Resurrecting a Falcon - Help appreciated

[catmando]

I had known non-working a Falcon board left over from a batch of parts I acquired some time ago and recently thought I'd have a go at resurrecting it.

There were some obvious problems:

1. The CODEC socket was broken, so I desoldered and replaced it, checked all the traces against a working Falcon that I have.
2. A broken CAP 100uF 16v CAP by the reset switch - removed and replaced with new same value cap
3. The 1uF 50v CAP also by the reset switch had a +10 35v cap piggybacked alongside it, so I removed both and replaced them with a single new 1uf 50v

You can see some photos of the board prior to my fixes






So now I fitted a known working power supply, keyboard, floppy drive and memory module and hooked it up to my VGA monitor.

When I power it on I get the following signs of life:

1. Fan spins up
2. Keyboard power LED comes on.
3. Floppy drive makes a brief noise

But I'm not getting any display.

So what would be my next thing to check/replace?

Thanks in advance (of course if anyone thinks they can fix it for a reasonable price then please PM me).

[paul92706]

are you getting a Black or White screen at power on? I recently did a full repair on my Falcon and my CT60 boards, it took me some time, as this can get very complicated to repair.

[catmando]

are you getting a Black or White screen at power on? I recently did a full repair on my Falcon and my CT60 boards, it took me some time, as this can get very complicated to repair.

Black screen

Also,

Reset switch causes no noticeable affects

No keypress sounds through headphone jack, but can hear the speakers turn on when I power it up/down

[paul92706]

you stated you replaced Codec socket right? did you install Codec IC? it looks to be missing on Picture

[catmando]

you stated you replaced Codec socket right? did you install Codec IC? it looks to be missing on Picture

Yes new IC from Best electronics installed, the old IC was never present when I acquired it.

[paul92706]

i also would revise that clock patch there, and make sure it is all good. was this board running before? if so how did it become dead?did you do anything to make it dead or asume you did something wrong?

[paul92706]

i also notice a lead going from one of the GAL IC's to the MPU, i would look up that signal and see why that lead is running to the MPU, and make sure there is continuity from that PAL pin to MPU pin.

[catmando]

i also notice a lead going from one of the GAL IC's to the MPU, i would look up that signal and see why that lead is running to the MPU, and make sure there is continuity from that PAL pin to MPU pin.

The board is PERITEL (which I think is French)

It is also a B serial board, so that lead is present on other B serial boards

[paul92706]

ahh ok, also did you check your PSU? i am sure you did with your other Falcon right?

[paul92706]

i am looking at your motherboard closely from the Atariwiki, i will check to see any shorts or broken pins and any other oddities, i will let you know what i find.

[catmando]

ahh ok, also did you check your PSU? i am sure you did with your other Falcon right?

Yes PSU and everything else that plugs in is definitely okay.

[paul92706]

this is a clean Falcon motherboard, nothing ugly looking. My concern is why the heck is clock being injected from GAL u67 pin 19 (E) direct to MPU, this should come from Combel, and splitted into CPUCLKA/B/C (8/16mhz) CPUCLKA= FPU and CPUCLKB= MPU and CPUCLK=Expansion Connector. hmmm strange why manufactuer do this is on These Revision boards., maybe same signal? I would check this signal with a scope make sure clock signal is there.

[Robson]

Do you have an oscilloscope to check clocks, etc? A TTL tester also would be useful to see if the CPU is in Halt or not.

In the service manual there are detailed steps about troubleshooting a dead unit. You'd need a diag cart. I have one and depending on where in London you are we might be able to check your board with it.

[catmando]

Do you have an oscilloscope to check clocks, etc? A TTL tester also would be useful to see if the CPU is in Halt or not.

In the service manual there are detailed steps about troubleshooting a dead unit. You'd need a diag cart. I have one and depending on where in London you are we might be able to check your board with it.

I don't have an oscilloscope but I do have a TTL tester and a diag cart that I borrowed off a mate, is there a download link for the service manual anywhere?

[Robson]

Here you go. From page 67.

http://dev-docs.atariforge.org/

You know you can connect the serial port of the falcon to a PC with hyperterminal to read the messages...if there are any at this point.

