1088XEL Atari ITX Motherboard DIY Builders Thread

[bfollowell]

I'll play around with the scope some this weekend and see if I can clean those signals up, or determine if they're actually an accurate representation of what I have. Like you mentioned for yourself, I really haven't used a scope much to speak of in 30+ years, and I only bought this one last week, so I could be messing things up. That being said, I did most everything about the same way you did, right down to pressing run/stop to get a good, still signal image. I think I connected my ground connector to the ground point on J1, the PSU connector, so I'm sure I could probably find another ground spot a little closer. Also, my scope has IC leg covers for the scope leads, so I'd already pulled off the standard cover and put on the little IC leg lead cover to help me hold it stable on the legs. I'm certain that I have a lot to learn with it though, so never assume that I know anything, because there's a good chance that I don't.

 

I really appreciate your guys' help!

 

[StickJock]

9 hours ago, DrVenkman said:

I use a feature that is not necessarily obvious to someone who hasn’t used an oscilloscope for long - on most o-scope probes, the contact end is a little retractable micro-clip you can grab a wire or resistor leg with ... but you can usually pop the plastic end of the probe right off, exposing a slender metal pin for point measurements.

It's a good idea to keep the adapter on the probe tip when not using the scope in order to protect the probe tip itself from getting damaged (like from knocking it off of the table to the floor).  For this reason, we always referred to the adapters as "probe condoms".  Safety first, right?!!  ?

 

[+DrVenkman]

I disassembled my 1088XEL again today to get some comparison readings with Phi2 right off of SALLY (yellow, pin 39) versus the buffered Phi2 (B02) signal as delivered to POKEY pin 7 (purple), after passing through the 74F08 chip. Since I had to remove my XEL-CF3 adapter card to access that row of pins on SALLY, I went ahead and made a comparison of SALLY Phi2 (yellow) versus Phi1 (pin 3, in purple). As you can see, they're 180 degrees out of phase with one another but there is a slight bit of overlap; Phi1 starts to rise before Phi2 has bottomed out, and vice versa. (Note that I have the vertical axes set to overlap on the scope; these two signal amplitudes aren't quite the same. So don't use this image for measurement, only as a point of comparison for what signals general ought to look like).

 

SALLY pin 39 (Phi2, yellow) vs. POKEY pin 7 (B02, purple):

 

 

SALLY pin 39 (yellow, Phi2) vs. pin 3 (purple, Phi1):

 

[bfollowell]

I'm curious if I've bought the wrong version of the VBXE for my 1088XEL. I finally received my order from Lotharek after waiting for three months. I bought the XE version of the VBXE, not the XL version. Now that I look at it, it looks as if, once installed, it will hang overtop of the GTIA, which is where my Sophia DVI is installed, which is going to be a problem. Is this right? I can't be the only person that's installed a VBXE and a Sophia DVI in the same machine. Do I need to stack five or six more precision sockets on top of the one on the board to give my VBXE enough height to clear the Sophia?

 

[+mytek]

The 1088XLD was only meant to have individually a Sophia RevB (RGB) or a Sophia RevC (DVI) or a VBXE (RGB). There was no intention to have more than one video enhancement board at any given time. I suppose with enough stacked sockets something could be made to work, but that would likely be pretty unwieldy. A better plan would be to design an elevation board.

 

As for the VBXL version, that looks like it might work, but I give no guarantees . However if you ever plan to install a Rapidus then you'd have a new clearance issue because it would overhang that area where Rapidus needs to go.

 

VBXL Version

VBXE Version

 

[bfollowell]

OK, but I was asking about the 1088XEL, not the XLD. I could've sworn I'd read of several people that had installed both, but maybe I imagined it.

 

No plans for a Rapidus though, so the Sophia/VBXE conflict is my main concern.

 

 

[Mr Robot]

I've sent you a PM

 

[bfollowell]

Thanks Mr Robot!

 

[+mytek]

5 hours ago, bfollowell said:

OK, but I was asking about the 1088XEL, not the XLD

Opps I didn't realize what topic I was in . Hopefully Mr Robot got everything sorted out for you.

 

[bfollowell]

He did, and I did a quick and dirty translation using Google Translate. It looks to be a little more involved, but not horrible. It's more mechanical than anything else, coming up with stand-offs, etc. to raise the VBXE up about the normal Sophia DVI mounting point. Hopefully, that won't change things enough that I have to move from the case I'd planned to use.

 

Here's the translated document for anyone that may want it and need it in English.

 

Thanks!

 

<attachment deleted>

[Mr Robot]

@bfollowell The reason I didn't share that publicly is that Sleepy, the author chose not to share it publicly with me or Marlin. I figured there was a reason for that and did the same. I assume you asked sleepy and he said it was OK to post?

[bfollowell]

1 hour ago, Mr Robot said:

@bfollowell The reason I didn't share that publicly is that Sleepy, the author chose not to share it publicly with me or Marlin. I figured there was a reason for that and did the same. I assume you asked sleepy and he said it was OK to post?

Ahh, no. I had no idea that he didn't want it shared. Sorry. I'll message him and make certain it's OK.

 

If a moderator could remove that file from my post, I'll repost it once I know that Sleepy is OK with it.

 

Sorry about that.

 

[Mr Robot]

23 downloads now, I think it's a bit too late if he wants it kept private!

[bfollowell]

He made the thing for others to use, obviously. He wishes everyone luck at the end. He wasn't wishing himself luck. Obviously the instructions were meant for others to see and use. It would seem silly to make something like this to help others, then keep it private.

 

Still, you're right, I should've confirmed that first.

