A600s faulty video

Hi, me again, sorry!

I have got two A600 (and now I have three of them!) from a sale. They are oldie ones with the R37.299 kickstart.

Except the one who give them to me was trying to power up it with the bigger/newer PSU but it doesn't work so it sold it as completely mobo broken.

My luck I have the original PSU so after the deal, I have booted them. They work nice and since I am a floppy lover, I have plenty of food for it.

Going to real issue, I have two issues: each for Amiga and regarding video output.

The first one has working RF modulator but it seems the red line does not work via the DB23 port. Since, I prefer the SCART way, could you give some tips if it is a well-know issue? The cable is working in my original Amiga. I don't want to try to find&replace DB23 port if it is due to a know capacitor issue.

The other one is the opposite: it works via DB23 port but the RF modulator is a mess (the signal is not stable). It is not a big deal because I use the SCART but I would like however to repair it. Is there any separate RF modulator selling or hacking suggestion?

Thanks for any suggestion!

Simone

[demolition]

Originally Posted by Dokugogagoji

The first one has working RF modulator but it seems the red line does not work via the DB23 port. Since, I prefer the SCART way, could you give some tips if it is a well-know issue? The cable is working in my original Amiga. I don't want to try to find&replace DB23 port if it is due to a know capacitor issue.
The other one is the opposite: it works via DB23 port but the RF modulator is a mess (the signal is not stable). It is not a big deal because I use the SCART but I would like however to repair it. Is there any separate RF modulator selling or hacking suggestion?

It is most likely not the DB23 connector where the problem is unless you can physically see it been burnt or otherwise damaged.
Does it have proper colors on RF and composite output?

For the second one, does it have a proper signal on the composite output?
It is not impossible to replace the RF modulator and several people probably have a spare lying around after removing it to fit a VGA port (like I have), but I don't think they are the usual ones to die.

[Loedown]

I had some A600 mainboards to fix some time back and you will need to replace all the capacitors near the video and for the one that is missing red go look at the driver transistor for the red signal, little SOT23 part, most likely open circuit.

Originally Posted by demolition

It is most likely not the DB23 connector where the problem is unless you can physically see it been burnt or otherwise damaged.

I have checked the DB23 port for faulty pin 3 for the red line and it seems fine.

Originally Posted by demolition

Does it have proper colors on RF and composite output?
For the second one, does it have a proper signal on the composite output?

The RF is working fine with all the colors for the first one...but I can't try the composite atm because I have no cables for it. I'll get one and I'll try.

Originally Posted by demolition

It is not impossible to replace the RF modulator and several people probably have a spare lying around after removing it to fit a VGA port (like I have), but I don't think they are the usual ones to die.

Need to troubleshoot it a little more then, maybe the the regulation screw is loose.

Originally Posted by Loedown

I had some A600 mainboards to fix some time back and you will need to replace all the capacitors near the video and for the one that is missing red go look at the driver transistor for the red signal, little SOT23 part, most likely open circuit.

Thanks for the transistor tip! If that SOT23 is broken, the missing red affects only the video port, isn't it? From your experience, is it hard to replace it?

Thanks for the help again,
Simone

[Loedown]

SOT23 = 3 pin SMD package, reasonably fine tipped iron and a dental pick, failing that bend a paper clip to have a fine hooked end, grind it down with a file or sandpaper. I use a dental pick or hot air depending on location.