Tuesday, May 20, 2014

Attempting to fix a Sceptre Monitor Power Supply Board

I found what seemed to be a great deal on a computer monitor at the local thrift store. I paid $25 for this 20" flat panel monitor it and brought it home. It worked great for a day or two. Then it started shutting off. I guess that's why it ended up at the thrift store.

Before I bought it, I plugged it in and it powered up with an image on the screen, so I figured it was good to go. I remembered I had a different Sceptre monitor a number of years ago that also died. That should have been my first clue. But lucky for me, there's the internet and I found that the most common problem with these monitors is that the capacitors on the power supply board go bad.

This Sceptre X20G-NagaIII has the same AIVP-0017 power supply board as the infamous Gateway monitors. But this one is rev. E and has a different connector on the side. I found the Gateway rev power supply for sale on ebay for $30, but I've had bad luck un-soldering large connectors, so I figured I'd try repairing it instead of replacing it.
AIVP-0017 after replacing capacitors and removing connectors

So I started doing a visual inspection and didn't see any bulging capacitors. There was a spot on the 12 volt LDO regulator, but it was still functioning. The 12 V and 5 V outputs were fine. So I unsoldered five of the 470 uF capacitors so that I could test them.

Original capacitors:
Brand: SAMXON
Value: 470 uF
Vmax: 25
Tmax: 105 C

My multimeter only measures up to 40 uF, so I just checked for shorts and opens and found no shorts and no opens on any of the five. So I brought them to work and tested them on the HP 4284A LCR meter that I had in my lab. All five had capacitance values between 130 and 170 uF. But I'm not sure if those were good readings.

I ordered some replacement capacitors from Mouser.com and replaced all the 470 uF and the two large 68 uF power supply capacitors. It still had the same problem.

I bet the engineers who designed this power supply are still upset about the poor reliability. Where I work, we make sure that the MOSFETs we sell will have no more than 5 ppm fail after 10 years at the maximum rated gate voltage, near the maximum rated temperature. So, to have a capacitor have the life of a light bulb is totally unacceptable to me.

Since I didn't have a circuit diagram, I decided to give up and order a replacement board. As my luck would have it, the board I got didn't match the picture. The picture was of my board, but the one they sent me was for a Gateway monitor.

I unsoldered the connectors and soldered them on the replacement board. I noticed that my replacement board had some capacitors replaced. They didn't match the originals. It was a "repaired" board. So it was a big disappointment, but not much of a surprise when I turned it on and it had the exact same problem.

Monitor at thrift store $25
Capacitors $15
Replacement board $40

Realizing that some deals are too good to be true . . . priceless.
I may spend a little more time on this project later. If I find the fault, I'll update this post. 

Building an Entry-Level Workstation PC

Have you ever been frustrated with slow computers, or worse, a computer that frequently crashes? I have an old PC at work that regularly crashes after about an hour of use, almost every time. Luckily it's just for a vision module on an Electroglas prober, and I can re-start it when I need it, which can be up to several times a day. I don't know if it's the memory, processor, motherboard, hard drive, or software that's bad.

Have you ever watched General Conference videos where the frame rate was about 1 per second? I know, I shouldn't complain. It wasn't too long ago that we had to wait for a single picture to load. But that was when the internet was the bottleneck. It was time for me to replace my computer (and hand off the old one to someone else in the family). My requirements were that it had to be:
  1. Stable (reliable)
  2. Capable (fast)
  3. Secure (not so vulnerable to viruses or hacking)
  4. Customize-able (which kind of rules-out laptops)
  5. High bang per buck
I looked around and figured that a workstation PC would fit those requirements. It's been almost a decade since I last built a computer. That one was built around an Intel motherboard that I got on clearance on ebay. I think it was about $15. It was the most stable computer I ever owned until it crashed hard a few years ago. The computer I replaced it with was a surplus computer from a going-out-of-business sale. Even though the processor had a faster clock speed, the computer didn't seem any faster. So after a few years of that one, it was finally time to upgrade.

The main reason I wanted to build my own PC was so that I could get exactly what I wanted without having to spend extra money for features I didn't need, or even preferred not to have.

Build Specs


Motherboard
The motherboard is what you start with, to build everything around. I looked for a workstation motherboard that was made for a workstation, not a server. I found the Supermicro X9SRA. It appeared to fit my requirements and my budget. Most of all, it was able to use just about any kind of memory, and had eight slots for memory. With this, I can upgrade without having to remove my old memory modules.

