Originally Posted by IRJ
OK I have a model # TCD 652160
I have opened the casing and inspected the capacitors, but find no signs of any bulging. This is actually quite disappointing as it leaves me directionless. Unless of course I try a Hail Mary and anyways replace ALL the capacitors even though they look good. Usually I like to leave well alone. So now I am stymied as to what to do next!
Well, you can get a voltmeter and check the plug from the power supply onto the motherboard.
The way you do it is to hook the meter's negative lead (should be black) to the chassis on the side away from the power supply--either alligator clip it or friction fit it into a hole or cutout.
Then set the meter for DC, range 0-20 V (or 25 or 50, depending on what the meter's options are), and stick the positive probe (should be the red wire coming from the meter) down into the various holes in the plug on the motherboard with all the wires that go back to the power supply.
You don't need to test the black wires, those are DC ground, just like the chassis. The yellow is supposed to be +12V, the red +5V, and the orange +3.3V., and all the wires that are the same color are in parallel with each other, so measuring one red one, for example, is measuring all of them.
Try it with the combo data/power cable plugged into the back of the hard drive, and with it unplugged, to see if there's much variation in the voltage regulation when the load changes.
You're very unlikely to get exactly 12 and exactly 5 and exactly 3.3, but it should be close, like within a half a Volt or so above or below, and it shouldn't be very different with or without the hard drive drawing power.
And remember the first rule of opening up a TiVo
ALWAYS KNOW WHERE BOTH ENDS OF THE POWER CORD ARE AT ALL TIMES!
There's exposed high voltage on the power supply itself, so keep your hands no nearer to it than the plug on the motherboard, and it's best if you hold the red probe with one hand and keep the other hand in your pocket.
As for the idea of replacing all of the caps (You don't need to worry about the very biggest one that's rated at 200V, it doesn't work very hard, and the little ones are probably fine too, it's just the medium sized ones clustered around the heat sinks where there's likely to be one or more bad ones sooner or later), you can think of it as doing it now and saving yourself the trouble of doing it later.
And while you have the TiVo open anyway, you can take the hard drive bracket out with the drive on it, hook the drive to a PC, and boot the PC with a cd with the drive maker's diagnostic software on it and run the long test on the drive to see if it's likely to give trouble anytime soon.