Søk etter:

New 17Mar2025, updated 03May2026. This note is in group Technology and My e-fun notes (electronics fun).

This note describes a hack which makes it possible to use a single cable with a USB-C connector in both ends and a USB-C power to charge the soundmaster IR6500SW radio. It would also go as a tip of how to approach similar problems. It also logs a series of problems I have experienced. This radio is so hard to trust that I might try to find a similar radio. But I admin, this is hard, I did quite some searching to find this one.

Disclaimer

Don’t even attempt to do this if you don’t have a ton of experience with electronics modifications. For this reason you won’t need a detailed description since you’ll just know. The fact that it worked for me doesn’t guarantee anything for you. You would need your own experience to ensure that it will work for you. Be careful! Measure around before applying any power.

Maybe there is a newer version of the radio where this modification is not needed. I don’t know whether soundmaster has fixed this in a HW upgrade. I haven’t asked them. In that case they could have sent me a replacement connector board. This would have saved me the visually appearing downgrade..

You can also just use the USB-C (in the radio) → USB-A cable, then an USB-A → USB-C (for the charger) adapter (or cable) to solve the problem if you (like me) do want the option of a USB-C charger. The latter seems to contain the required resistors. Test this before you attempt my hack since it may save your radio!

Intro

USB-C charger and full USB-C cable problem

For my radio it would only work if the cable has a USB-A connector at the charger end. The radio itself has a USB-C connector. The designers must have forgotten to add the required resistor(s) to make a USB-C source actually apply the 5V. That is, provided they were thinking that a USB-C power supply should be possible to use. If not, I guess they didn’t really «forget» anything as such. Even if using a USB-C connector in the radio indicates to me that a USB-C power should be possible. The USB-C standard requires a resistor for each up- and downstream power direction.

To apply higher voltages requires the USB-C charger to communicate with the radio over the wires intended for this. Inferring from the fact that it needed a USB-A at the charger end I don’t think this communication is done here. Plus the original text label «DC IN 5V» also implies this. Plus, for 5V it’s not needed. But I haven’t scoped it.

The radio draws max. 1A @5V. The red charging indicator in the radio changes to green when the battery is fully charged. Nice!

To fix the problem I simply added an Adafruit ID:4090 breakout board, see Adafruit USB Type C Breakout Board – Downstream Connection. It’s got the required resistors that tells the USB-C charger to deliver 5V at max 1.5A.

(Update: The Magical Christmas Bulb («Den Magiske Julekula Snøfall«, developed by Andreas Wahl) seems to have the same problem, see here.)

This radio is at soundmaster’s page as at Portable WLAN-internet/DAB+/FM-radio with Bluetooth®, rechargeable Li-Ion battery. I like it a lot, and its SW has even been updated from time to time. The last update I have is from Jun2024 (SW 20240617.1446). My «radio version» is 202207.0.1535.

But I was increasingly frustrated with not being able to use a cable with USB-C connector in both ends. The resistor I think they forgot to mount I have found no way to solder onto the original internal board since the USB-C connector’s wiring is by and large hidden between the connector and the board. This goes for CC1 and CC2 which are the wires I’d need. So I found no other solution than to add a connector instead. It was easy to test the concept before I started with the painful work. I electrically inserted the breakout board in an external cable and then used a USB-C charger. The charging indicator lit up as expected.

Here are some pages to read yourself up on this, to understand what soundmaster didn’t do and you don’t have to do either:

1. USB-C (Wikipedia)
2. Designing with USB-C: Lessons Learned (Apr 5, 2021 • matthew)
3. ALL ABOUT USB-C: RESISTORS AND EMARKERS (by Arya Voronova January 4, 2023)
4. Why do some USB C cables not work for certain devices? Is there a «right» kind of USB C cable to buy? (by Cease_Cows_, Dec2022)

Full USB-C cable solved

But then, just using a ready made breakout board with the 5.1k (or other values) resistors is perfect!

I opened the radio and disconnected the wires and cleaned the connectors for old silicon or glue. I then carefully cut out the battery from the department (it was also glued). But this was after I had decided to fasten the breakout board onto the same battery compartment’s wall. I used 2.5 mm metal screws. But before that I had to make hole in the radio box itself. Since the USB-C connector does not protrude from the board I had to make the hole way «too large» to get the rather bulky USB-C connector’s «electronics box» safely sitting in place. The large hole was necessary.

(Thinking about it a second time while I write this I probably could have filed away the material that’s on the side of the connector and then made the connector protrude and then made a hole exactly the size of the original! Blush..) (Thinking about it a third time: that would have removed the fastening holes. It is perhaps more important with a sturdy mounting than a nice opening. Unblush..) (But there are other breakout boards).

I then soldered two wires from the breakout board to the original USB-C board. Plus and GND.

I then used silicon to fasten the battery and connectors again. Plus the «air» in the radio of my big opening I also filled with silicon. This also protects the radio from being filled with dust. (When the silicon has hardened it’s not as shiny as on the photo. And using a black marker pen or matte black paint on the silicon after a day or two probably is a good idea.)

Now I can use any cable in the new connector. USB-C ↔ USB-C or USB-C ↔ USB-A. Or even better: I don’t have to carry a USB-A charger or adapter for this only reason.

