Potterton Netaheat 10/16 controller burnt?

[T i m]

Ok.

Agreed.

Ok.

From the recent findings with RLB coming out with a pull with my finger and thumb and then the igniter txfmr falling out when I dropped the PCB on the carpet, I suspect dry joints (especially on this bigger stuff) were rife. ;-(

I've checked that and it is (was) a 1A Dave. (Would it normally be a std, quick or slow-blow? I'm guessing std?). It says F1L250V

I'll check for that.

I've managed to get hold of a s/h (and what looks like later) controller so after checking things like the resistance of the fan I might just try this spare board. If there is something broken enough to take out this spare board then that would probably suggest it might be waiting to see what Warmfront (or whatever they are called now) come up with?

Will do.

Thanks for all your time ...

Cheers, T i m

[T i m]

It does, doesn't it. ;-(

The coil are ether side of the end with 3 connections aren't they Chris (with the relay common in the middle) and so I think there were ok. It was one of the main contact pins that look like it had been the start (or part) of the issue.

Received, and thank you *very* much, I'll have a good look though them in a bit.

As mentioned elsewhere I do now have a spare (s/h) controller so after finding a new fuse for (it didn't come with one for some reason?) and testing things like the resistances of the various loads (especially the fan) I might give it a try. If all is well I may also look at repairing the old one, just for the S&G's. ;-)

Thanks very much again for all your info and help.

Cheers, T i m

[Mike Tomlinson]

En el artículo , T i m escribió:

That looks much better made. I had a similar issue with the PCB for a Poxi Batterton boiler - a Suprima - it's featured in this group many times, and the redesigned PCB from Baxi was of far superior construction.

The boiler featured on Watchdog and after I sent off a snottogram referring to the programme, BP refunded the cost of the replacement.

It would be worth metering the fan and the gas valve just to make sure they're not a dead short before trying the replacement board.

[Mike Tomlinson]

En el artículo , T i m escribió:

[T i m]

It does, doesn't it. ;-)

Shame the fuse holder is two separate pieces and they aren't aligned properly. ;-(

And that's fine if there aren't often 'stupid money' as you would just treat it to the better version.

Will-do. If they don't look 'bad' I was even considering hooking the fan up directly and checking the current draw, prior fitting the controller?

Cheers, T i m

[T i m]

Hmmm, well, yes ... but it was guaranteed as 'working' so we will see. He might have nicked the fuse for something else?

Again, I can just power it up with no load and check that at least it doesn't blow it's fuse like that etc.

Cheers, T i m

[Mike Tomlinson]

En el artículo , T i m escribió:

A good idea. Lash up a mains cable with a 1A fuse, if you can find one, in the plug?

[Andy Burns]

I was going to say I didn't think you could get BS1362 1A fuses, but it seems you can ...

Are they non-standard? The BSOL "pseudo PDF" renderer is so slow I can't be arsed to wait for it to load.

[Mike Tomlinson]

En el artículo , Andy Burns escribió:

You can (I have a few). They are labelled BS1362. I got them from RS.

although 100 might be more than you want :-)

The problem is, they're black, so can be confused with 5A unless you check the printed rating.

Don't see any reason why they should be. They're useful for things like lamps, especially if the flex is long and thin.

[T i m]

I was thinking if I first measure the resistance and see that it's 'reasonable' then I could just hook it into the boiler incoming choc block and leave the DMM in series and see what current it draws?

Cheers, T i m

[Dave W]

Yes, the "F" on the fuse means quick blow. Slow-blow would be "T". The terminal pins on the new board are not in the same place so I hope it's obvious how to connect the wires. I agree with your plan to measure the resistance of the fan to check that it's reasonable.

[T i m]

Ah, I thought I remembered there being a key, thanks (but as has been mentioned, 'quick' isn't often quick enough where semiconductors are concerned). ;-(

Oh? It looks like they are the same from the units themselves?

Ah, cool, thanks. I'll give everything a measure and note them in case they are of interest to anyone else working on this model (assuming it works etc). ;-)

Cheers, T i m

[Geo]

Thats one of the benefits of lead-free solder.. and why it is not used in aviation or military equipment.

[Johny B Good]

Please keep in mind, when checking the fan motor, you may find a 'low' resistance value of maybe 30 or 40 ohms. A perfect motor would have zero DC resistance. However, if it shows a short circuit, that's unlikely to indicate the use of a 'perfect motor', more likely just simply a short cct.

[T i m]

Leaded solder you mean (on aviation and military equip)?

I was talking to a guy who had once worked on some missile gear (back in the day). He suggested they used to solder all the components together for in the form of a big 3d ball and once complete, screw the ball up into it's smallest space and then just tease it apart and test it. If it still worked it would be dipped in resin. Apparently, (and possibly what you were saying), the 'G' forces of something like a Rapier missile on takeoff would rip most components off any PCB?

Cheers, T i m

[T i m]

Ah, ok.

If it was made from superconductors you mean?

Understood ... that or it's getting VERY cold in her kitchen. ;-)

Cheers, T i m

[Roger Mills]

Not if it was properly soldered in. But it's a bit chicken and egg. The overheating might have melted what were previously perfectly good solder joints. Or a dry joint may have caused the overheating.

[Chris K]

FYI the fan motor coil resistance is about 86 ohms (at least the dead one I replaced for bearing failure is).

IIRC the sequence is something like turn on fan, when pressure switch shows cabin pressure reached, turn on igniter and pilot valve. When flame sensor shows pilot lit turn on main gas valve. If flame sensor shows no flame, or fan fails, turn off.

All done with 3 transistors, two relays - and no software.

HTH

Chris

[T i m]

Brilliant, thanks.

Yup, not only does that make sense it's what I read in the stuff you kindle sent me.

And looking at the diagram you created, it's all very clever indeed. ;-)

I was a datacomms service / tech (BT and more) and was happy with faultfinding most serial / digital datapaths, or even analogue / audio when you had a 'path' that could easily be scoped. It's when you get these clever voltage divider / forward / reverse biased diodes > feedback > logic loops then I have to really try to work out what it's doing. ;-)

Again, I'm sure it will (I have some 1A QB 20mm fuses now so might pop over in a mo to have a look).

Cheers, T i m

[T i m]

Understood, especially for the joints around the burnt bit. It doesn't however explain the igniter txfmr (nearly) falling off that is at the other end of the board. ;-)

Cheers, T i m