Tripp-lite SMART1000LCD not charging, no emergency power!

[Eddie3]

I have opened up the case and saw no visible parts / board damage. Initially I removed the battery; measured about 9V. Then I had put it on trickle charge until it got charged to 12v, but problem persisted when I put the battery back. It appears my Smart1000LCD UPS will turn on but it will not charge the single 12v 7AH battery, nor operate in emergency mode. It lights up when powered on, but I'm unable to power test the device (holding power and Speaker button simultaneously).

Took voltage measurements of battery:
charge mode: 11.8 DC Volts (in unit)
battery backup mode: 11.8 DC Volts (in unit)
battery removed: 12 DC Volts

I measured 124 AC Volts in both battery and surge side of all outlets, when powered on. Measured zero Volts, when power is off (battery backup mode).

Not sure if someone has seen the schematic, but I would appreciate it if I could get some help on fixing the charging / discharging circuit.

Thanks.

[Eddie3]

A schematic diagram would be helpful; like to see what point can cause failure for the optoisolator .

[temyth]

in these UPS i would check all the mosfets and relay's, they are likely to fail

[Eddie3]

Thanks. I've started at the 120V input side. Beginning with testing the electrolytic caps:

C4 680uf 25v ( Jamicon )
tested bad
158.6uf
Vloss= 19.9%
ESR= 4.95 ohms

C3 680uf 25v ( Jamicon )
tested ok
569.1uf
Vloss= 1.7%
ESR= 0.02 ohms

C19 1000uf 25v (Gemcon)
tested ok
973.8uf
Vloss= 2.1%
ESR= 0.02 ohms




diodes D1 thru D5 tested ok

[Eddie3]

Saw the under side had to much light…this pic is better.

[Eddie3]

Found another bad cap C10 (marked 470uf 16v) measured 47.36uf, esr = 136.7 0hms, Vloss = 98.1% and bad R44, with board discoloration (burns) and a lifted pad on R44. R44 measured 47 ohms (marked 10 ohms +- 1%). R44 is across C10, and the lifted pad also connects to D7. Looks like it got hot near K2. D7 and D41 are good.