Weird A1200 mobo problem! - Page 2

8bitbubsy · 24 September 2009, 08:45

Okay, I see...
But what about those with four digits? "1001"...

Toni Wilen · 24 September 2009, 08:52

Quote:

Originally Posted by 8bitbubsy

Okay, I see...
But what about those with four digits? "1001"...

Post resistor(s) identification numbers. (Rxxx)

8bitbubsy · 24 September 2009, 08:54

Quote:

Originally Posted by Toni Wilen

Post resistor(s) identification numbers. (Rxxx)

R303 and R304.
Amiga 1200 1D.4

They're hidden with the U3 chip, to the bottom right.

Toni Wilen · 24 September 2009, 09:15

Quote:

Originally Posted by 8bitbubsy

R303 and R304.
Amiga 1200 1D.4

They're hidden with the U3 chip, to the bottom right.

Seems to be part of audio preamplier (LF347) power supply components, 1.02k. (some parallel component is causing your "wrong" values, try measuring out of circuit)

8bitbubsy · 24 September 2009, 09:28

Sorry for asking too much, but how can I measure "out of circuit?
I just put the two multimeter pins on each pad/size of the resistor...

Toni Wilen · 24 September 2009, 11:43

Quote:

Originally Posted by 8bitbubsy

Sorry for asking too much, but how can I measure "out of circuit?
I just put the two multimeter pins on each pad/size of the resistor...

You need to remove the resistor (or desolder at least one side) and retest.

Anyway, this resistor won't cause your problems (it can cause sound problems like noise or low volume etc but not timing changes or mouse button problems)

rkauer · 24 September 2009, 18:16

I think you are in one of the few cases that sending the Amiga board to JJ (Amiga Repair Centre in France) will be economic (the posting, at least)!

Give the guy a chance, he make top quality service (albeit expensive).

Doobrey · 24 September 2009, 19:51

Quote:

Originally Posted by Toni Wilen

Check your schematics again, there is 68 ohm in left button (fire) line, nothing in right/middle button. (they are also used as a paddle/analog joystick lines, can't have extra resistors there..)

I've triple checked the A1200 schematics I've got here, they definitely show a resistor+capacitor on each _FIRE,POTY, and POTX.

Would it be for something simple like debouncing button inputs?

Quote:

CIA? U3 is Paula

Please set up a filter to reject any posts I make after midnight.

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24 September 2009, 08:45	#21
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,711	Okay, I see... But what about those with four digits? "1001"...

24 September 2009, 09:28	#25
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,711	Sorry for asking too much, but how can I measure "out of circuit? I just put the two multimeter pins on each pad/size of the resistor...

24 September 2009, 18:16	#27
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	I think you are in one of the few cases that sending the Amiga board to JJ (Amiga Repair Centre in France) will be economic (the posting, at least)! Give the guy a chance, he make top quality service (albeit expensive).

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