How Falcon troubleshooting should *not* look like

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mikro
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How Falcon troubleshooting should *not* look like

Postby mikro » Thu Aug 02, 2018 6:59 am

Hi guys,

if you want to be amused, read on. :) Sharing my experience so maybe someone else can learn from it although I doubt someone here is equally retarded as I am.

A week ago I changed wiring in my CT2 Falcon because, well, it looked horrible, wires were dirty, old and most importantly - loose at some places what definitely didn't help with CT2 stability in general. Since I'm not so bad with soldering anymore I was like OK, it's 14 wires, most of them soldered to ICs and/or IC sockets.

So I was really careful, the end result was very nice (I'm going to post something about that later on), proudly switched the Falcon ON... and nothing. No video output whatsoever, both VGA and RGB.

Double checked, triple checked, ... all the connections, pins, contacts, CT2 pin numbers, motherboard solder points... nope.

So OK, my last possible hope - Jookie and his oscilloscope. For reasons I'm not going deeper into (you wouldn't believe anyway ;)) we were forced to meet at 4.30am (yes, that's in the morning). He checked my wiring, PCB, ... nothing suspicious.

Let's fire up the oscilloscope then... thanks to the F030 Service Guide we knew what to look for first - HALT and BERR pins. This finally brought something interesting, Jookie managed to change "no video" to "white screen" on the first reset. Sometimes. What's more interesting - you would think the white screen mean good, right?

Wrong. During the white screen the SDMA received 8/12.5 MHz instead of regular 16/25 MHz (/ = CT2 clock). During the no video state the SDMA clock was as it should. However both XHALT and EBERR on the expansion slot were in "1", as they should in both scenarios.

Actually, it wasn't that clear from the beginning because Jookie were speculating whether HALT (CPU) --> XHALT (expansion slot) doesn't mean inverted HALT however after checking in a working Falcon this theory was busted. Another funny mistake was measuring wrong pins because the Service Guide describes pins from the connector point of view, i.e. on the motherboard they are in reverse order (be careful about that!)

So that leaves us... nowhere because obviously the basic stuff works. Even Ax/Dx lines worked. So Jookie tried some 'magic touches', blows (?), even some CPU resoldering (on the CT2, with heatsink on!) ... nope. And then I would look at the PCB and ...

... put the memory card back. ;)

Yes. That was is. Naturally, the question "from what moment exactly this machine has started working?" was in the air and nobody could really tell. I'm not even sure whether I had *ever* put that card back before rechecking the wiring etc.

But anyway, it seems there must have been something wrong at least on some level because the white screen indicated something really messed up.

What does it all mean? Well... don't diagnose your Falcon at 5am in the morning. ;)
Last edited by mikro on Thu Sep 20, 2018 10:40 am, edited 1 time in total.

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alexh
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Re: How Falcon troubleshooting should *not* look like

Postby alexh » Thu Aug 02, 2018 9:03 am

Heh. I've done something similar with the MegaSTe and the ACSI->SCSI adapter. Taken it out and not replaced the jumpers.

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Re: How Falcon troubleshooting should *not* look like

Postby derkom » Thu Aug 02, 2018 9:20 am

mikro wrote:For reasons I'm not going deeper into (you wouldn't believe anyway ;)) we were forced to meet at 4.30am (yes, that's in the morning).


Around here, the explanation would be that that's 30 minutes after the bars let out, which doesn't help with troubleshooting either. :cheers:

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Re: How Falcon troubleshooting should *not* look like

Postby wongck » Thu Aug 02, 2018 12:04 pm

Really you guys are just too too too deep into hardware soldering... iron, oscilloscope ..... hell !! CPU resoldering.
For someone like me, I would just give a push to the whatever not soldered on... including the memory card.

Glad you had a nice time together at 4 am :lol:
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Re: How Falcon troubleshooting should *not* look like

Postby Rustynutt » Thu Sep 20, 2018 9:21 am

Great read!

