Amiga.org

Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Tension on March 26, 2010, 02:16:42 PM

Title: Never seen an A1200 doing this before!
Post by: Tension on March 26, 2010, 02:16:42 PM
Just got an A1200 for free. When I turn the thing on, there is about a 2 second delay before the Power LED comes on.  The HD light actually comes on first!!

The system is a bit unstable, as could be expected for a 17 year old system.  Tried loading Parasol Stars as it was the first disk I could lay my hands on at the time.  After loading, the Power LED goes completely off, but the system still works fine.

I know that when the audio filter is off, the LED dims (or is it the other way round..) and I know that on early A500s the LED would go off instead of dimming, but I've never encountered this behaviour on an A1200 before.  Also, when soft resetting, the light goes out for a few seconds.  Pretty kewl I thought.

Anybody else have one of these motherboards? or is there just something wrong with my one?

Hmmm........
Title: Re: Never seen an A1200 doing this before!
Post by: Philophus on March 26, 2010, 03:29:23 PM
Could be a failing capacitor problem.
Title: Re: Never seen an A1200 doing this before!
Post by: Tension on March 26, 2010, 03:33:35 PM
Quote from: Philophus;549770
Could be a failing capacitor problem.


Seems unlikely in my opinion.
Title: Re: Never seen an A1200 doing this before!
Post by: tone007 on March 26, 2010, 03:36:00 PM
Sounds like whatever makes the power LED light up in dim mode is malfunctioning (power LED is generally supposed to be dim for a second or two on powerup before going bright on a 1200, correct?)
Title: Re: Never seen an A1200 doing this before!
Post by: Hell Labs on March 26, 2010, 03:47:18 PM
Weird. My hard disk light doesn't work at all.
Title: Re: Never seen an A1200 doing this before!
Post by: save2600 on March 26, 2010, 03:47:30 PM
Quote from: tone007;549772
(power LED is generally supposed to be dim for a second or two on powerup before going bright on a 1200, correct?)

That's an Amiga attribute AFAIK. Any Amiga I've ever used seem to exhibit that upon startup anyway. That would include all models sans a 3000T, 4000T, CDTV, A1500 or a 500+. lol

Maybe someone performed a hardware hack bypassing the audio filter? Have you opened it up yet to clean out the dead spiders and cockroaches? lol
Title: Re: Never seen an A1200 doing this before!
Post by: Tension on March 26, 2010, 04:02:30 PM
Quote from: save2600;549776
That's an Amiga attribute AFAIK. Any Amiga I've ever used seem to exhibit that upon startup anyway. That would include all models sans a 3000T, 4000T, CDTV, A1500 or a 500+. lol

Maybe someone performed a hardware hack bypassing the audio filter? Have you opened it up yet to clean out the dead spiders and cockroaches? lol


Yea its been thoroughly cleaned, seemed fine on the inside.  Very very strange...
Title: Re: Never seen an A1200 doing this before!
Post by: save2600 on March 26, 2010, 04:17:01 PM
Quote from: Tension;549777
Yea its been thoroughly cleaned, seemed fine on the inside.  Very very strange...
So you looked REAL close at the circuit board? By the LED power connector from the CPU board? How about up on the keyboard where the wires lead to for any broken or cut traces?  

Does the light instantly come on after the machine has been on for a while and you perform a warm boot? If it does, than yeah - sounds like a bad cap.
Title: Re: Never seen an A1200 doing this before!
Post by: davideo on March 26, 2010, 04:29:09 PM
A daft statement - but are you sure someone hasn't had the diode board out and refitted it the wrong way round?!

Dave G
Title: Re: Never seen an A1200 doing this before!
Post by: Tension on March 28, 2010, 06:28:24 PM
Quote from: davideo;549781
A daft statement - but are you sure someone hasn't had the diode board out and refitted it the wrong way round?!

Dave G


That really was a daft statement lol.
Title: Re: Never seen an A1200 doing this before!
Post by: Karlos on March 28, 2010, 06:56:47 PM
Quote from: tone007;549772
Sounds like whatever makes the power LED light up in dim mode is malfunctioning (power LED is generally supposed to be dim for a second or two on powerup before going bright on a 1200, correct?)


Isn't the power LED brightness level supposed to indicate the status of the low pass audio filter?
Title: Re: Never seen an A1200 doing this before!
Post by: Karlos on March 28, 2010, 07:01:19 PM
Quote from: Hell Labs;549775
Weird. My hard disk light doesn't work at all.


Assuming you have a working hard drive installed, have you checked the little circuit board that the LED's are on? I've had one or two of these "fail" over the years where a solder connection cracked.
Title: Re: Never seen an A1200 doing this before!
Post by: tone007 on March 28, 2010, 07:28:13 PM
Quote from: Karlos;550052
Isn't the power LED brightness level supposed to indicate the status of the low pass audio filter?


Might be multipurpose, like save2600 said, they dim during boot/reset as well.  No idea if the filter is toggling at that point.
Title: Re: Never seen an A1200 doing this before!
Post by: delshay on March 28, 2010, 07:54:17 PM
check or change r639 to the right of the LED connector.
Title: Re: Never seen an A1200 doing this before!
Post by: tokyoracer on March 28, 2010, 07:56:31 PM
I know it sometimes flashes bright / dim a few times when there's an error (usually followed by the red flashing box of death).
Title: Re: Never seen an A1200 doing this before!
Post by: Boudicca on March 28, 2010, 08:00:32 PM
Quote from: tokyoracer;550064
I know it sometimes flashes bright / dim a few times when there's an error (usually followed by the red flashing box of death).


Ah I couldn't remember where Microsoft nicked that idea from. Ta. !