Panasonic720-Installing a New Internal HDD- How to do it


Active Member
I have read much on this and other forums re the impossibility of replacing the internal HDD in the 720 without getting either a genuine spare part HDD or an impossible to obtain “Service Disc” to “format” the HDD. It’s reported that there has to be a “special partition” on the HDD that the Service Disk can create. I have even read that this special partition contains the firmware for the 720 and that the partition is 100Mb in size.

Well none of the above is true! It is easy to replace the HDD and it only requires less than 20Kb of data to be copied to it first. Most of this data is for the DRM associated with HD recordings.

I have not tried to install a larger HDD, 1Tb is more than enough for me! I fitted a WD Green AV 1TB HDD, very cheap at the moment and available for £34.

If there is any interest in obtaining the data and how it can easily be copied onto a HDD do post a reply and I will attach a file with the data and construct a method statement on how to copy it to a HDD.


Active Member
Hi jonoro, well it looks like I am the only person interested in this?! I'm somewhat surprised. Even though all recorder HDDs will fail at some point.


There is not really any need to upgrade the hard drives in the modern machines as they support up to 8 external hard drive to expand capacity and / or backup titles.


Active Member
I agree, it would be useful to have the option to do this in the event of a HDD failure, that can pretty much happen any time these days...


Active Member
Sorry for the delay, been a bit busy.
I guess that a written procedure on how to write the data to a HDD would be useful, as you can't just copy the data due to there being no partitions.
I'll construct the procedure I used over the weekend and post it along with the data required.
I assume that most would want a windows procedure rather than a Linux one?


Active Member
Attached are two files:
Firstly a "Panny720HDD.rar", a compressed data file of all the data that needs to be written to the HDD.
Secondly "Procedure to Copy Required Panny720 Data to a HDD Under Windows-v1.2.pdf".
I have used a free Hex Editor "HxD" in the procedure, this is one of the few Hex Editors I know of which will "mount" non-partitioned disks.

The data can also be copied to a HDD using Linux and "dd" but I have not documented this.

Good luck!

Oh dear just discovered that AVForums does not allow rar files to be uploaded, so I have zipped the rar file to overcome this restriction. So "Panny720HDD.rar" is NOT ATTACHED, but "" (which is a zip of the rar) IS ATTACHED


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  • Procedure to Copy Required Panny 720 Data to a HDD under Windows-v1.2.pdf
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Active Member
I think also that this could be definitely cost effective and convenient for replacing a failed Hdd.
Pity about losing recordings from the original drive though and more than likely the "up to 8" backed up on USB drives for all the DRR reasons as I understand it?


Active Member
It may be possible to spoof the HDD id that the Panny looks at when it's looking to see if the HDD has been changed but it's a lot of messing with the HDD and different manufacturer's implement the id in different ways.
I know that when registering the id the Panny only changes about 5 bytes of data on the disk, apart from clearing the pointers to the recordings. I did try changing those 5 or so bytes on a HDD to what they were after registration/formatting but the Panny still insisted on formatting.


Active Member
Thumbs up to jonoro! I successfully replaced the HDD in my Panasonic BWT740 with a Western Digital WD10EURX from CCL (a cheaper "pulled" one from equipment wiped etc with 1 year warranty). I did get a bit confused with the new HDD as it had a wiped partition which was recognised by Windows. I don't know whether this would have made any difference but I did delete it with Acronis Disk Director before loading the extra data you provided. I was going to try to un-initiate it, but there was no need.

Time will tell whether the intermittent freezes have gone.
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Active Member
Thanks - you have reminded me that I already have WD Data Lifeguard Diagnostic installed and forgotten about the zero writing facility. Maybe the Panasonic sorted this out when getting through the formatting stage or do you think that there is extra junk there that shouldn't be?


Active Member
I don't think the left over junk will cause any problems at all, after all its a HDD not a SSD, so no need to clear out nonindexed junk.
It would only be if you wanted to take the HDD out and extract the recordings when the junk would make following the recording chains muchmore difficult.

Hope the stuttering stops, I had similar on a Sky box along time ago and a new HDD fixed it. Much eadier with Sky to change the HDD!


Active Member
Well unfortunately the problem recurred. At least I proved the HDD can be changed. Can't see that it's worth the disruption taking it for repair when the fault is so unpredictable.

Next course of action is to check my aerial - the worst there can be but has worked perfectly for a number of years. There were no problems with my previous BW780.

