I found Michael’s video extremely useful - these additional notes might help others too. My RCD-M41DAB had stopped accepting Bluetooth streams, even though the Bluetooth device connected properly. I tracked the problem to the fact that the device had overheated (June ’23 was v. warm) and the in-built Denon Protection system had restricted various functions. A three stage process cleared this: 1. Unplug the unit. 2. Hold down the ‘Source Button’ and ‘Forward-Skip’ buttons and connect the power lead. This showed ‘PROTECTION: AMP’ 3. Press and hold the ‘Play/Pause’ button for several seconds. This clears the Protection setting. The Bluetooth function now works cleanly.

A hairline crack or gap is the most common problem on all circuit boards, I use an incandescent light bulb to shine behind it on the component side while using a magnifying glass to trace the cracks and hairline gaps on the copper tracks.

Dear Michael. Many thanks for posting this video. Congratulations on getting it working. These machines and there Ilk are so bad to work on I just no longer look at them. But they do make very good doorstops. We probably have around half a dozen of this type of mini system scattered around our workshop that won't see the light of day again. Kind regards Allan.

Another interesting and educational video - thank you for sharing it with us. I never knew this type of device has an internal "error log", I always learn something every time I watch one of your excellent videos. Well done for spotting the hairline crack in the PCB track.

Good job you spotted it - proper rabbit hole chaser that would've been

A classic problem that can take hours to spot. Well done!

Awesome Mike, I’ve had this with an intermittent line filter. It was going on and off, discovered a crack on side of one on the power board same connector.

I've got 4 of these DAB receivers and all working, but thanks for pointing this out 👍

Removed the comments to the original 500 dash issue, keep up the good work.

Great spot!, I am glad you got your unit fixed. I have the same issue "flashing red light" and I currently diagnosing it, Can you please share where you found the service manual for the RCD M41DAB, I can't seem to find it. Thanks. A quick update, I could get may unit to power up and operate only if I short the relay to the main transformer, so I think problem I have is when only the sub transformer is on.

Good spot!! I wonder why the track broke? I guess that's why they sometimes put that white gloop on large components to prevent movement and possible damage!

Well spotted

Brilliant catch Micheal maybe it’s been dropped ? Nice fix as expected from you thanks

Hello, can I ask for a diagram of this amplifier? My equipment is completely dead, only the power supply has 3.3V.

Hello Michael. Thank you for your RCD-M41DAB video - it's very interesting and informative. My device does not play Bluetooth devices (devices connect OK, but do not play - the Play and Pause icons on the display flash when in Bluetooth mode), and there is a slight speaker 'pop' when the device is powered off. I have a couple of questions: 1. Do you have any insights into "Protection: AMP" message (when pressing "Source" and "Forward Skip" buttons and applying power? 2. Could you let me know where I might obtain the service manual / full circuit diagram that you refer to in your video. Many thanks, Regards /Stewart

This is why I like hot wires and high volts! Valve technology doesn't play tricksy little games last like this. Just out of curiosity, are there any domestic electronic products with, effectively, an OBD port for this kind of diagnostic and fault clearing?

My kids had a 16th birthday party and goosed my DM41....it just goes click clack and the red light goes on and off....been played at full volume for a protracted period Transformer?

Good ole Hawkeye

Can you repair my denon doing same red light flashing

Hi Michael, I have been looking for copy of the service manual for this model, not been able to find it online. Can I ask where you got your copy please? I have a unit that's dead, flashing it's red light, no display and clicking the main relay. The factory reset etc does not work as the unit does not respond, just carries on flashing and clicking. I am pretty sure it's a mainboard fault as i've tried the board in another good unit. The symptoms went across with the board. It may not be easily repairable, but I did find what appears to be a couple of shorted SM capacitors, so would like to see the diagram in order to work out if that makes any sense or if i've actually hit on the problem. Thanks 🙂

Well spotted, the cap pin solder joint also looked dodgy. The apply power technique (4:37) made me laugh, thank the lord for low voltage secondaries. You know I am only joking around.

Well spotted, proving once again that a little luck can trump logic occasionally!.