Little Dot II++ humming.

[Arci996]

There is a rubber ring between the toroid and the upper plate, can't say the same for the bottom part, I'll try to fit something insulating at the bottom, only thing I have lying around is cork that I used to dampen vibration from my speakers, that should do the trick I guess.

 

[merlin el mago]

Be care for using flamable materials, bitumen pad or damping rubber will be better, but you can try to know if works.

 

[Arci996]

Yeah not ideal long term but at least I'll know if it works, later I'll try resoldering the capacitors and I'll let you know if it worked, in the meantime thank you again for all your support.

 

[Arci996]

UPDATE: I re-soldered the capacitors, and well, either I'm very bad at soldering, or I broke something. Basically it's like the audio is muffled and extremely low quality (like a radio when the radio signal is really bad, don't know how else to explain it). Could this be caused by bad solder joints?

 

[OldHector]

It is not a good idea to change two things at a time. If I understand correctly, you removed and replaced the capacitors in order to test them, and cut the jumpers for setting the gain. I think you need to restore those jumpers so that you can be sure the capacitors are replaced correctly, then look at gain as a cure.

 

[Arci996]

nono the jumpers are on, they have a little cap that can be put on or off I never removed them. I just removed the capacitors, tested them, and put them back on, evidently I also did something else not on purpose. I also noticed now that it won't turn off unless I pull the plug.

 

[OldHector]

Here is a schema.

It was located here, on the head.fi forum:
Little Dot MkII rebuild

 

[Arci996]

I also found that but unfortunately it's for the Little Dot MkII, mine is a Little Dot 2++ that's the older (and discontinued model). The lower part seems to be kinda similar tho, different values for the capacitors but the wiring looks like mostly the same.

 

[OldHector]

nono the jumpers are on, they have a little cap that can be put on or off I never removed them. I just removed the capacitors, tested them, and put them back on, evidently I also did something else not on purpose. I also noticed now that it won't turn off unless I pull the plug.

Having given myself a very unpleasant shock off a capacitor, please be careful with them. I wonder if you have somehow disrupted the link to ground, so that the capacitors do not discharge when it is turned off, except through the circuit? If so, they can carry a surprising amount of energy for a surprising amount of time ;-/

 

[OldHector]

I think the circuit should be roughly the same - maybe just the choice of driver tube. There are only so many ways to skin a cat.

The manual is here, btw ...
Little Dot MkII manual

 

[Arci996]

Thank you again, I'm being careful with the capacitors. Btw my friend told me that the only way to be sure they are good is getting new ones, so I went ahead and bought the three big ones, we will try soldering them on when they come in.

 

[merlin el mago]

Be care for cold solder joints normally appears like bumped and without brightness like smoked.

 

[Arci996]

Looking at them the solder joints seems fine, don't know how to know for sure tho, every capacitor shows 170V between poles like they did before I desoldered them so I really don't know what could cause the problem, I also tried the old tubes just to be sure I didn't damage them but there was no change.
Should I try testing the blue rectangular capacitors? Is it possible that I damaged the capacitors when desoldering them the first time? Even if they read fine with the lcr tester?

 

[OldHector]

The main thing is that the polarity is correct. Sometimes it is handy to take a few photos before working on the board so you have a record of the prior state.

Can you send some pictures of how it is now?

 

[Arci996]

I'm pretty sure I put them on on the same polarity, I attached the photo so you can double check.

 

[OldHector]

Yep, looks identical as before!

 

[Arci996]

New capacitors came in, I soldered them aaaaaand now it's like I'm listening to unamplified signal, I can hear the signal I'm reproducing but it's very faint :S Tubes are getting hot but I don't know how to check if they are receiving a signal.