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markybhoy
Posted: Thu Jul 10, 2008 11:48 am Reply with quote
Joined: 01 Oct 2006 Posts: 9 Location: Greenock, Scotland
Like a lot of people I have mistakenly left my topfield on since Christmas time almost contantly with timeshift on (so its basically been accessing the drive constantly for 7months). At Christmas time I upgraded my 250GB Spinpoint drive with the 500gb WD5000AVJB after much deliberation but after reading the forum decided against putting in a case mounted fan.
On Sunday night my toppy froze when I was scanning through a live tv programme that I had missed the start of . When I turned on again it had a black screen and then I switched off and on and the original menu came up with the recording options greyed out and the box basically working only as a standard freeview box.
I remove the hard drive and put it in to my USB caddy and tried to access the drive using altair which wasn?t visible and then tried using TPHDRW which was able to access my drive but told me all my files where the wrong size.
I?ve been following the forum and las night tested the voltage output and found that when I turned it on it had readings of 15.21v and 4.65v. when left on for 15-20mins the voltages dropped steadily to 10.98 and 4.52. I?ve spoken to a friend who has suggested that this is quite dangerous and that I should switch the box off until it can be repaired.
I put an old 40gb drive in which I formatted and is working fine (although I have now switched off the timeshift feature and am leaving it on Standby when not used).
My box was purchased around March 2006 and worked fine until about 6 weeks ago when I started getting the odd bad recording then it would freeze when doing a time shift.
I have a friend who is handy with a soldering iron who could replace the capacitors but I?m worried about the dropping voltage as I haven?t seen anyone else mention this. Would replacing the capacitors fix this. I?ve checked the existing caps and they are the Sam Young ones which I?m sure I read somewhere on the forum are crap. Any help would be most appreciated.

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MikeyP
Posted: Thu Jul 10, 2008 11:52 am Reply with quote
Frequent contributor Joined: 17 Jan 2006 Posts: 4816
it's not exactly dangerous, but it could tip a piece of hardware/IC over permanently if used like this for a long time.

So yes best not to use it 'til it's sorted to preserve it.

the six capacitor replacement WILL bring all the volts back up to normal Very Happy

don't use cheap ones, see my sig for some properjobs I can supply if you get stuck


Last edited by MikeyP on Thu Jul 10, 2008 12:06 pm; edited 1 time in total

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markybhoy
Posted: Thu Jul 10, 2008 11:58 am Reply with quote
Joined: 01 Oct 2006 Posts: 9 Location: Greenock, Scotland
Mikey, in your experience is the drive (which is practically new) likely to be trashed or will a format and reinstall sort it out. (wont hold you to it). Also would you recommend the additional fan.

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MikeyP
Posted: Thu Jul 10, 2008 12:03 pm Reply with quote
Frequent contributor Joined: 17 Jan 2006 Posts: 4816
depends if it was writing to it when the supplies are below par (in your case the 5V is below spec as soon as you power it up)

and if it was it might muck up the FAT or just one or two files

So I would wait and see , it's doubtful it's hardware fubared , you will almost certainly just fix the PSU and be back on your way (if you haven't struggled with the poor supply for weeks)

I don't recommend the fan (especially across the 5v and 12V), it's just my opinion. t's your choice though

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TopTapper
Posted: Sun Jul 13, 2008 6:55 pm Reply with quote
Frequent contributor Joined: 29 Jan 2006 Posts: 150 Location: London, UK
MikeyP wrote:
Anyway your fixed and refurbed (caps) PSU is on it's way back as we speak today Very Happy

First up, many thanks to MikeyP for the fix, great service and advice. Not only is my Toppy better than new but I'm still alive. Hell, it's almost worth that forum donation! Wink Thanks also to jumbo and all other forum contributors - assistance and advice much appreciated.

I've been trying to put together a safety guide for newbies. It could be factually inaccurate and incomplete so review would be appreciated. Ideally, there would be a "Hardware fixes & modding" forum where the (sanitised) article could be stickied for prominence. Anyway, here's the current blurb...

