A1200 + 1084s-d1 = brown kickstart screen

[DerSheriff]

Hi there,

Since I got my A1200 1d4 a year and a half ago it always gave brown kickstart screen, instead of purple.. I thought that the blue channel got very weak because of a leaked capacitor. Fishy smell was there, so in the last days I managed to give her a healty full recap.

Came back with my freshly recapped A1200, connected the cables and powered it on!
WOW, surprise. A purple kickstart screen. I was very very happy, I thought I solved the problem by changing the old fishy capacitors.

But after a while (1-2 minutes) came back to brown color, just like before, then again back to purple, back to brown, etc etc. The last time I got it boot with the purple colour I left it powered on for 20-30 minutes and kept the right color, but then reverted again to brown.

Just to make sure, as a last resort, I connected it to my GBS-8200+IBM monitor (the disgusting setup where my A500 is connected to) and while I was expecting a brown screen I got the regular purple kickstart screen That test was made using the same cable I use on the 1084 of course, just to be sure.
So, the amiga seems to output the right colours.

That makes me think that the problem is in the 1084.... I tried today to resolder the DB9 socket in the 1084 in the hope that pin 5 (blue) got loose but no joy, it's still the same, nothing changed.

Link to a video I made showing the problem.
https://mega.nz/#!QJsiTBgT!wTkuVoJow...MY93DHVgP5EuLw


Any hints for my issue?


Thank you,
DerSheriff

[talybont]

Probably a cold solder joint somewhere else in the 1084?

Check out this video, he shows some of the joints that might be an issue: [ Show youtube player ]

[DerSheriff]

Originally Posted by talybont

Probably a cold solder joint somewhere else in the 1084?

Check out this video, he shows some of the joints that might be an issue: [ Show youtube player ]

Probably, who knows.. I just resoldered the pins of the DB9 under the monitors pcb, nothing else.

I'll check better the video for possible ideas, I did see it today in a hurry, he repairs other kind of failures.

Thank you,
DerSheriff

[talybont]

Yes, he had a different problem, but if you watch the entire video he mentions and show some common points of failure.

[DerSheriff]

Originally Posted by talybont

Yes, he had a different problem, but if you watch the entire video he mentions and show some common points of failure.

Good. Tonight I'll watch it more carefully.

Thank you again
DerSheriff

[DerSheriff]

Watched the video, also watched the part 2.
Regarding my problem I think I can check the blue colour connection on the tube and on the board attached to the tail of the tube. I don't know what other to check beside that. Tonight/tomorrow I'll try reflowing these solder joints.

DerSheriff

[nobody]

Connect something else to the monitor to check if it's working properly.

[DerSheriff]

Originally Posted by nobody

Connect something else to the monitor to check if it's working properly.

If I recall correctly, when I used it with A500, i remember loading "State of the art" demo disk and seeing the hands/figures at the beginning being brownish (instead of blue). Surely I'll retry again, I'm not 100% sure.

Does 1084 have bleeding resistors? How much time it will take to discharge?

Thanks,
DerSheriff

[DerSheriff]

Something strange is happening....

I remembered badly. I tried an A500 and the colours on the 1084s seems all OK. Tried "State of the art" demo and I can see brilliant blue tones, just perfect!

With A1200, still brown.... So I have to think that the monitor works ok...

My A1200 however, when connected to the GBS8200 scandoubler, acts ok. With 1084s it is not ok... That's a mistery, i'd say..

Any hints for me?

Thanks,
DerSheriff

[nobody]

Not an expert but maybe the a1200 is ntsc (either is the cable, not suitable for what the CRT expects)

[DerSheriff]

Originally Posted by nobody

Not an expert but maybe the a1200 is ntsc

How can I check? It's an Italian amiga 1200, I think it's PAL

[talybont]

Do you have the same issue on the composite output?

[nobody]

On second thought after reading some similar issues I think there is some bad solder on motherboard or a cracked one.

[DerSheriff]

Originally Posted by talybont

Do you have the same issue on the composite output?

Tried now. On composite is the same, brown instead of purple (in crappier quality, of course).

[DerSheriff]

Originally Posted by nobody

On second thought after reading some similar issues I think there is some bad solder on motherboard or a cracked one.

I think so, but I don't know what could it be.

Also, strange thing is that if I connect it to my scandoubler it seems to be OK With the 1084 it gives troubles. Maybe a weak signal that is too weak for the 1084 but OK for the GBS8200 scandoubler?

Thanks

[idrougge]

Originally Posted by nobody

Not an expert but maybe the a1200 is ntsc (either is the cable, not suitable for what the CRT expects)

Doesn't matter on RGB.

[DerSheriff]

Tried to resolder the DB23 Video out socket on the amiga, checked some resistors under the motherboard, resoldered the video cable, etc etc. Still the same.

A thing I noticed inside my 1084s is a big black capacitor that looking on the top it seems a little inflated. Don't think it's related to my problem, but i'll change it when I find a suitable one.

Also tried with my Panasonic CRT TV with a SCART cable. I get a purple kickstart screen (Not so brilliant purple, but is still purple, so it's OK!). The only monitor that hates my Amiga 1200 is my 1084s

I thought of a lack of blue because of the brown kickstart screen, but of course the blue is there. Surely it doesn't lack totally.

Help me!

Thank you all,
DerSheriff

[DerSheriff]

3+ years are passed, but now I installed Indivision AGA MK3 inside my A1200... Colors are perfect, all good, never seen again a brown kickstart screen. So the problem probably has to do with something down the line after lisa (maybe the video DAC, or who knows)...