Here are my favorite features on the X9SRA:
  • 8 memory slots
  • Wide range of compatible memory types - almost any DDR3 
  • Uses a Xeon processor (workstation CPU)
  • Nice built-in audio
  • No onboard video so I can choose a video card without paying for a cheap one I won't use
  • RAID support
  • Intel based
I do wish the documentation had more explanation of some features. The user's manual is minimal, at best. It should be called a quick start guide, instead.

The fans are labeled FAN1, FAN2, FAN3, FAN4, and FANA. I emailed customer support and Mark told me that it doesn't matter what fan gets plugged in where. I would think that there should be one dedicated to the CPU to regulate temperature better. But why would one be labeled FANA?

I wanted the variable fan speed feature so that the PC would be quiet when it didn't need to have the fans on high. But there was a problem. The fans would jump to full speed about every 19 seconds, then slow down, repeatedly. Mark at Supermicro customer service emailed me and told me that BIOS version 3.0c lowered the minimum fan speed to about 200 RPM. 

When the computer is turned on, the fans start out on high, then slow down to an idle. If any fan drops below the minimum speed, then it makes all fans speed up like I was seeing.

I downloaded and installed the latest BIOS update, version 3.0c, and that fixed it. Now it's super quiet. The status messages during the BIOS update were slightly confusing. It said success, but wasn't done until several more success messages, and then showed the DOS prompt.

If you use this motherboard, be careful on mounting the motherboard in the case. Make sure that there are no stand-offs where there aren't any mounting holes. I had to move one, and remove another stand-off to match the mounting holes. There are stories in the customer reviews about memory errors because they didn't take out the standoff under the memory, and it was shorting memory pins to ground.

Processor
The most expensive part of my PC was the processor - a six core Intel Xeon E5-2620 v2 processor running at 2.1 GHz. I thought, "only 2.1 GHz?" But don't let that number fool you. It's still plenty fast.

It didn't come with a cooler, so I ordered Intel's standard LGA2011 cooler, part number BXRTS2011AC.

What I didn't realize at the time was that the E5-2600 series processors are designed for dual processor (DP) applications. You can get a motherboard with two 2011 processor sockets and put two of these on it. While it'll run fine on single processor motherboards (UP), it isn't taking full advantage of its dual-processor capabilities. A more cost-effective solution for single processor motherboards is the E5-1600 series. You get the same performance, but save about $100.

If you get the E5-1600 v3 or E5-2600 v3, then make sure your motherboard has the 2011-3 socket, not the plain old 2011 socket.

Case
The case needed to be professional looking, not gamey. I wanted a decent case that had plenty of room inside. And I wanted a case that came without a power supply so I could choose one separately.

I don't see a need to have a clear panel on the side with a bunch of LEDs lighting it up. I guess I kind of like the form-follows-function look. I like understated performance better than looks that can't deliver.

So I decided on the Corsair CC-9011014-WW. I'm pretty happy with it. But there was one draw-back. I wanted 4-pin PWM fans, and this came with two 3-pin fans. The motherboard needs the 4-pin style to regulate the fan speed by temperature. But I like the fact that there is a fan filter in the front of the case. That should keep the dust levels low inside the case.

Power Supply
The power supply needed to have plenty of reserve power, and also be efficient. That's why I chose the Corsair AX760. As a bonus, it's fully modular, meaning unneeded cables can un-plug from the power supply and be stored elsewhere.

The cooling fan doesn't need to even turn on until the system load reaches 70%. I assume that means 70% of 760 W, or about 530 W. If that's correct, this fan may never turn on, and never fail. At 70% load, the power supply is about 91% efficient, and only dissipates 48 W while delivering 530 W.

The whole system appears to be extremely efficient. My AC current meter says the computer (without peripherals) only  draws 0.57A as I type this. At 122V on the wall, that's only about 70 Watts total!

Storage (Hard Drives)
Since hard disk drives can really slow down a computer, I decided to go with solid state drives. Sometimes drives fail. It's time-consuming to make full backups or do a restore. If a drive crashed, I just wanted to be able to continue normally. RAID gives me that option.

I picked two 240 GB SSDs made by Seagate. Unfortunately, I didn't think ahead about mounting the 2.5" drives in a 3.5" bay, and had to order this mounting bracket later. The power supply cables can't be mounted that close to each other, so I have the drives facing opposite directions in the mounting bracket. Only later I found out that the case already had holes to mount 2.5" drives in the 3.5" trays.

I made a mistake on setting up the RAID volume. I first loaded my operating system, complete with all the latest updates. Then I tried to set up RAID afterwards. When I finally noticed the RAID menu during boot-up (after I enabled RAID in the BIOS), I already had the operating system set up. When I set up the RAID volume in mode 1 (mirror: stores the same data on two drives), the computer said it would erase all data on my hard drive. So I got the experience of installing the operating system again. 

