On the Workbench: An Old Dell DImension

A little backstory...

(no, not that kind of backstory!)

This is an old Dell Dimension 3000 PC made around 2005.  I was given it about a year ago, and it appears to have had VERY little use.  It still has the original installation of Windows XP, complete with MS Office 2003.  This was a low end machine when new, and I never cared for these low end Dimensions even when new.  Why am I even bothered to fix this low end, antiquated machine machine?  Simple, this machine will serve perfectly fine running amateur radio logging software for my club (and has already done so in one contest). Also, because I can.

So, what's wrong with it?

When getting this machine prepped in time for the next club contest I discovered a bulging capacitor on the motherboard.  I remember this machine running very sluggish when it was last used (even considering its about 15 years old), and this capacitor failing may explain that.

Is this thing even worth the cost of a new capacitor?

Long answer: It depends
Short answer: No

I am in no way planning to spend $$ on a new name-brand capacitor.  I have a kit of no-name Chinese capacitors and will use one of them.  The original capacitor is a Nichicon 1000μF at 10 volts while my Chineseium replacement is rated 1000μF at 16 volts.

Notes on Testing Capacitors

 

Bad Capacitor

Good Capacitor

I have a fancy component tester that can tell me the Capacitance and ESR of capacitors.  I figured this project was a good excuse to demonstrate it.  ESR means Equivalent Series Resistance and is a good indication of what is a good or bad capacitor as a capacitor can appear perfect physically, and read proper capacitance on a basic LCR meter yet still be bad.  As you can see from the two readings, the bad capacitor in this case is painfully obvious as its capacitance is reading at less than 20% of its rated value!  I believe the original capacitor should be rated at either ±10% or ±20% tolerance.  This thing is reading over 80% off!  In regards to ESR, a typical ESR value chart can be found here.  According to that chart, a typical 10v 1000μF capacitor should have an ESR around 0.12Ω and can be roughly twice as high and still be good.  That wold put our high side tolerance at 0.24Ω.  It reads 6.0Ω.  That's not even in the same country, let alone ballpark.  Definitely bad.

Repair Success!

After soldering in the new capacitor (which was a real pain in the butt for my little 30 watt soldering iron) I reassembled the machine and powered it on.  It booted up much quicker than I remember it taking when I last used this machine.  It was running like brand new.  I suspect this capacitor has something to do with the IDE controller as I originally thought the painfully slow boot times were due to it being a old, slow IDE hard drive.  Of course, I have no idea how long that capacitor will last, but it should last long enough for another free computer that I save from the trash pile to take its place.

Tools and such

Below are some links to tools and supplies that I used in this project.  It is by no means an extensive list, but purchasing using these links will help me out at no cost to you.

Capacitor Kit
PCB Holder 
Component Tester

Adding a Supplimental Cooling Fan to a Kenwood TS-711A or TS-811A

This will be a quick and dirty overview of adding an extra cooling fan to a Kenwood TS-711A or TS-811A transceiver.  This may work for the Asian and European versions of these rigs as well.  This mod is intended for radios that will be powered off of the built in AC power supply and will not work properly when powering the rig from the DC power jack on the back.  I performed it on both my TS-711A and TS-811A as they were getting a bit warm to the touch on the back when just scanning some local repeaters.  The fans work, but I don't trust the 30+ year old motors.  If your fans are completely borked, you can get a 60mm PC fans and install it inside where the original was. I found that after a couple hours of scanning I did not feel a noticeable warmth on the rear of my rig with the added fan running.  Mission accomplished!

Standard common sense disclaimer:  I AM NOT RESPONSIBLE IF YOU FRY YOUR RIG BECAUSE OF THIS GUIDE.

Fan Guide

First, Remove the top and bottom covers (be careful of the wire for the speaker!!!), then locate this area near the power plug on the bottom side.
 

This is where we will be tapping into the 13.8 Volts DC that the internal power supply creates.  When running from AC power these connections are switched with the main switch, so your fan won't be running constantly






When servicing equipment, I like ans many things to be modular as possible, so I do not recommend soldering the fan directly to the power connection.  You can use whatever connector you feel like using, but I also like being somewhat lazy (and cheap).  My fans already had a standard 3-pin connector, so I pulled a 3-pin fan header from a dead motherboard.  See the image for the removed header with pin-out information.




Solder a pair of wires on, and heat shrink over the connectors to prevent shorting.







Since I am leaving the original fan in my rig and mounting an 80mm fan externally we will need a place to run the wire through.  I am a big fan of not putting extra holes in a cabinet, so I decided to use the already provided hole that the optional computer interface connector goes in as I don't have the interface in my rig.  Be sure to install a grommet to protect the insulation on the fan wire.






Next, I had to remove the audio board to get access to where the fan cable will run from the top half to the bottom half.  Unscrew the nuts on the Ext. Speaker and Key jacks (don't loose them, or the washers!), and fold the daughter board back out of the way





Its probably a good idea to mount the fan now so you can get an idea of how much wire slack you have.  My fan model has a super long cable that goes right over to where I am tapping in the power.  If you fan's cable isn't quite this long, you can make the leads on your power tap longer.  The original Kenwood fan is set up to exhaust air out the back, so that's what I have set up with the computer fan as well.

Its a tight squeeze, but I ran my fan's cable down next to the back edge of the frame where there is already a bundle of wires










Remove the power connector and use a small pointy thing to hold back the plastic tab and pull out the orange wire on the end.  On the wire, whittle away at the insulation to expose the conductor then wrap your lead for the + terminal on the fan header around and solder.  I don't know what kind of wire Kenwood used, but I found that I had to use some flux to get the solder to flow.






Add some heat shrink and carefully reinsert the pin into the connector.

 



Solder the negative lead to chassis.  I found the bare lead going to the nearby terminal tab bade a good spot.












Plug in your fan connector.  I added some extra heat shrink for protection (not yet shrunk in this pic).










Tuck the wires out of the way, then reassemble.

Final Notes

When choosing a fan, I suggest using one that has a fluid dynamic bearing as those are the quietest, but a ball bearing is also a good choice for reliability.  Avoid sleeve bearing fans as they are not designed for longevity, and also will fail very quickly (sometimes within a couple months) if the fan is pointed up or down (or angled).  I used Arctic F8 80mm fans (available at this link, or in a 5-pack; eBay affiliate links).  These are a good balance between price, build quality and noise level.

Of course, this is just an overview of what I did for my situation.  Feel free to improve upon it, or change your steps to fit your needs.

73.