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Vandal968

1450 XLD motherboard build, assorted questions

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I've decided to try to build a 1450XLD from one of those 1450 motherboards that Best Electronics sells. I've been building up a BOM for the past two weeks working from the Atari schematic (lots of errors) as well as the Polish schematic (all the Atari errors, plus some new ones). I didn't see the Atari BOM until a few days ago, and it would have saved me a ton of time if I had started there instead, but I didn't know about it. In any event, it has errors too, but slightly fewer and different from the ones on the schematics, so it's a good cross-reference. I've been able to figure out most of the discrepancies by playing detective and tracing things out as well as comparing components to what Atari used on other computers and looking at photos of assembled 1400 and 1450 motherboards. It's a big job, and a very slow process. It would be very easy if I had an actual motherboard here to copy, but I don't. I can see why so many people have talked about doing this, but haven't finished. For the items that are beyond my skills, I've been speaking with a friend of mine who is an electrical engineer/rocket scientist. Seriously :)

 

When it's finished (about 95% complete now) I will post the complete, corrected BOM which also includes Digikey part numbers for most items. I'm still not sure if I will be able to get my hands on all the necessary parts, I thought it was a big score when I managed to get the SC-01-A speech chip and 74HC942 modem last week. I'm also putting together a list of corrections for each of those sources that I've been referencing.

 

First question: DIN Power Connector. The schematics call for a 7-pin DIN connector for power, the Atari BOM calls for an 8-pin. The motherboard can accommodate either since it has enough holes, but doesn't seem to require the 8th pin. What was used on the factory motherboards? The pictures I've seen are too blurry to make it out. I am specifically wondering about the variant built on the "1450" motherboard (NOT the Tong), since they may have done different things on different boards. Anybody got one that they can check? My first thought was to ask Curt, but I emailed him a week or two ago and haven't heard back.

 

Thanks for the help,

v

Edited by Vandal968
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Nice!

 

show pics of it working when done?

 

 

sloopy.

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The 1400 board (and, the Tong board) have 8-pin power connectors.

 

post-14708-0-70976200-1313433394_thumb.jpg

 

 

The 1450 board has 7-pin power connectors.

 

post-14708-0-97316100-1313433451_thumb.jpg

 

You can get the bare board? They still have some? How much?

 

Bob

 

 

I've decided to try to build a 1450XLD from one of those 1450 motherboards that Best Electronics sells. I've been building up a BOM for the past two weeks working from the Atari schematic (lots of errors) as well as the Polish schematic (all the Atari errors, plus some new ones). I didn't see the Atari BOM until a few days ago, and it would have saved me a ton of time if I had started there instead, but I didn't know about it. In any event, it has errors too, but slightly fewer and different from the ones on the schematics, so it's a good cross-reference. I've been able to figure out most of the discrepancies by playing detective and tracing things out as well as comparing components to what Atari used on other computers and looking at photos of assembled 1400 and 1450 motherboards. It's a big job, and a very slow process. It would be very easy if I had an actual motherboard here to copy, but I don't. I can see why so many people have talked about doing this, but haven't finished. For the items that are beyond my skills, I've been speaking with a friend of mine who is an electrical engineer/rocket scientist. Seriously :)

 

When it's finished (about 95% complete now) I will post the complete, corrected BOM which also includes Digikey part numbers for most items. I'm still not sure if I will be able to get my hands on all the necessary parts, I thought it was a big score when I managed to get the SC-01-A speech chip and 74HC942 modem last week. I'm also putting together a list of corrections for each of those sources that I've been referencing.

 

First question: DIN Power Connector. The schematics call for a 7-pin DIN connector for power, the Atari BOM calls for an 8-pin. The motherboard can accommodate either since it has enough holes, but doesn't seem to require the 8th pin. What was used on the factory motherboards? The pictures I've seen are too blurry to make it out. I am specifically wondering about the variant built on the "1450" motherboard (NOT the Tong), since they may have done different things on different boards. Anybody got one that they can check? My first thought was to ask Curt, but I emailed him a week or two ago and haven't heard back.

 

Thanks for the help,

v

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You can get the bare board? They still have some? How much?

