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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: orange on April 04, 2009, 02:53:49 PM

Title: blown R401 on A500
Post by: orange on April 04, 2009, 02:53:49 PM: I got one A500 with totally burnt resistor (R401).
The 'rings' cannot be identified, does anyone know the value?

(The A500 boots fine, though. That resistor is near mouse/joystick ports so that would probably be broken.)
Title: Re: blown R401 on A500
Post by: BinoX on April 04, 2009, 03:07:59 PM: If I can read resistors correctly still, it appears to be a 470 ohm resistor (In any case, it's the same value as the R408 next to it)
Title: Re: blown R401 on A500
Post by: kamiga on April 05, 2009, 03:45:17 PM: I have two different sources which have parts lists and schematics for the A500.

Neither of them indicate a R401, but they DO indicate an RP401 (probably RP = resistor pack) which is 4.7k x 9. The revision of the motherboard is REV 5, Rock Lobster.

They are pull-up resistors on pins 1-4 on each of the joystick ports.

Should be located top right of the motherboard.

I'd be willing to bet earlier rev motherboards had individual resistors instead of the resistor pack. The value should likely be the same.

I hope this helps.

kamiga
Title: Re: blown R401 on A500
Post by: orange on June 01, 2010, 07:34:15 PM: ok, sorry to resurrect this one but i have almost identical problem again but this time with A500+.
I bought it as 'nonworking' and after plugging in, i heard a large POP, bang!
opened it up and resistor R408 is blown away completely! interestingly its in same place as the one mentioned above in a500

can someone tell me the value? its the only a500+ i got.
(R408 is next to R401 in a500+)

edit: i just read the thread. is R408=R401 in A500+ too?
btw, BinoX, thanks for the answer, it repaired my a500.
Title: Re: blown R401 on A500
Post by: ferix on June 01, 2010, 07:49:34 PM: R401 is a 470 ohms, 1/4 Watt resistor (on rev 5 motherboards). I'll check for A500+

Edit:

Looking at the A500+ parts list, R401,R406 and R408 are 4.7 ohms, 1/2 Watt, 5% resistors.

Edit (again):

A500+ parts list says exactly this:

Code: [Select]
----------------------------------------------------------- | RESISTORS 1/2 W, 5% | ----------------------------------------------------------- | 901600-50 | CF 4.7 OHM | R401, R406, R408 | | 901600-48 | CF 5.1 OHM (SUB FOR -50) | R401, R406, R408 | -----------------------------------------------------------I don't know what "SUB FOR -50" means, so you better check R401 and R406 first.

Edit (last time):
I just realized "SUB FOR -50" means "SUBSTITUTE FOR 901600-50", so as I said, check R401 and R406.
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