Embedded Files
Every time I am stumped on a repair I turn to the internet for help. This page is my attempt to make information about repairs available for others to use. Since I am the Technical Systems Manager for a College, every day I am encountering and solving technical problems. Besides Computers and Networks, I also cover Sound systems, Video systems, Energy management, Fire Alarms, Clocks, and Telephone Systems.
How to fix bad LCD screens with LED's
Have you ever wished you could fix a laptop screen that has a bad backlight without spending $100 to $250 or more to replace the entire screen? It is possible to retrofit some LCD screens with LED's for backlighting. Recently I repaired a Sharp Actius by using 20 x 3MM, 40 degree viewing angle, 16,000 MCD LED's. They take three volts each so I made five strings of 4 LED's. Then I connected them together and added a 100 ohm resistor. Then I connected them to a 9 volt battery for testing. That did not work so I then used two 9 volt batteries in series to get about 16 volts (they were used batteries) for testing. That worked well because the power to the inverter was 16 volts when on AC power and 12 to 14 volts when on battery power.
You first need to remove the screen from the laptop computer. Then you need to remove the metal trim at the bottom of the screen, assumeing that is where the light is located. Some screens have connections to the screen that go around the backlight and make in nearly impossible to remove the light. Once the light is removed the LED's can be glued in with a clear glue. You might want to solder the LED's together in groups of 3 for 9 volts or 4 for 12 volts first. I used 1/2 inch spacing between the LED's for more even lighting. Once the LED's were glued in and working I used alumimum tape like what is used on furnaces to make a 1/2 inch strip to go on the display to cover the LED's and to replace the metal strip I had removed. Be very carefull as the tape and the cover are conductive and will easily short out the LED's. I used electrical tape to insulate the cover and my connections.
How do you know if the inverter or CCF tube is bad? Well first obtain a NE-2 light bulb. You old guys like me can remember using them to test flyback transformers. Well they work for inverters too. You will need to turn off the room lights. Align the NE-2 over the high voltage output transformer on the inverter. At some point it should light up. To test the CCF tube you will need a 700 to 900 volt inverter power source. I know it is scary to put that much power into a tiny little tube. I usually take some 1 K resistors and stick them into the plug coming from the CCF tube. Then aligator clips connect them to a CCF inverter normally used to light up a computer cabinet.
New toy - IDE to USB adapter
Years ago I made an adapter to allow me to plug a laptop hard drive into a desktop computer. I ended up making about 3 of them. Eventually adapters were available to do that. This adapter made it easy to Ghost a laptop hard drive to another drive, and to test out faulty hard drives. Now the problem is solved in a better way. You can buy a device on Ebay that allows you to plug a desktop or a laptop hard drive into the USB port of your computer. This is WONDERFULL! My computer at home has 6 hard drives in it, and I can only get 3 of them to work at a time, and only if I play around with the jumpers. Now I can add or remove a hard drive without powering off the machine. I just made a Red Green Show DVD using some old shows that were on a hard drive that was attached via the USB connector and the DVD program had no problems wiht the USB drive and it did not slow down the process either. This is the best new toy I have had in years! The model I purchased also has a SATA connector on it for use with those SATA hard drives.
Socket 754 mobile processors on desktop motherboards
If you are inclined to try a mobile socket 754 processor on a desktop motherboard let me first say it is risky. But if you are so inclined here is how it can be done. First I purchased a MSI K8MM-V VIA Unichrome motherboard. Around the inside corners of the heat sink mounting bracket there are 4 little bumps. Remove them with an exacto knife (With a thicker shim this is not needed). Then put heat sink compound on the processor and then put a 1/8 inch thick by 1 to 2 inches square copper or aluminum shim on top of the processor. Install the heats sink then remove it to check to make sure the silicone heat sink compound is smushed when the heat sink is mounted. Some heat sinks do not mount tight enough to make good contact with the processor. My first attempt lasted 5 minutes then the processor died. I suspect it overheated because the heat sink was not tight enough, or the shim was too thin.
