Concept2 Forum

Would anyone know a fix for a PM-2 with the bottom line of the LED segments not filling in. I ran the reset and the 5 shows in full on the screen. Once I press off and back on the bottom segment of each character place in the top two rows remains off when it should light up to fill out the number. I set the LCD into a known good monitor and it lights up fine. I have time and a soldering iron and I know how to use it however I don't know how to go about troubleshooting the board.
Any help is appreciated
Stephen

Clean all the contacts on the board with a cotton bud and some IPA- Isopropol Alcohol. Also clean the elastomer strips the same way.

The problem is most likley due to corrosion, you have lost the connection between the LCD driver, the large IC near the batteries and the LCD contact pads.A track is typically eaten through where it goes from one side of the board to the other through a via. Inspect all the tracks in the battery area. hold the board up to the light and check all the holes through the board are clear. Battery acid Corrosion is the number 1 killer of the PM2.Sounds like you have more than one track not working.

The test screen if you have not found it already is entered by pressing the Ready button and then the display button at the same time.

Carl
you might have hit it. I found a break located at the far left trace line at the connection point to the LCD screen contact. The location is the same side of the board which batteries are though on the flip side. The corrosion showed just a bit darker than the trace line. I zoomed in on the LCD traces, probed them and immediately picked up on it. Could you specify a fix idea for it. Overall length of damage is milli and it's a pin heads distance from the contact area.
Thanks

Ok basically you need to remove the protective coating from the copper so you can solder it.

I use what is called a fibreglass rework pen to remove it and then you get some hookup wire and remove a strand of it from the core and tin it with the iron so you have a single 0.2mm strand of copper, feed it through the hole and solder it both sides. The wire can be bent and run along the track to bridge the break and soldered. The whole job can be done to a standard that it very very tidy. Once I have found and repaired all the breaks I clean the board and mask off the battery tabs, hold a piece of cardboard vertically down the board near the tabs and spray the board with a clear conformal coating like Electrolube CPL. This protects the board and the whole power supply area under the batteries from any future possible corrosion from battery leakage.

The Monitor is good! The LCD is full and the 5 shows. I first tried to solder a wire strand to the hole and I was unable to get a solid attachment. On the second try I tinned a wire and clamped it perpendicular to the break, heated it and the solder flowed into a bridge. The board appears to be in fine shape otherwise with no signs of corrosion. I appreciate the help.
Thanks
Stephen