 

Bob

The bare board is $25 (P/N: CB102222). I had a semi-broken 800XL and mangled 1200XL that are being used as parts donors, I have recycled every possible component, both to save costs and to not waste Atari goodness. Even so, I have just crossed the $200 mark on this board and I still don't know whether I will be able to get all the parts that I need to complete it or not. It may turn out that this endeavor simply illustrates that this project is not possible or practical. I'll know very soon, and I'll share everything that I learn here. If it works out, maybe some of us can build the machine that we've always wanted, and if not, hopefully I'll save everyone a bunch of time and expense.

 

You're 100% certain that it's 7-pin? If so, I'll start soldering that bad-boy (I bought both just-in-case).

 

BTW, is that your 1450 board in the picture? Does it work? Maybe I could get you to tell me the codes on one or two tricky components?

 

thanks for the help,

v

Edited by Vandal968

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Vandal, stupid question, but what will you use for a case? Carve holes into the 1200xl case? :)

If I go through with making it a 1450XLD I'll try to machine a case from scratch. I've got a pretty well-equipped machine shop in my garage (manual and cnc mills & lathes) so this should be do-able. The big question is whether I'd be able to work something out for the drives. I've heard that they didn't always work properly. If I can make the mobo work, but not the drives, I'll probably finish it as a 1400XL instead.

 

cheers,

v

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Both of my 1450 boards have 7-pin power connectors.

 

I don't know how you are going to get the Freddie chip running. Or the drives - can't see a controller anywhere. I would convert it to SRAM and 65816 if I had a blank board. That would eliminate a bunch of chips. Anyway, ask me whatever you need.

 

I actually don't know if it works. One of them does, at least, because I remember scoping the buss.

 

Thanks - time to call Best.

 

Bob

 

 

 

 

You can get the bare board? They still have some? How much?

 

Bob

The bare board is $25 (P/N: CB102222). I had a semi-broken 800XL and mangled 1200XL that are being used as parts donors, I have recycled every possible component, both to save costs and to not waste Atari goodness. Even so, I have just crossed the $200 mark on this board and I still don't know whether I will be able to get all the parts that I need to complete it or not. It may turn out that this endeavor simply illustrates that this project is not possible or practical. I'll know very soon, and I'll share everything that I learn here. If it works out, maybe some of us can build the machine that we've always wanted, and if not, hopefully I'll save everyone a bunch of time and expense.

 

You're 100% certain that it's 7-pin? If so, I'll start soldering that bad-boy (I bought both just-in-case).

 

BTW, is that your 1450 board in the picture? Does it work? Maybe I could get you to tell me the codes on one or two tricky components?

 

thanks for the help,

v

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...I'll probably finish it as a 1400XL instead.

Aesthetically preferable, IMO. In either case, this will be really awesome if you get it working.

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I can email you a large TIFF format scan of a 1450 board. PM if you want that. Also, aren't their P.A.L. equations for the the 1450? I know there was for the 1400.

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I can email you a large TIFF format scan of a 1450 board. PM if you want that. Also, aren't their P.A.L. equations for the the 1450? I know there was for the 1400.

 

KHeller2,

PM sent.

 

I assume that PAL is program array logic? Is this basically the same as an FPGA or is there a difference?

 

Bob1200XL,

the power connector thing is very strange. You attached a picture of a 1400 board that clearly has 8 pin power, but I came across a picture a few days ago that clearly has a 7-pin, and the bottom view of the same board shows that it doesn't even have the hole for the eighth pin, WTF?

 

Similarly, I also found a picture of the 1450 board that seems to have the 8-pin. This at-least makes some sense because you can easily add either a 7 or an 8 with the 8-hole pattern, but what is going on with the 1400 board? There must be multiple versions of these boards?

 

I'm attaching other people's pics so you can see what I mean. A 1400 with 7 pins and not capable of 8, and a 1450 that seems to have 8 (notice the shiny stripe on the back center of the connector).

 

Weirdness abounds.

 

cheers,

v

post-30038-0-61792800-1313478813_thumb.jpg

post-30038-0-12493600-1313478824_thumb.jpg

post-30038-0-14691300-1313479169_thumb.jpg

Edited by Vandal968

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Fudge... you are correct. The Tong and 1450 boards have 8-pin connectors. The 1400 boards have 7-pin. I must have mixed them up.

