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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).
 
Hi, I ended up taking the unit to a local repair shop as I didn't feel confident removing the old capacitor. They changed the capacitor for me. I've just got home and the unit starts up fine but it doesn't recognise any data storage! Any idea what they might have done? I can't hear the disk start up at all.
 
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Put it in the wrong way round; blown something else up; not reconnected the disk.
You need to provide detailed, in focus, pictures.
 
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(See an earlier post in this thread showing the schematic for this circuit)

I think I can see what they have done comparing to my Hummy. When they removed the old cap they have moved the cap up the board and reattached it to the ground plane which is 0 (zero) volts and not where the cap should be attached (to the now missing pad). They have then attached a wire link from the same 0V to the top of the small 1K resistor which goes to the Collector of the small transistor to the side of it. The 12V incoming line should have not been affected unless something is going on under the cap but having ripped off the top pad they may also have damaged the trace leading to the 1K resistor. The top of that 1K resistor also goes to the Gate of the FET which is now connected to 0V so will not conduct so you have no 12V going to the HDD - but can't guarantee they haven't also fried the FET during their work. (Before and after pics attached trying to show this.)Before.jpgAfter.jpg
The only answer is to remove the cap and link and recreate the circut properly. I'm not sure I would trust your local repair shop to do this. I assume they don't normally do micro soldering?
 
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P.S. As the steady state for the circuit is for the transistor to be turned off, if you cut the link as a temporary test that should restore the "HDD 12V supply" if the FET is OK as its Gate will no longer be grounded. (Cut the wire link with the power off to avoid shorting anything)
 
Thank you @John1212 for your input. I fed all this back when I took it to the repair centre. They had another go and spent quite a lot of time on it but unfortunately I'm in the same position, it starts up but there's no power to the disk. And I'm not that electronic savvy. They emailed with the following

When you came in you asked us to replace the capacitor as you requested. You showed us pictures and instructions for the repair. We explained at the time it was not a good idea to replace a 4.7uf electrolytic capacitor that is 25v on this machine. The original is rated at 35V 4.7uf and a smd Capacitor. You agreed for us to put our part on. You should not change a smd capacitor for a through hole version. You should replace like for like. You can put a higher voltage on it but not lower. Capacitance should be the same, not lower or within 10% higher.
On removing the capacitor, the pad under the -VE came off. This does happen with weak pads. We then put a link wire from the 1k resistor to the -VE side of the capacitor. We could only see one broken track. We did this as there are no schematics available. We did not put it on the 0v Earth plane. We then turned it on and it powered up. We did not test the signal or the hard drive as you said you had replaced the hard drive. With no remote we could not test further. You were then contacted and you came and collected.
We then got an email after hours and we said please bring it back in with the remote and we will see. You came in the next day and said you had been on the hummy forum and said that we had done it wrong. Instead of saying you had an issue, and the hard drive was not working. We were quite happy to have a look and see from you drawing what was wrong. We said we would get it on the bench as soon as we can as we were very busy and in the middle of some jobs. We only got to it after we closed on Wednesday 19th March. I had a read of the forum, all 15 pages to understand what was going on. You said “Hi, I ended up taking the unit to a local repair shop as I didn't feel confident removing the old capacitor. They changed the capacitor for me. I've just got home and the unit starts up fine but it doesn't recognise any data storage! Any idea what they might have done? I can't hear the disk start up at all.”. And another comment was “The only answer is to remove the cap and link and recreate the circut properly. I'm not sure I would trust your local repair shop to do this. I assume they don't normally do micro soldering?” Looking at all the repair images, we were shocked to see how bad some of these are. These people are hobbyists and not professionals. We have over 70 Years experience repairing electronics and other devices. We certainly do micro soldering, and clearly they do not.
We opened it up again and followed the details on the forum. We then connected a link wire from the 1k Resistor to the -VE pad on the capacitor to the 10k Resistor. We tested it and made sure we had connectivity. We then tested the machine and had the same issues.
Thursday is our day off and we came in to have another look at it. We got a donor Humax Fox T2 from our humax dealer for testing. We tested their box and all was working. We then took readings from the machine and compared them. We detected that we had 12v to both legs of the mosfet when the machine was in standby. When we turned it on, Blue light, still had 12v to both legs. We then thought the mosfet was at fault. We then switched mosfets between both machines and made no difference. Your mosfet on the donor machine worked ok. So we changed over the u24 and u551 to see if it would make any difference and it did not. We tested all around the area and got the same results as the donor machine. We have put all your components back onto your machine and tested again and still no success. We tested your hard drive and found it is coming to the end of life. But testing the donor hard drive on your machine had the same results.
We now deem this a mainboard fault. This is not caused by any work we have carried out. We now class this as an uneconomical repair due to second hand machines selling online for £40 upwards.
We have included pictures to show what we have done.

Not sure what to do now. Does anyone have one for sale? I have a disk full of recordings, if I put the disk in another hummy will I be able to access the recordings?
 
Oliver said:
if I put the disk in another hummy will I be able to access the recordings?
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If they are decrypted then yes. If not then no, without further action. You can set the key on any new box to match the one on the old one. Or they can be decrypted externally. Make sure you have a note of the MAC address and the serial number - without these you will never be able to access them if they are still encrypted.
 
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