Dead Falcon - no boot / coloured screen only

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Greenious
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Re: Dead Falcon - no boot / coloured screen only

Postby Greenious » Sat Feb 02, 2019 1:23 pm

It should work.
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Re: Dead Falcon - no boot / coloured screen only

Postby Rustynutt » Sat Feb 02, 2019 4:14 pm

I've never experienced any oscillator failure, guess it's possible. The ST clock should be fine.

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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Mon Feb 04, 2019 9:16 pm

OK well i have changed the Y3 crystal in the Falcon for a known working one and no change

I should note that the faulty screen appears immediately when switched on and not after a few seconds or after any boot time

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Re: Dead Falcon - no boot / coloured screen only

Postby mpattonm » Mon Feb 04, 2019 10:00 pm

as Greenious said it is probably Combo IC gone wrong. Did anyone mess waround the board with soldering iron on?

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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Tue Feb 05, 2019 10:30 am

It's a factory board, totally untouched

Well, i do have a Combel IC

The BIG question is do i just remove the old one and fit the new one? it's a big job and not something i'd want to do unless i knew it was the Combel for sure :|

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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Wed Feb 06, 2019 8:55 pm

What's the easiest way to remove a Combel?

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Re: Dead Falcon - no boot / coloured screen only

Postby dhedberg » Wed Feb 06, 2019 9:25 pm

I would use a hot-air rework station. It would be the easiest and safest way. Should be doable with a soldering iron and solder-wick as well, but more work.
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Re: Dead Falcon - no boot / coloured screen only

Postby mpattonm » Wed Feb 06, 2019 11:10 pm

I second that, hot-air is the only sane option. Pre-heat the surrounding bottom area of the PCB (about 5x5cm, from bellow) to 230-250stC. Then pre-heat IC legs with a circular motion, top-down, same temperature. Quickly apply enough flux gel on all the legs and set the temperature to 380-400stC (yes, that much). With nozzle facing downward, circle over IC legs, while very(!!) gently lifting the corner of IC, you should see the legs to start freely lifting off the PCB (in 15-20 sec). Do not rush it, do not use force, otherwise you will tear pads off. If you tear just one pad off, STOP. If the legs do not start to go off after more than 30 seconds, STOP.
Its not really easy process and it is very risky for someone without experience.
Last edited by mpattonm on Thu Feb 07, 2019 7:04 am, edited 2 times in total.

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Re: Dead Falcon - no boot / coloured screen only

Postby dhedberg » Thu Feb 07, 2019 1:13 am

Just want to add that if you don't have any experience in doing this (and you don't know anyone with experience willing to do the job), don't do it without practicing. Watch some videos on youtube, find some old electronics and start practicing desoldering SMD chips, once you've successfully desoldered a chip, don't throw it away, use it again to practice soldering, that is, solder it back! Can be done with the hot air station as well, or by drag-soldering, and remember, use plenty of flux gel and be patient! Nobody is an expert at soldering from birth, you get skilled at it by practicing! :D
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Re: Dead Falcon - no boot / coloured screen only

Postby mikro » Thu Feb 07, 2019 7:31 am

I would definitely check with a scope first. Unsoldering is actually the easier part, not to frakk up putting the new Combel in place, that's the real challenge. You can easily mess things up even more.

So I'd do it only in case you're 100% sure there is a signal or signals on the Combel which are supposed doing something and they are not.

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Re: Dead Falcon - no boot / coloured screen only

Postby joska » Thu Feb 07, 2019 8:25 am

mpattonm wrote:I second that, hot-air is the only sane option.


Only if you have experience with it. I've had one for years but have so far been unable to desolder anything with it without destroying something.

If I have to desolder a broken SMD component I do it pin by pin by heating the solder pad with my soldering iron and lifting the pin with a neede. Hold the pin until the pad has cooled down. Repeat.
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Re: Dead Falcon - no boot / coloured screen only

Postby sety » Thu Feb 07, 2019 8:45 am

It doesn't always work, but a good test before you start desoldering innocent chips is to drown your suspect IC in HFC freeze spray. If it comes good, then you know for sure that it's your culprit. :)
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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Thu Feb 07, 2019 8:42 pm

OK thanks for your replies guys

I'm going to have a think and maybe get someone to have a look at it before removing Combels without knowing for sure it's that

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Re: Dead Falcon - no boot / coloured screen only

Postby sety » Fri Feb 08, 2019 10:41 am

Did you try the HFC spray? It's expensive (like $30AUD a can) but a lot less expensive than a Falcon. :) I froze a chip on a 4MB Falcon card once and worked for months, so never bothered changing the IC out. Just waited 'till I could find a 14MB replacement.
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