Coolsat 8000 broken

[rrob311]

My coolsat has been acting up and now when its on for a few minutes it shuts off. Now it won't even power up. Has anyone ran into trouble with these? It has the most sensitive tuner out of all of my boxes. It pulls in marginal signals better.

[musicmanitou]

Check the capacitors in the power supply

[rrob311]

OK, I got the board out and it only has about 3/4 of the required voltages in the main outputs to the tuner board. Just need to figure out how to check these Caps.

[musicmanitou]

First check the capacitor for obvious defects, leaking, bulging at the top or sides.
You can use an analogue multimeter as an ohmmeter to test the capacitor. Remove the capacitor from the circuit board, if the board is not marked, mark where the negative lead goes into the board, You'll want to replace it exactly as removed.

Discharge the capacitor by shortening its leads. Use a wire and connect the leads of the capacitor together.

Put your multimeter in the high ranges 10K-1M. Connect the multimeter to capacitor leads making sure you connect the positive to positive lead and negative to negative lead. As the leads make contact,the meter will register near zero. It will then raise slowly to infinity. The meter will register infinite ohms because the capacitor is being charged by the meter.

If the capacitor is no good(in this case shorted),it will register at zero ohms and stay there.
If the capacitor is open (still no good) there will be no reading on the meter.
Sometimes I use the voltage setting on my meter and put the negative lead on the ground on the circuit board and placing the positive lead on the tops of the electrolytic capacitors ( cylinder types with metal tops) for about 5 seconds, I find where the voltage is usually not what it should be, more time than not is is lower. Hope this helps

[rrob311]

do I do this with the board powered up? what voltage readings am I looking for? DC?

[rrob311]

I got another power supply coming so I will start testing caps on a rainy day. I have a scope to but I am not sure how to use it for circuit boards.