Elektronika MK-52: The MK-61 big brother?

[jebem]

(11-15-2014 11:38 PM)Francois Lanciault Wrote:  I was hoping this could be my problem too... But after removing the four capacitors, they all test good. I will put everything together and check the voltage.
François

Hi, Francois,
I started by checking the output voltages first, and it were wrong and with a lot of ripple noise (to check this you need a oscilloscope besides the multimeter).
In my case, the problem was on the defective capacitors.

Sometimes the capacitors measures well on the capacitance meter, but this do not mean it are good for use.
The reasoning here is that the vast majority of capacitance meters are not able to check the capacitors at the required operating frequency of our application.
This is a switching DC-DC converter operating at a very high frequency, so the capacitors may be good at low frequencies like 1 or 2KHz, but it will fail at the required operating frequencies used here (about 70KHz).

So, assuming you have wrong output voltages, and when in doubt, replace the capacitors.
If it do not fix the problem, continue to check the remaining components in the DC-DC converter, but I would recommend you to acquire an oscilloscope to do the checking.
It is a nice investment for the future and you can find plenty of them at eBay for low cost, specially the used models from the 70's and 80's.