The aerial is a loft mount X Beam with variable gain 1 - 25 dB screened amplifier feeding 2 other TV's via splitters and satellite grade cable. Not too far from Waltham.
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Active Member
In my experience the symptoms of a bad aerial and a bad hdd differ.
When the aerial s/n or ber gets too bad the picture starts to get frozen and distorted blocks before it gets so bad that the whole picture freezes.
With a failing hdd you dont get the blocks, its the whole picture that freezes.

A real clue would be if you get the failure when viewing a recording, does it always fail at same point in that recording?
Do you ever see bad pictures when viewing the live output of the dvr?

I had a bwt700 once that had v poor aerial performance, turned out it was the tuner module, water had run down inside the coax and the inside of the tuner can was rusty, I could see the rust if I looked atthevaerial socket.

Otherwise favourite would be the power supply,. It's 12 volts that powers the whole unit, could be a little flaky and the extra current drawn during recording tips it over the edge.
If you feel confident you could check its voltage?


Active Member
Thanks jonoro. You may be aware that I am running almost the same commentary with Gavtech on the Panasonic DMR-BWT740 Bluray Recorder Master Thread. At the moment he has put forward a check on the effect of HDMI interference. I have found and replaced 2 poor quality coax leads with double screened ones and will test this first.

The problem has been total picture / sound freeze for no more than a couple of seconds occurring randomly and very infrequently. Anyway I have probably proved it's not the HDD.

I have seen water damage more than a couple of times in other people's systems with old outside aerials, bad connection covers and air cored polythene insulation around the cable central conductor.

Your pointer to the BWT's 12v PSU is well within my capabilities and if I continue to get this problem, I will test it. When I replaced the HDD, I reworked the soldering on some of the PSU's connections as failures can eventually often occur there.

Years ago I worked on UPS up to 30KVA which had hazards working 3 Phase rectified 440v which was fed into transistorised inverters synched to give 3 phase 440v out - the DC side backed up with a load of batteries in series. So there were hair raising occasions when there were nasty and dangerous failures. And years before that what about the old xmas tree valve tellies with 2 core mains feed one side to chassis! I don't go as far back as tellies with EHT derived from a mains transformer. How times have changed and I am lucky to be still alive.
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Active Member
Hi xyzbird, thanks for the update.
I had not realised that there was a parallel thread, almost like a parallel universe!
I have once had an hdmi lead problem, led to loss of many channels, just moving the hdmi lead made significant changes to the ber but no change to sig strength.
Guess you could eliminate this possibility by temporarily using scart or cvbs to connect, but make sure youremove the hdmi lead!
So you never have seen frozen pixel blocks, only whole un blocky picture freezes?
Again have you ever had the freezing on live tv through the Panny?

Doy ou have circuit of the psu, if not I can post it?

UPSs, 30kva - small fry!! How about the Anton Pillar 100 and 200kva units? Now when they go wrong, it's a very big bang!

You remind me of the tvs with flyback eht systems and valve eht rectifiers. And yes the mains straight to the chassis, amazing what was got away with then.


Unfortunately these machines have no analogue video outputs so it is not possible to test for HDMI interference by trying that diagnostic procedure ( of using scart instead of HDMI)

The degree of HDMI interference is dependent on the nature of the content going across the HDMI interface... It is made worse by 'busy pictures' i.e. high definition fast moving content, which results in critical frequencies emanating from the cable interfering with the incoming UHF signal.
When the problem is slight, the effects can be just as described - very occasional wipeouts of the signal.
When worse it can knock out a whole multiplex and when truly bad it can knock out the reception of all multiplexes.

As analogue connection is not an option here, one possible way of indicating whether HDMI interference is the problem is to turn the output resolution right down.
Proof is difficult though or less clear cut when the problem is relatively rare in any case.

Hopefully you will get positive results anyway by having changed your flyleads.
You could also try other HDMI leads. Some exhibit this problem and some don't - and there seems to be no rhyme nor reason to it.
... and keep the HDMI and UHF leads as far apart as possible of course.


Active Member
It was Crockett who gave me a link to this thread.

So far the change of flyleads is holding up. There was another aspect that caused interference - my satellite receiver connected by scart to the BWT740 (very rarely used) - just in case I wanted to record something. However when it was powered up, BBC1HD on the TV (not the BWT740) was totally blanked out, no other channels affected. This does not happen now that those leads have been changed.

As I have already said, the momentary interruptions were total picture / sound freezes. No squares, missing bits or sound clicks. I have never seen a disturbance of the BWT740 on the TV directly or on the TV only.

