T30 Ethernet Problem - Fix (Pic Warning)

[Harryc]

I recently received a T30 with a problem. When a CAT5 cable was plugged into the on board Ethernet port, the machine went online fine, worked fine, etc. The problem started when I went to dock this machine. Ethernet no longer worked through the port in the dock. I then checked all the pins at the dock connector...fine. So, I though maybe I have a bad dock. I tried my X30 in this same dock and Ethernet worked fine. Then I started looking at the T30 itself. I looked inside the on board Ethernet jack on the T30, and this is what I saw -



I then used two tiny jewelers screwdrivers, one underneath the bent pin to support it, the other to bend it back into place. I docked the machine and it worked fine.

So, what was happening is that when you plugged a cable into the on board Ethernet port, it moved the bent pin (shorted to its' neighbor) just enough so that Ethernet worked normally. When the cable was pulled out, the pin touched its neighbor again and shorted the Ethernet port, so that when it was docked it did not work. Hopefully this will help someone if they ever run across this very weird problem.

[Peter_Peril]

Classic Detective Work HarryC--emphasis on the TECH I recently had a client who had a similiar problem. Turns out they had built their own Cat5e cables, but used an incorrect crimping method. This prevented the terminal from being compressed properly which subsequently wouldn't allow it to fit in the jack correctly. The connection would work intermittently(if it all). They shoved the terminal in the jack anyway spent almost a grand for the technical support to resolve it. One look at the hacked patch cable was all it took for me to score a quick repair fee

[Harryc]

Peter_Peril, nice work!. I am jealous...I miss those days when I worked in the field for IBM. Did it for 20 years. Seems like a long time ago ...

[Peter_Peril]

... I worked in the field for IBM. Did it for 20 years. Seems like a long time ago ...

Wow! Two decades at Big Blue...hope you got stock options On a serious note... why are circuit schematics for thinkpads so hard to come by?

[Harryc]

Schematics were never released by IBM or Lenovo. I'd assume it is because they were worried about guarding proprietary information. But in the last decades the Chinese and Japanese became quite adept at copying electronics with just the device in house, so I'm not really sure what advantage there would be to safeguarding schematics ...

[jdhurst]

Schematics were never released by IBM or Lenovo. <snip>

Generally true. However, I have Technical Reference Manuals for XT and AT class machines and they *did* have schematics. I was able to identify a bad crystal in an oscillator circuit on a diskette controller card with the schematic and my trusty Tek 'scope.

Later, I had a Baby Blue card go bad, and found the same problem (no schematic for the Baby Blue). BB Tech Support were curious/impressed that a homeowner could troubleshoot their board correctly and sent me a free crystal.
... JDH

[Harryc]

I still have a 100% complete and functional XT (with an expansion chassis) in storage JD...now that was a boat anchor . Great machines, weighed a ton ...