Chriske

1 hour ago, Dr_Ju_ju said:

It will depend on where in the frequency cycle the switching occurs, if you are switching at the mid point of frequency cycle, you'll be ok, as you'll effectively be switching 0v, but if you are switching at the peaks, then you will be switching at full voltage, which then could have high voltage\current switching transients, very much dependent on load type, i.e. resistance\inductance etc. 

For it to always to be switching at the mid point, would require some form of frequency synchronisation, which isn't available in these 'simple' systems, although I have used it in broadcast equipment for certain type of equipment.

Hey guys,

How do I know this : It will depend on where in the frequency cycle the switching occurs.

Meanwhile all parts except for the heatbed are replaced and re-connected.

7 minutes ago, Icosahedron said:

This is more likely the problem.

Thanks..!!!

All SSR's I used in all printers will be replaced asap

53 minutes ago, Dr_Ju_ju said:

But what was the SSR bolted to ??  as the back metal plate of the SSR should have been connected to earth ...... 

Why is that ...?

Bed 'seems' ok
80 Ohm(the old one) and I had a spare and measured 82 Ohm.
The built in thermistor and a new one both 125K.

Fingers crossed...?

Thanks guys for all the help...
The thing is, two months ago my best pal Marc died. We were a close team. I did the designing/drawing of telescopes and other stuff and he did all the electronics.
I have a basic knowledge electronics, but mostly I'm in the dark.
There is another guy helping me from time to time, but his free time (due to his work) is very limited. And don't dare to ask him to often.

So again, THANKS very much to you all.

Oops...did not know...!

Dam..

The 240V bed is earthed...of course..!  Safety first..!
I never use anodised alu.

Wonder if that silicone bed is still OK...

What you are saying JuJu, all these SSR should not be used in PMW systems...??

Dooh...!
NOW I understand...! Yes that's it...!!!

The moment the SSR is completely molten, then the bed stops warming automatically.
Silly me, not trusting the manufactures of this nice looking JUNK... !..😡

Did some 'dismantling', I have not been gentle...🤗
Emotional people should skip this post...
You have been warned...!

Here we go..
Tools needed to do this job : Hammer , screwdriver, pliers, lots of force..!

Before

A few seconds later

 another 20 sec later...

A bimetalic thermostat, would not last very long. The beds are all PMW powered.

1 minute ago, Dr_Ju_ju said:

...but even name brand parts are also sub-contracted out to the far east..... 

Sadly enough...!!!

Planning to install a second Arduino, or a Nano, to do a extra temp-check on both heaterblock and bed, parallel with the primary thermistors.
When something like this happens again, the secondary safety circuit will cut power completely.

Frankly, I had no idea these (made in RC) rubbish parts were this bad.
I'd think a safety margin or a fuse was built in...NOT...!
Problem these days : All things we buy here in European countries are also marked 'Made in RC'

Good thinking maybe I could buy from RS in UK

Not were I live, dam...

1 minute ago, Dr_Ju_ju said:

Nooo, you can buy from RS\Farnell directly, I do it all the time....

I'll replace them all asap
Problem is you need to run a company/business to buy from them.

Hi all,

I always build my own printers. One of a 'standard' part in all my printers is a SSR, like this one. I've also built a few of my printers for friends.
Anyway : Suddenly that SSR got stuck. Silicone heater bed kept warming.  I entered my workshop and a burned electronics odour immediately set me in 'alarm' modus.
Bed temp at that moment was 265°C...!  Glass(bed) all over the place..!

Lucky me I was at home...!😳
I'm absolutely sure many of us (printer builders) use these SSR's....!
You've been warned..!
 Main question now : were do we buy trustworthy SSR's...??

15 hours ago, AlentejoSkies said:

I put a discarded print piece (the same PET-G) in the icebox for a few hours and took a hammer to it this evening. I had to give it quite some blows to chip a first piece off and I didn't get its structure to break before I felt I had to stop to not disturb my neighbours.

Very professional and scientific approach indeed...🤣🤣🤣🤣

23 hours ago, kbrown said:

Why did I read this as "Your wife will never be the same again..."

Well, now that you make a joke out of it, the thing is...

When we first started building printers and our very first part was 'born'. My wife looked at it, lifted her eyebrow(maybe two, don't remember) and said : 'Yeah.... toys for boys'
Seven years later, I lost count how many, small tools and replacements have been made by me for my dear wife, printed with that 'Toy for boys' machine. And what's more I don't even ask to make all these things. When she needs something for here hobby, or something small is broke, she comes to me and  asks if I could make/repair something for here.
😁

'Glow in the dark' filament would have been better imo..🤗

(just kidding)

Nice job btw..!

In those days we thought it was 'normal', but these big DarkStar scopes are far to heavy imo.
We're going to dump the tube and will install trusses.

Looking for a self-made (very) low profile focuser I didn't found any, except for the one I made.
But there's a printer involved.
Anyway, completely focused 'inward' it's only 28mm high.