A1989 820-00850-A no power

[hgoncalves]

Hi,

I have an A1989 820-00850-A that only powers on conected to the port of UB300. In all other 3 ports it only has 5V on ampmetter, and 0.25A.

Client arrived today from flight and says that it just stoped charging the battery with no reason, and it still doesen't charge the battery..

CB306 and CB300 were burnt and his traces exploded. I've replaced UB300, but it keeps with the same behavier (it stays w/o CB306 and CB300).

RB260 was a bit burnt and I've replaced.

Strangely I have 0V on PP1V8_UPC_TA_LDOA, and 0 on diode reading (mesured on test pad).

PP3V3_G3H_RTC = 3.3V

Diode readings:
UB400:
PP1V1_UPC_TB_LDO_BMC = 0.491
PP1V8_UPC_TB_LDOD = 0.461
PP1V8_UPC_TB_LDOA = 0.497
PP3V3_UPC_TB_LDO = 0.497

U3200:
PP1V1_UPC_XB_LDO_BMC = 0.488
PP1V8_UPC_XB_LDOD = 0.459
PP1V8_UPC_XB_LDOA = 0.495
PP3V3_TBT_X_SX = 0.515
PP3V3_UPC_XB_LDO = 0.499

U3100:
PP1V1_UPC_XA_LDO_BMC = 0.510
PP1V8_UPC_XA_LDOD = 0.477
PP1V8_UPC_XA_LDOA = 0.517
PP3V3_TBT_X_SX = 0.514
PP3V3_UPC_XA_LDO = 0.500

UB300:
PP1V1_UPC_TA_LDO_BMC = .521
PP1V8_UPC_TA_LDOD = 0.3486
PP1V8_UPC_TA_LDOA = 0
PP3V3_TBT_T_SX = 0.523
PP3V3_UPC_TA_LDO = 0.500

Can you help?

 

[2informaticos]

"PP1V8_UPC_TA_LDOA = 0"
Did you really mean zero (short to ground), or OL (open)?
Open Line means there is no connection from CB306 to UB300.
May be caused by broken trace, or bad solders underneath.

BTW, CB306 is more critical than CB300.

 

[hgoncalves]

SORRY!!!

OL on resistance and diode reading.

I've wired the trace to the CB306 PP1V8_UPC_TA_LDOA pad, but now I have 2.9V there and on test pad, and 0.526 on diode reading, and I get the same behavier on all other USB ports.

 

[2informaticos]

Then UB300 is bad, if generates 2.9V on 1V8 LDO...

 

[hgoncalves]

Hi,

Just replaced another CD3215 (from a different board), but still have 2.9V on PP1V8_UPC_TA_LDOA test pad, however i have 5V in all USB ports.

PP1V8_UPC_TA_LDOD has 1.783V

Any idea?

 

[2informaticos]

That's no good; you may have leakage between internal traces.

 

[hgoncalves]

Hi. But I get OL when measuring. That should indicate that nothing is connected there, right?

I even wired on it an 1.8V line, but when Ido that, I get 1.8V but still only 5V on all ports.

When measured right after the CD3215, I still get 3V there.

Can I do anything else?

 

[2informaticos]

That voltage is internally generated by CD3215.
It only requires an external capacitor, for stability.

 

[hgoncalves]

Understood. TKS.