Anushri gone dead, PSU getting warm?

I have only just started to play with my finished Anushri. Up to now the unit worked and I was getting sound etc. Suddenly it went dead, and on restarting either no lights flash (but power is present as hum can be heard from the audio out), or sometimes the 3 vertical lights come on together with the top left and top right (but not middle) lights. No flashing, they just light, but there is no functionality at all. I tried restart with Run/Stop button.
I wonder if the PSU is the fault as it is getting pretty warm, and if so has it fried something or is my firmware corrupted, and if so where do I get the firmware??
Thanks for any help forthcoming,

If it worked and now stopped and the PSU gets war to hot thats an hint for a short/bridge somewhere…

Check for any snipped legs or bits of solder, may have created a short. Sometimes the metal sticks to the flux.

Could also be some debris in the stacking connectors (i know what I’m talking about…)

thanks for the replies, problem not yet solved but I’m working on it…

Hi again
My PSU is set to 7.5v, however at the power in I’m getting 5.2v and then 2.7 instead of 5v on the red points on the board. Is my PSU to blame?

Try setting it to 9V - looks like its a bit weak…

I’ve tried it on 9v and 12v and always get the same result

Is there a short between one of the power rails and ground?

I don’t think so, it has been soldered very well. The main point is that at the power in the voltage measures 5.2v whether I select 7.5, 9 or 12v, surely it is the PSU to blame?

it really looks like there is a short. I don’t mean to be rude, but you should really check it in details instead of just trusting the soldering work.
It’s normal to spot something like 5.2v after the regulator, although it looks quite high to me. If it’s directly at the output of the PSU there is really a problem with your build.

Ok I understand. I haven’t done this kind of thing before, I’ll take it to a guy who knows what he’s doing!

You can simply start measuring the resistance beetween the DC input and the ground, with the unit being unplugged. If it’s a very small resistance, there is a short. If so, you can remove all the chips (with caution) and measure again. If the resistance is still low, there’s some tin ball or some kind of wire or something like that between 2 pads, just a visual inspection should provide you the answer. If not, please post again and we can discuss what you need to do then.
There’s absolutely no wizardry in it, all you need is a bit of patience and a multimeter, which you already have :slight_smile:

sorry to all who replied to my first post - I found, after MicMicMan suggested removing the chips, that one of the chips was in upside down After correcting that I have a fantastic sounding Anushri


You’re welcome, what matters is that you’re happy with your synth. Maybe your example will encourage other people who would encounter the same kind of issue to better check their assembly :slight_smile:

@dpaulo also consider replacing that chip-while it may be working fine now, its lifespan has probably been shortened…

Thanks for that advice gwaidan. Having now gone right through the features could this explan why the following is faulty:
the Glide and VCO Range functions are both operated on the Glide knob alone, in other words the VCO Range knob doesn’t work, and the Glide not only glides but also raises the note from very low to very high as you turn it. It’s a mad effect but I’d rather the VCO Range knob worked properly.
Also I’m still not sure if the Sub Osc switch to -2 octaves works it doesn’t seem to affect the sound, whereas -1 and DCO do work.
The upside chip, by the way, was either IC18 (4051N) or IC20 (MCP4822), I’m not certain which it was…

Your problems are likely related to a bad interconnection between the two boards. Check for shorts or bad solder joints on the 2x8 connectors that tie the two boards. Your Glide/VCO range problem is for example likely to be a short between the two signals - which are adjacent all the way from the ADC mux to the pots.

also consider replacing that chip-while it may be working fine now, its lifespan has probably been shortened….
If a chip is working fine despite having been plugged backwards, I don’t think there is a problem?
I wouldn’t say so regarding a regulator or a power transistor or something like that, but I don’t think in this case that it’s likely to fail tomorrow if it’s working today.

Have sorted out the Glide and VCO Range knobs by cleaning debris off the board. Still to sort out the Sub Osc 2 setting there looks like a join with very little solder (top right of the 6 solder pads for the switch) on so I’ll do that next.