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130XE Repair: Bad RAM, motherboard variations


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#1 Timothy Kline OFFLINE  

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Posted Sat Jun 25, 2016 5:40 AM

I'm in the process of trying to decide what to do with a 130XE I bought pretty cheap-- sold cheap because the seller, upfront, explained that it has bad RAM. Specifically, every other block is red during the self-test. Both the OS and ANTIC chips get pretty warm, as well.

 

However, I decided to compare the innards with my other two working 130XE systems, and I discovered that only one of the working systems has a mainboard similar to the befuddling 130XE on my bench.

 

If you look at the attached pics, the broken 130XE is the same mainboard as the one I labeled "Type 2," including the two wires you'll see.

 

However, the other 130XE, which is seen in "Type 1" not only is missing the wires, but ALSO has a jumbled mess up by the SIO port. Yet it works just fine.

 

I was just wondering what anyone else makes of all this...?

 

Submitted for your perusal,

Tim

Attached Thumbnails

  • 130XE Mainboard - Type 2 1280px.jpg
  • 130XE Mainboard - Type 1 1280px.jpg


#2 orpheuswaking OFFLINE  

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Posted Sat Jun 25, 2016 7:15 AM

The jumbled mess in the second picture is the same capacitors next to the SIO in the first picture - if you compare you will see that there are ten caps all neatly laid out, 6 to the left and four underneath. Bottom line you can remove them all in both machines and get a better more stable SIO.

The wires you see are in a lot of 130xe machines, usually added in the factory as issues arose.

#3 Rybags OFFLINE  

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Posted Sat Jun 25, 2016 7:28 AM

The official "Rev" is on the PCB just to the left of the keyboard connector.  Can't quite make out the first one, is it "B" ?

 

Unsure how many 130XE revisions there were.  At least 3 considering they started using the 4 x 4 bit Ram chips probably around 1986.



#4 Timothy Kline OFFLINE  

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Posted Sat Jun 25, 2016 9:22 AM

The official "Rev" is on the PCB just to the left of the keyboard connector.  Can't quite make out the first one, is it "B" ?

 

Unsure how many 130XE revisions there were.  At least 3 considering they started using the 4 x 4 bit Ram chips probably around 1986.

 

The one without the wires is Rev "4" which, one would think, comes after "B" yet has the jumbled mess around the SIO AND the missing wires. Also, on the Rev "4" boards, the CO14805 (GTIA) is socketed but on the Rev "B" boards the CO21697 (ANTIC) and CO14806 (CPU) are the ones that are socketed.

 

The Rev "4" board has a white label on the bottom; the Rev "B" has the usual darkish gray sticker.

 

--Tim



#5 Timothy Kline OFFLINE  

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Posted Sat Jun 25, 2016 9:23 AM

The jumbled mess in the second picture is the same capacitors next to the SIO in the first picture - if you compare you will see that there are ten caps all neatly laid out, 6 to the left and four underneath. Bottom line you can remove them all in both machines and get a better more stable SIO.

The wires you see are in a lot of 130xe machines, usually added in the factory as issues arose.

 

Really? It's fine to remove them? What were they intended to accomplish? Do you know?

 

--Tim



#6 Rybags OFFLINE  

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Posted Sat Jun 25, 2016 9:29 AM

Missing wires would be logical in a later revision since the function would be just merged into the PCB design.  The caps near SIO, supposedly the intention is reduction of interference but they cause problems at turbo speeds that modern devices are capable of as they tend to flatten out the overall waveform which just leads to IO errors.


Edited by Rybags, Sat Jun 25, 2016 9:30 AM.


#7 Timothy Kline OFFLINE  

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Posted Sat Jun 25, 2016 10:19 AM

Missing wires would be logical in a later revision since the function would be just merged into the PCB design.  The caps near SIO, supposedly the intention is reduction of interference but they cause problems at turbo speeds that modern devices are capable of as they tend to flatten out the overall waveform which just leads to IO errors.

 

I suspect in this case that the Rev "4" is the earlier board over the Rev "B" since it makes more sense to me to find the added wires to resolve issues found in, let's say, the Rev "4" run of boards.

 

If the Rev "4" board doesn't have the wires because Atari corrected the issues in the PCB found in the Rev "B" run, then why would Atari have taken the cleaner layout of resistors around the SIO on the Rev "B" board and gone to the jangled mess found on the Rev "4" board? The cleaner layout would be found in a later version, is my conclusion.