If at first you do not succeed, cry cry again. My next attempt at running a laptop processor in a desktop computer used a Athlon mobile 3200 I purchased for $29 on ebay. This time I used a 7000 series ALCU Zalman heatsink and it is on an Asus K8V motherboard. It is now in my main computer that I am using to type this. It has been working for about a month. The Zalman heatsink needs some modification as well. First replace the two about 1/2 inch tall spacers that came with the Zalman heatsink with motherboard standoffs that are about 1/4 inch tall. The next problem is that the screws that came with the heatsink bottom out in the spacers and must be replaced with shorter screws. Again make sure there is fairly tight contact between the heatsink and processor. When I first tested it CPU-Z reported the core voltage to be at 3 volts. I started sweating untill I uploaded a newer version of CPU-Z that reported a core voltage of 1.5 volts.
Watch out for older BIOS versions. I had a couple of computers that would shut off sometimes. Then I discovered that the core voltage was only about 1 volt. That is what happens when the BIOS does not recognize the processor. The prices for socket 754 motherboards and processors are going up on Ebay. Too many people are reading my web page and finding out how to get a motherboard and processor for less than $50 including shipping. I have now put together about a dozen of these computers. We are replacing Athlon XP's on MSI-6382 motherboards. It is a good thing we are replacing them their capacitors are blowing!
Dell Ultra Sharp 1800FP
My repair tip of the week is the Dell Altra Sharp 1800FP. It is a nice bright 18 inch flat panel LCD monitor. However the power supply in it has a tendency to die. You can easily adapt it to run off a power supply that can deliver about 3 amps at both 5 and 12 volts. There are some power supplies available on Ebay for the monitor but they want $50 for one that might also quit. The bottom side of the power supply identifies 2 pins as 5 volts and 2 pins as 12 volts. The other 4 pins are ground. I used a power supply extension cable. The cable I used had 12 volts as yellow and 5 volts as red. Ground went to the black wires. I soldered on the extension cable and then plugged it into a small 120 watt AT type power supply. Then I covered the wires with spiral wrap.
I had another LCD monitor to fix recently. It was an industrial monitor with an external 12 volt power supply. The power supply tested good, the lights came on but the screen did not work. It turns out that the AC adapter dropped to about 5 volts under load. The solution was to use a new AC adapter.
Dell LS series LCD cable
Over a year ago I met a student who had a really small laptop computer. I was impressed by the size and lightness of the computer. Recently I was given a pile of these sick Dell laptop computers. Almost all of them had nothing on the screen. I quickly discovered that the problem was the cable that runs to LCD screen. It gets torn by opening and closing the laptop. Replacement cables are available on Ebay for about $30 to $35. Don't buy a used one, I tried that and one worked out of three. Since these cables fail after three years of use many companies are replacing them before they fail and some are then selling these almost bad cables.
To disasemble this computer there is a hole above the keyboard on the right side that releases the cover to the left. Then one screw releases that end of the ribbon cable. Removing the screen end of the cable is harder. Six rubber covers are removed and the screws under them are removed. Then 4 screws holds the screen down. On the back side of the screen yellow tape holds the ribbon cable in place.
The next problem is the power supplies. These laptops use special Dell power supplies but will actually run off any 16 to 19 volt AC adapter. The laptop will even run off a 15 volt 1.5 amp power supply, but it would not charge the battery. To convert the laptop for a normal power supply you can remove the 3 pin jack and replace it, but there is limited room under the ribbon cable. Another option is to use an external female jack and solder the wires from it to the internal jack. From the front of the computer the pin on the left side is the negative and the pin on the right side is the positive pin. You can see this modification if you look closely at the picture.
The laptop computers did not come with either a CD rom drive or a floppy drive. At first I tried to get used Dell products for use with the computers. Then I discovered it is cheaper to get generic USB floppy drives and CD roms. A PCMCIA CD rom drive is another option. This way you can use the drives with any laptop computer. Windows 98 will need drivers to work with the external USB floppy drives. I set up one laptop hard drive using a desktop computer to transfer files and then made a ghost image to set up all of the other laptop hard drives.
