Aussie lowboy with hinged metal control panel

[Zebidee]

Good to see you have it working!

While sorting the PC you could always...

Pull the CP, remove your controls and put the thing in the oven on low for a while!
Or on the dash of the car with the windows shut on a sunny day?

A little tropical sun goes a long way in hardening paint.

Bobby! That is a good idea! Thank you

A while back, after 2 days drying, I tried baking the panel in the sun, next to our swimming pool for a few hours...

Somehow, some dust and bugs managed to impact the paint! I had to re-sand and refinish...

This happened twice, because I somehow could not believe it the first time.

And those dimples at the front? Well, I drilled holes to put black M6 nuts there instead, except some of my drilling got hot and caused the paint around the holes to bubble.... So more re-sanding/re-painting.

One good thing is that the M6 nuts are effective, look good and prevent the dimpling. After that repaint, I left it about 2 weeks to dry off. Still not good enough.

For the record it had been raining solidly for about 2 months. May have something to do with it. Humidity sux.

I've wasted so much time on re-painting that panel, it makes me depressed thinking about it.

Anyway, your idea to put it in the oven is a good one. I will sleep on that. If I can stomach sanding/painting another time. I've been wanting to put a bar heater on it but we don't have one. Oven, yes!

[Greenman]

Where on this great planet are you located Zebidee?

[Zebidee]

Greenman, good sir, I am from the Wonderful World of Oz-tralia, but am in the Land of Smiles (Thailand).

When I said 2 months of solid rain, I may have underestimated. It has been a long wet season, prolly more like 4 months with occasional periods of sunshine.

Australia has been getting more than their fair share of liquid gold too. Lately is just flood after flood after flood.

I just swam back from the shops with some more sandpaper and black paint. We all know what that means...

That means I want to re-do this control panel and get it in the oven (hopefully before wife comes back from Bangkok and freaks).

[bobbyb13]

Has hardly rained at all at my house in 8 months.

A triple dip La Nina will not be doing well for our precipitation levels at least.
Lots of great surf from the west with little wind probably, but squat for rain.
Time to up the ante on irrigation for the goats!

Hope you get your CP baked before you are in trouble.
I warm our oven to 175F, turn it off, put the item to be gently roasted in there with the door ajar and then wait until it has gone ambient temp again.

Works great for drying out recently washed pcbs too!

[Zebidee]

I measured the oven and it was at least 8cm too short, even diagonally.

On local online market I found exactly one variety of small double bar electric heater (2x300W), no fan! Perfect. Cost about US$10, awaiting delivery!





Some parts of Thailand do get a little cold in the cool season.

On other news, am going to have to upgrade the relay in my power distribution arrangement. Seems that the amp + 2x50W speakers is causing the cheap Chinese $1 10A relay to get a bit stressed, especially when I turn the volume up. 10A should be more than enough for the whole system, which should not draw more than 5A max, but who knows for sure about long-term performance and on/off current peaks etc.

In addition, the Chinese mechanical relay often sticks ON when I turn power off, meaning residual current is still generating enough voltage to spark across the relay contacts as they are released - and then making them stick again, something like welding. You can gently tap it loose with a screwdriver. Anyway, the issues will only get worse.

I could install a "snubber", but I suspect that won't solve all the issues.

So I'm going to try replacing it with a solid state 40A relay, similar to this one. More on that next time

[Zebidee]

A triple dip La Nina will not be doing well for our precipitation levels at least.
Lots of great surf from the west with little wind probably, but squat for rain.
Time to up the ante on irrigation for the goats!

Yeah there are some weird weather cycles going on.

That La Nina brings repeated flooding to Oz, droughts to the other sides of the pacific.

There was a hurricane off Vietnam couple weeks ago, and all the rain depression from that came over Laos and then our place here. It really isn't that far! We didn't get the winds, just the rain.

[Zebidee]

So I'm going to try replacing it with a solid state 40A relay, similar to this one. More on that next time

So, I replaced the relay with the new solid state 40A one (~$2.50), and so far it is working well, much happier than the cheap Chinese 10A one (<$1).

Unfortunately, the 24v power supply had partially failed. Possibly because of the cheap relay? Maybe. I was only getting about 6.8v out of it, enough to run the audio amp but not the LED strip.

So I pulled the PSU apart and had a good look, nothing unusual. Checked all the diodes (OK), then checked the big and small transistors (all OK).

Finally I got out my Dick Smith ESR meter and went over all the electrolytic capacitors, and found one 47uF 50v capacitor that looked normal, but with ESR way high out of range! I pulled it and measured with DMM, was only reading ~30uF. It was obviously on the way out.

This cap is on the controller chip Vcc input. If it doesn't get charged, the IC won't turn on, and the secondary stage of the voltage conversion won't happen. Which is why I was getting 6.8v, not 24v.

I replaced it with a Rubycon cap with same specs. Now all is good again

Very happy to have been able to diagnose and fix that problem for myself. If you ever find yourself in a similar situation, I found this video very useful. This dude has a very strong accent, and an amusingly intrusive cat, but knows his stuff and is very informative:





Another issue is with shared grounds between 24v PSU, PC and IPAC via audio ground.

I was seeing pause and admin (<SHIFT>/enter) "get pressed" repeatedly... especially when playing music.

At first I thought there was a short in my wiring, checked everything I could, but both buttons are way up/back in the marquee area. I've already cable tied it in, I didn't want to rip it out needlessly. Good thing I didn't.

I am now 99% certain it is ground loop related. If I pull out the audio input from PC to the amp, the button problems magically go away.

So I ordered a 3.5mm plug-in audio ground isolator, see how that goes in 2-3 days time.