Denver DAB-43C PLUS radio teardown
This will be a simple, non-thorough teardown of a DENVER DAB-43C PLUS DAB/digital radio (with FM). For my own interest, I wanted to see how much design work is put in the product by the final manufacturer (in this case, DENVER). I know of some DAB modules and integrated circuits, like the Atmel DAB-On-Chip ATR2740, and are always interested to see what other solutions are used in the most lowest cost consumer products. My intention is to, some time, add DAB functionality to an old FM/AM radio.
4 screws must be removed from the back
Pry the cover open from the bottom, it's hinged on the top
In total there are 4 screws to remove, one in each corner on the back of the radio. Start prying from the bottom on the front cover because the cover is hooked to two fastener clips on the top.
If you don’t have a nylon tool for opening cases and are afraid to scratch your product, just pry on the underside of the radio so any possible scratches won’t be visible when you’re done.
The inside reveals a very modular design, as expected. The main PCB has a standard 0.1″ header pin footprint for mounting a ready-made DAB module from Quantek, model Q7+. As stated by the manufacturer, the module is delivered pre-programmed to it’s costumers wish, so no programming for the LCD controller or switchboard is necessary. That must make it a breeze to implement.
Main circuit board
Overview of the insides
Quantek Q7+ DAB/Dab+/FM module
All additional circuitry on the main board are power conditioning, audio amplifiers for headphones (TDA2822M) and speaker (TEA2025B) and connectors for connection to the outside world.
Roughly drawn block diagram of the product
External PCBs include LCD screen module (looks to be the very standard one popular in DIY builds, so should be easy to change if you want a different colored one)
LCD module
Unpopulated diode?
Line out connector labeling
Lots of glued down components means the manufacturer has put some effort into making the product sturdy, but it also makes for some messy visuals when inspecting if it’s done in a hurry, like here. There’s super glue all over everything, but I guess it doesn’t really matter.
Since all components are trough-hole, and not not all solder joints are uniform in size, it’s fair to expect this product is hand soldered and assembled.
The designer has conveniently labeled all inputs and outputs that goes to the line in/out and power input.
| GND | Ground | |
| DAB_L | Antenna | |
| DAB_R | Antenna | |
| R_IN | Line in Right channel | |
| L_IN | Line in Left channel | |
| P_SW | Power switch | |
| R_OUT | Headphones line out Right | |
| L_OUT | Headphones line out Left | |
| GND | Ground | |
| VCC | +6V |
A couple of very easy to spot design errors caught my eye. The first one being the LCD ribbon cable connector is rotated 180 degrees compared to the LCD position. This causes the cable to shorten a bit, and the tension from the left most wire actually pulls the connector outwards.
LCD connector
The second error looks a bit funny. It’s a big electrolytic decoupling capacitor on the supply voltage pin of the TDA2822M, the audio amplifier chip for the headphones. I can image that cap must be a real pain to solder, so I hope that poor technician built himself a simple rig of some sort for the job. Also there’s a single wire from the ground lead on the cap to a solder pad on the DAB module where it’s supposed to sit a screw. Who knows if the screw was missing first, or if they removed the screw so they could attach the wire? It could be fun to have a look at the audio output with and without the cap. maybe later. My guess is that a less cheap AC/DC adapter would also do the trick.
Big capacitor bodged on by hand
UPDATE
On request, I’ll add the key mapping with schematic and inputs for my radio. I had some trouble tracing the input lines, also as requested, as it only seemed to go straight trough the headphone amplifier chip and out “line out”.
Keypad drawing
Keypad schematic
New blog post: DAB radio teardown. Lots of pictures and a few funny design errors http://t.co/BGqEFLqi
Wow, looks like a real mess inside, at least the caps are anyways, they could’ve used some hot glue or something. How much are those units?
I haven’t bothered asking :) They have used lots of hot glue, only not where they should have.
Hi Henrik,
first of all, nice Pics!
As I lately had to open my DAB Radio (HDigit Fii-Posh) (it was broken) I also found the Q7+ Module. Found your page via google and also Quantek’s main page with the rather poor dokumentation. However the little note of the Aux-Input and also the Ipod thing got my focus. I dont really think that they Programm each Module seperately, hence it should be possible to connect an Ipod to the module. Therefore, for a first test it would be glad if you could send me a more precise schematic of the Line in path to the module and also the Keypad schematic with the row and col info, so that I can try to rebuild your keypad on my radio, to see if the Line In works on my radio.
Thanks and Greetings from Switzerland
Roman
Hi Roman,
Glad to see you have taken interest in my post. About programming the module separately, I guess some functionality will always be be on the module, like hardware lines (in/out), but roughly 50 pins to support all types of LCDs, keypads and iPod functionality i think is optimistic.
Sure, I will update the post soon with more info on the keypad and audio lines. I’ll send you an email. It’s sad I don’t know Swiss, as your blog post seems very interesting and google translate is a bi*** to read…
Hi Henrik,
well I thought that all the electrical engineers are optimists ;-) ? Well to be honest, I just like to try it ;-). Just wondering how they got all the stuff out of the iPod, as I made an FM-Tranmitter (more Power that the cheap ones you can buy ;-) and further supporting RDS) for the iPod. And maybe I I get some more info about the iPod Accessory Protocol that the other folks.
Therefore looking forward to hearing from you!
Well I know I really have to switch my blog to english but I guess you know the problem with the time ;-).
Greetings
Roman
That’s a real project you’ve got ahead of you at least! The post is now updated with pictures. I will take a closer look at the line-in traces some time soon.
I guess you will be notified by mail now.