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Start Up Fails When HDD Connected

Black Hole said:
You would never fit a non-electrolytic 4μ7 cap on the board!
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Actually you could using modern MCC capacitors. You can certainly get 4.7uF, but I'm not sure what voltage they go up to. But my memories of the photos of what needs changing I would expect to get one in there.

But personally I would use a teardrop tantalum one, unless the circuit designer is relying on some leakage through the capacitor.
 
Black Hole said:
25V or 50V.

They top out at 10μF, but I didn't realise they went that far up in such small packages.
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Yeah, the cellphone market (along with other miniature devices) has really pushed the sizing. You do have to be careful though, as the capacitance value derates the closer you get to maximum operating voltage. By the time max V is reached you can be at 1/3 to 1/4 rated C, especially for low voltage ones, like below 10V. Standard thing to do is use a capacitor that has a massively greater V rating than the circuit seems to require, or make allowances for the derating.

The other problem (just mention it to an audiophobe) is that they are microphonic, in standard ceramic/crystal microphone style, and/or because of the capacitance change with voltage you get 'modulation' effects when using them as coupling capacitors.
 
Hi, all I found this thread looking to cure my FOX T2 after it hit the constant starting issue, I have no Electronics background {mech engineer} but had determined disconnecting the drive allowed the box to at least operate as a tuner, so was considering changing the drive as assumed at that point it was at fault, started searching to see if anyone had determined a good replacement....
Having ploughed through the thread I thought I was not going to able to be understand how to fix the pvr , but as I can use a soldering Iron, thought I can manage that.

So acquired the RS part 571808 and have today undertaken the replacement process and I have a working unit again.:)

Many thanks to all those who analysed the underlying problem and letting us all know how to effect the fix.
 
Another grateful Hummy owner here that has replaced the dodgy capacitor after suffering the same constant cycling issue on start-up. Not pretty but it's been running fine for the past 3 weeks now. Very grateful to all concerned.
Screenshot 2025-02-07 152548.png
 
Sourdough said:
Another grateful Hummy owner here that has replaced the dodgy capacitor after suffering the same constant cycling issue on start-up. Not pretty but it's been running fine for the past 3 weeks now. Very grateful to all concerned.
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Our unit is still going strong more than three years after this repair, so certainly worth doing.
 
Sourdough said:
Another grateful Hummy owner here that has replaced the dodgy capacitor after suffering the same constant cycling issue on start-up. Not pretty but it's been running fine for the past 3 weeks now. Very grateful to all concerned.
View attachment 7358
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Eek, I wouldn't be happy with the length of those leads. The way they are bent leaves them very close to contacting the cother components on the PCB.

As a bodge to verify that it solves the problem is one thing, but I would want to clean it up somewhat to make it safer from vibration causing a later problem.
 
The leads are stiff enough and the component light enough there is little risk of that, and I see nothing close enough to worry about, and anyway – what vibration?? Ye panics too much. I strongly advise DO NOT REWORK, there is greater risk of destroying the PCB than risk of shorting. Don't even try bending the leads more (or less). Ugly it might be, but nobody's going to see it.

The one thing I suggest is to stabilise the capacitor exactly where it is with a hot glue gun, in case of shock/drop.
 
Yet another satisfied customer! My original HDR started randomly rebooting at the same point. Initially I was confused as the HDD worked in a caddy, the HDR worked fine with a 500G SSD, and scheduled recordings were fine from standby once It decided to boot. Then I found this thread. I was reluctant to try the fix on this machine first, so I bought a faulty one on ebay for £30 which was described as having a reboot loop. Removing the disk allowed it to boot so I went up to my stockroom (loft) and retrieved a couple of 4.7u 25v tantalum beads, I used flush side cutters to nip off the old capacitor, cleaned it all up and soldered in the new one. Bingo - £30 spent, and a fully working PVR. Repeated the process on my original and all working again. Many thanks to all for the info. in this thread. I now have three working HDRs and one HD-Fox. Couldn't live without them (or the custom firmware).
 
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