Scandoubler crashes Amiga 500

hese · 08 November 2009, 14:39

For some reason I can't get any scandoubler to work on my Amiga 500.
Amiga begins the POST (changing the colors from grey to white) but crashes before reaching to white background giving a guru meditation #00000004.xxxxxxxx.
Amiga works fine on a Commodore monitor but not with a scandoubler.

The Amiga is unexpanded so the PSU shouldn't be a problem.
I have tried both an external and an internal scandoubler but the result is the same.
The scandoublers are ok, they both work on an another Amiga 500 with the same PSU.

Something broken/failing on the motherboard?

Toni Wilen · 08 November 2009, 15:43

Possible KS ROM genlock detection (too high load on sync signal lines). Which KS version? At least 1.x bootup detection routines are quite bad..

Some fixes here (not exactly the same problem but similar fix should work): http://eab.abime.net/showthread.php?t=46172

Mad-Matt · 08 November 2009, 16:46

I had a timming fixed A1200 that wouldnt boot (powerled stayed dimmed) when the scandex external scandoubler was connected. Never did look into why as the sd works fine with other escom and commodore a1200s I had (all three were 2B rev)

rkauer · 09 November 2009, 03:54

Check the voltage levels on the PSU prior to blame the Amiga motherboard.

Even good old PSU can have the capacitance inside filter capacitors reduced by aging.

hese · 06 December 2009, 19:30

I have checked the voltages using two PSUs (a lightweight made in Taiwan and a heavyweight made in Singapore). Here are the results:

Code:

                No scandoubler    With scandoubler
   Heavy PSU    +12.05V/+5.01V    +11.99V/+4.90V
   Light PSU    +12.05V/+5.01V    +12.13V/+4.99V

Amiga crashes when it tries to spin the floppy drive motor.

Both Kickstart versions (1.3 and 3.1) give the same result.

Chain · 06 December 2009, 21:22

did you tried to disconnect floppy? they are pretty hungry so if its a power issue maybe you can find it out this way

kriz · 06 December 2009, 23:18

I also had or maybe still have a A1200 mainboard that would refuse to work with an external scandoubler. The Eyetech external scandoubler still works fine on a A4000 and worked well on another A1200 mainboard.. But i never got to investigate further on this annoying problem..

hese · 05 January 2010, 19:52

Ok, I got this sorted. It was a genlock problem as Toni suspected.
I used the same hack as Anemos and now the scandoubler works fine.
Although I had to remove the capacitor on horizontal sync or I couldn't get any picture.

08 November 2009, 14:39	#1
hese Registered User Join Date: Sep 2008 Location: Somewhere Posts: 223	Scandoubler crashes Amiga 500 For some reason I can't get any scandoubler to work on my Amiga 500. Amiga begins the POST (changing the colors from grey to white) but crashes before reaching to white background giving a guru meditation #00000004.xxxxxxxx. Amiga works fine on a Commodore monitor but not with a scandoubler. The Amiga is unexpanded so the PSU shouldn't be a problem. I have tried both an external and an internal scandoubler but the result is the same. The scandoublers are ok, they both work on an another Amiga 500 with the same PSU. Something broken/failing on the motherboard?

06 December 2009, 19:30	#5
hese Registered User Join Date: Sep 2008 Location: Somewhere Posts: 223	I have checked the voltages using two PSUs (a lightweight made in Taiwan and a heavyweight made in Singapore). Here are the results: Code: No scandoubler With scandoubler Heavy PSU +12.05V/+5.01V +11.99V/+4.90V Light PSU +12.05V/+5.01V +12.13V/+4.99V Amiga crashes when it tries to spin the floppy drive motor. Both Kickstart versions (1.3 and 3.1) give the same result.

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08 November 2009, 15:43	#2
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,553	Possible KS ROM genlock detection (too high load on sync signal lines). Which KS version? At least 1.x bootup detection routines are quite bad.. Some fixes here (not exactly the same problem but similar fix should work): http://eab.abime.net/showthread.php?t=46172

08 November 2009, 16:46	#3
Mad-Matt Longplayer Join Date: Jan 2005 Location: Lincoln / UK Age: 45 Posts: 1,853	I had a timming fixed A1200 that wouldnt boot (powerled stayed dimmed) when the scandex external scandoubler was connected. Never did look into why as the sd works fine with other escom and commodore a1200s I had (all three were 2B rev)

09 November 2009, 03:54	#4
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	Check the voltage levels on the PSU prior to blame the Amiga motherboard. Even good old PSU can have the capacitance inside filter capacitors reduced by aging.

06 December 2009, 21:22	#6
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	did you tried to disconnect floppy? they are pretty hungry so if its a power issue maybe you can find it out this way

06 December 2009, 23:18	#7
kriz Junior Member Join Date: Sep 2001 Location: No(R)Way Age: 42 Posts: 3,222	I also had or maybe still have a A1200 mainboard that would refuse to work with an external scandoubler. The Eyetech external scandoubler still works fine on a A4000 and worked well on another A1200 mainboard.. But i never got to investigate further on this annoying problem..

05 January 2010, 19:52	#8
hese Registered User Join Date: Sep 2008 Location: Somewhere Posts: 223	Ok, I got this sorted. It was a genlock problem as Toni suspected. I used the same hack as Anemos and now the scandoubler works fine. Although I had to remove the capacitor on horizontal sync or I couldn't get any picture.

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