Help Needed Please! Electric Machine Fault.

[Scruples]

It could be a failed capacitor (usually a large one) that is designed to smooth out the DC after rectification. They can short out internally which would wreck a fuse holder after a few attempts to start the machine again.

 

[MorrisWoodman12]

I think @AES is correct in his comment that brushless motors were far from common in the 80's and 90's. I'd guess not from having the ideas or the drive electronics but rather the rotor position sensor.

 

[AES]

UPDATE:

I still (!) haven't got the PCB out but have now had a reply from Dictum, the seller.

The PCB costs Euros 149.90 and a spare fuse (I shall order 2) Euros 4.90 each. Delivery time is quoted as 3 weeks.

I shall go ahead and order today (if the existing PCB is repairable I'll just keep that as a spare). And no quote for postage charges. No doubt, as we here are NOT EU, but Dictum is, I shall pay some Customs Import Duty too! But to keep the postage charge reasonable (compared to us in Switzerland, Germany is VERY cheap anyway) I'll order some more spare (Pegas) blades at the same time.

Once I do manage to get the PCB out I'll post pics. I SHOULD be able to do that before the above 3 weeks are up!

P.S. A note and a Question for Excalibur owners only:

1. NOTE: I see from the Dictum quote that the PCB is officially described as "old model". The S/No of my machine is 22249914 if that helps any other owners (I don't have the year of manufacture but I bought it mid-year 2015).

2. QUESTION: As above, getting this machine apart is NOT easy - and it's taking quite a long time as I'm photographing and making notes and listing P/Nos as I go. Obviously of NIL interest to those who don't own Excalis, but I know there are several other owners on this Forum. So when complete shall I post all the dissassembly info here (on the Scrolling & Scroll Saw Section)?

Again thanks to all for the help and encouragement.

Cheers

 

[pulleyt]

So when complete shall I post all the dissassembly info here (on the Scrolling & Scroll Saw Section)?

That would be very helpful, thanks.

 

[AES]

OK, will do. But "don't hold yer breff"!

 

[AES]

UPDATE. Monday 16th Oct:

SUPPLY:
I now have all the info needed from Dictum in Germany:

The price of the PCB is €125.97 and the fuse is €4.12. Courier delivery is €13.40. Items are both available on the shelf for immediate delivery from Dictum.

BUT: Dictum seems to have changed their rules: They will only accept credit card payment if you live in Germany. For everyone else payment is by Proforma Invoice (i.e. you pay, then when they get notification of payment from their bank they ship the goods). But at least you get a 2% discount on the total value of the goods if paid within 10 days of Proforma Invoice date!

Their Invoice will be paid today, so even with this delay I expect to have the goods in my hand within 7 to 10 days.

A couple of points for anyone in UK thinking of buying from Dictum (as Germany is EU whereas neither Switzerland nor UK are, so I expect the following will apply more or less equally):

The courier will charge me a Customs Clearance charge ("admin fee"). Based on past experience this will be excessive and bear NO relationship to the actual "work" involved in clearing the goods through Customs (I have done that myself in several countries quite a few times and with the right paperwork - i.e. a Proforma Invoice and Customs Ref Nos for the items, - it's no problem, AND goes pretty quickly too). AND the courier charges are NOT related to the value of the goods either.

In other words it's just a con - IMO anyway! But one has no choice except pay up!

AND Swiss Customs MAY also charge Import Duty (my experience here is mixed - sometimes they do, sometimes not). When I know what these extra costs are I'll post details.

THE MACHINE:

I'm STILL working out how to get the PCB out! I cannot see any reason why I need to remove the motor itself (from the spare parts diagrams in the Manual nothing shows) but I still cannot get the "Control Cover" off to get the PCB out. I've done a lot of online searching about changing the PCB on the Excalibur (and on similar machines) but though I found several pix of the PCB itself, NOTHING found on getting into the machine to remove it.

So I'll be going onwards with that today. First I'll need to make up a "special tool" to lock the motor solid while I remove the nut holding the motor spindle onto the eccentric drive.

More later .................

 

[ajs]

UPDATE. Monday 16th Oct:

SUPPLY:
I now have all the info needed from Dictum in Germany:

The price of the PCB is €125.97 and the fuse is €4.12. Courier delivery is €13.40. Items are both available on the shelf for immediate delivery from Dictum.

BUT: Dictum seems to have changed their rules: They will only accept credit card payment if you live in Germany. For everyone else payment is by Proforma Invoice (i.e. you pay, then when they get notification of payment from their bank they ship the goods). But at least you get a 2% discount on the total value of the goods if paid within 10 days of Proforma Invoice date!

Their Invoice will be paid today, so even with this delay I expect to have the goods in my hand within 7 to 10 days.

