Only one oscillator of cowbell working

I just finished my Yocto from the first batch this week (there was a long period of rest between start and finish

). But because of my delay I am hoping to get one of those sweet metal cases.

First of all I want to compliment Vincent on this amazing project. The kit was carefully put together and the instructions were very clear. This was my first DIY project and I had limited soldering experience, but almost everything seemed to work pretty well the first time I powered up the machine.

There is one significant issue. Only one of the two cowbell oscillators is playing. The one that is tuned by TM2 plays and sounds alright I guess, but the one that is tuned by TM1 remains silent. Now since I don't have any experience with troubleshooting, I thought maybe people here would be able to provide some tips.

I don't have an oscilloscope yet, but I am planning to buy one, although my budget is quite limited, so it would probably be an older second hand analog or a new USB scope. It would be great if I could use it to calibrate the noise voltage as well, since I don't have a RMS meter. I think only digital oscilloscopes can calculate RMS voltage, but since I don't really have experience with this as well maybe someone can tell me what to look for or guide me towards alternatives.

When this is fixed I might want to fine-tune some of the instruments, but at least all the other instruments are playing and sounding pretty much like their 808 counterparts.

Your help is much appreciated!

By messing around with an audio cable and audio explorer I found the problem is probably at Q15, so I will replace that and see if it helps. I also found that I can use audio explorer to tune the oscillators, so I probably won't be needing an oscilloscope, just something to measure the noise voltage.

Both oscillators are tuned too low though, so I will have to replace some resistors as well.

For replacement of Q15 do I just have to get another 2SC945 transistor and I'll be safe?

Okay, upon desoldering I realised Q15 was in the wrong direction, so after turning it around the cowbell worked just fine.