Alesis Nanosynth - buzzing sound output (before that, no sound out)

[roygBiv]

Hi Guys

Thought I would give this a shot here.

I have an old Alesis Nanosynth I've had for ~ 20 years.

Stopped using it ~ 10 years ago, if I recall because there was no sound output.

Dug it out today, powered it up, and only output now is a loud buzzing sound.

Possibly I have the wrong power supply (don't have the original, but did use a 9V AC 1000mA unit), but I don't think that is it.

 

The buzzing sound makes me suspect possibly bad capacitors.

 

So, I opened it up - it is remarkably streamlined for something made in 1997!  Few serviceable components, lots of large integrated chips!

 

Anyway, the only potentially "obvious" capacitors to change that I could find are:

1 Scatronice 2200 uF, 16V (big, black)

1 Scatronice 1000 uF,  16V (slightly less big, sky blue)

5 Scatronice 35v10uF  (small, sky blue)

 

Most of components are pretty packed in there, and look surface-mounted (some right next to chips). 

 

Thus, my meager soldering skills will be challenged if I try to swap out these capacitors.

 

My question:  anyone have experience working on Alesis Nanosynths, and is this worth trying to fix?

 

Thanks,

 

Dave

 

PS - there is also a flat battery in there, which I assume has probably died by now.  So I would probably need to replace that, but I'm not sure how that could cause a loud buzzing on the output.

 

[Jose EB5AGV]

Effectively, capacitors are the first suspects on any old electronics. I understand you don't want to mess with SMD ones, but they are usually in worse condition than regular ones. The reason is that the seal breaks and they leak, losing capacity and damaging nearby components, traces, vias (inter layer connections) and such.

 

The first thing I do is a careful visual inspection. Look around caps for any sign of leakage/ damage. Looking at the PCB at an angle with some strategic lighting helps. Also, if you apply heat with a soldering iron to the capacitor tabs, the rotten eggs smell a bad capacitor produces is a tell tale.

 

A very handy tool to determine a capacitor condition without removing it is an ESR meter. I use a PEAK ESR70. It can measure the ESR and capacity same time, giving you an accurate view of the capacitor condition. There are other cheaper meters, of course, but be sure you get a trusty one in case you go this way.

 

Please, keep us updated on your advance.

 

Good luck!

 

Jose

[roygBiv]

sorry for the long delay, been hectic at work - thank you for the detailed suggestions Jose, I will look for the rotten egg smell (or smell for the rotten egg smell).

roy