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Old 14 April 2015, 16:16   #1
kipper2k
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How to make the A500 rev 6 turn off its power LED

Just to revive this old thread, i have a request to try to make a Rev6a motherboard affect the audio filter LED in the same way as the Rev5... i.e. make the power LED toggle on and off and not just dim when the audio filter turns on and off.

I can prevent the LED from flickering when the audio filter turns on and off by simply lifting pin 3 from Odd CIA as suggested earlier in this thread. I have compared the schematics from Rev 5 and Rev6a to see what difference there is in the 2 designs. The only differences i can find is the values of the following

Left channel (U14)

Rev5 C321 = 0.047uf
R321 = 750 ohm

Rev 6a C321 = 0.1uf
R321 = 360 ohm


Right channel (U14)

Rev5 C331 = 0.047uf
R331 = 750 ohm

Rev 6a C331 = 0.1uf
R331 = 360 ohm

Does anyone know before i start swapping out parts if this will cause the same effects as the Rev 5 board if i swap out the Rev6a components and replace with the Rev5 values?
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Old 14 April 2015, 16:56   #2
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So do you want to affect the LED or the filter?

If you want the LED to turn off on a rev6 or newer board, remove resistor R507.
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Old 14 April 2015, 17:50   #3
hooverphonique
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Quote:
Originally Posted by kipper2k View Post
Just to revive this old thread, i have a request to try to make a Rev6a motherboard affect the audio filter LED in the same way as the Rev5... i.e. make the power LED toggle on and off and not just dim when the audio filter turns on and off.

I can prevent the LED from flickering when the audio filter turns on and off by simply lifting pin 3 from Odd CIA as suggested earlier in this thread. I have compared the schematics from Rev 5 and Rev6a to see what difference there is in the 2 designs. The only differences i can find is the values of the following
it will not be capacitor-related, and if you disconnect the cia pin, you also disable the ability to affect the filter.. depending on how the circuit is designed, and what cia pin level causes which led state (can't remember anymore), my bet is, you will either have to short or remove a resistor on the newer board to get the led to turn fully on/off.
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Old 14 April 2015, 18:05   #4
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I only know the A1200 schematics, but the transistor that brightens the LED simply shorts out a 100R resistor that drives the LED from +5V. Removing that resistor will stop the LED from lighting up at all, unless the filter is enabled. From Jope's post, that resistor is R507 on those boards...
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Old 14 April 2015, 18:36   #5
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Kipper2k said what I really wanted. There is a rev6a where the power LED now is always on. I do not want that...other people do want it..like the original post, but me...I want it like the "gooooood old days". Back then in the old days on rev5 board...the filter forces the power LED off...and if the Amiga crashes it also forces the power LED to turn/off number of times indicating type of error.

The rev6a board now however does what the original poster wanted...it is always 100% on and will only dim and undim if it crashes. For me? I do not want that on rev6a board. I want to change it back like rev5. What modification needs to be done to make this possible? I have two pictures showing what I am looking for. Picture 1 shows originally the power LED is ON when I turn the system ON, the disk activity is on as it is accessing the game...then game while loading triggers audio filter, etc....and the second picture causes the power LED off while disk activity is still going. THAT...THAT...THAT what I want back in my rev6a...what needs to be done to have that happen again?

This is the power LED of the Amiga 500 on when you first turn the machine on and you can see disk activity at work.
http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/FpAAAOSwNSxVH4EP/$_57.JPG

The game runs..the audio filter takes effect or it does what needs to be done for the power LED to turn off
http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/Jy0AAOSwstxVH4EX/$_57.JPG

And poof...there you go. SEE THAT...that is the huge amount of community complained to Commodore about it and Commodore quote and quote fixed it. What I want is that "mistake" reimplemented back to rev6a what does need to be done to do this again?
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Old 14 April 2015, 19:36   #6
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Quote:
Originally Posted by Daedalus View Post
I only know the A1200 schematics, but the transistor that brightens the LED simply shorts out a 100R resistor that drives the LED from +5V. Removing that resistor will stop the LED from lighting up at all, unless the filter is enabled. From Jope's post, that resistor is R507 on those boards...
It works differently in the A500. See the bottom of this post.

Quote:
Originally Posted by xboxown View Post
And poof...there you go. SEE THAT...that is the huge amount of community complained to Commodore about it and Commodore quote and quote fixed it. What I want is that "mistake" reimplemented back to rev6a what does need to be done to do this again?
Ok, see my answer above. Remove R507.

Rev 5: http://jope.fi/amiga/rev5_led.png

Rev 6: http://jope.fi/amiga/rev6_led.png

Last edited by Jope; 14 April 2015 at 19:54.
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Old 14 April 2015, 20:12   #7
xboxown
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Quote:
Originally Posted by Jope View Post
It works differently in the A500. See the bottom of this post.



Ok, see my answer above. Remove R507.