But there is not much use for two connectors, so I just masked the original with some tape. However, if I use a USB-C to USB-A adapter in the original connector (and USB-C or USB-A ended cable in the new) I can actually use the old USB-C connector for an extra USB-A (but not USB-C) output.

Again, don’t do this if you are not confident that you are 100% up to it! Don’t ever rely on luck!

Log

Newest on the top:

Sep2025

SW version 202207.0.1535

1. Once it lost the all the three station presets. It said something about not having any preset stored for each of the three buttons. I knew it had had presets, so I turned the radio off and on again, and then the presets reappeared
2. Pressing preset 2 when listening to 1, the radio got silent as it should, but the channel did not come through at all. Back to 1, ok. Then pressing 3, station came through. Then pressing 2 – and that station came through! This was repeatable, at least on this «on» session. However, trying it again «now» (maybe after an off/on sequence), it went from ant preset to any other. I see no reason why the code should have any preset from → to state; the nearest would be some SW problem – it may also be related to point 1 above
3. It is possible to set the light of the display, or the dimmer level. This may be set to zero, nice if I want the radio to go dark after some time. However, if I want to change from 0 to f.ex. 1%, the menu takes me to a screen that has the present dim level, which is zero. It’s easy to think that something got wrong when a button takes me to a black screen. If I had written this SW I would have stated with text like «dimmer was 0 (black)» but then display the screen with something like 50%. Then it’s good design for the screen to follow the new value, as it does, even zero as black screen. But entering a black screen is immature software design
4. Menu and the On buttons (for some time?) (see below)

Summer2025

Port 443 blocked and waiting for the ⬅ button

I experienced at a hotel in Sweden that on the hotel’s open WiFi the mobile and the computer worked, but my Soundmaster behaved strange. I checked Network connection test and it said that most lines were Network:, IP:, NM:, GW:, DNS: OK, but Connection: Port 443 is blocked. The radio just stopped and got black. No response of the buttons or knob. (In Update below, I explain that the ⬅ button would have solved this! But since I must have stared at the display for more than 20 seconds and not paid attention to the last line, me and the radio fell into void together.) To try to rescue the situation (I was afraid that the radio had died forever) I pushed and held both the Menu and the On buttons (for some time?) – this restarted the radio again. I don’t know if this was the cue. You can’t take the battery out and in again very easily, can you – if that might have solved it. I saw all kind of bleak scenarios. When I retried it looked like it blinked and restarted all by itself.

Port 443 is the HTTPS default port. The radio has worked fine on other hotels’ open networks. I assume that this hotel’s fire wall had been configured rather restrictively?

However, when I successfully connected on the next hotel’s open network, and when all OK and Connection: OK, the radio also got black and unresponsive! It continued to play on the IP stream, but that was all. Dead buttons, volume control and black screen. Disregarding ⬅ I think it was pressing both Menu and On that restarted it again.

Update. The Network connection test has a Press ⬅ to quit. which may be is the problem here, provided the screen dims black before ⬅ is pressed. My «GUI memory» was too confused for this situation. The SW only seems to accept the ⬅ in this menu state. No other button or the knob is accepted. I have the fastest dim timeout here (20 seconds to black), which during the dim timeout period and when gone to dark, locks off any button or knob event here, except ⬅. Worse, in this state, no button or knob action reset the dim timeout. To get out of this situation, after a dimmed screen, I now have to press ⬅ and then ⬅ again. (Update 12Sep2025: This situation arrived again, for some other reason, but the back buttons did not help. However, the above explained shot in the dark rescue recipe to push and hold both the Menu and the On buttons (for some time?), then On for the required time – this restarted the radio again). I suggest some SW repair here: While waiting for the ⬅ then the dim should never time out to black, so that the screen will always be seen. I would have reset the timer to initial value and let the knob through as doing volume, plus let the Off button also work, so it’s possible to terminate this state by turning the radio off. I guess this is the closest to the intended behaviour, not disturbing too much of internal screen state machine. Then it won’t get this almost catch-22 situation. I don’t know if any other meny entry has the same problem. I have not pressed around to search for one.

There are two problems here, one for the hotel (Port 443 is blocked as of 05Jun2025) and one for Soundmaster (Network connection test has a Press ⬅ to quit. end criterion on version 202207.0.1535). I have mailed them both.

Update on port 443. The hotel tells me in a mail that «I’ve talked to one of the guys here about the radio thing and he says it’s a security barrier they have so that people can’t hack into our system here.» Since this is the HTTPS default port I found this so strange that I asked Google: «Is there any idea to stop Port 443 at wifi spots at hotels?«. Th AI response I got (08Jul2025) was «While some hotels might restrict certain ports for security or bandwidth management, blocking Port 443 (HTTPS) is generally not a good idea and could be illegal. It’s more common to see hotels blocking VPN traffic or limiting the use of personal hotspots, rather than outright blocking HTTPS.» It then lists up several paragraphs, some of which are: HTTPS is Essential (crucial..), Legality (may be illegal..), Common Practices (VPN blocking..), Security Concerns (could force users to connect via HTTP..) etc. Disclaimer: AI may be wrong. See An encounter with AI-powered Cursor text editor and XC