800XL Rev.D Rebuild

[deffroe]

I have just added the last few components to my eZcontents 800XL motherboard.  Just the IC's to insert in to the sockets and ready for the big turn on(oo er Mrs).

 

The only issue is....I'm scared😒, Is there a minimum amount of chips that will allow a boot, or, any tips, guidance etc to do before I pluck up the courage to flick the switch?

 

Thanks

 

Phil

[woj]

I would (but I am not an expert) remove all vital chips (anything that cannot be easily sourced new) and turn on empty for a quick some test, before that I would run with a multimeter around the board to check for shorts on connections that certainly should not have one (for example pairwise between all address and data lines). When on I'd check the voltages on the chip powering pins. 

 

Not sure what else...

[deffroe]

Anxiety subsided for now.  Looks like I missed a couple of IC replacements.  So probably be weekend at earliest that I get to stress again .

2 minutes ago, woj said:

I would (but I am not an expert) remove all vital chips (anything that cannot be easily sourced new) and turn on empty for a quick some test, before that I would run with a multimeter around the board to check for shorts on connections that certainly should not have one (for example pairwise between all address and data lines). When on I'd check the voltages on the chip powering pins. 

 

Not sure what else...

Thanks Woj,  This is pretty much the plan but thought there maybe some chips that need to be in to start getting voltages.

 

Phil

[woj]

I wanted to say "smoke", not "some".

[deffroe]

Thats not the kind of magic i want to experience.  

[Havok69]

Be a man, just do it!

[_The Doctor__]

Have people give your assembly a look, nice clear closer pictures. Extra eyes are always a good move.

[+Stephen]

6 hours ago, deffroe said:

I have just added the last few components to my eZcontents 800XL motherboard.  Just the IC's to insert in to the sockets and ready for the big turn on(oo er Mrs).

 

The only issue is....I'm scared😒, Is there a minimum amount of chips that will allow a boot, or, any tips, guidance etc to do before I pluck up the courage to flick the switch?

 

Thanks

 

Phil

I've built 3 full systems from bare PCB (1088XEL, XLD, and 576NUC).  My process for each was the same.  Before inserting any of the ICs, power up the machine and check for 5VDC at all sockets.  Once that checks out, I'd add all the ICs and double check, TRIPLE check to make sure of correct orientation.  Most of the large 40 pin will immediately be fried is in backwards.  After that, it's that scary moment of "just flip the switch".

[deffroe]

14 hours ago, Havok69 said:

Be a man, just do it!

Haha...err no! I prefer caution 😇

[deffroe]

10 hours ago, Stephen said:

I've built 3 full systems from bare PCB (1088XEL, XLD, and 576NUC).  My process for each was the same.  Before inserting any of the ICs, power up the machine and check for 5VDC at all sockets.  Once that checks out, I'd add all the ICs and double check, TRIPLE check to make sure of correct orientation.  Most of the large 40 pin will immediately be fried is in backwards.  After that, it's that scary moment of "just flip the switch".

My plan is pretty much this, going to power on without any IC installed, then add non Atari IC and power again.  Hopefully then I'll be man enough to do a full smoke free power on.

🤞I'll pull the missing  IC from one of my other XLs this evening and giving it a go.

 

Phil

[deffroe]

15 hours ago, _The Doctor__ said:

Have people give your assembly a look, nice clear closer pictures. Extra eyes are always a good move.

Not my tidiest but here she is...

 

[reifsnyderb]

Looks good!  A PAL system, too!

 

Where did you get the keyboard connector?

[deffroe]

Keyboard connector is from a 65/130xe motherboard I murdered last year🥴

4 minutes ago, reifsnyderb said:

Looks good!  A PAL system, too!

 

Where did you get the keyboard connector?

 

[_The Doctor__]

A number of components are under-filled, make sure the solder fills the via, some are so low they look empty or skipped.

 

The chip with writing on it, I can't see pin 1 dimple or indicator... verify orientation.

 

Lastly the electrolytic caps on the PCB silk screening are not what I expected... the aren't using + - indents or shading to indicate polarity that I can see on the PCB except in one place(that one the indent is opposite the only + polarity indicator seen). I'd speak with the designer or check against schematic...

Edited April 26, 2023 by _The Doctor__

[Marian]

Hi,

 

don't be scared, it's not so hard as you think. I'am not experienced soldering master, but my motherboard worked on third attempt with some luck. I had faulty RAM chips, GTIA and CPU. And finally I found some cold joints. But there were no smoke or another dangerous situation.

[deffroe]

I will give things another look but motherboard is clearly marked, but hey, measure twice cut once. 👍

[deffroe]

4 minutes ago, Marian said:

Hi,

 

don't be scared, it's not so hard as you think. I'am not experienced soldering master, but my motherboard worked on third attempt with some luck. I had faulty RAM chips, GTIA and CPU. And finally I found some cold joints. But there were no smoke or another dangerous situation.

Very nice, looks good in black. Thanks for the boost.

[deffroe]

Good news for me😁.  Pulled the IC I am missing from one of my other 800XL's, a Hong Kong rev.A fully socketed, and I have a booting machine.  No fizz, no bang and no magic smoke.

Now, the only little issue I have is sourcing a Y1 crystal.  I tried a 3.579Mhz but I end up with a B&W screen(tried in another machine with same result) so guessing that slight speed difference is causing this.

Can anyone recommend a UK seller?

[deffroe]

Quick question about installing a 64K SRAM module.  It says then you can leave the existing ram in, just remove the resistors.  Do you still need to remove them if the ram is removed?

Reason for asking is I removed the parts I'm waiting for from another machine to do a boot up and got video and no magic smoke.

Now I have installed the SRAM, connecting CI to u18 pin 10 and ExtSel to u18 pin 9, I get nothing.

[_The Doctor__]

You would want to remove them making the antennae path shorter... less noise out and less noise in by keeping that isolated and short.

[deffroe]

Well, removing R140-R147 didn't change anything.

[_The Doctor__]

It's working correct? Just need the proper crystal is what you were saying. I think people outlined using another crystal or oscillator and dividing it down for our needs in some threads on AA etc.

If you can't get what you need exactly, you may go that route.

[deffroe]

Yes, after finishing soldering all the components and borrowing some IC's from another machine, it was working.  As I couldn't source a delay line I opted for the 64k SRAM module by lothorak.  As per my earlier post using the vbxe manual to locate CI and ExtSel(according vbxe it's u18 pins 10&9 respectively) I got no video signal.

U18 is the ls08 although I have replaced that with f08.

20 minutes ago, _The Doctor__ said:

It's working correct? Just need the proper crystal is what you were saying. I think people outlined using another crystal or oscillator and dividing it down for our needs in some threads on AA etc.

If you can't get what you need exactly, you may go that route.