EHX Bass Microsynth Issue

[karter2000]

Hi all,

I have a friend's Bass Microsynth, and it's acting up.  Basically it works fine for a while, then it will turn off completely (LED turns off as well).  If left for few seconds, it will turn itself back on.  It does it both when the effect is one and when bypassed.

Any ideas?

Thanks,
Lyle

[theehman]

I'd guess it's a bad solder joint somewhere.  Check around the power supply section of the circuit board.  There's a large transistor there that may be the problem.

[karter2000]

Thanks for your reply!

I looked around the board last night, and the solder joints look okay.  I have the schematic in front of me, I take you are talking about the 2n6110.  Could I test it, or should I replace it altogether?  It says on the schematic that the 2n6110 is "normally too hot to touch" so maybe it's fried over time?

Would the RC4558 give any problems?

Thanks again,


Lyle

[theehman]

Since the LED is turning off it would have to be a power issue.  Touch up all the solder joints in the power supply area just to be sure.  Check the power cord and on/off switch as well.  The switch may have been bumped and is partially opened.

[StephenGiles]

What you could do is disconnect the power supply and connect two of the larger 9v batteries to see if the fault still persists. If it does then the problem lies elsewhere.

[Jarno]

I came across this thread as I'm interested in getting a microsynth. If they say that the transistor is "too hot to touch" then it might over time has wriggled loose its solder joints, I have had this happen to me in a Marantz receiver, one of the output mosfets had bad solder joints. Proper engineering is having some overlength in the legs of the transistor to have act as a spring, absorbing thermal expansion.

[karter2000]

I ended up fixing it.  Not entirely sure if this was the issue or not, but I replaced the 2n6110 transistor (the one "too hot to touch).  It's been working ever since.

The solder joints looked fine before I replaced the transistor.