Toppy PSU failures appear fairly regularly on the forums. There are also some great guides for would-be fixers and hardware modders. If you're a new to electronics like me you need to be aware of the dangers before going into DIY mode. The novice may be 'surprised' by two potential killers:

  • The main heatsink is particularly dangerous. It doesn't just conduct heat - it's live and can burn and blast your socks off (or far worse) with up to 350v. It's also fairly prominent, set for unintentional contact. Cover it with a small jiffy bag to be safe. See how an Australian Toppy owner nearly died, trashed his Toppy and ended up selling his TV.



  • Residual charge can linger for a long time after the Toppy is powered down. In my case, component R2 failed and the board held potentially lethal charge for at least a day. Normally, the charge dissipates quite quickly (within 30 seconds) but you need to test voltages to know whether you should attempt a DIY fix.

Testing the PSU board
The DC outputs pose the least danger - that's the motherboard and drive power feeds. At this point we should be seeing relatively low DC voltages. Use the white blocks, bottom-right of the board or the motherboard input block and drive molex connector to test your voltages. In some cases it may be worth testing mains AC voltages at the fuse top-left of board (see below). Unless you really know what you're doing don't attempt to test voltages anywhere else on the PSU board.

Measuring voltages
You'll need a basic multimeter which you can pick up from the likes of Maplin. To test the PSU outputs, set the meter to measure DC volts. If it has manually selected ranges, start with the highest; if you get a reading move down to the lowest range that matches the reading for a more accurate result.

Place the negative probe (black) in the output block's first output where the black wire exits. It's easier to make contact with the metal than it looks - don't ram the probe spike in. Next, place the positive probe (red) against the block's second output where the first white wire exits. Then work your way up with the positive probe, measuring each of the outputs. See this guide http://members.optusnet.com.au/toppytools/pwrcircuit.html for images and instructions.

If you get no readings, check that the probe has been making contact by switching to the PSU's feed to the motherboard. Either work on top of the block or unplug it and insert the probes in the appropriate slots. You can post your results to the forum for a sanity check and diagnosis (not psychological). However, if you still get no readings, be particularly careful, the board could be in a dangerous state. It's time to test the PSU board's fuse.

The PSU fuse
Change the multimeter to measure AC voltage - again start with the highest range - and carefully place the probes on either side of the fuse while it's in place.
  • If you get a very low reading (say, 0.1v) then the fuse is good, danger is high and it's DIY repair game-over.
  • If you see a high reading (240v) then the fuse has blown and needs replacing. The new fuse should match the exact spec of the old - a 2A 20mm time glass delay (e.g., Maplin). Power off and be very careful not to touch any of the neighbouring components when you change the fuse. If the new fuse blows straight away (240v again) then it's too dangerous to attempt DIY repair.
  • If you get no reading, check the board's mains supply. Still using AC volts on the highest range, unplug the grey connector top-left of board and insert a probe inside each contact. If you still don't get a reading, check the wall socket with another appliance and double-check the plug fuse. If both work then the multimeter or plug housing might have failed.

If you reach game-over you need a new PSU board (hopefully, with the same connectors as your current motherboard) or help from a professional. If you take the PSU board out, handle with extreme care.

EDITs:
- added post result to forum & mains input check
- corrected fuse type


Last edited by TopTapper on Tue Jul 15, 2008 8:45 am; edited 2 times in total
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javamark
Posted: Sun Jul 13, 2008 8:34 pm Reply with quote
Joined: 13 Jul 2008 Posts: 1
For about two years I've been removing / swaping out the hard-disk whilst the unit was on standby !!!

Well that was until today. I can see why it tripped the main house fuse and nuked the PSU. In my case the metal frame holding the hdd must have shorted with that evil heat sink ! ! ! !

So 1 toppy down - and looking for a new PSU? Because the old one is toast.

Still at least I live to tell the tale.

In short don't be lazy - always unplug!

What the best way to get hold of a PSU, and how much will it cost ?

Cheere all!

Mark
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simonc
Posted: Sun Jul 13, 2008 9:26 pm Reply with quote
Frequent contributor Joined: 12 Apr 2005 Posts: 5617 Location: Cheltenham
Turbosat. 45+10 p&p
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Andy K
Posted: Sun Jul 13, 2008 9:48 pm Reply with quote
Frequent contributor Joined: 14 Jun 2005 Posts: 3499 Location: Owner of 3 Topfields
javamark wrote:
For about two years I've been removing / swaping out the hard-disk whilst the unit was on standby !!!



