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Question: How long will a defective power supply (model ST7002-BW0G) last in a TiVo HD?
Answer: Just until the parts warranty expires.
Yesterday some friends of mine dropped their TiVo HD (TCD652160, manufactured 11-Jan-2008) off at my house so I could try and figure out why it wouldn’t power on correctly. It was reported to me that tapping various parts of the power supply would make it power on and off intermittently, so I set to look at why this happened.
When removing the board from the chassis I’d noticed that the substrate appeared cracked around a central screw hole, but an initial check on the copper side of the board showed that this damage didn’t extend through the metal. However, after reproducing the problem and finding it isolated to the 5V and 12V rails, I flipped the board over and found that the crack ran all the way to the edge of the board, severing a few traces in the process.
This was fixed by removing (scraping) soldermask as needed and soldering salvaged resistor leads (from here, specifically) across the gaps. This, plus the extra solder surrounding the lead, should make for a nicely permanent fix. The fixed PCB can be seen here, from a different angle than the above image. After the fix was put in place flexing the PCB on the bench nor pressing / tapping on it while installed in the housing caused the power to glitch.
