Fixing my DTT3500

For years I am using a great 5.1 speaker system: Cambridge SoundWorks DTT 3500. It was quite expensive at the time when I was buying it, but it is still playing really great nowadays. Of course it is not a top product for audiophiles, but the sound quality is totally sufficient as a 5.1 speakers to the Kodi media center in my living room. To be able to use it with my new PC, I had to switch my source from original Digital-DIN (Creative-only audio cards, like SB Live/Audigy) to more general and wide used: optical output of my Asus mainboard.

Unfortunately when I switched to optical a new problem occured. The amplifier had to warm up before it was playing correctly. When I powered it up it was crackling and the Dolby Digital indicator LED was blinking. The playback settled down usually after about 3-5 minutes. When the amplifier was warmed up, cycling power doesn’t do any harm – it was ready for work. I was suspecting the capacitors.

Happily google helps me a lot with this issue: I found this forum thread on Overclockers Forums:

This was it! The guys have identical problem and a cure for it!
Under the Faraday cage three capacitors needs to be replaced.
I decided to buy and replace those three capacitors.

First I was searching for these capacitors at TME, but all of them was too high to fit under the Faraday cage (it has to be low profile, 7 mm max).

Fortunately the guys on the forum also provided a part numbers for some popular electronic online stores.
After some basic research i decided to go with Farnell element14.
I ordered the following capacitors:

The shipment was really cheap: 16PLN (considering the package was from UK to Poland). And what was really cool: I have the package next day after placing the order!

I was ready to start the process. The forum thread has many information, tips and photos which was really helpful. Nevertheless I will provide also mine photos from the work. Maybe you will also find it helpful if you are in the similar situation 🙂

Including assembling, the whole work took me about 3-4 hrs. I was not disassembling the main volume knob so I had to be careful about a wire which was constantly connected to it.
As I suspected, I had some small problems soldering out the Faraday cage. I was using a hot air tube for this but the board resisted much (and was also deforming a little when I was trying to pulling it out), but finally I’ve made it – it was also probably because some kind of glue on the soldering pads. The capacitor replacement was much nicer; soldering the cage back was the easiest task.
As you can see on last photos I have another one capacitor leaked, but due to the fact that I was not prepared to replace this one – I just leave it untouched – so far without any harm in my case. I can also see that this capacitor is bad eg. here on the following pics:

… so this seems to be another general problem with this hardware.

After reassembling and connecting back to speakers, there was a moment of truth.
Fortunately – the operation went successfully – no crackling, Dolby Digital LED still green – all is working great!

Before, it was really annoying when I had to power it up, then go somewhere waiting until it stop crackling, go back and use it.
Finally I can now power up my amplifier whenever I want and just start use it immediately! This is really awesome!

Big thanks for guys from Overclocker Forums!


  1. Hello. I have the following system: Creative Inspire 5700 Digital, which I believe has a very similar amplifier, if not the same. Internally they seem almost equal. In any case, I have quite the opposite problem: my system works well when “cold”, and for a couple of minutes, sometimes hours. However, after being “warmed up”, the optical connection stops working and the cracking noise (when volume is at max) appears. Everything stays ok with the analog inputs. I think I will follow this guide, maybe it solves my problem too. Thank you posting your case, it will be of great help. Best regards.

    1. Oh yeah, i remember that in my case the analogs was also playing fine all the time 🙂
      Please share about your results! 🙂

  2. Hey manio,

    Thanks so much for posting this, together with the links to the overclockers forum.
    I have successfully repaired my dtt3500 with this. Thanks a bunch!!

  3. Great photo’s, helps a lot.
    I also have the last picture blown cap issue. With this dtt3500 the centerspeaker doesn’t get sound, plus there’s the crackle sound after a while. I removed the cap featured in the last picture, though there’s a resistor attached to the cap. Don’t know whether that’s supposed to be there if not whether this dtt3500 had an earlier repair. Does anybody know where I can find the circuitboard diagrams.
    Any information will be appreciated.

    Thank you.

  4. So I’ve done the thing and the popping stopped, but I have no Left Surround anymore… Any idea what I should be looking for? Everything else works…

    1. If you done everything properly than it is rather impossible that it stops working. I bet that you have introduced some disconnection somewhere in the Left Surround channel… check again for the wiring, all plugs etc…

  5. I am glad I am no the only one still trying to keep my beloved DTT3500 alive. I bought it brand new almost 20 years ago and have now repaired it twice! The first time I repaired it I replaced the 3 capacitors under the cage but to get better rated capacitors in there I just cut a hole in the top of the can…lol
    Fast forward about 10 years and now as an electical engineer it is time to do it again. I just finished my second repair to this receiver and it is nothing short of amazing again. Over the last two or year the quality and functionality had been declining. First the opto input went out, then one of my 3.5 inputs and the audio clarity started degrading. Last week it started crackling a little bit and I couldn’t take it anymore.
    Onto my second repair and this time around I know a lot more. This time I again replaced the 3 capacitors under the cage but this time they are with 50V and 125C rated Nichicon capacitors of the original capacitance values. I also replaced all of the capacitors on the main board that were near the heat sink and in between the volume level knobs.
    Back up and running and I forgot how good this thing used to sound and all my inputs work again.. no more having to bluetooth my phone to my computer so I can use one 3.5mm jack for both phone and pc audio…lol

    1. Hi Paul, thanks for your input about it 🙂
      I also bought brand new but fortunately I had to repair it once so far and it is still being used in the living room. I even buy exact same DTT3500 set from second hand (very cheap) and using it in my room 🙂
      In both cases I am using it from linux using a single Toslink cable and configured AC3 encoder to 5.1. This way it is really nice hardware and it can still be used even without dedicated Creative sound cards, as probably all mainboards has optical-out nowadays…

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