Surprised no ones helped you on this. On the 2246 its rare that the large 3 pin secondary electrolytics fail. The common fault causing tripping is C2210 (4.7uF), usually accompanied by failure of Q2209 or Q2210 (TIP32C are ok replacements if I remember right). Components around C2210 will look burned and overheated but are almost always ok. If you are unlucky Q2214 fails also. You can test the power supply out of the case using the fan as a load for a quick test. (Carefully!) Beyond those component fails, the switching transformer and multiplier can fail. (Disconnect the flying lead from the transformer to check the multiplier)
The secondary diodes also fail, 4 are schottky and show low on a test meter but are usually ok, the others should read the usual 0.6 or whatever your test meter shows for a standard diode.The 3 pin caps need to be low ESR, so if you bought standard caps I would put the originals back in as they are good quality caps.
Point of caution, if you run the supply on its own the 3 pins near the multiplier (tube heater) will retain a nice surprise for you long after powering off
If you are not familiar with switching supplies BE CAREFUL! They can be lethal. JC
---In TekScopes@..., <chris@...> wrote:
I had posted about my 2246 scope a few days
ago but have had no replies.
I have the feeling the 22xx power supplies issue
has been covered and maybe people are tired of it?
I am poor with the Yahoo group search function.
I have been able to dredge up that capacitors
and the ZS/ZM diodes are to be replaced and
that sometimes a transformer fails.
The symptoms I have are that I am in chirp mode
if the main board is attached.
Without the main board the scope will come up but
my cheapie volt meter reads -41VDC when I go
black to the chassis and red to the 43V TP on the power
supply board.
I do have a lot of the black ZS diodes. I have changed
out all the silver colored, grounded case electrolytics.
I have not changed out the big initial electrolytic or a
couple of small ones.
Any advice for me?