Thanks for your offer but I was fortunate to buy a PDF of the BWT740 Service Manual off eBay albeit suffering from translation making it extremely difficult to follow service mode instructions (5+9+Red etc). I was unable to get a parts list but I don't think that would be necessary as beyond the PSU it's all SMD and specialist soldering.
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Active Member
Alas, the interruption is still there. The PSU seems OK - the 12v supply measures a constant 12.08v whereas the Manual says 12.3v. There is a 5.9v supply as well measuring 5.9v. Nothing seems amiss there irrespective of any function.

Anyway since I chucked out the Sandstrom HDMI cable and returned the standard £5.00 cable I used with the machine's predecessor, there have been no problems.


Active Member
Thanks for the feedback.
I have found Poundworld HDMI cables just as good as expensive ones, the physical routing of them is more important I think.
Also I guess the shorter the better.
Another thought, try altering the gain of your head amp, if its too high you could be getting cross mod in the tuner front end, if its too low could be makingi it prone to interference.


Active Member
If I turn the head amp gain down, the DVB Signal Condition normally showing 10 for Quality & Strength starts showing a drop on the strength, even if it's turned ever so slightly. The TV's Signal Information shows '0' bit error level for all the channels I have set up for favourites.

I used to get interference when some old banger from the 1920's went by but I recon he has got better suppression on his magneto now.

Thanks for your interest.


Novice Member
Hi all,

I’ve just found this fabulous website and thread which hopefully will solve my problem.

Up until two days ago my DMR-BWT720 was working perfectly and then all of a sudden, the picture and sound started to skip and stop, there’s no blocking effect to the picture, just freezing. Sometimes the sound stops before the picture does and sometimes visa-versa, and on the odd occasion the playback stops completely throwing me back to the live TV broadcast. When the playback stops, the clock on the unit front also stops and then it starts again as the picture starts, sometimes missing several seconds. Also the Direct Navigator is very slow to load, with the thumbnails frozen. If I watch the live TV broadcast output of the DMR-BWT720, everything is perfect.
All of this leads me to believe that the HDD is failing and me eventually finding this thread.
Having never done anything like this before, I’d like to ask a couple of questions if I may.
Firstly, is the HDD easily accessible in the machine or do you have to remove loads of other components to get to it?
And secondly, does it matter what type of replacement HDD I buy? I’ve realised from reading this thread that WD do an “AV” disk but there seem to be several different types for sale:

WD 1TB AV-GP SATA 6GB/s 3.5" 64MB Hard Drive from
WD 1TB AV-GP SATA 3Gb/s 16MB 5400RPM 2.5" Hard Drive from
WD AV-GP 1TB SATA III 3.5" Hard Drive with 64MB Cache from
WD AV 1TB 2.5" SATA Media Hard Drive SATA-II 3Gb/s Interface 5400rpm / 16MB cache from
WD AV 1TB 3.5" SATA Media Hard Drive SATA-III 6Gb/s Interface 5400rpm / 64MB cache from

Could I ask which one would be the best to buy, 2.5” or 3.5”, 16MB or 64MB cache?
Many, many thanks in advance.


Active Member
It does sound from the symptoms that the problem could be the hard drive, or could well be the power supply board.
I suggest that its worth trying the hard drive first.
The hard drive is easy to get at to replace.
Firstly top cover, 3 screws at the back, and one on each side (make sure you unplug it first!)
You will see the hard drive at the front.
You need to unclip the front panel, no screws just plastic clips - 3 on the bottom one on each side and one top centre.
It is plugged in with a ribbon cable in the centre. You can manage without unplugging this bit its easy to put back it just pushes in.
You will see the hard disk is on a mounting frame held in place with 4 screws
remove these and then prise off the two connectors, one data and one power. Don't pull them off using the cable, just prise the plug body off the hard drive.
They only go on one way round so no worries.
then remove the hard drive on its mounting frame.
Once free just unscrew the 4, I think, screws and replace the hard drive and reverse the above to reinstate.

In terms of hard drives.
it should be a 3.5"
It does not need to be a 64mb cache one or a SATA III one either, just pick the cheapest 3.5" SATA drive, any of the above drives except the 2.5" would do.

I have been trying to post a picture of the inside but it keeps failing.
I'll continue to try later today.

good luck
Any questions, just ask.


Active Member
Here's the picture!.
Seems I could post the words without being logged in! But for the picture needed to log in.


  • Panny720-TopOff.jpg
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