The TI486SXL2-66 (PGA-132)... & repair!

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The TI486SXL2-66 (PGA-132)... & repair!

Postby 386_junkie » 2017-3-03 @ 00:01

Took a while to find her, but she arrived, untested and broken…

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I also came under some competition from other Vogoners to buy her and at the time, after the amount it rose to plus unknown to the condition she was in… I felt pretty shitty. I was eager though for her to arrive and find out where I stood.

When examining the PCB I noticed a small jumper, anyone have any idea what it maybe does?
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So getting setup, I dig out some spare 386 sockets, helping hands, magna glass, and Iron which I’ve not used in silly donkies! Must have been last year before I’ve last warmed her up… shows how busy work keeps us!

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… and of course, solder!

Not the best solder job I’ve done, but the connections are bridged and man did it take an effort. There was hardly anything to solder onto on what was left of those pins.

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It turned out in the end that I didn’t need the jumpers, I couldn’t close the CPU onto the socket as there was no space! After snipping them off, I got the DMM and checked for continuity… lo’ and behold there was still a bridge with out the jumpers.

So, the sockets on…
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Next, was to find a decent sized heat sink. Having a good old Worzel Gummidge in my spares box I found a nice 386 HSF.
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With a bit of Arctic Silver… It’s on!
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Now the “heart in mouth” moment. Bringing the Systempro out of hibernation for the first time this winter I plug in the SXL2-66 and...

...

...

... it worked!

Relief more than anything swept over at first.

Being away much of this week again with work, I got back today with one thing on my mind, apart from food of course, benching! The results from benching on the Systempro are below: -

viewtopic.php?f=25&t=52795

The results obtained were using EISA bus. When I get the time I'll look to dig out one of the faster VLB systems I have as a test rig.
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby kixs » 2017-3-03 @ 00:53

Very good job... Wish I had your skills :D
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby feipoa » 2017-3-03 @ 02:06

386_junkie wrote:I also came under some competition from other Vogoners to buy her and at the time, after the amount it rose to plus unknown to the condition she was in… I felt pretty shitty.

You guys are crazy! I'm looking forward to the day I sell everything! Might make for a good retirement bonus.

I don't quite follow your pin repair job. I originally thought you were going to actually solder on 2 pins, not a PGA-132 socket. So the male-to-female socket adapter made contact with the existing broken pins and you ditched the wires altogether?

For solder of that size, you should really use some 30 AWG solid wire, usually with kynar.
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby 386_junkie » 2017-3-03 @ 08:36

feipoa wrote:I don't quite follow your pin repair job. I originally thought you were going to actually solder on 2 pins, not a PGA-132 socket. So the male-to-female socket adapter made contact with the existing broken pins and you ditched the wires altogether?

For solder of that size, you should really use some 30 AWG solid wire, usually with kynar.


In defence, it's the best performing 386 CPU made... after Blue Lightning of course. Where would I find another?

Soldering on two pins would be near impossible unless you use gold and have craft like the Jewellers, but then you might burn out the chip!

With surface mounted components, huge consideration must be given to the temperature of the soldering iron. 400 degrees C is too hot so a lower setting; 200-300 must be used. Also, the iron cannot stay on the contacts for a long time... literally I dabbed them with the iron and took it away as fast as I could.

The wires were folded over outside of the PGA and formed almost like a hook, that could hang the chip onto something but the CPU could not be secured down onto the socket. I snipped the wires away but left the solder on both what was left of the pins and the solder that comes up from the socket terminals... if not for this solder and a bit of the copper remaining, there would be no connection.

Not heard of kynar before. To me solder is solder, it melts and pools on the tip of your iron and can make a small pool or a big pool depending on how much you put on. I have many different sizes of solder tips which I can change when the iron cools down and depends on the size of job. This repair I used one of the smallest tips I have... it was no easy fix, believe me... once I had soldered one jumper, the slightest tug and the other came off! This way is good though... I should never have to split the CPU from it's socket, like Darth Vader and his suit!
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby feipoa » 2017-3-03 @ 08:55

I believe Kynar is the insulator surrounding the 30AWG wire. It is the wire shown here: viewtopic.php?p=229840#p229840

I am surprised that you could not solder the pins back on. It is a bit tricky, but I have made this same repair. Forget which chip it was, but it was going into a ZIF, so the risk of falling off was minimal. But like yours, the pin broke off right at the base. Best to ensure you don't flow solder across the whole pin. This way you maintain gold-to-gold contact. Since the CPU doesn't insert fully, there is still a 1-2 mm or so gap and that is where your solder is located. Obviously, the strength of the pin will not be near to what it was originally. For CPUs going into a non-ZIF, I would probably also add the male-to-female PGA-132 over it.
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby 386_junkie » 2017-3-03 @ 20:19

Yea, there's literally nothing to solder a copper twist on to.

