Phoenix, MOBO & SMR MKII assembly help needed


Alright. All the parts are in. The motherboard was a messy assembly, but I can’t find anything that is not soldered correctly.
I connected the boards and plugged in a 9v adapter.
It doesn’t work.



I’m thinking of buying a new motherboard with parts.



No, don’t give up yet. I’ve seen much worse boards here.
Lets start slowly and work step by step. The No1 rule is to go slowly. Plugging in the power before doing some simple tests can easily fry parts and make things much worse.

First step: Unplug the power. Use your multimeter in beeper mode or resistance mode and check for continuity between the power rails and GND. (check between all three combinations: 5V & GND, -5V & GND, -5V & 5V). If the resistance is very low (20Ohms and below) you have a shortcircuit somewhere.

Second step: Power up only the filter board. Measure the voltages on the two power rails. If they are anything other than the specified 5V /-5V, stop immediately. I know your meter showed ±6V. Please try to verify that your meter is okay or get another one to compare against.



Hello slow growth,
Thanks for responding.
I only have this multimeter. I do have a new adapter. I measured again and this came up.



Any ideas on how I can check my multimeter with this new adapter? to make sure that it’s really broken.



Maybe the battery of the multimeter is almost empty?



Hi Gert,

I just put new duracells in them. So the readings are not correct? Then I just have to get a new multimeter and contact the seller. To be continued

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Allright. Measured like this:

Here are the readings

black - Red
(input) gnd - +5 = 1.6
“” - gnd= none
osc= none
vca= nothing
etc. Nothing gives a value except for the +5.



I don’t know but it looks like you inverted the polarity of your AC adapter.
For the Shruthi to work, you need tip = plus, sleeve = minus.
In the picture showing the measurement of your new AC adapter, the black probe is inside and the red one on the sleeve and the multimeter reads a positive voltage.
If the polarity was right, it should read a negative voltage.
Anyway, there must be something wrong with your multimeter because your new AC adapter is a switching power supply, means it is regulated and your multimeter should read 9V whatever the load is.

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Thanks Modulart. I Emailed this thread to the company that sold me the multi meter. I Will get the new adapter today and hope it Works.



anyone in the netherlands know how this works and can help me for cash?



I don’t know if your meter is wrong, but I’m pretty sure that if it is reading a positive voltage even though you have the COM (black) plug inserted inside your DC jack, it means that you need to reverse its position.
I bought plenty of those universal power supplies and they all give you the possibility to take the DC plug out and reverse it. Just follow the small drawing on the plastic, there is an arrow on one side of the cable end and two corresponding to both possibilities of polarity on the plug itself. Just pick the right one (positive + in the center) on the DC plug and align its side with the arrow on the cable.

Always double check the right polarity with those power supply before inserting them. Been there, done that.

Even though your Shruthi should power up with 7.5V.

You should see if anybody in your surroundings have an extra multimeter to spare so you can rule this problem out.



Hello Paulus,

Yes I changed it and checked the board through the instructions i got in this thread. There are a lot of connectiins not connected​:grinning::nail_care:t2:
I have learned. I asked a friend to help me and he knows a Guy.



Sure, just contact me directly.



And it works now. Thanks to gphg.
Thanks everyone.

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