|
Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE! |
|
Thread Tools |
17th Jul 2016, 7:00 pm | #1 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,060
|
Matsui DA-1 DAB Tuner
These tiny DAB tuners were sold by Currys between around 2004 and 2007. I think the original selling price was around £35 and they dropped to around £18 towards the end of the run.
They were intended for use with hi-fi and audio equipment that doesn't have DAB, and are as small (15cm wide, 6.5cm high) and basic as could be made with the technology of the time. The display is a 2 x 16 characters LCD with blue LED backlight. It came with a proper remote control (not the horrible credit card sized type) and separate 6V nominal power adaptor. The aerial is jut a couple of feet of wire, permanently attached. Output is two phono sockets. And that's it. I purchased mine on eBay for £20 plus £3 postage, which is about the going rate for these now. It included the remote control and adaptor, and was sold as working - which indeed it did. However it had a tendency to freeze for no apparent reason. This would mainly happen when scanning for stations or using the remote control. A scan for stations on the wire aerial found about 20 or so, but there were some omissions - in particular Gold which is the main station I listen to (or rather have playing in the background) while working. From some Googling I discovered that this was on the Bournemouth 11B mux, along with Wave 105, Heart, BBC Solent and a couple of others. I was confused initially because I had those three, but it turned out that they are also on the South Hampshire 11C mux - which I was getting - but Gold isn't My block of flats has a full compliment of aerials - TV, FM and DAB along with satellite - on the distribution system, so my plan was to arrange a proper aerial connection to the DA-1. As an initial test I stripped the end of the aerial wire and poked it in the FM/DAB outlet. With another scan Gold and the other 11B stations appeared but they were breaking up badly with an error rate display of 70+. However it confirmed that a proper connection should help. First job, disassembly. The case is held together with two screws and several clips. When attempting to undo the screws the pillars they fix into broke away. I just removed them and decided to come back to that later if the clips alone were insufficient. The unit consists of three main parts:
Once it was apart the likely cause of the freezing was found - two swollen electrolytic capacitors on the motherboard. They were both 470uF 10V. There are four of this value in total so I decided to replace the lot. There was also some glue on the board that had gone brown, which I removed. The only other large capacitor is 2200uF 16V which looked fine. I would have replaced it for good measure, but didn't have any in stock. |
17th Jul 2016, 7:01 pm | #2 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,060
|
Re: Matsui DA-1 DAB Tuner
The aerial wire connects directly to the DAB module. There is no room in the case to fit an aerial socket so I decided to just use a flying lead. This wouldn't be able to go through the hole vacated by the original aerial wire because the voltage regulators were in the way. To avoid tight bends I decided that the left side of the case was the best place for the cable to exit, so made a suitable hole.
The cable I used is a standard aerial flylead, 0.5m long. I cut the plug off one end, threaded it through the hole, and stripped the end. The main screening in this type of cable is aluminium foil, so there were only a few strands of screen wire. I connected the inner core to the pad where the original wire aerial was previously connected, and the screen wires (sleeved) to an adjacent ground pad (verified with a meter). A cable tie around the cable by the exit hole provides some support, though I still need to handle it with care to avoid twisting. Fortunately when reassembling the case, the plastic clips were adequate, so the broken screw pillars were not an issue. |
17th Jul 2016, 7:03 pm | #3 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,060
|
Re: Matsui DA-1 DAB Tuner
Connected to the aerial outlet and another retune, and I had about 38 stations, including Gold.
Error rate is now between 0 and 5, with no audible issues. The bitrate is 128k stereo, which probably explains why this particular station sounds better than some others! Overall a straightforward repair and upgrade, but very worthwhile. |
17th Jul 2016, 7:26 pm | #5 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,736
|
Re: Matsui DA-1 DAB Tuner
Well done, Paul. Another bit of modern kit that will remain working longer than its maker anticipated! I often wonder why failed electrolytics seem to crop up so frequently in modern gear, but it could also be because much equipment is left running or on standby 24/7/365. It doesn't take many years to clock up tens of thousands of hours.
__________________
Phil Optimist [n]: One who is not in possession of the full facts |
17th Jul 2016, 7:31 pm | #6 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,060
|
Re: Matsui DA-1 DAB Tuner
About 8,700 hours per year. Life hours is based on running at the maximum temperature and will increase at lower temperatures.
Apparently these units use almost as much power on standby as they do when running. The case is tiny too, with almost no ventilation and three linear regulators squeezed in, so these capacitors right next to them are likely to be slow-roasted for years! |
17th Jul 2016, 9:00 pm | #7 |
Nonode
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 2,039
|
Re: Matsui DA-1 DAB Tuner
Interesting! - I wonder how much power is being dissipated by the regulators + heatsinks, bearing in mind the mains adaptor is rated at 6 volts?