Cybex Commander KVM
We were given a Cybex Commander KVM. It is really old, perhaps one of the oldest KVM's I have ever seen. It came with some cables but not enough. So I have made my own cables. By using a voltmeter I have come up with a wiring chart. I do not know how to connect the mouse as none of the cables that came with it have a mouse plug. The keyboard pins are not normal, they are numbered counterclockwise looking at the end of the connector. The other connectors all had numbers on them.
25 pin Other ends.
-- ------
1 Vga 15
2 Vga 13
3 Vga 3 Blue
4 Vga 2 Green
5 Vga 1 Red
6
7 Kbd 3
8 Kbd 5
9 Kbd 2
10 Vga 14
11 vga 11
12 Vga 12
13 Vga 4
14 Kbd 1
15
16
17
18
19
20 Vga 6,7,8,10 Ground
21
22
23
24
25
Keyboard pin numbers;
1[]6
2 5
3 4
Dealing with Virus's, Adware, Spyware, and Toolbars
In recent days this junk has taken a big turn for the worse. This stuff used to just annoy us, but the writers were not being paid for their work. If they were caught they might even go to jail. NOW THEY ARE MAKING MILLIONS! For instance a computer infected with a virus can become an unsecured mail server to send out spam. All real mail servers have antivirus and antispam software on them. The virus writers can charge admission to use the infected computers. Who would be so sick as to pay to use an infected computer? Of course the casinos, the pornographers, and the illegal drug sellers. I am just waiting to get a spam that says "Order your Heroin here!". There is no low that these people will not stoop to.
A brief history of Virus's
In the early days viruses were funny. There was the one that caused letters to drop to the bottom of the screen, Another one flipped the screen upside down for a short while. A third one stopped because water was detected in one of your drives. Then it would make a sound like it was spin drying the hard drive. Viruses were just silly. They were spread by floppies in those days.
Then viruses became a little worse. One virus made your computer unbootable. Then if you booted from a floppy that was not write protected it was rendered unbootable. Soon there was a virus that on a certain date would erase your hard drive. Another ruined all the pictures on your computer and on any server it could find. Another would turn your computer off at 5 PM on Monday. Viruses were being spread by Email in those days.
Then with Windows XP there came a new generation of virus's. They not only rendered your computer useless but they could spread over the network and do the same to other computers. These viruses can spread by email or even worse over the network. Anyone on the network who was using Windows XP would be infected. After three or four computers were infected the constant searching of the network to find other computers to infect would slow the network to a halt. However there was one giveaway. The hub would light up on the port that the infected computer was on. Just unplug them and the network would start working again.
Now viruses have become even smarter. They only jam the network in short bursts. That way you cannot disconnect them as it goes away. They now target your antivirus programs. They will shut down your antivirus protection and in some cases even go as far as to delete your antivirus software.
Now there is Adware or Spyware
My first experience with adware was when my wife had problems with advertisements popping up while doing word processing. She could not save her work and had to shut down the computer, loosing all of her work several times. The pop up advertisements had no x in the corner, or it was off the screen. I know enough to use alternate, control, and delete to get rid of such things. Anyway after a lot of studying what was wrong with her computer, I discovered what we know today as "Gator". It is found in program files, common files, Gator, CME or CMII. I just deleted the directory and used Start, run, MSconfig, startup, to uncheck the box associated with it. I checked with Symantec.com but they would do nothing about it, since it was "adware".
Next there was another computer where Internet Exploiter would crash repeatedly. Eventually I solved that by deleting all of the Java files on the computer. Another solution is to just switch to Firefox from mozilla.com.
Years later at work a more serious adware program came up. It is called "optomize". I could not get rid of it. Then a friend told me about AdAware from Lavasoft.de. It can remove most adware and it is free. Some adware removal tools only install their own adware/spyware programs. However my computer at work would keep going to strange sites when I would do a search for things. It was not until AdAware SE came out a few months ago that I was finally able to fix that bug.
Toolbars
Toolbars are another annoyance. If you get enough toolbars there will be no space left to actually see the web page you are trying to go to. AdAware will remove some of them, but others can be removed by going to Control Panel, add/remove programs, and select the toolbars from the list.
