Apollo 1240 Blank screen, was working fine.

[checksum]

Hi Guys,

I recently aquired an Apollo 1240 with 32MB Ram, Its was working fine for about 5 hours and when I was swapping out a fan for it and then failed to boot let alone display anything on the screen, here is what happened...

Previously:
When I first tried the card it would not work, blank screen no FDD clicks etc so I investigated the components.

The card had some minor battery leakage on the component "texas instruments 76A7Y4F F74" which is right next to the battery and had greened up badly on the legs.

I cleaned up the legs as best I could is IPA and re-installed the card and it burst into life.

I ran some tests in classic workbench sysinfo etc.. and then ran a game "Elite Frontier 2" for about 5 hours as a burn in test.

All was working really well so I decided to remove my test rig of sticky back heatsinks with a 40mm fan blowing on them and try work out a better solution for when the case all goes back together.

I disconnected the wires from the fan and just left a single long heatsink on the CPU to drag some heat off which worked rather well.

I connected up a blower from a pile of old laptop parts and had a workable solution for cooling so I took it all apart and that is when it failed to start up again.

Things I have done to try and get it to work again:

1, Reseated the RAM and cleaned the terminals with IPA.
2, Swapped out the crystal oscillator for a new 50mhz part from RS.

Still nothing... blank screen, the card powers up and CPU gets slightly warm.
no other components get hot.

I have since removed the battery suspecting it may have caused the issues in the first place.

Are there any other tests which you think I should do?

[checksum]

Or do we have any members who can diagnose and fix these cards, alas my soldering skills are rubbish so I do not want to make things worse than they already are.

[checksum]

Failing that this could be a candidate for 060 conversion as it has the mach131 chip.

[checksum]

acid damage on chip attached.

[eXeler0]

Yes there are a couple of Wizards lurking in these forums. I can recommend user @mjnurney as he performed magic on my Apollo 1240. It was not a repair per se but an upgrade to 1260 + RAM limit upgrade (to 64MB with one slot) + fixed RTC. And the 040 CPU was surface mounted, now the 060 is socketed.

Now... If he has time or interest however is not something I can say :-)
But yes, you should be able to get help. Try AmiBay too... and look around.

[trixster]

Alternatively try Stachuu on Amibay. He upgraded my Bliz 1240 to 1260. Superb workmanship, very reasonable price, very quick turnaround.

[jbenam]

@checksum

It's definitely that IC. It's an F74 and it's directly connected to the oscillator. If that one doesn't work, the card won't boot at all.

I had the same issue and replacing it while fixing a few tracks worked wonderfully.

I'd offer myself to repair your card, as I'm based in the UK as well, but I haven't got my tools here (still back home in Italy!) - there are a few UK based users that do this kind of repairs in any case.

[checksum]

Thanks Guys
@eXeler0 I have sent a PM to mjnurney, hopefully he will respond

@trixster thanks for the contact although when i signed up for an account on Amibay I was instabanned due to an error, hopefully they will fix this soon.

@jbenam, thanks for the sanity check, it does look like the problem as the rest of the board looks fine to me.

I cannot find an exact replacement IC but if its broken this looks close enough:
SN74F74DG4
Texas Instruments Flip Flop D-Type Pos-Edge 2-Element 14-Pin SOIC Tube

Hopefully the IC will be OK and will just need removing cleaning, tinning and refitting?

[checksum]

[Sandro]

1: clean the connector using alcohol

yet doesn't boot, try changing the crystal oscillator for a new one 25 mhz or higher

[jbenam]

Not sure about the IC compatibility as I can't check now (it needs to be a 74F74D, and yours seems one), but yes, just replacing it should be okay. Obviously you'll also need to check for traces continuity to be sure that nothing was corroded too much. Be really careful when removing the old IC, since they've got acid on them, you can risk lifting the pads - hot air with a gradual thermal curve is definitely advised for removal.

[hese]

As long as the edge connector of the card isn't faulty, I can fix this. You can drop me a PM if mjnurney and other UK'ers are too busy.

[checksum]

@Sandro, Yes did that, no change

@jbenam, yes they do have acid on them but I have included a better picture after a bit more IPA treatment with a paint brush. It looks like the 74F74D is quite common http://www.mouser.co.uk/Search/Refin...Keyword=74f74d

@hese, thanks very much, I just made contact with mjnurney and am explaining the situation to him, thanks for the backup

[jbenam]

@checksum
Seems probable that the pads-to-via tracks are broken. Or maybe the via themselves... Anyway, should be an easy fix if it's just that It'll be like new with mjnurney's help!

[checksum]

I guess mjnurney must be busy.. no response

[checksum]

Contacted and looking at 68060 upgrade

[AlfaRomeo]

Hi guys, sorry for hijack this thread..

I have same problem that checksum had but a little worst
In my Apollo 1260 50Mhz the IC F74 legs are so corrupted that, when I tried to clean them, the entire IC droped with the soldering pads included.
So the pads and via tracks are broken.

Does anyone have the scheme of the part of F74 connections of Apollo 1260 so I can try to fix it?

[Zetr0]

I posted this on a thread a while back - where was it now.... aha!

[click here]

[AlfaRomeo]

@Zetr0: Thanks mate, your phot helped me

Did the pin 9 connect to any component (maybe in non visible layer) or it´s a dead end?

[Zetr0]

@AlfaRomeo

I did do a schematic of this part of the board but I couldn't find it - its possibly posted in the thread linked - the picture is from a fellow EAB'er and hacker Dimlow =)

Now that pad is not connected at all - the Apollo 060 is only a two layer board if memory serves.