I have three of these very capable little tuners. I bought them as remaindered stock from the local DSG Currys outlet just before it closed down. Here's some photos of the one I use for everyday audible wallpaper - usually Smooth Radio, sometimes Classic FM (... the latter requiring a rebrand in a few years time, perhaps ). [TOPICSWERVE] The second two shots show the increase in signal errors when the LED lighting is switched on in the kitchen, just the other side of the wall. I did a previous post on this issue c/w spectrum analyser photos showing the ~10dB increase in RF cr4p across the VHF-DAB band. [/TOPICSWERVE] With acknowledgements/thanks to Dr Wobble, who will recognise the loudspeaker stands; also to mark_in_manc, who will recognise the tuner-amplifier! Best wishes Guy (P.S. - sorry about the unwanted rotation of images ... )
__________________
"What a depressingly stupid machine." [Marvin: HHGTTG] |
17th Jul 2016, 9:37 pm | #8 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,060
|
Re: Matsui DA-1 DAB Tuner
I read somewhere online that the output from the adaptor is rather more than the nominal 6V, though I don't know if that was measured on load though. It is an unregulated transformer type.
The 2200uF 16V capacitor is across the DC input so they were probably expecting rather more than 6V there otherwise a 10V or even 6.3V cap would have sufficed. I didn't look at what the regulator ICs are, but if one of them is a 7805 (for 5V) the input would need to be at least 8V. The adaptor seems to get warmer than the actual unit. It may be interesting to try a switch mode one set to 6V, though it could cause the same sort of problem as your LED lighting. My kitchen LED lighting doesn't affect mine, but with an outside aerial I wouldn't expect it to. |
17th Jul 2016, 10:45 pm | #9 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
|
Re: Matsui DA-1 DAB Tuner
The supplied "6V" wall-wart produces around 10.5V off-load and around 7.5V with the 350-400mA load of the DA-1 (as you say, decreasing very little in standby!). The regulators are a LM317 for the 3.3V supply (the unheatsinked one) and two MAX-series LDO types for the 5V rails (one for display, the other for the main Frontier Silicon module). The wall-wart runs quite hot and, over the years, the plastic becomes dangerously brittle (a trait shared with older Pure radio wall-warts). At one of the Dunstable Downs rallies, someone was flogging apparently new Netgear 7.5V 1A SM wall-warts at 50p each, so I use one of these (with appropriate DC connector change), it's been in continuous service for over a year now, it runs cool with no discernible AF output noise or effect on signal strength/reception ability. I'm pretty certain that using a 6V regulated adapter would give 5V regulator headroom problems, even with the LDO types fitted.
There are two DA-1s here, one in car with a dropper resistor for 12V, the other in the house as above. After re-capping (as with many modern things, pretty much a standard mid-life overhaul!), I've been very pleased with them. The design shows its age with its relatively high power consumption but the same Frontier Silicon module features in a swathe of respected tuners with good sensitivity and sound quality- it dates from the era when DAB stations had good bit rates and was expected to produce the goods. |
17th Jul 2016, 10:52 pm | #10 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,060
|
Re: Matsui DA-1 DAB Tuner
That's interesting. I will keep a look out for a wall-wart like that.
I have just taken a close look at one of my photos (full size version) and the visible regulator on the heatsink is SPX2940U-5.0. From the datasheet here http://pdf1.alldatasheet.com/datashe...2940U-5.0.html it has a dropout of just 280mV at 1A and 400mV at 1.5A so it should be able to run OK from a 6V regulated supply. |
17th Jul 2016, 11:14 pm | #11 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
|
Re: Matsui DA-1 DAB Tuner
That's a pretty impressive spec, and considering that they'll obviously be running at well under 1A means I was being a tad pessimistic. Call me old-fashioned, but I still feel uneasy at less than (silicon junction + a bit + ripple/noise) though!
|
18th Jul 2016, 12:07 am | #12 |
Dekatron
Join Date: Jan 2006
Location: Ramsbottom (Nr Bury) Lancs or Bexhill (Nr Hastings) Sussex.
Posts: 5,814
|
Re: Matsui DA-1 DAB Tuner
A very interesting and opportune repair Paul. These are the little blighters once on sale, as you describe, that have been referred to by myself and others-most recently on the Silver Ghost "DAB signal convertor for an old AM radio" thread of June 27th [post 17]. I have not been the only one to be surprised to find that nothing like this seems to be available but I suppose that, these days, there's no perceived market. This doesn't help if you want to convert a vintage item though
Dave W |
18th Jul 2016, 12:17 am | #13 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,800
|
Re: Matsui DA-1 DAB Tuner
They often use a PNP power transistor as the series-pass devive running in common-emitter mode, so the lowest drop you can get is the device's saturation voltage and is much lower than one Vbe. The downside is that the base current goes out the reference pin, to ground. To combat this they either developed high Hfe power PNPs, or they went to integrated power MOS.
Some ultra low dropout regs are a bit iffy on stability. David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
18th Jul 2016, 7:51 am | #14 |
Nonode
Join Date: Aug 2007
Location: South Bradford, West Yorkshire, UK.
