Huge mistake with power supply?

Hello all,

I finally started building an Ambika and I just got on to the voltage testing phase. I was under the impression that I could use an 1SPOT as a power supply, but after getting absolutely no voltage readings from the instructed spots with my multimeter, I started researching the matter and found out that the 1SPOT is not an AC adapter after all… So the question is that did I fry precious components? Will the board now only make nice burning material for a fireplace? Please answer so I can decide if to go berserk or not!

Small chance of damage with a DC supply. I used a DC supply by mistake first and my Ambika was fine. Don’t worry too much.

Nothing will get damaged if you power the Ambika with a DC supply. It just won’t work at all because there won’t be any negative supply.

So get yourself an AC supply!

Thank you for your swift answers. I got an AC supply today and now I get correct readings on my multimeter.

A slightly off topic question: can I get decent measurement probes for 10-20 euros? The probes which came with my multimeter are absolute and utter shit and I’m wondering if the quality is any better with a pair of 10 euro ones. I had to wiggle the probes alot just now to get the instructed readings. Measuring resistors is impossible unless I have perfectly still hands and testing for continuity goes along the same lines. Attached video related.

Something like this should do

If your soldered joints are coated in flux then you will need to wiggle the probes around a bit to get to the solder.

Thanks for your recommendation, shiftr. Here’s something new on my mind: I haven’t made any new progress as I’m waiting for some tools to arrive from Germany, but meanwhile I noticed that I had totally missed the bridge on R_LED. I’d like to ask if I need a 100 ohm resistor or just plain metal wire. Here’s what I bought:

Bonus n00b question: May I remove the stickers behind the LCD unit…??

For R_LED only a wire bridge is needed for your Newhaven display.

Still waiting for the same tools from Germany… Meanwhile I’d like to ask something which has been keeping me up every night:

Does the main board have to be powered on while I’m uploading the firmware through an ISP-programmer (bought a blank AVR chip)?

With the AVR ISP mkII programmer from Atmel: yes, it needs to be powered.

With another programmer: check the manual of the programmer - some of them have switches or jumpers to switch between programmer-powered and board-powered modes.

USBASP - no power needed and switchable between 3.3 and 5V.

Thanks for the replies. Bought an AVR ISP mkII programmer at same time when I sourced parts for the Ambika mobo.

Yesterday I finally got the mobo finished and today I finished my first voice card. Only problem: no sound. It receives MIDI ok (lights are flashing here and there). I don’t have a SD card yet, so no presets, but I’m assuming the default settings preset is an audible one. I’m using a TubeOhm ladder filter card.

No sound would suggest a break in the signal path somewhere?

Always a possibility, but I find it unlikely as everything else is working so fine. I’ve mailed Andre asking his opinion.

> everything else is working so fine

Not so fine since you have no sound! An assembly mistake in the analog circuitry will not prevent the digital side to work. And there’s a lot of analog circuitry on the voicecard!

Simple mistake: missing jumpers on the voicecard?

Here are some pictures of the boards, if anyone is interested in taking a look.

Motherboard front
Motherboard back
Voice card front
Voice card back

Jumpers should be correct.

Insult to injury: I tried measuring the voltages again on the voice card and when I brought the other measurement probe on the AVR chip, both LEDs on voice card flashed once and now shine only very dimly… Voltage readings still however show as expected.

> when I brought the other measurement probe on the AVR chip, both LEDs on voice card flashed once and now shine only very dimly

Voicecard locked itself in firmware upgrade mode (probably due to all the power on / off cycles during troubleshooting).