Video Card
I'm not much into gaming. But I do like reasonably good video frame rates for youtube, etc. I may use some CAD software. A workstation graphics card fit the workstation theme, so I chose an NVIDIA Quadro K600. I like the fact that it supports two monitors. After experiencing two monitors at once, I really like it. It's like doubling the work area of your desk.

The K600 came with two adapters - one that converts the DisplayPort to DVI, and a DVI to VGA converter. But you can't connect the DVI to VGA converter into the DisplayPort to DVI converter. Also, the DVI to VGA converter doesn't allow some monitors like the Samsung T24C550ND to run in full 1920x1080 resolution. I had to get a different DVI to VGA converter to get it to work with full resolution.

The two DVI connectors are different and won't fit together. So you can only run a VGA monitor on the DVI port, not the DisplayPort output. I haven't tried a different adapter for this purpose though.

It came with the low-profile mounting bracket pre-installed, and the standard size bracket in the box, so I switched them so it would fit my case.

There are faster gaming video cards out there for the same price, but I figured if I installed a CAD program, it might require features present on a workstation video card. A gaming card emphasizes frame rate over rendering accuracy. A workstation card emphasizes accuracy over frame rate. 

Memory
I wanted more than the 4 GB I had, but didn't want to go high on the budget. Since the motherboard can accept more of the same, I got two 4 GB sticks of registered ECC RAM from Crucial, part number CT2K4G3ERSLS41339.  I was hoping to get LRDIMMs, but the price was still too high, so I settled for 8 GB registered ECC RAM.

I wanted the registered, ECC memory so that I hopefully won't have problems with memory errors. Who knows how many bits got flipped because a memory cell got hit with a gamma ray from a decomposing radon atom? 

Operating System
It goes without saying, if you have a PC, you run Windows, right? Not this time. I sometimes like to do things differently. It's kind of like a challenge to see if I can live without Windows. So far, so good. I may even install and run some Windows programs on an emulator, but only if I can't find a Linux version first. 

Fans
The motherboard supports 4-pin fans for variable speed control. I ordered three Bitfenix Spectre Pro PWM fans: two 140mm intake fans, and one 120mm exhaust fan. (Also there's an Intel 4-pin fan that's mounted to the CPU heatsink.)

Update Jan 14, 2017: The computer spent most of its time on, so the fans were running on low speed most of the time. The 120 mm fan was starting to make noise, so I replaced it. The 140 mm fans could no longer stay over 300 RPM at idle. One 140 mm fan failed. It wasn't a bearing. The motor started wearing out and the computer would raise the speed of all fans if one dropped below 300 RPM. So basically, all three Bitfenix fans wore out in less than three years. But they did last longer than their 12 month warranty.

A while ago, I added a copper chipset cooler with a tiny 4 pin PWM fan. That keeps it cool.

Performance Benchmarks

CPU Blowfish 1.509 s
CPU Cryptohash 837.84 MiB/s
CPU Fibonacci 1.76 s
CPU N-Queens 0.63 s
FPU FFT 1.14 s
FPU Raytracing 4.81 s

I ran these with the power profile in BIOS set to efficient. I made no attempt at over-clocking. I don't want to run anything too hot. The benchmarks reported that the CPU was running at 1200 MHz. I have no idea why.

Graphics card benchmarks

Video Card glmark2 score
Quadro K600 2047
GTX 960 6529
R9 270 2532


If you want to run the same benchmarks for comparison, install Hardinfo on Linux. If you're not running Linux, you can download a CD image, burn it, and boot off the CD to run what they call a "live session". You can install Linux Mint Hardinfo from the software center, but it's not permanently installed in a live session. The video card benchmarks were done with glmark2.

I didn't want to pay to get the 64 bit Geekbench software, so I just ran the 32 bit version for Linux. Geekbench (32 bit) score = 12364.

Cost
Yes, that's the big question. Here's the itemized list.

Motherboard 281.90
CPU 404.75
CPU cooler 21.26
Case 79.99
Power supply 179.99
Drives 119.99 x2
Drive bracket 9.99
Video card 169.99
Memory 113.99
Fan 120mm 12.99
Fan 140mm 16.99 x2

Total (without tax or shipping): $1548.81

So, was it worth it? I'm not sure. By that, I mean I could probably get by with something cheaper, but it sure is nice to have a tool that works. Also, it was fun to build.
Inside the workstation PC (still needs some cable clean-up)