 

Sorry about that - good thing you are awake.

 

Bob

 

 

 

I can email you a large TIFF format scan of a 1450 board. PM if you want that. Also, aren't their P.A.L. equations for the the 1450? I know there was for the 1400.

 

KHeller2,

PM sent.

 

I assume that PAL is program array logic? Is this basically the same as an FPGA or is there a difference?

 

Bob1200XL,

the power connector thing is very strange. You attached a picture of a 1400 board that clearly has 8 pin power, but I came across a picture a few days ago that clearly has a 7-pin, and the bottom view of the same board shows that it doesn't even have the hole for the eighth pin, WTF?

 

Similarly, I also found a picture of the 1450 board that seems to have the 8-pin. This at-least makes some sense because you can easily add either a 7 or an 8 with the 8-hole pattern, but what is going on with the 1400 board? There must be multiple versions of these boards?

 

I'm attaching other people's pics so you can see what I mean. A 1400 with 7 pins and not capable of 8, and a 1450 that seems to have 8 (notice the shiny stripe on the back center of the connector).

 

Weirdness abounds.

 

cheers,

v

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:) It seems bob has the 6th copy of the 1400 board. That picture above is of my 4th copy before I sold it. I do recall the 1450 and 1400 boards used different power supplies... Or so I was led to believe and had. My 1450 supply has the 8 pin diagram but as I recall I had to build my own plug for it as it was cut off so I'm not sure what I wired now. Another thing to dig out of storage. ;)

 

Also notice on the two 1400 boards, the middle(?) pin isn't installed. The slot is empty going to the motherboard.

Edited by kheller2

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So... 8 pin I guess supplies 9V AC or 12V DC to run the drive mech?

 

What about Freddie - is there some difference vs the one used later on?

 

Re the boards themselves - does anyone have one working in the intended configuration of the production machine, or only in a sort of "cut down" configuration where some stuff isn't present ?

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So... 8 pin I guess supplies 9V AC or 12V DC to run the drive mech?

 

What about Freddie - is there some difference vs the one used later on?

 

Re the boards themselves - does anyone have one working in the intended configuration of the production machine, or only in a sort of "cut down" configuration where some stuff isn't present ?

Phew! Glad we got that power jack figured-out.

 

Rybags,

yes, the 1450 board uses a 5v/12v supply and seems to use the 12v portion for both the drive mechanism as well as the relay for the modem circuit. That's why it uses a more expensive DPDT switch instead of the SPDT switch used in the 600XL, 800XL, 1200XL. Of course, I'm still left wondering why the 1400 board uses that same expensive switch if it only has the 5v supply. Oh well, that's a question for someone else to figure out, I've got enough work to do already. I asked about the Freddie a few days ago in another thread and was told that although there are multiple part numbers (depending on supplier) there appears to be only one Freddie chip.

 

My version of this board is going to be slightly different than the ones already in the wild. I am using the National Semiconductor 74HC942 modem chip instead of the TI daughterboard that everyone else seems to have. I'm curious about why all the other 1450's use the TI chip. I'm hoping that it was a supply issue, and not a problem with the National chip working correctly with this mobo. There are jumpers to solder depending on which modem is used. Similarly, the 1450 uses two crystals instead of one like on all the other Atari's. One is fixed (Y3) although two different chip form-factors are supported. The other one is another choice, you can use a crystal(Y1) and some extra components or you can use an oscillator in a 14-pin DIP (Y2), all the boards I've seen use this second approach, so I'm taking that path.

 

bob1200XL,

I'm pulling together a list of a couple of components that I'd like you to double-check for me. You ready for the pain?

 

cheers,

v ;)

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This thread makes me want to pull out my 1400XL board and see if I could populate it and shove it in a 1200XL case. Then again I'm not exactly sure what I'd do with it once I did that, it's not like the 1400XL is anything all that special. The 1450XLD on the other hand...

 

Tempest

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Sure!

 

I promise to be more careful...

 

We can just read/copy the PALs, I would think.

 

I'll see if I can find my power supply and fire up a 1450.

 

 

Bob

 

So... 8 pin I guess supplies 9V AC or 12V DC to run the drive mech?

