I recently replaced the circuit board in my 1998 Dakota spa (Balboa board) and am not getting current to the spa light. All other functions are working fine now except the light. The bulb is good as I connected a 9 volt battery to the wires coming off the board and it lit up and the fuse is good. The board is slightly different than the original (upgraded) dak100 and supposedly all of the jumpers are set right. The light was working with the old board. I'm looking for any possibilities before I pull the board and send it back. I thought maybe the transformer could be the problem but the top side lights are working. Any ideas would be appreciated

You say 'top side lights'?

What kind of top side lights do you have? Or are you referring to the topside control panel?

Yes, the top side control panel lights are working. The dc voltage at the circuit board terminals and at the fuse terminals was 0. The ac voltage seemed to flucuate. From reading this forum I'm getting the impression it should be 12 volts ac at the board. Is that correct?

So when you press the light button on the topside, you still get zero volts at the light output correct?

Can you hear the (very slight) sound of a relay clicking on and off when you activate/deactivate the light button?

Yes, no dc volts when I push the light button. I do hear the clicking of the relay tho.

Try measuring AC volts, not dc.

Lighting outputs are not rectified to dc because there's no need for it. You should be measuring at the terminals or plug/socket where the lighting output power is expected to be.

I measured the ac at the terminals and it is 0 across the light terminals. When I ground either of the terminals individually, I get 18 volts. That voltage is unaffected by the light switch on the top side control. I was told the board should not be grounded to the case which it isn't. I thought about grounding one of the wires to the light while the other is attached but was afraid of frying the board.

Now I am totally baffled. Went out and did more testing. If I disconnect the right side wire for the light from the board and ground it to the box, I get 20 volts at the plug coming out of the box but the light still does not come on when I plug the light in to the box. When I test voltage from the disconnected terminal on the board to ground, I get no voltage but the other terminal to ground is 18 volts. What voltage is supposed to be coming out of the terminals? Is one of the terminals a ground? The light still works when I hook up the 9v battery.

Likely your board is supplying an output via a triac (multi-level) and not a relay perhaps?

Post a decent photo of the enclosure/board.

After reading about triacs, I believe you're right. I did some more testing and got a reading of 5 volts from the spa light plug coming out of the box but when I plug the light in, it still doesn't come on. I have attached a gif of the board.

Lower left hand corner of the board is the light triac... (3 legs, screw in the top of it).

Are you using a standard light bulb to test this thing? My guess is with the light plugged in the voltage goes to zero?

There is a small fuse on the lower left corner next to the triac. Be sure that fuse is good. (Power down, pull it and do an ohms check on it).

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last thing... does your spa have a blower on it? If so, then you need to get a screw into the blower triac on the lower right side - (larger triac - three legs missing the screw). Without a screw tying it to the support post (heat sink) it will overheat.

The fuse checked out OK. I am using a digital electrical tester to do the checks. I checked the leads from the light triac and got 22v on the outside leads and 4.5v on the inside lead and the voltages did not change when I activated the topside light switch. I checked the voltage out of the box at the plug and it is 6v. Is it possible the board is bad?

Well, this is a multi-level light system. It's not going to give you 12v directly. Additionally, checking the other legs of the triac are not going to give you anything that will make sense. The triac is pulse triggered, and to make any definitive determination of function you'd need an oscilloscope.

Press one time, full brightness, second time, medium brightness, third time, low brightness. With a NORMAL bulb - I'm talking about a (4-11 watt) lawn light type of bulb available from home depot etc, NOT an automotive bulb, it should work like that. To test voltage you need to do it under load - (good working light installed).

So, it's 3 presses for light, last press is off. If you're not getting that with a good light bulb - you've either got a defective board, or your topside control isn't working correctly (But assuming it still is according to your initial post that would leave the board as faulty).

I'm assuming everything else works correctly here, if not, then you've got a board/topside proprietary mis-match issue.