Are you mad !!! Shocked
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jumbo
Posted: Mon Jul 14, 2008 12:05 am Reply with quote
Frequent contributor Joined: 11 Apr 2005 Posts: 4733
javamark wrote:
So 1 toppy down - and looking for a new PSU? Because the old one is toast.
Given your confession, I shouldn't say this but I doubt that you have truly nuked the PSU! The fuse will have definitely tripped (as designed) and you may even have killed a couple of other PSU components but all may not be lost. On the down side you may have nuked the hard drive and/or motherboard. If I were you I'd go down the MikeyP route (if he's up for it get him to repair/MOT your PSU) before opting for the more expensive new part from Turbosat.

PS Never attempt anything potentially dangerous on the 13th Wink
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MikeyP
Posted: Mon Jul 14, 2008 8:12 am Reply with quote
Frequent contributor Joined: 17 Jan 2006 Posts: 4816
@Toptapper - Bravo - Very clear Cool and despite your own admission of being new to electronics, you seem to have picked up on all the salient points better than I could have put myself.
I hate to think what would happen to the unwary of the PSU reservoir charge. (especially when in a particular fault mode like yours)

One thing that could be added as the only other mains side check is to confirm the board is getting 240v, by sticking the two probes in the grey connector in the rear left corner where the mains enters. this and the check across the fuse will confirm the mains side has mains.



As long as Javamak hasn't killed the chopper IC (I can't source this anywhere so far) , the PSU can be sorted easily. Just PM me if you need to do this.

Quote:
For about two years I've been removing / swaping out the hard-disk whilst the unit was on standby


Foolish - with a capital F Shocked Exclamation

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jumbo
Posted: Mon Jul 14, 2008 12:59 pm Reply with quote
Frequent contributor Joined: 11 Apr 2005 Posts: 4733
MikeyP wrote:
As long as Javamak hasn't killed the chopper IC (I can't source this anywhere so far)

http://www.darisusgmbh.de seems to stock some peculiar and difficult to find electronics (such as used in the Toppy) with reasonable shipping costs.
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TopTapper
Posted: Tue Jul 15, 2008 7:14 am Reply with quote
Frequent contributor Joined: 29 Jan 2006 Posts: 150 Location: London, UK
MikeyP wrote:
@Toptapper - Bravo - Very clear Cool

Great, thanks.

MikeyP wrote:
and despite your own admission of being new to electronics,

You say that like it's a bad thing. Perhaps I confessed too readily. Wink

MikeyP wrote:
One thing that could be added as the only other mains side check is to confirm the board is getting 240v

Good idea - I'll update now. Cheers.
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MikeyP
Posted: Tue Jul 15, 2008 8:20 am Reply with quote
Frequent contributor Joined: 17 Jan 2006 Posts: 4816
one more update Smile

Quote:
PSU quickblow fuse


the correct fuse is a 2AT fuse 20mm(antisurge, not quickblow) Exclamation
Very Happy

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TopTapper
Posted: Tue Jul 15, 2008 8:38 am Reply with quote
Frequent contributor Joined: 29 Jan 2006 Posts: 150 Location: London, UK
MikeyP wrote:
the correct fuse is a 2AT fuse 20mm(antisurge, not quickblow) Exclamation


Thanks! Don't know how I got there - jumbo even pointed me at the right type earlier in the thread.
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MikeyP
Posted: Tue Jul 15, 2008 8:49 am Reply with quote
Frequent contributor Joined: 17 Jan 2006 Posts: 4816
jumbo wrote:
MikeyP wrote:
As long as Javamak hasn't killed the chopper IC (I can't source this anywhere so far)

http://www.darisusgmbh.de seems to stock some peculiar and difficult to find electronics (such as used in the Toppy) with reasonable shipping costs.


they do have a version of the IC Very Happy , but it's not the exact item Crying or Very sad , there is a suffix to the part that I have been too lazy to look up yet Rolling Eyes

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