 

The question is, then, whether the wires continue to appear in the 1986 board which went to a 4-chip RAM matrix.

 

I'd be curious, too, if there's a way to know externally that a 130XE has the 4-chip RAM matrix, say through the serial number. I wouldn't mind adding one to my Atari family. ;)

 

--Tim



#8 Rybags OFFLINE  

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Posted Sat Jun 25, 2016 10:25 AM

Timestamps on some ICs might give a clue but might be unreliable given Atari's hoarding tenancies. I don't know if there's a definite way to correlate serial to date with the XEs.

#9 kheller2 OFFLINE  

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Posted Sat Jun 25, 2016 11:24 AM

The FSM silks dated 4/10/85 show the version of the board with the caps mounted along the SIO port.  My rev 3 has a soldered 6520 from the 5th week of 85 os its very hard to tell just from this samples what order they came in.  I've seen REV-5 PAL boards.  The 4 RAM chip boards seem to use a different part number, but they do have the spaces for caps around the SIO.

 

 

For comparison purposes here is a REV 3 (note that the GTIA is the only officially socketed chip, the others were done by someone else).  Also note that the solder side has number scribbled out opposite the Fuji symbol.  On REV-5 boards its "1885" (not a typo).  

Attached Thumbnails

  • IMG_2754.jpg
  • IMG_2755.jpg

Edited by kheller2, Sat Jun 25, 2016 11:35 AM.


#10 Timothy Kline OFFLINE  

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Posted Sat Jun 25, 2016 11:29 AM

The FSM silks dated 4/10/85 show the version of the board with the caps mounted along the SIO port.

For comparison purposes here is a REV 3:

 

 

 

 

Same jangled mess up there, lol!

 

Now, we just need a 4-chip RAM matrix board to see where it all ended up.

 

I'm curious: do the 65XE boards run the same way? I've never bothered with hunting down a 65XE.

 

--Tim



#11 kheller2 OFFLINE  

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Posted Sat Jun 25, 2016 11:44 AM

NTSC 65XE board are completely different.  

There are also different versions of the 4 chip as I recall.



#12 Stephen OFFLINE  

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Posted Sat Jun 25, 2016 1:45 PM

I'm fairly certain the only time a 130XE board will have a socket for any chip, is if it failed initial tests (as in machine didn't work off assembly line).



#13 Rybags OFFLINE  

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Posted Sat Jun 25, 2016 9:42 PM

Re 4 chip boards, aren't they 130XE only, and 65XE also uses it and gets the ECI as a bonus?



#14 kheller2 OFFLINE  

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Posted Sun Jun 26, 2016 6:29 AM

Re 4 chip boards, aren't they 130XE only, and 65XE also uses it and gets the ECI as a bonus?


The 130xe 16 chip boards were used in the non-NTSC 65xe and the 130xe
The 130xe 4 chip boards were used in the non-NTSC 65xe and the 130xe
The 65XE board, as far as I can tell, was only used in the NTSC 65XE. (And if memory serves correct it was delayed in the states because of a surplus of 800xl parts).

#15 JD6502 OFFLINE  

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Posted Mon Jun 27, 2016 2:06 PM

I have a rev 3 and a rev 4. Neither has jumpers. The rev 3 has one cap soldered directly to the SIO, the rev 4 has none. Can't remember if there are any on the PCB's. They both have a mess of diodes on  the SIO. I've seen a number of pics of XE boards and one oddity I've noticed is that they invariably have MT DRAMS except for the upper left, which always seems to be some other brand. I assume there was a reason, but what?

 

As it happens I finished repairing bad ram on the rev 4 just yesterday. The pattern on the memory test was bad even numbered cells for bank one and three, and all bad cells for bank two except 5 and 6. This is a pattern other people have reported as well. Testing all the chips in a working XL showed that only one chip was bad, but I replaced the eight main bank chips anyway and installed sockets. ( The second bank was replaced with a Newall 1meg ages ago). I lucked out on replacement chips, the local electronics parts store (creatively named "The Electronic Parts Store") is a quirky old place that's been around forever, and has an astonishing number of parts that have been on the shelf for the same period of time. They had exactly eight TI and OKI 4164's NOS.



#16 deffroe OFFLINE  

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Posted Sun Feb 26, 2017 6:15 AM

Hello, 

I'm new on this forum but a long time Atari fan, the 800XL was my first computer way back in 1985.

