Dead Falcon - no boot / coloured screen only

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

Postby Chandler » Mon Jul 15, 2019 10:25 pm

keyboard attached and there is no blinking floppy LED

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

Postby Greenious » Mon Jul 15, 2019 11:46 pm

Chandler wrote:Well i finally go around the changing the Combel.......

Sadly no change, same faulty screen appears :x


Maybe you have been focusing on the wrong side of the board?

After helping ppl with their falcons lately, I've noticed that noone bothers to check the underside, there's lot's of smd resistors, capacitors that tend to get ruffled when people are working on the topside. They move, causing shorts etc...

Also, I found out the other day, dev-docs now has some excellent high-res scans of the falcon PCB. Both sides. It's great comparison material.
Updated my guides as of june 28th, 2016. Check'em out and feedback!
viewtopic.php?t=5040

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paul92706
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Re: Dead Falcon - no boot / coloured screen only

Postby paul92706 » Tue Jul 16, 2019 2:14 am

Chandler wrote:keyboard attached and there is no blinking floppy LED

Looks like your CPU is not strobing address’s. I would make this my starting point. Check clock signals going go the CPU, i would trace the clock rail and make sure there is a clock signal present.
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Re: Dead Falcon - no boot / coloured screen only

Postby paul92706 » Tue Jul 16, 2019 2:16 am

Greenious wrote:
Chandler wrote:Well i finally go around the changing the Combel.......

Sadly no change, same faulty screen appears :x


Maybe you have been focusing on the wrong side of the board?

After helping ppl with their falcons lately, I've noticed that noone bothers to check the underside, there's lot's of smd resistors, capacitors that tend to get ruffled when people are working on the topside. They move, causing shorts etc...


Also, I found out the other day, dev-docs now has some excellent high-res scans of the falcon PCB. Both sides. It's great comparison material.



Your right Greenious, i just fixed my DSP problem and there was a short at Resistor 179 (10k ohm)which was being shorted into a via giving me (70ohm’s) that is a good point you made!
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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Fri Jul 19, 2019 7:20 pm

Can see no damage on the rear of the board, it's sat in it's case and metal backing all it's life anyway

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Re: Dead Falcon - no boot / coloured screen only

Postby dhedberg » Fri Jul 19, 2019 7:29 pm

Well if any soldering work has been done on the top side of the PCB, the PCB will have been heated up and surface mount components on the back side may have moved around.
Daniel, New Beat - http://newbeat.atari.org. Like demos? Have a look at our new Falcon030 demo and feel the JOY.

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Re: Dead Falcon - no boot / coloured screen only

Postby Greenious » Fri Jul 19, 2019 8:57 pm

dhedberg wrote:Well if any soldering work has been done on the top side of the PCB, the PCB will have been heated up and surface mount components on the back side may have moved around.


Yes, that is what I have been seeing. Some of these smd components are also placed very close to throughholes and vias, making it very easy to create an unfortunate short.
Updated my guides as of june 28th, 2016. Check'em out and feedback!
viewtopic.php?t=5040

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Re: Dead Falcon - no boot / coloured screen only

Postby paul92706 » Sat Jul 20, 2019 1:14 am

Dhedberg and greenious i agree with you both 100%
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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Tue Jul 23, 2019 9:03 am

OK well i have been over the motherboard underneath with a powerful magnifying glass and can see no shorts or problems

Have looked especially around heat areas and where i changed the Combel

I don't believe it's this anyway, the guy who had this board originally was using it and then suddenly one day this problem starts

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Re: Dead Falcon - no boot / coloured screen only

Postby paul92706 » Tue Jul 23, 2019 11:57 pm

If you changed the Combel i would look over the solder on the pins and make sure no bridges or solder blobs. Also make sure your Pin #1 is in the right position. I am guilty of doing both wrong.
Atari Falcon CT60/CTPCI 14MB+ 512mb ATI9250 + NetUSBee
Atari Falcon030 CF 4gb + NetUSBee+ 14MB Ram
Atari TT030 2meg STRAM/16meg TTRAM + Nova Adaptor +Maxtor SCSI HD + DaynaPort Pocket SCSI

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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Wed Jul 24, 2019 10:28 am

Yes Combel is in correct position and the solders are factory spec

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Re: Dead Falcon - no boot / coloured screen only

Postby paul92706 » Thu Aug 01, 2019 3:13 am

Hey chandler have you checked to see if your clock signals are present?
Atari Falcon CT60/CTPCI 14MB+ 512mb ATI9250 + NetUSBee
Atari Falcon030 CF 4gb + NetUSBee+ 14MB Ram
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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Thu Aug 01, 2019 7:57 pm

i wish i could but i need a scope, really want to get one but haven't a clue what to buy

Any advice on what scope would be good for Falcon and Atari in general

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Re: Dead Falcon - no boot / coloured screen only

Postby dhedberg » Thu Aug 01, 2019 8:18 pm

I would recommend the Rigol DS1054Z if you want a new digital scope. It's a very capable 4 channel scope and an awesome deal for what you get really.
Daniel, New Beat - http://newbeat.atari.org. Like demos? Have a look at our new Falcon030 demo and feel the JOY.

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Re: Dead Falcon - no boot / coloured screen only

Postby mpattonm » Thu Aug 01, 2019 8:25 pm

And if you need something cheap to start with, good USB scope is a good option too: https://www.dreamsourcelab.com/product/dscope-c20p/
costs around 100USD

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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Mon Aug 05, 2019 6:40 pm

So with this USB PC type scope i could do basic checks and tests for clocks etc?

What are the limitations of the USB / PC type scope for Atari repairs?

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Re: Dead Falcon - no boot / coloured screen only

Postby sety » Tue Aug 06, 2019 7:15 am

I have a little $16 frequency counter from eBay. I put mine in a plastic case and attached a probe so I can use it in a similar fashion to a logic probe. It's really handy.

https://www.ebay.com.au/itm/High-Accura ... ctupt=true
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Re: Dead Falcon - no boot / coloured screen only

Postby Chandler » Tue Aug 06, 2019 8:22 am

Cool, so with that you can check for clocks etc?

Shame they only ship within Australia!


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