0 Members and 1 Guest are viewing this topic.
On the schematic, I had measured voltages form T948 transformer (in input -100V) and on output pin 19, 20 and 22 used for 5.2V and 8.6V is 0V.
Hello azu_,Apart from the ticking noise, is the scope working normally?If it is working, does the ticking affect any of the traces shown on the screen?Regards,Relayer
Quote from: azu_ on July 05, 2018, 08:14:24 pmOn the schematic, I had measured voltages form T948 transformer (in input -100V) and on output pin 19, 20 and 22 used for 5.2V and 8.6V is 0V.Just two weeks ago I repaired a 2230 with identical symptoms. I believe their power supplies are identical.The two outputs of T948 are recitified and then C-L-C filtered. The first filter capacitor (820uF) on the 8.6V side was shorted. Very unusual for a 'lytic to fail by shorting. I replaced it with 1000uF @ 25V low ESR and it started up fine. I then replaced all the other 820uF caps. may as well while you're in there. Since then, I have been using it onthe bench and really like it. It may become my main scope for troubleshooting/repair work.
I had tested all C-L-C filter capacitors for 5.2V, +-8.6V (C960 - C964, C968, C970) and capacitors seems good (measured capacity around 1000uF). So I don't think the problem is here.
Did you test them for ESR?Caps can measure perfectly for their capacitance, but falldown due to higher ESR.Regards,Relayer
How I can measure ESR? I only have two multimeters.