 

A few years back, as many have done, I wanted to re live and enjoy the games I once loved on real hardware again.

I bought a 130XE which at the time I bought it turned on but would not respond to any keystrokes except Reset.

This ended up getting put away as even though it didn't work I couldn't bare to get rid of it.

It got opened it up and looked at to see if anything was a miss, but to be honest I don't know what I was looking for.

Except there were wires running around from a couple of chips to other points on the board, this made me think that a previous

owner had botched a repair or upgrade.

 

After coming across this thread a few days back I decided to get it back out and have another look and try it again but now it doesn't even power on.

 

But looking at the motherboard revision and what has been mentioned on here intrigued me.  It's a Revision 5.  

And seeing the pics on here of wires running around the motherboard looks similar to mine, well maybe there is a chance I can get it working again....with some advise ;)

 

I have attached some pics, What intrigues me is the differences between this board and the two images at the beginning of this thread.  Namely the SIO area, there are NO resisters and at the bottom of the board Y2 is empty on the other revisions but is populated on my REV.5 version.

 

If anyone has any tips or suggestions to try and get my 130Xe up and running again it would be much appreciated.

 

Thanks

 

Phil

Attached Thumbnails

  • IMG_20170225_185213.jpg
  • IMG_20170225_184746.jpg
  • IMG_20170225_184735.jpg
  • IMG_20170225_184648.jpg


#17 russg OFFLINE  

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Posted Sun Feb 26, 2017 9:12 AM

Hello, 

I'm new on this forum but a long time Atari fan, the 800XL was my first computer way back in 1985.

 

A few years back, as many have done, I wanted to re live and enjoy the games I once loved on real hardware again.

I bought a 130XE which at the time I bought it turned on but would not respond to any keystrokes except Reset.

This ended up getting put away as even though it didn't work I couldn't bare to get rid of it.

It got opened it up and looked at to see if anything was a miss, but to be honest I don't know what I was looking for.

Except there were wires running around from a couple of chips to other points on the board, this made me think that a previous

owner had botched a repair or upgrade.

 

After coming across this thread a few days back I decided to get it back out and have another look and try it again but now it doesn't even power on.

 

But looking at the motherboard revision and what has been mentioned on here intrigued me.  It's a Revision 5.  

And seeing the pics on here of wires running around the motherboard looks similar to mine, well maybe there is a chance I can get it working again....with some advise ;)

 

I have attached some pics, What intrigues me is the differences between this board and the two images at the beginning of this thread.  Namely the SIO area, there are NO resisters and at the bottom of the board Y2 is empty on the other revisions but is populated on my REV.5 version.

 

If anyone has any tips or suggestions to try and get my 130Xe up and running again it would be much appreciated.

 

Thanks

 

Phil

It is almost certain that some, or all those MT drams are bad.  It would be a pretty major job just to replace those.  To be honest

it would maybe be better to buy a 800XL or XE that is working, A stock 800XL will run probably 90% of games.  Good luck.

Try ebay.



#18 deffroe OFFLINE  

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Posted Sun Feb 26, 2017 11:18 AM

Thanks for your response, a shame if that's the problem.

 

I'll have to continue with Chuckie Egg on the emulator for now.

 

Cheers

 

Phil



#19 russg OFFLINE  

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Posted Sun Feb 26, 2017 5:43 PM

Thanks for your response, a shame if that's the problem.

 

I'll have to continue with Chuckie Egg on the emulator for now.

 

Cheers

 

Phil

I looked at 800xls on ebay.  They aren't that many and the prices are high.  don't remember right now, but it could cost $100 for

a tested working 800xl.   So, maybe I'm wrong.  New drams would certainly cost less than a total XL replacement.  And it would

be an experience to replace all 16 of them.   So, maybe an investment in a soldering station and iron might be a better

way to go.   You'd also need a solder sucker pen.

If you knew a electronics person, that might be useful, (sorta unlike my comments.)

edit.  You could give a simple test, and maybe identify a faulty dram, just power it up and wait a minute or two and see if

any of the drams are warm, maybe even hot.

While you're at it, put your finger on all the chips to see if one is warm.


Edited by russg, Sun Feb 26, 2017 5:49 PM.


