Re: Lisa 1.8A Power Supply Problem

>Pay attention: This status is short before the cap will "explode".
>You should not use the power-supply further more until you replaced
>that cap!

I agree the big capacitors ( C8 and C9 ) are suspect and something to replace while you have the PSU apart regardless.

However, the circuit breaker issue may be a mystery as there is a 3 Amp fuse in the PSU, and this should have blown if there is an internal short. I suggest you check that there is a fuse in there, and if it has been bypassed or replaced with a piece of wire, put a fuse back in.

There is only one fuse in the PSU which is in the hot AC line. If the wiring of your power cable or wall receptacle is incorrect (with hot and neutral reversed), then a short circuit in the PSU might trip the breaker without blowing the fuse... if this is the case, the wiring should be corrected for safety reasons.

If your circuit breaker is a "GFCI" then it may be tripping because of a current leak to ground rather than a short circuit condition. This could be due to bad C3 / C4 / C5 / C6, and perhaps other faults.

If replacing C8 and C9 doesn't solve the problem, I suggest you measure the resistance of the AC input when the failure occurs to see if you do have an intermittent short, and also the resistance between each AC input pin and ground to see if you have a current leak. This might help narrow down the problem component.

Good luck!

-- 
-- 
-----
You received this message because you are a member of the LisaList group.
The group FAQ is at http://lowendmac.com/lists/lisa.html
To post to this group, send email to lisalist_at_email.domain.hidden
To leave this group, send email to lisalist+unsubscribe_at_email.domain.hidden
For more options, visit this group at http://groups.google.com/group/lisalist
--- 
You received this message because you are subscribed to the Google Groups "LisaList" group.
To unsubscribe from this group and stop receiving emails from it, send an email to lisalist+unsubscribe_at_googlegroups.com.
For more options, visit https://groups.google.com/d/optout.