Currently there is a new Virus or Adware that messes up computers. Neither Norton nor AdAware will get rid of it. It is identified by a strange bunch or files found in Program files, system32. These files will be created on the infection date and start with random letters. You can sort by date to identify them. Start, run, Msconfig, Startup, and unchecking their boxes is fruitless. The next time you start the computer they are back! So far the solution has been to start the computer is Safe or DOS mode and delete the files. You cannot delete them under Windows as they are "in use". Chase down all of the strange files referenced to in the Msconfig, startup folder and delete them. Then uncheck them and restart the computer. Hopefully that will do the trick.
The virus war continues. Now it is to the point that once or twice a week I need to replace an offending computer. Neither Norton, AVG, Adaware, Spybot Search and Destroy, HiJack This, or Microsoft Anti Spyware can fix them. I am thinking of putting hot swap bays into the computers and weekly replacing their hard drives. I am loosing the battle. Some thoughts are to upgrade all of the old Windows 98 machines to Windows 2000 SP4 or XP SP1 (if they can tolerate the slowness), and either Norton 2003 or Norton Corporate edition. The problem is that the old machines with the old Norton antivirus do not automatically update (some were a year out of date) and it does not stop email virus's untill it is too late. Norton Corporate edition would be the best but it sometimes fails to update.
Weapons for this war
Here is an inventory of software you may need to carry with you on your USB thumb drive. I also burn disks of these weekly and distribute them on the campus. With viruses that delete your antivirus software reinstalling the antivirus software is a necessity.
AdAware from lavasoft.de
AVG antivirus from Grisoft.com
Firefox from Mozilla.com
Remember to check Start, Run, Msconfig, Startup, and uncheck the garbage.
Remember to check Windows Explorer, WinNT, System32, View Details, Sort by date, and look for junk that has installed itself.
Dell Ultrascan P1110
We have a few Dell Ultrascan P1110 monitors that are just too bright. I opened one up and discovered they had eliminated the screen control. It was now all electronic and the adjustment is not easily possible. So I studied the G2 wiring and came up with this design. The 800 volt source goes through a 2.2 meg resistor to the collector of the voltage regulator. It should be about 500 volts. There are also two 10 meg resistors in series going to the equivalent of ground. First I tried increasing the value of R458, the 2.2 meg resistor. I increased it to 7.2 meg by adding 1 meg ohm resistors one at a time. It made little or no difference. Then I tried decreasing the value of R459, one of the 10 meg resistors. I added another 10 meg resistor on the back side of the board across R459. It worked great! I have run out of 10 meg resistors and am now using two 4.7 meg resistors in series as seen in the picture.
After collecting two of these monitors that did not turn on for 5 to 10 minutes I thought it was time to figure out how to fix them. Remove the power supply circuit board. You can leave it hanging by the smaller wires to work on it. Locate IC651 and short together pins 2 to 4. This is the filament standby circuit and you are hot wiring it to stay on all the time. Without this change the filament voltage will be .5 volts and slowly climb to 5 volts. With the change the filament will read about 5 volts instantly.
While I am on the subject of fixing Dell and Sony monitors let us look into the dim picture problem. As stated earlier the screen voltage should be about 500 volts. You will usually find the screen running about 450 volts on the dim monitors. The simple fix is to locate the 10 to 20 meg ohm resistor going from the collector of the high voltage transistor that controls the screen voltage to the volatge sensing circuit. You can unsolder one end and add a 1 or 2 meg resistor in series. Another option is to add a 1 or 2 meg ohm resistor to the low voltage side of the 10 or 20 meg ohm resistor to ground. Either way you are telling the voltage sensing circuit that the high voltage is lower than it actually is. You can check the screen pin on the CRT socket to see if it is now 500 volts. Normally with the brightness all the way up you should see some scan lines off the edge of the picture.
