Thank you all for the opinions and lessons... I've changed all output capacitors, some of them was measuring more than 50% of original value. For instance: 1000uF measuring 1600uF, 470uF - 700uF and so on... But the PS is continuing clicking and oscillating... So I've decide to remove the filtering capacitors (4x 470uF 250V) and now I have the correct voltages. But the voltages decreases a lot when applying charge on it (back on 1650A mother board). Tomorrow I'll buy new filtering capacitors and see what happens. Thank you guys, JL On Wed, Mar 6, 2013 at 7:27 PM, John Honniball <coredump@gifford.co.uk> wrote:
Jose Luiz Martins wrote:
The power source clicks and the voltages are not correct. 7V instead of 12V, 4,5V instead of 5V and oscillating.
Clicking is a sign of current overload. Oscillation is a sign of too low capacitance, i.e. not enough smoothing.
I have not experience in PS repair, but someone told me that the electrolytic capacitors may be dry due the time it was stored (as well as de condition, one it was in Rio de Janeiro, and at summer time, the room temperature may be more them 120F)
Yes, that's quite possible. May be best to see if any electrolytics have begun to bulge on top. If so, replace then right away.
Could someone confirm that please ?
Another possible failure is tantalum capacitors. They fail short at any time, and will overload the supply. I had one fail today in a Tek scope module (5A22N). It smoked a resistor, too. Worth checking, if there are tantalums on the power supply rails on the boards of the 1650A.
-- John Honniball
_______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/