On PCB's you would have a solder pad which the solder would stay on but a pin stub has nothing. I wouldn't trust a ZIF socket after doing something like that... if the pin came off and got stuck in a motherboard socket you could effectively render the motherboard useless. How would you get the pin out of a hole in the socket? :lol:
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby feipoa » 2017-3-03 @ 20:33

Using a strong magnet. I also believe the ZIF covers come off. I did not have an issue with my pin falling off or loosening. I just soldered a cylindrical gold pin to the remaining pad on the CPU. I believe there are also solders which dry a little stiffer.
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby feipoa » 2018-2-01 @ 00:50

I recently purchased one of these upgrade modules. It arrived today. Similar to your case, exactly two pins are missing! They are kinds difficult to see and I didn't see them immediately. I will attempt to solder on some gold pins from a donor CPU, similar to what I did for a Cyrix 5x86-133/4x in the following thread, viewtopic.php?f=5&t=58247

The issue, of course, is the lack of thermal mass, which the ceramic provides. It is easy to overheat the pins on interposers and sockets, thereby melting the housing. I hope I have better luck than you did. Luckily, I have one gold/gold male/female PGA132 socket to place the chip in. I looked in the rigid foam, but could not locate the two missing pins, so it was unlikely that shipping caused the pins to break off.

On the other hand, I noticed that this upgrade module actually has what looks like a male/female PGA132 socket on its bottom. I suspect it is soldered on, but have you tried to remove it on yours? I very gently pryed at it, but it didn't budge. Fearing damage, I did not put much torque into it. In the last photo provided, I am trying to show the side where the PGA132 socket is, but could not really determine with certainty if the socket is soldered on.

I hope to use this item to further my work on the TI486SXL2-66 PGA168 to PGA132 interposer. viewtopic.php?f=46&t=54953

The chip was well packaged for shipping, the best I have seen. The pins were placed in rigid anti-static foam, and soft non-static producing foam was placed atop.

Some images below:

TI486SXL2-G66_Packaging.jpg

TI486SXL2-G66-HBN.jpg

TI486SXL2-G66_Broken_Pin1.jpg

TI486SXL2-G66_Broken_Pin2.jpg

TI486SXL2-G66_Socket_Side_Image.jpg
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby xjas » 2018-2-01 @ 01:42

Is it just the 66MHz version of this that's rare as hell, or is it because it comes as a drop-in upgrade package rather than a surface-mount chip? I was looking around and it seems 50MHz SXLC2s are fairly readily available.

Either way good on you guys for putting in the time to fix these up and get them going. Pretty neat chips.
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby feipoa » 2018-2-01 @ 01:51

I don't think the surface mount QFP144 TI486SXL2-66 CPU's were all that common, certainly not as common as the same speed chip in the PGA168 package. I certainly run across a lot more of the QFP/PGA SXL2-50 chips, in both, QFP144, PGA132, and PGA168 packages.
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby Anonymous Coward » 2018-2-01 @ 04:55

Don't bother trying to pry off that white "socket". It's part of the module, and it doesn't come off.
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby Anonymous Coward » 2018-2-01 @ 05:01

xjas wrote:Is it just the 66MHz version of this that's rare as hell, or is it because it comes as a drop-in upgrade package rather than a surface-mount chip? I was looking around and it seems 50MHz SXLC2s are fairly readily available.

Either way good on you guys for putting in the time to fix these up and get them going. Pretty neat chips.


SXLC2 is designed to go in a 386SX socket. Slightly different animal. The SXL2 (sans C) is for upgrading a 386DX.
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby feipoa » 2018-2-01 @ 05:28

Anonymous Coward wrote:Don't bother trying to pry off that white "socket". It's part of the module, and it doesn't come off.

'eh? Are you sure? Take a look, for example, at the Transcomputer and the Buffalo BL3 modules. They have pins coming straight out of the PCB. The Transcomputer modules came without even an additional socket on the PCB. The Buffalo came with a gold/gold male/female PGA132 socket on the pins, which stick right out of the PCB. That PGA132 came right off. Unfortunately, in my photo here, https://www.vogons.org/viewtopic.php?f=46&t=53096 , I happen to have a blue PGA132 inserted, but it comes off. That blue PGA is not made of plastic (ABS?) like the black PGA sockets are made of, but rather some PCB or fibre glass type material just as with this particular TI486SXL2-66. This past experience leads me to believe that the PGA male/female socket on the TI486SXL2-66 comes off. Unless you have specific information which leads you to believe it is soldered on?

I did notice that my blue PGA132 socket takes considerably more force to remove than the black-coloured gold PGA132.
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby feipoa » 2018-2-01 @ 21:04

I took a closer look at the interface between the PCB and the included male/female PGA132 socket using 25x magnification. It appears to me as if the included PGA132 is, in fact, a socket and that this particular PCB doesn't have male pins coming out of it; it has solder pads. It looks to me as if the included socket (female end) is soldered onto the PCB's solder pads. I am not 100% sure, but this is sort of what it looks like and there is solder flux around the female socket to solder pad intersection. I could be wrong still. It seems like this would be more difficult to solder on.

Nonetheless, I managed to solder the two missing pins onto the upgrade module. I placed the additional socket on and off to ensure the pins are holding and tested the connection with a conductivity meter. All is good there.

TI486SXL2-G66_Pin_Repair_1.jpg

TI486SXL2-G66_Pin_Repair_2.jpg

TI486SXL2-G66_Pin_Repair_3.jpg
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby kixs » 2018-2-01 @ 22:11

Nicely done, sir! I knew you will succeed :)
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Re: The TI486SXL2-66 (PGA-132)... & repair!

Postby feipoa » 2018-2-02 @ 00:18

kixs, have you received your TI486SXL2-66 upgrade module yet? Did you test it? Any missing pins?
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