Amiga 500 with two problems

[tomcat666]

Hi all.

I have an A500 with two problems which i would like to fix:

- The video output is always black and white. Whichever connector I use - I know the Mono output on the left-most side of the amiga is supposed to be black and white, but I tried my normal Monitor cable to 1084S, I tried the A510 modulator to TV and the modulators Video out (which is in colour on the other A1200 I have) and in all cases the output is greyscale. I also noticed the picture fades and moves slightly whenever the floppy is accessed... which is weird (I changed the power supply to a known good one and still the same)

- The floppy disk has aparently a floppy inserted detection problem. It randomly pops up "Insert Volume xxx..." message and then after a second (or when I press Retry) it goes away. If you leave the disk in for a while it starts accessing it after 10 seconds or so just like you re-insterted the floppy. What should I check for this ?

Anyway, could the capacitors be the problem for the Video in black/white ? I haven't changed them so this would probably needed to be done anway? If any1 has any suggestions on how to fix these then I would love it. It is a very nice amiga otherwise - has a trapdoor expansion so it is basically what I had when I was a lad

[Loedown]

Originally Posted by tomcat666

Hi all.

I have an A500 with two problems which i would like to fix:

- The video output is always black and white. Whichever connector I use - I know the Mono output on the left-most side of the amiga is supposed to be black and white, but I tried my normal Monitor cable to 1084S, I tried the A510 modulator to TV and the modulators Video out (which is in colour on the other A1200 I have) and in all cases the output is greyscale. I also noticed the picture fades and moves slightly whenever the floppy is accessed... which is weird (I changed the power supply to a known good one and still the same)

Video problems are hard to diagnose because there's so much that can be wrong, you're almost better to get a second A500 board and do a transplant. With the second part of the problem, where the video shifts slightly when the floppy is accessed indicates a possible capacitor problem, sounds like the supply is being badly filtered and it never takes too much to lose the colour. It could also be that it's an NTSC A500 on PAL system or vice versa, I know that NTSC signal shows up as black and white on PAL systems, not sure about the other way around, nor what TV system is prevalent where you are

Originally Posted by tomcat666

- The floppy disk has aparently a floppy inserted detection problem. It randomly pops up "Insert Volume xxx..." message and then after a second (or when I press Retry) it goes away. If you leave the disk in for a while it starts accessing it after 10 seconds or so just like you re-insterted the floppy. What should I check for this ?

Two small switches on a normal FDD drive ( high density ), these need to be cleaned with a drop of isopropyl alcohol or contact cleaner, place a drop on the shaft and press the switch about 20 times. Switch is located where the floppy disk has its write protect switch, if that makes sense?

Originally Posted by tomcat666

Anyway, could the capacitors be the problem for the Video in black/white ? I haven't changed them so this would probably needed to be done anway? If any1 has any suggestions on how to fix these then I would love it. It is a very nice amiga otherwise - has a trapdoor expansion so it is basically what I had when I was a lad

Capacitors can always be a problem, but A500 units seem to be fairly indestructible

[tomcat666]

Thanx Loedown for the information. I have time tommorow and will take the amiga apart and try to fix the problems. Anyone has a list of capacitors to change in A500 ? Especially if there are specific ones I should target first (like you mention filtering of the power supply) ?

[Loedown]

Originally Posted by tomcat666

Thanx Loedown for the information. I have time tommorow and will take the amiga apart and try to fix the problems. Anyone has a list of capacitors to change in A500 ? Especially if there are specific ones I should target first (like you mention filtering of the power supply) ?

There's two schools of thought on this, change all of them, caps aren't expensive and it saves you from having to pull it apart again. I count about 15, but it depends on board revision.

[tomcat666]

Originally Posted by Loedown

There's two schools of thought on this, change all of them, caps aren't expensive and it saves you from having to pull it apart again. I count about 15, but it depends on board revision.

Okie, will do that then... better safe than sorry In the store they always ask me what kind I want - what should I say ?

[Loedown]

Originally Posted by tomcat666

Okie, will do that then... better safe than sorry In the store they always ask me what kind I want - what should I say ?

http://www.badcaps.net/

Have a read, some supposedly reputable electronic stores here stock absolute crap, If you fire off a PM to Cosmos he may have some good ones in stock, he's off in France. I can get them for you too and send them over if you like but postage will be nasty from here to there.

You want good quality ones, 105 degrees. Nichicon, Rubicon, Jamecon, Panasonic etc.

After all this it still may not fix your issue, as I originally said video problems can come from many sources, it's not like a disk drive where it's either the disk drive itself or the disk controller / translator.

[tomcat666]

Hi all.

Just to let you know both problems are repaired. The caps fixed the video out and I used a floppy from a dead external-enclosure floppy which was the same model as the internal one and works perfectly. My amiga is BACK Thanx !

[Loedown]

Originally Posted by tomcat666

Hi all.

Just to let you know both problems are repaired. The caps fixed the video out and I used a floppy from a dead external-enclosure floppy which was the same model as the internal one and works perfectly. My amiga is BACK Thanx !

It's good you got it going again, first port of call in any older electronic equipment is usually capacitors followed by the actual fault itself, but if you don't do the caps too it usually leads to premature failure.