Ramblin' Dan's Workshop

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Ramblin' Dan's Workshop Blog

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Ramblin' Dan's Workshop Blog

Short stories and reader feedback

DELL Desktop Computer OptiPlex GX755 (part 2)

The computer has arrived. It's a heavy little bugger. Must go about 15 pounds.

The machine has a bit of a problem. I am running Linux OS on it but first tried to initialize the installed Windows 10. What a scary experience that was. Scary because of the invasion of privacy agreements Microsoft wanted me to sign off on. There are at least a dozen options which are defaulted "ON" about tracking and reporting every action taken on the computer back to Microsoft. This intended to make my "experience" as a user better! I said "NO" to every one of them. I want the computer to run my CNC machine, not give me a great social experience.

I suppose that is the reason they at least provide the option to say NO. But a dozen options to invade and REPORT my private use? I find that extremely disturbing.

But not to worry. I put in the proper time zone, keyboard type, and other standard setup information then the authorization code. It would sit there for a few seconds, blink the screen. then hang forever. I though it was because I said "NO" to all the privacy questions. After about 6 tries, I said yes to them all but still no boot.

Hmm... a bad software load of the Microsoft 10 initialization program. No sweat, I want to run Linux Debian realtime anyway.

I rebooted with the Debian realtime 32 bit kernel, LinuxCNC install disk. It does most of the software load but it too then crashes and starts asking for an additional disk. It never did that with the load on another computer using the same DVD. What's going on?, I thought...

I had a 64 bit Debian standard install DVD so I switched to it. The realtime CNC disk is 32 bit Linux. The 64 bit Debian loaded with no issues. A full boot-able install. I used the disk check to read the hard dive and it reported 12 bad disk sectors. I think this is the reason Windows 10 would not initiate. The Debian install and disk format must have now locked out these bad sectors. Probably in the Master Boot area of the disk.

I went back to the LinuxCNC install DVD and ran that install again. This time it went in without a problem.

I have let the realtime Debian do all its network updates. It seems to be operating just fine. I plan to do more run-in testing to see if there are further problems with the hard drive. The network update incremented the version of realtime LinuxCNC so the machine is running the most current version.

The bad sectors are a concern, but only if the hard drive continues to fail. Since they are being reported, they are certainly locked out.

The shipping box looked a bit worse for wear and one Styrofoam corner block was broken inside the package. It certainly suffered some rough handling in the trip from the refurbisher. They would never have used a broken corner block. I always look inside for loose cards and connectors. All looked very good inside the case. The memory was secure.

I think I just found a bigger issue. The parallel port seems to be defunct. (dead), This is not the first time I have discovered this on a refurbished computer. A lot of these machines were used in POS (Point Of Sale) service, like checkouts in retail stores. The port was used to tie into the receipt printing systems. Most people don't use the parallel port so I suspect the referb people may let them slip by.

I am going to plug in a PCI port card for the parallel port as it will run up to three times faster than the standard MB port. They are cheap, costing between $12 to $25 depending on brand name. All work the same.

Update 2/20/17

After almost two full days of trouble shooting and trial and error, I discover the original parallel port is functioning just fine. I had installed the second port and it too wouldn't function, so I figured it had to be something else in the system. The BIOS was reporting both (what Linux calls) Parports  just fine.

The CNC controller I was trying to talk to required a "charge pump" input before it would enable communication. None of my other controllers have this function.

Mach3 was providing the proper "Charge Pump" signal, but I finally determined LinuxCNC, although configured to produce the charge pump signal, was not doing so. Or at least not in a form detected by the BOB. My CNC controller BOB (Break Out Board) is undocumented but I spied the jumper that defeats the Charge Pump requirement.

I turned it off and both parallel ports (the original and new) are functional and the entire system is performing perfectly. So I am going to call this one a learning experience. It actually feels good to solve such a difficult problem.

This also confirms there was nothing wrong with my $100 computer except the bad sectors on the hard drive. Those have caused no further issue. All is well. I just lost some time and spent $20 on a second, but high performance  parallel port.

DELL Desktop Computer OptiPlex GX755
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Friday, 23 June 2017
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