
Bare 600 OK
604 + RTC + ECS Problem
604 + RTC Problem
604 + ECS Problem
604 OK

Amiga 600 V1.5 board
ECS Firmware 1.0.1 & 1.10

07 October 2015, 12:51	#1
Dahman Registered User Join Date: Oct 2015 Location: Dublin Posts: 18	Amiga 600 rev. 1.5 port 2 joystick up-left issue Seems to be an known issue but no one have a solution. In my Amiga 600 rev 1.5, my joystick in port 2 is acting up. Basically, when I press up, it registers up-left with high frequency. I use a a604n, but the issue persists even without it. I tested voltage on U34 and it was 4.92, so no point of changing PSU, nevertheless I tested it anyway on three different ones (brick, light, homemade pcs). There is not damage on the board, no capacitor leaked, etc. Do you know anyone who had that problem and managed to fix it?

07 October 2015, 13:25	#4
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	Just to recap what I know about the issue so far (what Dahman probably have read elsewhere): My A600 with the issue is a Rev 2, while the other, Rev. 1.5, does not show the symptoms (I'm guessing revision is not relevant). A low 5V line will make the issue worse. Thus adding expansions like additional memory, Indivision, accelerators etc. can make it worse or 'tip it over the edge' so it starts showing the symptoms. Increasing the PSU 5V line to etc. 5.2V if possible might be a fix for some to compensate for the voltage drop. Heat might affect the issue. In mine it seems to become worse after a little while. A full recap did not improve this issue. I also added significant additional decoupling capacitors to the 5V line beneath the CPU, at the expansion port and beneath the floppy power header. Also no improvement. It seems to me like it could be a timing issue since the two signals are multiplexed together by U34 in time slots controlled by CCKQ_A and one signal is leaking into the other when decoded. Maybe messing with the RC values of E128 could help since it will change the timing of the CCKQ_A signal. Or perhaps the problem is internally in Denise. I am not sure which clock signal Denise is using to separate the signals, but it is not connected to CCKQ_A. I am guessing CCK. I am adding sockets to one of my 600 board, so could then test various Denise chips to see if it follows the IC. It could also be U34 or E371. My best guess would be to tweak E371 and/or E128 to see if this changes the issue. I have not had time to do this yet though (too many projects ). Edit: I have not heard about anyone having this issue on other Amiga models, so it would be nice to know if it only happens on the 600. If it is A600 only, that might also give clues as to finding the culprit. Last edited by demolition; 07 October 2015 at 14:57.

10 September 2016, 16:31	#20
Spacemonkey Registered User Join Date: Apr 2016 Location: Salisbury Posts: 87	Hi I have the same problem on my Amiga 600 Bare 600 OK 604 + RTC + ECS Problem 604 + RTC Problem 604 + ECS Problem 604 OK Amiga 600 V1.5 board ECS Firmware 1.0.1 & 1.10 Last edited by Spacemonkey; 11 September 2016 at 14:39.

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07 October 2015, 13:04	#2
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	Still have the same issue in one of my 600s while the other one is fine. I never found a fix for it though, so I would also like to know more about this if anyone has some insight.

07 October 2015, 13:04	#3
amigoun Registered User Join Date: May 2010 Location: Czech Rep Posts: 599	I had the same problem in the past on 2 of my mobos (were rev 1.5 also) but only when A603 / A604 was connected. As I did not managed to find any solution, I had to buy another mobo that finaly worked fine.

07 October 2015, 16:19	#6
Lord Aga MI clan prevails Join Date: Jul 2010 Location: Belgrade, Serbia Posts: 1,443	Yup, also had this problem. My was rev 2D. Never managed to solve it. It died completely after a while.

07 October 2015, 16:32	#7
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	Have you measured the voltage of the "up" line in the joystick or inside the port (pin 1)? it should be pretty much 0 when you press up. Also, left (pin 3) should be close to 5V and not change when you press up. Also, check for any cracked joints or foreign material around the multiplexer chip (U34) and Denise. There are a number of pull-up resistors and such involved. It's possible the chip itself if faulty or has a bad input - a high frequency signal like that can be caused in these cases. If you have a scope, check out the clock and output lines of U34 and see if the signals coincide.

07 October 2015, 16:45	#8
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	I have tried adding an extra pull up on the left signal to make the pull up twice as strong (half resistance). No effect. My board was very clean since it went through the dishwasher as part of the recapping. Using a continuity checker there did not seem to be any shorts between up/left. I have not checked the signals on a scope yet though. I do find it curious that everybody seems to have the problem with up/left and never with down/right.

07 October 2015, 16:59	#9
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	Yep, and having looked at the multiplexer, the multiplexed signals are up+down, not up+left as would give an issue. Still suspicious of the multiplexer though, would need to give it a look with a scope to get a better idea...

07 October 2015, 17:12	#10
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	On my schematic, pins 1A and 1B on U34 is connected to pins 1/3 which is FORWARD and LEFT. 2A and 2B goes to BACK and RIGHT, so it is indeed FORWARD and LEFT which is multiplexed together.

07 October 2015, 20:37	#11
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	Apologies, you're right - pins 2 and 3 cross over and I didn't spot that during my brief look earlier. That does sound more like a malfunctioning multiplexer then, though it could still be Denise.

08 October 2015, 19:03	#13
Dahman Registered User Join Date: Oct 2015 Location: Dublin Posts: 18	This must be the biggest mystery in Amiga 600 world :P Later this month I should have an opportunity to test another A604n. It's just a bummer that such a fine piece of machine has such a game breaking glitch. Any former commodore engineers on board?

08 October 2015, 20:40	#14
fgh Registered User Join Date: Dec 2010 Location: Norway Posts: 817	I had the joystick stuck up/left on my r1.5. It was fixed by changing the U34 as already suggested above. Here are some troubleshooting tips I got from one of the gurus: U34 (74LS157) is most likely, or components between U34 and port. It is 99% guaranteed if joystick signals in input side of U34 are correct. Use DMM to check them. It can't be problem in output side of U34 because it would also affect the mouse port. (joystick in mouse port would also have exact same problem)

08 October 2015, 22:39	#15
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	Maybe I should try to replace U34 to see if it can solve the problem. I don't remember if the problem exists on both joy ports, but the mouse pointer 'jitters' when it should be still, so I figured that was related to the joystick problem. I need to pull the 600 out and revisit this problem.

07 July 2016, 23:59	#18
amigoun Registered User Join Date: May 2010 Location: Czech Rep Posts: 599	I seem to be very lucky on this issue The third 1.5 mobo I got has this issue (occurs only when A604n connected). That particular mobo was already recapped. I am very curious if anyone will some day solve this.

08 July 2016, 00:18	#19
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	I can add that I did try to replace U34 with a new IC and it didn't fix it.

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