A1200 Wrong Colors

[Retrofan]

Originally Posted by Magno Boots

Just may be worth using the Anemos trick?..

Attachment 31874

I cannot locate the exact thread at the moment, but I had a board that was showing as pink and this mod worked with the LED alone.

No harm in trying.

Anemos trick:
http://eab.abime.net/showthread.php?t=43207

I have some leds, but it wasn't working. Perhaps I must buy a 1uF 16v one. Surely mines are 5 volts.
The led must turn on? Because mine wasn't.

Thanks Fol. I've looked at the solder points of U30, but I don't find anything wrong.

I think I'm going to search and buy some more leds.

Thanks both.

Edit: @Magno Boots can you give me an Ebay link to that diode/led?
And the info seems incomplete, as it seems he used a cap too. Which and where?

Perhaps there's something about it in his web -in greek- http://flashback-computing.com/

[NovaCoder]

Don't forget that an Indy will bypass these kind of issues.

[Retrofan]

Originally Posted by NovaCoder

Don't forget that an Indy will bypass these kind of issues.

LOL, I knew someone would tell it. I know. But I want it working too.

[Magno Boots]

Retrofan,

I just used a 3mm LED from some old junk equipment. I would guess that it's under 3 volt?

And yes, the LED does glow, but at half brightness.

Keep trying!

[Magno Boots]

Here's the thread on the MB that was eventually fixed with Anemos' hack..

http://eab.abime.net/showthread.php?t=40183

[Retrofan]

Originally Posted by Magno Boots

Here's the thread on the MB that was eventually fixed with Anemos' hack..
http://eab.abime.net/showthread.php?t=40183

Edit: It isn't that thread.

Thanks, but after soldering so much leds one of the points where I have to solder it disappeared... Well, the miggy works the same than before.
Btw: I've reopened the Anemo's trick thread http://eab.abime.net/showthread.php?t=43207

Edit: Seing it now, I haven't lost anything. The bottom left point and the top right "disappeared" both go to the point in the top left part. I need to find another led, as mines work from 1.9v, and there I have 1.23v.

Edit: By now I will forget about Anemos' trick. I don't see any other possible fault that U30. I've already desoldered it from my for spares board, and it wasn't so difficult with chipquik.

I think I must try to change it. Any objection?

[Retrofan]

Well, I think it's a bit late if you were going to tell me not to try to change U30...



Let's see soldering.

Yes, I'm online and posting step by step. This is after cleaning the pads with a desoldering wire:



Done:




But won't try it now. Later perhaps.

[Zetr0]

@retrofan,

Sadly my friend the fault you are having is a Bad (dying) DAC (Digital.Analog.Converter) its very common on the 1D1 board I have 3 of them that have suffered this fate in a box awaiting the day I can find the right revision of DAC.

There are 3 different DAC revisions used in the A1200, each with a subtle modification specific to the motherboard revision - I have a repaired one, but it has tearing on one side of the screen - as its not the right version for the board.

btw, U30 is the DAC =)

Sorry I wasn't here sooner to help.


Interestingly enough - any clip-on SCAN Doubler has its own DAC and by-passes this problem.

[FOL]

Originally Posted by Zetr0

@retrofan,

Sadly my friend the fault you are having is a Bad (dying) DAC (Digital.Analog.Converter) its very common on the 1D1 board I have 3 of them that have suffered this fate in a box awaiting the day I can find the right revision of DAC.

There are 3 different DAC revisions used in the A1200, each with a subtle modification specific to the motherboard revision - I have a repaired one, but it has tearing on one side of the screen - as its not the right version for the board.

btw, U30 is the DAC =)

Sorry I wasn't here sooner to help.


Interestingly enough - any clip-on SCAN Doubler has its own DAC and by-passes this problem.

Aye, I have already mentioned this to Retrofan.
If its doing it on both Compsite and RGB, then it has to be something common to both or a component linked.

BT101 is the component directly related to both.


@Retrofan, some nice soldering there. I would check each pin with a metre to make sure they are all connected perfectly.

[Retrofan]

Originally Posted by Zetr0

@retrofan,

Sadly my friend the fault you are having is a Bad (dying) DAC (Digital.Analog.Converter) its very common on the 1D1 board I have 3 of them that have suffered this fate in a box awaiting the day I can find the right revision of DAC.

There are 3 different DAC revisions used in the A1200, each with a subtle modification specific to the motherboard revision - I have a repaired one, but it has tearing on one side of the screen - as its not the right version for the board.

btw, U30 is the DAC =)

Sorry I wasn't here sooner to help.