 

What about Freddie - is there some difference vs the one used later on?

 

Re the boards themselves - does anyone have one working in the intended configuration of the production machine, or only in a sort of "cut down" configuration where some stuff isn't present ?

Phew! Glad we got that power jack figured-out.

 

Rybags,

yes, the 1450 board uses a 5v/12v supply and seems to use the 12v portion for both the drive mechanism as well as the relay for the modem circuit. That's why it uses a more expensive DPDT switch instead of the SPDT switch used in the 600XL, 800XL, 1200XL. Of course, I'm still left wondering why the 1400 board uses that same expensive switch if it only has the 5v supply. Oh well, that's a question for someone else to figure out, I've got enough work to do already. I asked about the Freddie a few days ago in another thread and was told that although there are multiple part numbers (depending on supplier) there appears to be only one Freddie chip.

 

My version of this board is going to be slightly different than the ones already in the wild. I am using the National Semiconductor 74HC942 modem chip instead of the TI daughterboard that everyone else seems to have. I'm curious about why all the other 1450's use the TI chip. I'm hoping that it was a supply issue, and not a problem with the National chip working correctly with this mobo. There are jumpers to solder depending on which modem is used. Similarly, the 1450 uses two crystals instead of one like on all the other Atari's. One is fixed (Y3) although two different chip form-factors are supported. The other one is another choice, you can use a crystal(Y1) and some extra components or you can use an oscillator in a 14-pin DIP (Y2), all the boards I've seen use this second approach, so I'm taking that path.

 

bob1200XL,

I'm pulling together a list of a couple of components that I'd like you to double-check for me. You ready for the pain?

 

cheers,

v ;)

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This thread makes me want to pull out my 1400XL board and see if I could populate it and shove it in a 1200XL case. Then again I'm not exactly sure what I'd do with it once I did that, it's not like the 1400XL is anything all that special. The 1450XLD on the other hand...

Heh... I don't see the attraction of two huge single sided disk drives these days. A 1200XL with integral PBI, on the other hand: now that would be something. Is there anything else that the 1450XLD offers over the 1400XL, apart from the disk drives?

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This thread makes me want to pull out my 1400XL board and see if I could populate it and shove it in a 1200XL case. Then again I'm not exactly sure what I'd do with it once I did that, it's not like the 1400XL is anything all that special. The 1450XLD on the other hand...

Heh... I don't see the attraction of two huge single sided disk drives these days. A 1200XL with integral PBI, on the other hand: now that would be something. Is there anything else that the 1450XLD offers over the 1400XL, apart from the disk drives?

What's to say you couldn't put something else in those bays...

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Sure!

 

I promise to be more careful...

 

Thanks bob1200XL, here are the last ones that I'm still trying to confirm. Almost 400 down, only 14 to go:

 

C124 (above and left of U35, mounted vertically) I assume that it's a .1uf but it's missing from both schematics and the BOM

C134 (below diodes under relay) should be .1uf, some sources say ceramic, some say electrolytic, which is it?

CR14 (below Y3) missing on both schematics, id #? if visible

Q3 (below RF channel switch) listed in schematics as 2N3904 listed in BOM as 2N3906, which is it?

Q8 (next to RF modulator) listed in schematics as 2N3906 listed in BOM as 2N3904, which is it?

R7 value? (above J8, mounted vertically)

R25 value? (below U8)

R45 value? (below U21)

R59 value? (above VR1, mounted vertically)

R62 value? (touching left side of modulator)

R141 value? (below RF switch, mounted upright)

R143 value? (below diodes under relay, mounted upright)

R145 value? (to left of U39 mounted upright)

R153 value? (next to RF modulator)

 

That should be everything, I located all of them on the board and I'm attaching a picture of the bare board to help in locating them, so hopefully it's not too horrible for you. Thanks for the help.

 

cheers,

v

post-30038-0-40315000-1313519888_thumb.jpg

Edited by Vandal968

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What's to say you couldn't put something else in those bays...

Ooo... like a sandwich?

I was thinking of mounting an SIO2SD in one of the bays instead of a drive, but the sandwich idea is a good one.

 

cheers,

v

Edited by Vandal968

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