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Old 08-26-2010, 10:25 PM   #1
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Join Date: Aug 2007
City & State: Michigan
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist Tech
Posts: 982
Default Motorola DSL Modem MSTATEA

Working fine then early one morning it cycles through the LED sequence but won't sync with the DSL signal. Another DSL modem syncs fine.

WV=working voltage of a functional unit
iESR=ESR in circuit cool
ESR=ESR out of circuit cool

EC1: CapXon 220uf 25v WV=11.9v iESR=0.06 ESR=0.06
EC2: CapXon 330uf 10v WV=3.3v iESR=0.05 ESR=0.06
EC3: CapXon 330uf 10v WV=1.6v iESR=0.15 ESR=3.3
EC4: CapXon 330uf 10v WV=3.3v iESR=0.01 ESR=9.6
EC5: CapXon 47uf 25v WV=11.9v iESR=0.30 ESR=0.35
EC6: Not populated, WV=3.3v
EC7: CapXon 470uf 16v WV=14.1v iESR=0.02 ESR=0.04
U2: Infineon PSB7100ZDW BGA

The working voltage of EC7 varies with the transformer.

The board is discolored around U2. EC3 and EC4 closest to U2 are bulged. Replacing EC3 and EC4 repaired the unit but since a DSL modem is a critical networking component and I don't like waking up to no Internet I recapped the rest. I used polys where available, increased the uf, and added an 820uf 4v OSCON poly at formerly empty EC6.

The DVE DSA-5W-12 AUS transformer
C9: LH.NOVA 680uf 16v
C1, C?: AiSHI 5.6uf 200v
C10: JEE 0.47uf 50v

The transformer isn't very hot and is easy to change out so I left these caps alone.
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Old 08-27-2010, 11:55 PM   #2
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Join Date: Oct 2005
City & State: Rockhampton, Queensland, Australia
My Country: Australia
Line Voltage: 240VAC 50Hz
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Posts: 1,958
Default Re: Motorola DSL Modem MSTATEA

Good repair job.
I still recommend replacing the caps in the transformer.
My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics.
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