Another option is to build a serial to TTL interface circuit and use some copy protected software (WinDas) with a work around for the copy protection to monify the monitor screen settings. The information on how to do this is available at http://www.geocities.com/gregua/windas/
Axiohm 716 receipt printer
Several years ago I predicted that printers would someday sell for less than $100. The salesman I was talking to just laughed. I remember when a dot matrix printer dropped to $300, I bought one, and it even printed in color with a four-part ribbon. Today they sell printers for free when you buy an ink cartridge.
A few years back we needed to purchase a receipt printer. I was shocked to find out that they still sell for over $300 for a mini dot matrix printer. What a waste of money! Worse yet after 3 or 4 years the printers are shot. Then someone told me to try a thermal receipt printer. My response, based on the old fax machines, was that that technology was antiquated. However I was wrong, thermal printers have made a comeback; they are very fast and quiet. They no longer fade out in a few months like they used to.
I picked up two Axiohm 716 thermal receipt printers on Ebay for about $25 each. They both suffered from one side or the other of the receipt being very faint. The problem boils down to the head assembly being accidentally pushed down. To slide it back up use a small screwdriver and rest it on the paper door stop. Slide the blade end under the aluminum bracket that the print head is glued onto. Do not push on or apply pressure to the print head. Then just pry the print head up to where it is even with the other side.
The next problem is with the drivers. I tested the printers with a generic text only driver and they were real fast and the printout was very dark and readable. Then in order to cut the paper automatically I downloaded the drivers. I tried Epson TM-85 drivers, Epson TM-300, and Axiohm Drivers, all of the drivers I tried slowed the printer to a crawl, made the font smaller, and lighter.
However the Generic Text only driver would not cut the paper, even if I added the escape i sequence, it would not cut the paper. When I started the computer up the printer would cut the paper 3 or 4 times. If I opened the printer paper holder and shut it the printer would cut the paper. I spent several hours on the telephone calling tech support to no avail. They even sent me a sheet of instructions on setting up receipt printers. So after trying every escape code known to mankind, I started trying combinations of escape codes. When I tried escape @, escape i, sure enough it worked. Escape @ is the printer reset command.
Motherboard Capacitor Problems
Contrary to popular Internet web sites the capacitor problem has existed for years. Back in the early 80's I worked for Bargers TV in Olean NY. A repairman I worked with claimed he could tell a bad capacitor by it's weight. One ingredient in the electrolyte is water. When all the water leaks out the capacitor stops working. TV set vertical output capacitors were usually the problem. The picture would get shorter and shorter eventually collapsing into a horizontal line across the middle. In some cases the problem was obvious. I remember one computer monitor where the capacitor was blown off the circuit board and was rolling around inside the monitor's cabinet.
At the hamfest I purchased some used MSI MS-6330 motherboards with blown capacitors. I haves also bought some motherboards with blown capacitors on Ebay. The computer I am writing this web page on was one that had blown capacitors. At the Hamfest I heard that the problem with the capacitors was in the formula for making the electrolyte for the capacitors. Supposedly the formula was stolen but it was not complete. I had always thought the problem was the 12 volt power supply being pulsed through a coil into 6.3 volt capacitors to get 2.5 volts. I had read years ago that using cheap capacitors in these switching regulators was someday going to result in a lot of bad motherboards. These regulator capacitors actually run hot to the touch!
These blown capacitors can usually be spotted as the capacitors usually are bulging at the top. They intentionally make the metal of the capacitors can thinner in lines at the top so if the capacitor is going to blow up it usually will just crack at the top and leak out the crud. Sometimes the capacitor will blow out at the bottom. This can be seen as capacitors with crud around the bottom or they are blown crooked from the seal popping out at one side. All of these symptoms are evidenced in the pictures. Sorry about the black markings, I use a black marker pen to identify the bad capacitors so that when I fix the board I do not miss some of them.
The capacitors can be replaced by ones of higher voltage and of slightly higher values. For instance a 10 volt capacitor can replace a 6 volt one. Also a 2000 uf capacitor can replace a 1500 uf capacitor. I used to remove all the capacitors and test them. Then I only replaced the bad ones. Now I go more by the manufacturer of the capacitor. Some companies make better capacitors, if the name starts with "L" replace it. In the picture to the right EVERY LAST electrolytic capacitor needs to be replaced! They are all made by the same company and 3/4 of them are swollen up at the top. When the old ones were tested only 4 of them were within 70 percent of their rated value! In the picture above of the MS-6330's only the three capacitors need to be replaced, the others are from another manufacturer and show no signs of swelling.
