Repair tips
Posted: 27 Nov 2011 21:25
Hello to all JUMA people,
I have been assembling several JUMAs lately and I have found following problem: There has been several short circuits
in PCBs especially TX136 and TX500 and PA-100 control boards. Also one TX 500 main board had short circuit in +14V line. It was the most fatal case since short was so strong that about 1cm of PCB foil was destroyed totally. Last week I found a short in one TX136 control board´s +5 V line. Fortunatelly +5V regulator had protection and nothing was broken. Shorts have been some times very hard to detect since they are almost invisible, very thin copper track under protection laquer. You need good magnifying glass to see those shorts.
So before you connect power to any JUMAs check the +14V and +5V lines against GND with multimeter in resistance measurement range.
Couple of shorts have been in some control line like relay control line and one was in I2C clock line.
The shorts are result of poor cleaning and particle contamination during the PCB manufacturing process.
Let the solder smoke!! Build JUMAs!
73 de Heikki OH2LH
I have been assembling several JUMAs lately and I have found following problem: There has been several short circuits
in PCBs especially TX136 and TX500 and PA-100 control boards. Also one TX 500 main board had short circuit in +14V line. It was the most fatal case since short was so strong that about 1cm of PCB foil was destroyed totally. Last week I found a short in one TX136 control board´s +5 V line. Fortunatelly +5V regulator had protection and nothing was broken. Shorts have been some times very hard to detect since they are almost invisible, very thin copper track under protection laquer. You need good magnifying glass to see those shorts.
So before you connect power to any JUMAs check the +14V and +5V lines against GND with multimeter in resistance measurement range.
Couple of shorts have been in some control line like relay control line and one was in I2C clock line.
The shorts are result of poor cleaning and particle contamination during the PCB manufacturing process.
Let the solder smoke!! Build JUMAs!
73 de Heikki OH2LH