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Greenious
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Re: How Falcon troubleshooting should *not* look like

Postby Greenious » Tue Oct 09, 2018 1:12 pm

:lol:

I hope Jookie gave you a good spanking for forcing him out at 4.30 in the morning... haha

I think we've all been there at one point or another, and since we all don't make mistakes like that (ahem), we always go for the most complicated faults we can come up with and reach for the oscilloscope... lol
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Re: How Falcon troubleshooting should *not* look like

Postby Atarieterno » Tue Oct 09, 2018 2:27 pm

Between forgetfulness and Murphy's law, we have all experienced encounters with the bad luck at some point.
A few weeks ago I connected my MO4 (SoundPool) to the TT because my number of MIDI devices continues to grow, but it did not work.
I changed the parallel cable, the MIDI cables, the driver for Cubase ... After asking for help from the comrades of this forum, of entrusting myself to Saint Tramiel, of uttering several voodoo curses and of throwing rays through the eyes: I checked the voltage of the power supply connected to the MO4 and the result was 0 volts, nothing, rien, niente, nichts, nic ...
I checked the PSU and located that one of the two threads was bitten and cut by my bunny.
Everything would have been easier if the MO4 or the PSU had an LED to indicate that it is on, or if I had started the checks for the PSU.
My little rabbit is called "Bolita", but I'm thinking of renaming her "Amiga".
Here is the culprit:

Bolita.jpg
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Greenious
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Re: How Falcon troubleshooting should *not* look like

Postby Greenious » Tue Oct 09, 2018 2:30 pm

Hehe, why not name her 'Bugs Bunny' ? lol
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Atarieterno
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Re: How Falcon troubleshooting should *not* look like

Postby Atarieterno » Tue Oct 09, 2018 2:33 pm

Greenious wrote:Hehe, why not name her 'Bugs Bunny' ? lol


Very nice! :lol:
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Greenious
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Re: How Falcon troubleshooting should *not* look like

Postby Greenious » Tue Oct 09, 2018 2:50 pm

Speaking of animals...

Some 25years ago when I was still living with my parents, I had been away one weekend and came home sunday only to find that our cat had been locked up inside my bedroom. Apparantly she must have been locked in there for a while because after a few minutes I noticed something really strange with my PC. It was a big tower, always open since Iwas always yanking new HDDs, gfx cards and whatnot in and out of it, but at the bottom there was now a small sea of cat urine. The damn cat urinated insde my PC! Not only that, I had left it on! Idk, but perhaps she enjoyed the breeze from the fans while taking a piss...

Anyway, the PC survived, and somehow I managed to get all that urine out, but I did learn one thing from that, cat urine is ultra corrosive...

Despite cleaning the bottom of the case started to rust away... Looked damn wierd and eventually I had to throw it.

In hindsight, I'm just happy she didn't take a dump in it aswell...
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Atarieterno
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Re: How Falcon troubleshooting should *not* look like

Postby Atarieterno » Tue Oct 09, 2018 5:04 pm

Greenious wrote: ...The damn cat urinated insde my PC!...


What are you complaining about?
The cat proved to have good taste, any living being can associate a PC with a toilet, especially if you used MS-DOS or its derivatives Windows: it was already full of excrement! :mrgreen:
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Re: How Falcon troubleshooting should *not* look like

Postby MiggyMog » Tue Oct 09, 2018 5:47 pm

Greenious wrote:Speaking of animals...

I did learn one thing from that, cat urine is ultra corrosive...



Yeah I had a mate at school who lost his C64 to a cat enjoying the heat from it...and then peeing on it

I am trying to stop our cat destroying any Atari hardware :coffe: that is a special task reserved for my lack of skills.

Which reminds me I need to get my falcon IKBD connector sorted after breaking it whilst trying to add the cosmosex IKBD injector.

The old adage of " if it ain't broke, don't fix it " springs to mind
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