HDR FOX T2 switching off randomly

[penshaw]

whoops typo meant PSU

 

[penshaw]

I've removed the PSU board and can see no obvious problems like swollen / leaking capacitors. The board appears generally to be in good condition with no indication of overheating, residue or dry joints.
The outputs are marked G,G,+5.8,+5.8,G,G,+12,+12
Testing the outputs without any load produces erratic readings. The 5.8v outputs produce unstable readings between 3.4 and 7.8 volts. The 12v outputs produce unstable readings between 10.8 and 14.2 volts.

Should the outputs be tested with loads? If yes whats the best way to load them.

Would it be worth just replacing all the electrolytic capacitors on both the primary and secondary sides of the board.

 

[Black Hole]

Should the outputs be tested with loads?

Hard to say, but as you have unstable readings without load, the next step is to see whether the readings remain unstable when loaded.

If yes whats the best way to load them.

The obvious load is the rest of the system. Considering your reported symptom, you need to measure the supply rails while the system is working and what happens to them when it shuts down. It could be (maybe, just maybe) that the PSU is shutting down because of overload... in which case the culprit is somewhere else.

If you want to go to the trouble of setting up test loads, filament lamps are a lot cheaper than power resistors. For example: a 5W car bulb (typical interior lighting) will load a 12V supply with about 0.4A (but note that this only applies when the bulb is glowing: when cold, the filament has a much lower resistance so the load on a 5V supply by a 12V 5W bulb is more than the ~0.2A one might guess from 29 ohms at working temperature).

It's best to load both rails not just one.

Would it be worth just replacing all the electrolytic capacitors on both the primary and secondary sides of the board.

That's a hard call. Normally I would say no, because you have no confirmation that any capacitors are faulty, and (more to the point) a "dry" capacitor doesn't really explain why it shuts down.

However, in the absence of any other ideas, you might feel you have nothing to lose... but I think that's clutching at straws in the extreme.

 

[prpr]

Testing the outputs without any load produces erratic readings. The 5.8v outputs produce unstable readings between 3.4 and 7.8 volts. The 12v outputs produce unstable readings between 10.8 and 14.2 volts.

As it happens, I have my unreliable one in bits as I've been shuffling disks, so I took the opportunity to do some measurements.
Off-load gives 3.3-7.9V on the 5.8V rail and 11.3-13.9V on the 12V rail. This is with a DVM so it's tricky to see what's really going on and my 'scope is broken. Maybe I'll look at one of the other good ones later.

Should the outputs be tested with loads? If yes whats the best way to load them.

Plug the motherboard connector in!
Without the disk, I measured 5.5-5.8V and 11.7-11.9V and then, on a different range on the meter, 5.6-6.2V and 11.3-12.3V.
With the disk connected it made no appreciable difference. There were no apparent spikes as the disk spun up either.

Would it be worth just replacing all the electrolytic capacitors on both the primary and secondary sides of the board.

I probably wouldn't, certainly not the big one on the mains side anyway. Do you have any facility for measuring the capacitors?

I'd be interested to know how much current each rail supplies in normal operation, but without butchering the cable it's a bit difficult.

 

[penshaw]

I have put the PSU back in the unit and here are the PSU outputs when loaded by the motherboard. There is minimal difference between the HDD being connected or not.

HDD disconnected: 6.5v stable, 6.6v stable, 12.28v stable, 12.28v stable.

HDD connected: 6.6v stable, 6.66v stable, 12.28v stable, 12.28v stable.

>prpr I have a simple digital mutimeter but unfortunately without capacitor testing.

Tomorrow I will try to meaure to measure the change in PSU outputs as the unit does a random switch off

 

[penshaw]

Switched on again this morning but it will not fully start ! The HDD starts up but all of the front display remains unlit.
No response from either the remote or the front buttons. I've switched off/on multiple times at the rear switch but to no avail.
The PSU outputs are stable at 6.89, 6.89, 12.28 and 12.28.
So, I think I'll put this on ebay for repair or parts and buy a new PVR
I bought the unit 7 years ago at a then new price of £196 and overall it has been reliable and value for money , but I am disappointed at the complete lack of support or access to documentation from Humax when a problem arises.
I have always found the help and advice given in this forum to be very informative and useful.

 

[Black Hole]

It looks like the PSU is OK. My preference would be to acquire a second-hand HDR-FOX (better the devil you know, plus we have the CF) and hang on to this one for spares for the working one.

Failing that, I'm sure there are people here happy to take it for spares - including me.