Rev 5: http://jope.fi/amiga/rev5_led.png

Rev 6: http://jope.fi/amiga/rev6_led.png
Hey Jope, Kipper2K tried your advice and it completely killed the power LED. It means that the power LED will never ever turn on again. That is not what I wanted.
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Old 14 April 2015, 20:26   #8
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Ok, please post here when you find the right solution. :-)

There may well be an error in the schematics. Back in the day this was "common knowledge" that it's a single resistor difference, but I never tried it out for myself.

Edit: the schematic snippets I posted match up based on a quick multimeter probe of a rev5 and rev6.

Edit2: I just did this to one of my rev 6s and now it works just like a rev 5. The LED is on when it's on and off when it's off. If I press the resistor back into place with my finger when the LED has been turned off, the LED glows dimly as it used to.

[ Show youtube player ]

Last edited by Jope; 14 April 2015 at 22:17.
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Old 14 April 2015, 22:48   #9
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Quote:
Originally Posted by Jope View Post
Ok, please post here when you find the right solution. :-)

There may well be an error in the schematics. Back in the day this was "common knowledge" that it's a single resistor difference, but I never tried it out for myself.

Edit: the schematic snippets I posted match up based on a quick multimeter probe of a rev5 and rev6.

Edit2: I just did this to one of my rev 6s and now it works just like a rev 5. The LED is on when it's on and off when it's off. If I press the resistor back into place with my finger when the LED has been turned off, the LED glows dimly as it used to.

[ Show youtube player ]
Thank you Jobe! Kipepr2K please look at it. Jobe..do you think he kipper2k did not reboot the amiga 500 to see if it turned on again or you think he made a mistake?
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Old 15 April 2015, 05:08   #10
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Quote:
Originally Posted by Jope View Post
Ok, please post here when you find the right solution. :-)

There may well be an error in the schematics. Back in the day this was "common knowledge" that it's a single resistor difference, but I never tried it out for myself.

Edit: the schematic snippets I posted match up based on a quick multimeter probe of a rev5 and rev6.

Edit2: I just did this to one of my rev 6s and now it works just like a rev 5. The LED is on when it's on and off when it's off. If I press the resistor back into place with my finger when the LED has been turned off, the LED glows dimly as it used to.

[ Show youtube player ]
i have to hang my head in shame, i forgot to put pin 3 back in the socket of odd CIA from an earlier test when i lifted the resistor and tested so of course there was no input to the LED at all so no LED.

Thanks for retesting Jope. Confirming that lifting R507 on a Rev6a does actually cause the power LED to toggle on and off with the enable/disable of the audio filter
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Old 15 April 2015, 05:37   #11
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Quote:
Originally Posted by kipper2k View Post
i have to hang my head in shame, i forgot to put pin 3 back in the socket of odd CIA from an earlier test when i lifted the resistor and tested so of course there was no input to the LED at all so no LED.

Thanks for retesting Jope. Confirming that lifting R507 on a Rev6a does actually cause the power LED to toggle on and off with the enable/disable of the audio filter

Don't worry your not the only one having a bad day... Atleast you can read (it was jope was who made me realise I couldn't in another thread)
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Old 15 April 2015, 06:09   #12
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Good to hear it was such a simple oversight. Don't worry guys, we all have these days when we're just too fast to reply. I've been guilty of it (and called out on it) many times here. :-)

This was also a learning experience: I never noticed that the schematics behind the user manual (the badly scanned ones that are floating on the net) are for Rev3 or something older. Especially the power LED circuit is different. Some day I'll pull out a rev3 board and see if it matches with that.

Last edited by Jope; 15 April 2015 at 06:55.
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Old 15 April 2015, 07:01   #13
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Originally Posted by kipper2k View Post
i have to hang my head in shame, i forgot to put pin 3 back in the socket of odd CIA from an earlier test when i lifted the resistor and tested so of course there was no input to the LED at all so no LED.

Thanks for retesting Jope. Confirming that lifting R507 on a Rev6a does actually cause the power LED to toggle on and off with the enable/disable of the audio filter
Kipper2K I have being trying to reach you on IRC but you are unavailable so I am going to try it here, perhaps you will read it here. Deal is set.

Please email me Kipper2K with the complete invoice of all the items and as soooon as I receive your email..the instance I receive your email I will do the deposit to your paypal account and complete the transaction. (Could you also send me to my email address a youtue video showing the led flashing with the game damage? I wish to drool everyday on it as it comes my way).
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Old 15 April 2015, 12:57   #14
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Subscribing to this thread because I was subscribed to the previous one. Not sure what the problem is with necro-ing retro threads?

Will be modding my rev 6a to suit, thanks for figuring this out guys.

Last edited by breech; 15 April 2015 at 13:06.
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Old 15 April 2015, 13:15   #15
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This was not the same thing as the previous thread. The previous one discussed how to add a switch to enable/disable the filter at will. This new subject discusses the LED behaviour only, the filter behaviour is still just like the designer intended.

So the necro wasn't the problem, it was the change of subject that warranted a split.

Last edited by Jope; 15 April 2015 at 13:28.
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