 

If I don't hear anything back from him, I'll create my own set of instruction in English when I'm installing mine and will make those instructions available.

 

[bfollowell]

It's official. Sleepy was perfectly fine with posting an English translated version of his original instructions.

 

To anyone wishing to install a VBXE alongside a Sophia DVI, here's a great way to go about it.

 

 

1088XEL VBXE & Sophia DVI.pdf

[_The Doctor__]

2 hours ago, bfollowell said:

It's official. Sleepy was perfectly fine with posting an English translated version of his original instructions.

 

To anyone wishing to install a VBXE alongside a Sophia DVI, here's a great way to go about it.

 

 

1088XEL VBXE & Sophia DVI.pdf 1.94 MB · 2 downloads

Cool beans!

Glad to see permission gained.

thankyou @Sleepy and @bfollowell !!

 

good show!

[Sleepy]

On 6/7/2020 at 4:35 PM, Mr Robot said:

@bfollowell The reason I didn't share that publicly is that Sleepy, the author chose not to share it publicly with me or Marlin. I figured there was a reason for that and did the same. I assume you asked sleepy and he said it was OK to post?

Hi,

 

there´s no problem to share it; neither the german version nor the translated version! The reason I didn´t post it on AA was that I´d a german version only, and AA is an english-speaking forum... I gave it away some time ago to do a translation to post, but I didn´t track it... (thx to bfollowell reminding me!) The intention doing the report was to give help to other users who want to fit the XEL with sophia & VBXE and show the questions coming up and put the answers for this special case together. It was done to be shared! ?

 

Sleepy

 

BTW: I thought I posted the german version at the ABBUC-forum; but I can´t find it... thx again for the reminder!

Edited June 18, 2020 by Sleepy

[+Eyvind Bernhardsen]

I finally received the last part for my 1088XEL yesterday, tested the power levels on all sockets (just over 5V everywhere, and the power LEDs on the motherboard light up as expected), added all the ICs, then fired it up... only to be met with a black screen. My keyboard backlight comes on so it's receiving power, but the caps and scroll lock lights remain dark, and there's no sound at all.

 

The build is pretty plain: PAL, single POKEY, no VBXE or Sophia, and I haven't put the FT232 in yet because I want the port to be aligned properly when I get a backplate. I've tested the connections to all the pins of the TK-II and reprogrammed the PIC, with no change in behaviour. I realised after my first boot that I need the OSC jumper as well as the PAL/NTSC one, but adding that didn't change anything either.

 

I'm good with software, but not so strong on the hardware side. Any tips on how to debug the problem? I've read most of the posts on this thread and tried the suggestions I've seen. Don't have an oscilloscope, but I'm asking around to see if I have any friends who do.

[+mytek]

Something I've done on a few occasions is to get either the CPU or Antic, or both NOT inserted upside down (these 2 chips are suppose to be upside down as compared to the GTIA). So I would look at that to see if that is the case with your system as well.

 

 

Luckily I haven't seen any damage to the chips when I've done this.

 

[+Eyvind Bernhardsen]

Thanks! They appear to be correct:

 

 

 

I checked the other chips too, just to be sure.

[+Stephen]

28 minutes ago, mytek said:

Something I've done on a few occasions is to get either the CPU or Antic, or both NOT inserted upside down (these 2 chips are suppose to be upside down as compared to the GTIA). So I would look at that to see if that is the case with your system as well.

 

 

Luckily I haven't seen any damage to the chips when I've done this.

 

Don't put GTIA in backwards - it will get hot enough to blister your finger.  Don't ask me how I know this   Only chip I've ever fried, and it was a damn PAL GTIA to make matters worse.

[+Eyvind Bernhardsen]

6 minutes ago, Stephen said:

Don't put GTIA in backwards - it will get hot enough to blister your finger.  Don't ask me how I know this   Only chip I've ever fried, and it was a damn PAL GTIA to make matters worse.

Hehe, thanks. Now you made me triple check the GTIA

[+Stephen]

Next thing I would check, is plug in a set of external speakers and see if you get anything at all when powering on.  A click, hum, etc.

[+DrVenkman]

Another easy mistake to make (don't ask how I know this ... ? ) is inserting your U1MB offset to the left or right by one pin position. That will give exactly the same symptoms - just a black screen on boot. (Again don't ask how I know this ... )

[+MacRorie]

1 hour ago, Eyvind Bernhardsen said:

Thanks! They appear to be correct:

 

 

 

I checked the other chips too, just to be sure.

Here's my "something went 'kaka' checklist":

1. Check and touch re-flow all solder points on the bottom (maybe you missed *A* pin or got a cold solder somewhere or a small small bridge)

2. Doublecheck pins and insertion of parts (pins off by one, legs bent and not in the socket)

3. Check pin 1 orientation on EVERYTHING and check it with the SILK screen, not the socket.  Lord knows I have reversed a socket in my day and didn't notice until the chip went in socket-oriented and not board-oriented. ESPECIALLY the SIP Resistor networks.

4. R & R daughterboards (U1M, UAV) especially since that U1M has been repaired.  At least I am assuming it has been repaired since there is an empty pin and a jumper wire on the MMU connection.

5. R & R the 40 pin LSI with known good.

6. R & R the PIC chips with known good.

7. Crystal contact insertion with the SIP pins

8.  Prayer, Mr. Saavik, the 1088 don't take prisoners.

9.  Jumpers

10.  R & R other socketed chips.

11.  Start over at the top and make sure I really did all of the steps instead of saying to myself "Oh, that's not it!"  because as soon as you say that, it is.