A1200 timing?

salaxi54

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I've got a bit of a problem, dunno if it's serious or not. The A1200 mobo for my A3KT project is a REV 1B. It actually works with the Zorro busboard, but when i plug the accelerator, i only get a black screen.
The accelerator is this one: http://www.amigahellas.gr/uploads/photos/602.jpg
From what i have read up till now, a timing issue usually comes with an 040 or an 060 card, and actually not on a Revision like mine.
Could it still be that there's a needed fix in my case?
Thanks all around! :)
 

fitzsteve

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Does this accel work in other A1200's or without the Busboard?

I had trouble getting my Apollo 1240 to work with a Micronik Busboard so the problem could be there.

Steve.
 

salaxi54

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Dunno yet Steve, i'm still trying to dig out an A1200 psu to do that. Only means immediately available for power is through the busboard right now. Which means, if i disconnect it, i've no power to the mobo..
Unfortunately this accelerator was bought more than a year ago (stated as working) but never tested up till now, so yes, i do suspect it is at fault...
 

rkauer

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The Apollo accelerators are a pain on the back to make work.

Can you check the +5V on the card, Vasilios?
 

salaxi54

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Alright, here's the deal: I found my original A1200 psu, took off the busboard, and set up the rest of the hardware (just the mobo and the accelerator) Same results! I also considered the wattage of the psu, and found a "reinforced" modded pc-psu that had the same results.
I then gave it to a friend who's got another REV 1B mobo, and he reported it wasn't working...
 

rkauer

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Do you measured the +5V rail that reaches the card?

If the worst happened, the battery on the card leaked and corroded traces under the 74F74 (you need to replace the chip, too). Common problem on Apollo.

Send the board to the nearest skilled guy to fix it for you.
 

Zetr0

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@salaxi

My friend, inspect and or replace the crystal, would be my first port of call with this unit - Also reseat the PLCC chips to ensure a propper clean fit. (let me know how you get on)

Then try it with no ram installed with the RAM jumper OPEN


@rkauer

This is the Apollo (ACT) Mk3 and uses a lithy coin battery, the main fault with these cards is bad clock (xtal) connections and flakey CPLD's

I noticed that this unit has been modified as the stock model NEVER had a second sim-port fitted (this wont fit in an A1200 desktop with memory fitted in the rear slot.
 

salaxi54

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Thanks for the advice Z, as soon as i find that 40 Mhz crystal i'll swap it(y)
I will also be trying this on a different revision mobo in a couple of days, just in case..
Yes, the second RAM slot has been added by the previous owner.
 

salaxi54

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Alrighty then, here's the current status:
Changed the oscillator!
WINNER1.jpg


WINNER2.jpg


From cold boot the machine starts, and i get the card detected!

WINNER3.jpg


However! This isn't a stable situation. The longest it runs ok is about a minute and a half. Usually just about enough to get into desktop, where i can see that the memory is working...

WINNER4.jpg


I have swapped the crystal as already mentioned, and the thing would still not startup, thus i pulled the chips out of their sockets, cleaned around, and reseated the chips. That's when i got first go.
Now, if (when) it freezes, i can leave it unpowered for say around 5 minutes, and once i turn it on, it looks ok. Then after a real short time it freezes again! Any chance it's a heat issue? The cpu is hot, but not "barbeque-hot" :) Wattage is no concern, this is an AT psu plugged to the busboard..
 

rkauer

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From what I can see the CPU doesn't have a heatsink & fan, that's right? Put both.

Also replace the SMD capacitor, it may become faulty over the years.
 

salaxi54

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Any suggestions for an "appropriate" set like that maybe? This is a small footprint, SMD cpu... Thanks!
 

rkauer

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Grab a "chipset cooler" for any store. Or scavenge a heatsink for an old/dead PC motherboard (doesn't need to be dead already :twisted: ).
 

salaxi54

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Here's an update: I found a heatsink, put thermal paste on the chip, and secured it with tiewraps.

WINNER5.jpg


The results were the same! I'm starting to think that something else is at fault. Ok, i might not have put a fan yet, but still some of the heat should have been dissipated, right? After all, this card should actually be working as-is i think...
 

rkauer

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Take the HS out. You don't need one this size, at least.

Sack carefully the three PLCC chips, clean then with a rubber eraser or lemon juice (5 minutes in a glass cup), then wash on tap water, let dry or dry with a hair-dryer and reinsert.

And change the capacitor!
 

salaxi54

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A small update: I've cut the heatsink to the size of the chip, and put it back on. I also pulled the PLCCs out again, went through the grapevine -err, sorry, through the vinegar cleaning :whistle: dried the lot, and retested.
Same ol stuff...
I went looking for a cap like the one on the card, but was told that these are "industrial-type" items, not for hobbyists! Go figure...
Would an identical value regular electrolytic cap do the job?
 

rkauer

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In fact, a regular (non-SMD) capacitor will do the job better than the SMD counterpart.

Through-hole parts have less impedance (ESR) and are more reliable.
 

FOL

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In fact, a regular (non-SMD) capacitor will do the job better than the SMD counterpart.

Through-hole parts have less impedance (ESR) and are more reliable.

When repairing TV's, hifi, dvd etc etc. We used to do this, never had a problem with anything.
 

salaxi54

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Well, it ain't the capacitor either! That's a brand new cap there. I'm through i guess... :(

WINNER6.jpg
 

rkauer

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Last port of call: can you reflux the CPU and slot connector?

Also, did you checked the voltage on the board? It must have at least 4.85V or the current on the pins will go over and cause lots of problems too.

And, for a final possibility: how good is the solder joints on the back of the card?
 
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