#20 Sugarland OFFLINE  

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Posted Sun Feb 26, 2017 7:05 PM

deffroe it might be the 130XE keyboard mylar needs servicing or just a new keyboard. How do you know it's not turning on? The power light doesn't come on? Does it give video? The power light voltage is part of the mylar, which fails over time. Electrically conductive paint can be used to repair the mylar. Also your PSU might have failed, not the computer. Keep the 130XE but yes get another A8. You can swap components to figure out what's bad on it.


Edited by Sugarland, Sun Feb 26, 2017 7:07 PM.


#21 Kyle22 OFFLINE  

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Posted Sun Feb 26, 2017 7:28 PM

. . . They both have a mess of diodes on  the SIO. . .

 

Those aren't diodes, they are capacitors sealed in glass.



#22 1050 OFFLINE  

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Posted Sun Feb 26, 2017 7:34 PM

Except there were wires running around from a couple of chips to other points on the board, this made me think that a previous
owner had botched a repair or upgrade.

Those jumpers are done by Atari at the assembly house used for that
machine. There are apparently several different assembly locations
or bosses in charge of them as there is a gamut of odd ball wiring
additions just like this one, and this one is commonly done too.
 

I have attached some pics, What intrigues me is the differences between this board and the two images at the beginning of this thread.  Namely the SIO area, there are NO resisters and at the bottom of the board Y2 is empty on the other revisions but is populated on my REV.5 version.

Those aren't resistors even if they might look like resistors.
They are capacitors and like most of the 'optional' addendum stuff
done by Atari again, they turned out to be worthless and even
detrimental to SIO workings. Most advice is to remove them and
I always do here.

Start with the basics, measure your power brick for 5+ volts first
at the jack not connected to the computer at all.
One side of the circle of pins will be positive and the other side
negative, three pins each IIRC. With the 'center' pin having no
connection to either positive or negative.

Tolerance on voltage is 15% plus or minus so sorta 5ish is good,
7 volts is not good at all.

For further help you'll have to confirm the voltage is proper first
then give screen symptoms as to what shows on the monitor/TV you
are using. Screen shot photos helpful but not absolutely needed.

#23 BillC OFFLINE  

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Posted Sun Feb 26, 2017 9:03 PM

Those jumpers are done by Atari at the assembly house used for that
machine. There are apparently several different assembly locations
or bosses in charge of them as there is a gamut of odd ball wiring
additions just like this one, and this one is commonly done too.
 
Those aren't resistors even if they might look like resistors.
They are capacitors and like most of the 'optional' addendum stuff
done by Atari again, they turned out to be worthless and even
detrimental to SIO workings. Most advice is to remove them and
I always do here.

Start with the basics, measure your power brick for 5+ volts first
at the jack not connected to the computer at all.
One side of the circle of pins will be positive and the other side
negative, three pins each IIRC. With the 'center' pin having no
connection to either positive or negative.

Tolerance on voltage is 15% plus or minus so sorta 5ish is good,
7 volts is not good at all.

For further help you'll have to confirm the voltage is proper first
then give screen symptoms as to what shows on the monitor/TV you
are using. Screen shot photos helpful but not absolutely needed.

For +5VDC the tolerance is plus/minus 5%(check the datasheets on  the ICs, you'll normally find operating voltages listed at 4.75 to 5.25VDC).



#24 _The Doctor__ OFFLINE  

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Posted Mon Feb 27, 2017 1:33 AM

yep I personally won't touch anything below 4.85 and 5.25 is upper limit.... just not worth it to allow anything else especially if you intend to run sio or bus powered devices!



#25 deffroe OFFLINE  

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Posted Mon Feb 27, 2017 7:27 AM

Thanks for reply's.

 

I've checked voltage of the power brick and it shows 5.14V.

 

While I've had it out these last couple of days I haven't had it hooked up to a TV,  When I turn it on the power LED stays of,

but when I first got it, it booted to the Ready prompt but wouldn't respond to any key presses.  No powering on with Start or Option.

 

 

While I've had it opened up I removed the metal plate of the motherboard n checked the LED is working with a coin cell, which it is.

But looking at the plastic keyboard membrane some parts of it are crusty, similar to what you find on contacts when an alkaline battery has leaked.

Sugarland are you saying that it might be turning on just with out the power LED?  Think I'll check that now.

 

I've read elsewhere on this forum about checking it with a multimeter, not sure what setting to have it on as continuity does nothing,

if I have it set to ohm's then sometimes there is a flicker of response sometimes but not sure if its responding to with the tracks or not.

 

I have a soldering station so it is a possibility of removing ram chips if need be but do I remove all the chips in one go?






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