To remove the old capacitors heat up the connection and add fresh solder. The new solder will add flux to improve the heat transfer to the other side of the motherboard. Then tilt the capacitor to pull out the heated lead. Next do the same for the other lead. Sometimes you need to go back and forth a couple of times to get the capacitor off the board. Then use a solder sucker on one side of the board and your soldering iron on the other side to clear the old solder off the board. If I cannot clear the solder out of the hole I will sometimes solder the new capacitor on the top side of the motherboard and glue it to some nearby components for stability.
This last picture is of a Gigabyte GA-7VKML motherboard. The capacitors look much worse than they do in the picture. It has 6 oozing capacitors and 2 bulging capacitors. It has become a regular thing that when someone says their computer is acting up I first check the capacitors. There does not seem to be a manufacturer that does not have this problem. Also if possible look at the capacitors in the power supply, they have the same problem and have the same effect of making the computer totally unreliable. Also if you have a pentium 4, check to see if the heatsink retaining clips are broken. Almost every pentium 4 system I have seen had a broken retaining clip. That is another reason I am a fan of AMD Athlons.
Cisco 2980 Switch repair
When I first saw a Cisco 2980 I did not know what it was. It looks like a hub, but no one makes a hub with more than 48 ports, right? The front is just covered with over 80 network style jacks! It really is a 80 port switch, not just a hub. The next question was, Why is it on the junk pile? It turns out that although it is a relatively new 80 port 10/100/1000 switch the power supply is no longer available. On top of that the power supply is a high failure rate device. It is rated to deliver a whopping 30 amps at 5 volts. Most AT style power supplies can only deliver 20 amps at 5 volts. Then two secondary regulators on the main board regulate the power down to 3.3 volts and 2.5 volts.
The power supply looks a lot like a heavy duty version of the old AT style power supply. So I dug through my boxes of AT power supplies to find the most powerfull AT power supply I could find. The best power supply was rated for 250 watts, +5V at 24A (max). Then the guts were removed and mounted in the Cisco's cabinet. There the power inputs are wired to the power connections. The two yellow wires that go to the 110/220 switch are connected together. Then the outputs are cut off at about 4 inches in length. The wires from the old power supply are also cut off and the two are then connected together. The yellow wires go to the yellow wire. The red wires go to the red wires at about 2 from the power supply to 1 from the cisco. The black wires connect together like the red wires. The other three seem to have the same colors but everything else works without them. They are -12 volts, -5 volts and power good. If someone out there knows if they should be connected let me know, but it works without them.
I have only used about 40 ports with no problems, and had to open it up again after a month of use to replace a fan, but other than that it works great. I did add a couple of extra heat sinks onto the left heatsink so it would run a little cooler. Someone has suggested adding another fan behind the power supply. That would blow air lengthwise across the power supplies heat sinks.
Mitsubishi Diamond Scan 17FS
Recently I came across a Diamond Scan 17Fs that has stopped working. However I remember it was working fine a few days earlier. I was about ready to throw it out when I came across it's twin. I noticed that the identical monitor had a homemade custom cable. Then it all came back to me. I had bought several of them about 3 years ago at a Hamfest for about $6 each. They had sold them as defective. The problem turned out to just be an unusual pinout. Although the monitor has a standared 15 pin VGA connector the pinout is not at all standard. I had reverse engineered the cable that was needed and after several tries to get the right color to the right pin they all worked fine. Somehow while sitting around this one had lost it's cable. So I collected all the strange VGA cables but none of them were the right one. The next step was to look up the adapter needed in my book. It was not there either! So I had to do it over again. Here is the pinout for the needed adapter.
