Duocast is doing Weird Sounds - Video

[Thomasyoung]

Hi All,

Really wanted to have your help on this issue with my Duocast, is doing weird sounds with the volume pots at noon, already tried to change the transistors but the problem stays the same.

Here is a video and a picture for better understanding and hopefully someone can help me to cross check the problem.

Thank you very much
Best Regards
Nuno

 

[hamerfan]

My guess: Any of your components is stressed by 27 volts?

 

[Thomasyoung]

Thank you for the reply, all the electrolytics are 35V, 50V, and capacitors above this voltage.
Don´t know if I change the Pot will stop doing this weird sound since if cranked or lower to level low this strange sound will disappeared.

 

[Harry Klippton]

Is your transistor loose in the socket?

 

[Thomasyoung]

Checked that and no, they are well connected.
I´ve attached the germanium and sillicon transistors into sockets, but one of the sockets the plastic cover was taken off, can be that ?
I can try to round a plastic from the socket into the legs of the transistors to see if the problem presists.

 

[hamerfan]

Some transistors and IC have a voltage limit as well.

 

[Thomasyoung]

Thanks the Germanium transistor is a AC125 (Instead of the OC71) and the IC is the LT1054

 

[MichaelW]

Is your transistor loose in the socket?

This.

Did you socket the GE transistor? It sounds like a loose transistor to me. Or if you soldered it in, try re-flowing the pads. OR, it could be a bad transistor. Either way it sounds like a transistor issue to me.

 

[Thomasyoung]

Ok, here is a macro photo from the socket, one dont have the plastic cover, can be this?

 

[KR Sound]

Ok, here is a macro photo from the socket, one dont have the plastic cover, can be this?

That won’t make any difference like that.

 

[music6000]

What happens on the Single Channel, Your demo is with both on?

 

[Thomasyoung]

What happens on the Single Channel, Your demo is with both on?

Happens the same but less pronounced.

 

[music6000]

AC125 should have a Dot marked on it which needs to go to C. The other 2 legs should be the same as pictured.
Are the legs of the transistor clean, you made need to tin the ends with solder for better contact???
I am not a Fan Of Sockets, its nearly the same effect as a dry solder joint what your getting!
This is what the Members do to the Legs so it fits in the socket Better

 

[Thomasyoung]

AC125 should have a Dot marked on it which needs to go to C. The other 2 legs should be the same as pictured.
Are the legs of the transistor clean, you made need to tin the ends with solder for better contact???
I am not a Fan Of Sockets, its nearly the same effect as a dry solder joint what your getting!
This is what the Members do to the Legs so it fits in the socket Better

View attachment 62410

View attachment 62409

Well I already changed the transistors and is the same, when the Level low is at noon this thing start to drive me crazy with this sound.
Don´t know if can be the cheap toggle switch or the level low footswitch OR some cable Or the POTs or any component

 

[music6000]

Well I already changed the transistors and is the same, when the Level low is at noon this thing start to drive me crazy with this sound.
Don´t know if can be the cheap toggle switch or the level low footswitch OR some cable Or the POTs or any component

You could try putting the switch on 27v position & solder a little jumper wire on those related 2 pads & se if it fixes it.
if it does not, that rules out the switch being the issue.

 

[Thomasyoung]

You could try putting the switch on 27v position & solder a little jumper wire on those related 2 pads & se if it fixes it.
if it does not, that rules out the switch being the issue.

Can you explain me how to do that ? which 2 pad are you talking about ?

Thanks for the help in advance

 

[music6000]

The 3 pads that you soldered the switch to, Solder a wire to the centre pad & the outer pad that is opposite side to where the toggle is pointing to 27v on the front of the pedal.

 

[Thomasyoung]

@music6000 Did what you asked me to do but didn´t work. Thank you for this tip, now I can order a better toggle switch than these ones really cheap. This is my 3rd project that I use this brand/type toggle switch and the problem came from this crapy TS.

Hope with a better switch this thing start working properly.

 

[Thomasyoung]

Hi again,

I´ve changed the toggle switch for a new one a better one and I am facing the same problem as the video on my first post.

Would like to know if someone can help with this?

Thank you
Regards

 

[chris.knudson]

Thanks the Germanium transistor is a AC125 (Instead of the OC71) and the IC is the LT1054

The AC125 has a maximum voltage rating of 32v. The LT1054 has a maximum voltage rating of 15v.