How to go about checking this PCB

[brianmoooore]

What startles me, is that during fireworks, the fuse did not go.

A word of caution when replacing burnt resistors in mains powered devices: Resistors that are likely to catch on fire under likely fault conditions are often special fusible resistors which are designed to combine the properties of a resistor and a fuse, and so not catch on fire (and burn your house down).
A fire caused by such a modification could possibly invalidate your insurance, if the insurance investigators managed to track down what had happened.

 

[picturevalve]

A word of caution when replacing burnt resistors in mains powered devices: Resistors that are likely to catch on fire under likely fault conditions are often special fusible resistors which are designed to combine the properties of a resistor and a fuse, and so not catch on fire (and burn your house down).
A fire caused by such a modification could possibly invalidate your insurance, if the insurance investigators managed to track down what had happened.

That’s why I queried the resistor value, the third band may originally have been red rather than brown - hard to tell the difference when it’s burnt up- but an order of magnitude difference in the resistance 1.5k instead of 150 ohm.
Unfortunately, when a design is “on-edge” these special resistors can give repeated faults, tempting some people to replace them with something “more robust”.
Having said that I don’t think this was a special, all the ones I’ve seen don’t burn up.

 

[picturevalve]

I checked the other resistors and compared the readings with the stripes and they were all a match except one where AI said it should be 33K Ohm but my tester just shows that it was 32.7 without specifying that it was in K.

The problem was that the protective coating the PCB and parts are covered in are difficult to scrape through.

I could not get any readings from the relay but the board was opening the valve so if that was what relay was supposed to do, then that is ok.

Your meter has a 3 1/2 digit display, so the max. reading on the 200k range is 199.9k, so 32.7 reading is 32.7k. You interpret the meter reading wrt the meter range selected.
On the 20k range, the max. reading is 19.99k. A reading of 0.32 on this range would mean 320 ohm so you would switch to the 2k range if you wanted more "resolution" on the reading - that 320 ohm would then turn out to be between 315 and 325 ohm, usually.
Read the manual that came with the meter.