[catmando]

Here you go. From page 67.

http://dev-docs.atariforge.org/

You know you can connect the serial port of the falcon to a PC with hyperterminal to read the messages...if there are any at this point.

I didn't know that

Thanks very much

[Robson]

I use it with a serial to USB adapter, still works. For Win7 or later you'd need to download hyperterminal.exe, it's not part of Windows anymore.

So just run hyperterminal, set the port as in the service manual..and start receiving. Hopefully you'll see some activity.

[catmando]

I use it with a serial to USB adapter, still works. For Win7 or later you'd need to download hyperterminal.exe, it's not part of Windows anymore.

So just run hyperterminal, set the port as in the service manual..and start receiving. Hopefully you'll see some activity.

Great, saves having to rig up another Atari, I have one of those USB adapters lying around somewhere

[firyembers]

you say you have another Falcon,try swapping the nvram module,i had a similar with a falcon I rebuilt and sold on ebay and found that the nvram was dead,fortunately I had a spare from Best Electronics from the last time I was there,fitted it and to life it came..
Just an idea if you have not done that

[catmando]

Okay, hooked up the non-working Falcon via the serial port to USB converter to hyperterminal, followed the com port settings as per the service manual, inserted the diagnostic cartridge and powered on.

On the hyperterminal display all I got was the letter 'P' and nothing else

Powered off, and on a few times more and still keep getting 'P'. On about the 3rd attempt the fan stopped working and now I'm not even getting a 'P' but keyboard power LED still lights up and LED on diagnostic cartridge lights up.

I tested the same setup with a working Falcon just to make sure and hyperterminal displays the full diagnostic screen, so I'm confident that is working okay.


So looks like I need to progress onto Step 2 in the diagnostic tests.

I don't have an oscilloscope but I can do the TTL test but what is the HALT pin on the 68030? and where should I connect the logic probe leads? Diagram would be useful.

[paul92706]

A /Halt signal indicates that the processor should suspend all bus activity. You should be ok to connect the Logic Probe, at any 5Vcc (becareful to what your probe is rated for) to Gnd. It is important to view the clocks wave forum on a scope, but you can check using your probe to see if there s activity from your clocks using your Logic Probe also. you should be fine connecting your leads to any 5Vcc (or rated voltage on probe), to GND. i used the 5Vcc and GND over at the cartridge port, it was easy to grab the connectors there.

[catmando]

A /Halt signal indicates that the processor should suspend all bus activity. You should be ok to connect the Logic Probe, at any 5Vcc (becareful to what your probe is rated for) to Gnd. It is important to view the clocks wave forum on a scope, but you can check using your probe to see if there s activity from your clocks using your Logic Probe also. you should be fine connecting your leads to any 5Vcc (or rated voltage on probe), to GND. i used the 5Vcc and GND over at the cartridge port, it was easy to grab the connectors there.

Thanks, any idea what location the HALT pin is on on 68030? Google is saying M10/D12 but no diagram (Found a diagram of a 68000 but not a 68030)

What points on the clocks should I check?

[paul92706]

pin 129 on 68030 should be the /Halt Pin, and check pin 6 (Clock) this pin should be were you have that wire lead going from the GAL to the 68030. you should use the Atari Service manual you downloaded, it has the pinouts for the 68030.

[catmando]

pin 129 on 68030 should be the /Halt Pin, and check pin 6 (Clock) this pin should be were you have that wire lead going from the GAL to the 68030. you should use the Atari Service manual you downloaded, it has the pinouts for the 68030.

Sorry, I should look harder, just seen the numbers are printed on the board itself

[paul92706]

pin 129 on 68030 should be the /Halt Pin, and check pin 6 (Clock) this pin should be were you have that wire lead going from the GAL to the 68030. you should use the Atari Service manual you downloaded, it has the pinouts for the 68030.

Sorry, I should look harder, just seen the numbers are printed on the board itself

ya i had to use a magnifying glass, to view those pin's, they are pretty small and hard to count. you may also catch those signals at the Interface connector port, but you need the Atari Falcon Schematics to locate the signals on Interface connector.