05-19-2020, 05:50 PM
Today was the soldering day.
I first soldered every TO-220 part on the heatsink.
Then I decided to inspect the board and while looking at large connectors (transformer to board, the outputs to the motherboard) and found a few pins looking like so: (look at the top pin).
How did that thing work.....beyond me.
So all the connectors, including the smaller ones, got some serious touch up.
Then upon inspection I noticed some small parts pins developed indentations around them some look like cracks started to develop.
I touched them up, some sputtered or cracled at me, I guess entrapped flux. Large hole were revealed, meaning the holes are much larger than the pins, and I am not sure the barrel is metallized, but if it is, the solder did not rise yp and remained a thin layer around the pin, which made it easy to crack. Well soldered barrel does not allow that to happen.
Then since the same large connector is on the motherboard, I also removed it (AGAIN!!!) And sure enough, saw the cracked solder, so I touched all pins up, and also did touch up the sole TO-220 part on it.
Then installed the power unit, and without connecting loads measured voltages.
All voltages are fine except one, +10V. I briefly investigated: the voltages are made with 8V 7808 LDO with the common connected to GND via 2.2V zener, which makes it output 10V. But the zener needs a bias, and it is provided with a 1.2k resistor. Of which one pin seems disconnected. So the Zener is not biased and the 8V LDO outputs 8V like a good boy he is.
I decided to wait until tomorrow: removal and installation of the power supply is an onerous thing.
Genug für heute.
I first soldered every TO-220 part on the heatsink.
Then I decided to inspect the board and while looking at large connectors (transformer to board, the outputs to the motherboard) and found a few pins looking like so: (look at the top pin).
How did that thing work.....beyond me.
So all the connectors, including the smaller ones, got some serious touch up.
Then upon inspection I noticed some small parts pins developed indentations around them some look like cracks started to develop.
I touched them up, some sputtered or cracled at me, I guess entrapped flux. Large hole were revealed, meaning the holes are much larger than the pins, and I am not sure the barrel is metallized, but if it is, the solder did not rise yp and remained a thin layer around the pin, which made it easy to crack. Well soldered barrel does not allow that to happen.
Then since the same large connector is on the motherboard, I also removed it (AGAIN!!!) And sure enough, saw the cracked solder, so I touched all pins up, and also did touch up the sole TO-220 part on it.
Then installed the power unit, and without connecting loads measured voltages.
All voltages are fine except one, +10V. I briefly investigated: the voltages are made with 8V 7808 LDO with the common connected to GND via 2.2V zener, which makes it output 10V. But the zener needs a bias, and it is provided with a 1.2k resistor. Of which one pin seems disconnected. So the Zener is not biased and the 8V LDO outputs 8V like a good boy he is.
I decided to wait until tomorrow: removal and installation of the power supply is an onerous thing.
Genug für heute.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