1 - ground
2 - Red (Normal pin 1)
3 - ground
4 - Green (Normal pin 2)
5 - ground
6 - ground
7 -
8 - Vertical (Normal pin 14)
9 - Horizontal (Normal pin 13)
10 - Blue (Normal pin 3)
11 -
12 -
13 -
14 -
15 -
In a normal 15 pin VGA connector the middle row (6-10) can be used as grounds.
Gateway 6330 motherboard
The Gateway version of the MSI 6330 motherboard is missing the connector for the front panel. The pins can be added by soldering them into the runs marked for them. Or you can use the gateway connector. Here is the pinout (reverse engineered) for the Gateway connector. Note that the Power LED connection is actually about 5 volts and may burn up some LED's.
P LED Res Hdd
| | | | | |
o o o o o o o o
o o o o o o o o
| |
Pwr
Viewsonic VA800/VG175/VG191 LCD Repair
I was given some Viewsonic VA800 18 inch LCD Monitors because they had horizontal lines all over the screen. The first thing I did was to change the electrolyte capacitors in the power supply. They were marked 1000 uf at 16 volts but varied around 800 uf on a tester. That did not help, so I removed several of the surface mount capacitors and thested them. One type of capacitor marked 47 uf varied in value from .7 uf to 13 uf, so I replace all of them to no avail. Then I tried a hair dryer and found that if you heat the center of the board within 1 second it started working perfectly. So then I heated the components in that area with a soldering iron. That nailed the problem down to C16, a 1 uf 16 volt capacitor (It might be C19 as I could have been reading the part number upside down). To test the repair with a non surface mount capacitor I gently rocked the old capacitor untill it's leads broke off. Then I glued in a axail lead capacitor and soldered it to the pads for the old capacitor. It works for those of you who do not have surface mount capacitors or the tools to solder and unsolder them. It would not hurt to replace all of the capacitors but replacing just this one will get it working for now. This repair has lasted over 2 years on 2 of these monitors.
Disasembling this monitor can be tricky. Actually if you wanted to leave the monitors base attached you could, but I always remove it first. There is a U shaped plastic cover that is attached to the base where the base attaches to the monitor. Remove it first. Then reach inside the round plastic cover attached to the back of the monitor and release the two catches. You can now remove the 4 screws that attach the monitor to the base. Next remove the 8 screws that attach the front of the monitor to the back. Then start in one corner and go around the monitor unhooking the front from the back. Now the control board is under the metal cover in the middle that is attached with over a dozen screws. You have to remove them all as well as some conductive tape that may be covering a screw or two. Then lift up the metal cover, you can leave the two wires attached that unplug through the metal cover. Now you can replace the bad capacitor. Reassembly is just the reverse of disasembly.
Several people have written me to thank me for this repair secret. However one person wrote me to say that it works for a Viewsonic VG191 monitor as well. They replaced C19 and the problem was fixed. They also sent me this picture of the repair for me to post for others to use. Note that the circuit board run for the top lead is easy to lift off the board, use caution and glue it if needed.
Behringer Mixer Repair
I recently picked up a Behringer MX2442 for $130 on Ebay. The catch was that 1/2 of the channels did not work. What the seller did not say was that something highly acidic, like a soda, had been spilled into the mixer. The results were that every slide control was shot as well as 3 or 4 other controls.
The slide controls are available from Digikey. They are Panasonic Slide Potentiometers for Audio Mixer Applications. They are 75 MM long, about 3 inches and have 60 mm of travel. The part number is PQ1060SA-ND for A taper or PQ1060SD-ND for D taper. I ordered 20 of them and it ran around $60. But there are actually 22 mono slide controls and 4 stero slide controls from what I can see. I still have not completed the job of replacing all of the slide controls. It takes about 2 nights to do one of the 8 channel boards.
To remove the slide controls I first cut the 4 pins closest to the edge of the circuit board. Then slide a screwdriver under it and unsolder the two middle ground connections. Then unsolder 2 of the far pins while twisting the control to the other side. Then twist the other way and unsolder the last 2 pins. My solder sucker will not clear all the holes so I use a dental pick or a really small screwdriver to clear the holes for the new controls to be installed.
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