Posts: 2,571
|
Re: Matsui DA-1 DAB Tuner
I have one of these tuners and found that the performance with it's wire aerial was fine in the living room with line of sight views of the Emley Moor and Holme Moss transmitters but when moved into a room on the other side of the house the error rate varied depending on movement in the room. I dismantled it and fitted an F type connector on the back panel wired to the front end board. This is connected to the aerial distribution system in the house which also includes a DAB aerial. Now reception is rock solid.
I don't leave it powered up and only switch it on when I'm in the room and want the radio on so haven't experienced any issues with the electrolytics... yet. It did have a problem with the display having a poor viewing angle but as it's a standard type of display there is a contrast adjust pin which, from memory, has a resistor to ground. The value of this resistor sets the contrast. I had to short the pin to ground to get it to display correctly. I did try it in the car once on a journey down to Birmingham. Apart from the inconvenience of having to provide it with a 6v supply and an aerial taped to the windscreen it did what it was supposed to do. Keith |
18th Jul 2016, 8:27 am | #15 |
Dekatron
Join Date: Mar 2008
Location: Worthing, West Sussex, UK
Posts: 5,185
|
Re: Matsui DA-1 DAB Tuner
I have two of these plus the Intempo badged version, like Keith, I only power them up when in use.
In my experience, cap failure is very common in any unit left in standby mode, personally the only devices I leave running 24/7 are my Freeview and freesat PVR's. These little units perform well for what they are, mine are used mainly to re-transmit DAB to MW. I do like the idea of fitting an F connector in place of the throw-out wire. I do have an outside DAB aerial awaiting installation when I find the time! Mark |
18th Jul 2016, 10:13 am | #16 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,736
|
Re: Matsui DA-1 DAB Tuner
I was amazed to discover that the rated life of an aluminium electrolytic at its 'rated' temperature of 105 deg C can be as little as 1,000 hours. This doubles with every 10 deg reduction in temperature. So a working life of just one year in equipment running 24/7 or on standby suggests a maximum temperature of 75 deg C.
__________________
Phil Optimist [n]: One who is not in possession of the full facts |
18th Jul 2016, 10:15 am | #17 |
Nonode
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 2,039
|
Re: Matsui DA-1 DAB Tuner
Matsui DA-1 tests
"The apparatus was set up as shown" Vsupply, V.......... 'Signal error' 5.39.......... >50 (non-op.) 5.42.......... 18-20 5.43.......... 6-10 5.44.......... 4 5.45.......... 3 >5.45......... 3 Vsupply vs. Isupply during operation: 5.50-6.50V .......... 410mA Isupply transients noted when power applied (Vsupply = 5.50V) [NB - unit defaults to stand-by]: 360-430mA Isupply transients noted when 'start' commanded via remote (Vsupply = 5.50V): 360 - 450mA Isupply in stand-by thereafter: 385mA, reducing to 360mA after 30s. Best wishes Guy (IsoTech PSU appears by kind courtesy of mark_in_manc]
__________________
"What a depressingly stupid machine." [Marvin: HHGTTG] Last edited by Nymrod121; 18th Jul 2016 at 10:20 am. Reason: formatting |
18th Jul 2016, 10:25 am | #18 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,060
|
Re: Matsui DA-1 DAB Tuner
That is very useful information, thank you Guy.
I ordered a 6V regulated switch mode on Amazon yesterday evening for £9 including postage https://www.amazon.co.uk/gp/product/B00IWQZ9FK - confident that the DA-1 would be happy with 6V. Your results have confirmed that. I am currently running it from a 7.5V switch mode supply (from a Roberts DAB radio) and it works with no problems. The supply is much cooler than the original, though the DA-1 itself is around the same temperature, as expected. The 6V adaptor should reduce the dissipation on the regulators in the unit by around 600mW (400mA x 1.5V) which although not a vast reduction should help with the long-term reliability. I need to look at the display contrast on mine too. I understand it's pin 3, which would be easy to link to 0V on the underside of the motherboard. I'll do it next weekend, by which time the power adaptor should have arrived. |
18th Jul 2016, 10:39 am | #19 | |
Nonode
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 2,039
|
Re: Matsui DA-1 DAB Tuner
Quote:
5.50V x 0.36A (stand-by) => 1.98W 5.50V x 0.41A (operating) => 2.30W - and hence for other (better regulated!) power adaptors than the OEM-supplied version, I estimate: 6.00V => 2.16W 6.00V => 2.46W 7.50V => 2.7W 7.50V => 3.08W Please feel free to demolish any non-valid reasoning ... Guy
__________________
"What a depressingly stupid machine." [Marvin: HHGTTG] Last edited by Nymrod121; 18th Jul 2016 at 10:52 am. Reason: tabular consistency |
|
18th Jul 2016, 10:50 am | #20 |
Nonode
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 2,039
|
Re: Matsui DA-1 DAB Tuner
Using OEM-supplied adaptor:
V no-load .......... 11.11V V stand-by .......... 8.08V => 2.91W V operating ........ 7.81V => 3.20W Guy
__________________
"What a depressingly stupid machine." [Marvin: HHGTTG] |