Interestingly enough - any clip-on SCAN Doubler has its own DAC and by-passes this problem.

Cof, cof... so you are telling me that the U30 I've soldered can be that doesn't work at all?

[FOL]

Originally Posted by Retrofan

Cof, cof... so you are telling me that the U30 I've soldered can be that doesn't work at all?

I have interchanged them before without trouble, the only way to know is to turn it on, after doing your checks to make sure there are no shorts or unsoldered legs.

[Retrofan]

Thanks Fol. I've got it connected, just waiting to press the On button of the Psu. Anyway, to test for continuity I don't have room to insert the multimeter in two different points. Just will look with the magnifying glass... but I'm getting nervous...

[Zetr0]

@FOL

Thats because YOU are awesome =)
(you little'n threatened to beat me if I didn't say that)


In regards to replacing the Vp101 with another from another motherboard, sadly my experience has not been as kind.

I removed said DAC from a 1D4 motherboard (which was given to me as dead) that had a damaged expansion port - in fact it was a little extra crispy where one of the copper tracks holding +5v decided to scuff up onto a ground track when someone inserted (perhaps a little too hastily) an Apollo 030...

Sadly the Apollo didn't make it.... but the Motherboard still fires up perfectly... just no chance of ever having an accelerator...

So this was my donor board, after removing the DAC I put a PLCC socket in its place for later. I then soldered the DAC to the 1D1, noting that its a different revision and the on board DAC that I had removed had some pins soldered together and had jump-wire - connecting them.

Sufficed to say, that my results were not that good (although better than the black screen I had before) - I had 4/5ths of the screen perfect, however the last 5th was teared with elements of the RGB.

From that I suspect that different DAC's have different Modifications on different motherboards - but to be fair.... I haven't checked those mods that CBM made against the DAC schematics / Pin Out either.


@RetroFan

My friend, check that you have orientated U30 correctly and then you will have nothing to worry about - it will either work, or not... it wont damage anything so press that button =)

[Retrofan]

Thanks Zetr0.... I've just tried it. First it was showing a red screen, but after resoldering the pins...


Now I've got the same than before. Not better, not worse


Edit: It must be an smd resistor, musn't it?

And Zetr0 my original DAC was 9244. This is 9235 (donnor rev. 1A). Both work here the same.

[FOL]

Originally Posted by Retrofan

Thanks Zetr0. I've just tried it. First it was showing a red screen, but after resoldering the pins...


Now I've got the same than before. Not better, not worse

On both Composite and RGB?

[Retrofan]

Ups... let me see (I will edit in 4 minutes). Edit: in 30 seconds...

Yep, it's the same (as my previous photos).

[FOL]

Originally Posted by Retrofan

Ups... let me see (I will edit in 4 minutes). Edit: in 30 seconds...

Yep, it's the same (as my previous photos).

Ok, what about removing all 3 caps, that go to the composite and rf circuit (this is from memory, dont have schematics to hand).
See if the RGB is still poor.

It still could be something relating to BT101.

[Retrofan]

I already changed C324. Tomorrow I'll try with the one on the left ¿C237? I can't see the number but the 7, and what else? C21(4)?

Edit: BTW Cosmos is banned in Amibay and I believe that the same here. I sent him a message as I have his mail, but he hasn't answered. I don't have a place to get the caps but my old 1A mb. Shoudn't you have those kits in Amigakit?

[FOL]

Originally Posted by Retrofan

I already changed C324. Tomorrow I'll try with the one on the left ¿C237? I can't see the number but the 7, and what else? C21(4)?

I didnt say replace them, remove them to test. Then if RGB still the same, reattach them. You can then rule them out.

EDIT:- We are working on sorting cap kits, were discussing it over a year ago, just never got round to sorting it.
I will try and sort something this week.

Have to ask, are you actually looking at the schematics?
Its pointless, trying to explain, unless you have that infront of you.

[Retrofan]

Originally Posted by FOL

Have to ask, are you actually looking at the schematics?
Its pointless, trying to explain, unless you have that infront of you.

Sorry, not at all, as I don't have an idea about schematics, I don't understand them.

Edit: I mean... yes a trace goes here and then to there... and what? It's the same in the board. I should know what makes to have green and what doesn't, and it isn't there.

Edit: That's why I post here, I hope you can tell me what to do... ... I'm just a "solder-junkie"...