A couple of points for anyone in UK thinking of buying from Dictum (as Germany is EU whereas neither Switzerland nor UK are, so I expect the following will apply more or less equally):

The courier will charge me a Customs Clearance charge ("admin fee"). Based on past experience this will be excessive and bear NO relationship to the actual "work" involved in clearing the goods through Customs (I have done that myself in several countries quite a few times and with the right paperwork - i.e. a Proforma Invoice and Customs Ref Nos for the items, - it's no problem, AND goes pretty quickly too). AND the courier charges are NOT related to the value of the goods either.

In other words it's just a con - IMO anyway! But one has no choice except pay up!

AND Swiss Customs MAY also charge Import Duty (my experience here is mixed - sometimes they do, sometimes not). When I know what these extra costs are I'll post details.

THE MACHINE:

I'm STILL working out how to get the PCB out! I cannot see any reason why I need to remove the motor itself (from the spare parts diagrams in the Manual nothing shows) but I still cannot get the "Control Cover" off to get the PCB out. I've done a lot of online searching about changing the PCB on the Excalibur (and on similar machines) but though I found several pix of the PCB itself, NOTHING found on getting into the machine to remove it.

So I'll be going onwards with that today. First I'll need to make up a "special tool" to lock the motor solid while I remove the nut holding the motor spindle onto the eccentric drive.

More later .................

@AES do you have any updates on this yet?

 

[AES]

@AES do you have any updates on this yet?

Yes I do. Will post today/tomorrow. After a LONG hassle I've now got the PCB out! AND I just heard from Dictum yesterday that the new PCB is on the way and should be with me next week.

As said, removing the present PCB was an AWFUL job (or I made it so anyway!) but there will be a full write up on the process, definitely today/tomorrow, or latest by mid next week. Meantime here's a pic of each side of the removed PCB (finally got it our yesterday)! Even allowing for camera shake/out of focus (my shaky hands with a mobile phone camera) I think you'll agree that PCB looks pretty much "as new"!

There are of course a number of leads I've removed from the board (from the motor; ON/OFF switch; speed control; etc).

Thanks for your interest; more asap:

 

[ajs]

Interesting. Not what I expected to see to be honest. There's no caps chunky enough in there to be smoothing the rectified power to the motor, must be cutting the waveform as traditional light dimmers did until florescent and LED.

Just to make sure I've reading the board correctly, I take it the mains comes in at the corner obscured by the connector to the speed control? And is that black rectangle at the top some kind of daughter board with surface mount components on it?

What does the MOV (circled in orange at the bottom) look like? Should be heatshrink covering flat, parallel sides excepting a wire from the board that disppears into the disc. Photo hints that it may be mis-shapen. Those are designed to short out any overload (e.g. a power surge) but return to normal once the fault disappears, unless they themselves get overloaded.

 

[AES]

Gents, I'm afraid I am "überfragt" as they say here (in other words, sorry I haven't a clue)! When I showed the above pics to my brother in UK, who knows "a bit more" about modern electronics than I do (that's NOT hard!) he said "AH YES, THAT LOOKS LIKE A CHOPPER"! (Well, I thought that's a kids bike). Seriously, as the little electronics I learnt was a LONG time ago, I was also surprised to see that PCB - I expected to at least see something like a Wheatstone bridge with 4 resistors arranged in a diamond shape, plus a couple of big can-tape capacitors. Shows how much I know!

I really am running under time pressure folks, very sorry, but despite your interest and readiness to help an old duffer like me, I have no time to post further until I've completed the promised "How To Remove" write up - as above, latest mid next week.

But before I log off for tonight, there's another pic below which MAY answer some of your Q's:

For clarification:

1. The red/orange/dark red cables going through the quick connector then get covered in black outer sheathing go up through the top arm to serve the speed control knob and ON/OFF switch;

2. Fairly obviously I think, the 2 x green leads disappearing off out of the LH side of the pic go to a common earth point, as does the green/yellow lead (soldered to the PCB) shown on the pic RH side;

3. The 2 x blue and 1 black lead go, in two cases via the spade connectors to the motor, and the 2nd blue cable goes direct to one side of the mains inlet "kettle socket".

Really sorry, but apart from the 2 yellow rectangular thingies (my brother says they're relays) I do not recognise ANY of the components on that PCB apart from; the two torroidal transformers (?); and the two power transistors (???) mounted with their respective ali heat sinks.

Please note that from the two previous pix, plus this one, that the PCB and all it's components look "perfect" to me. I see NO sign of dry joints on either side of the PCB (I DO know what they look like!); no sign of any distortion or discolouration on any components (that I recognise anyway); nothing is loose; there's no residual smells, and apart from a very small amount of "normal household dust" on the inside of the plastic moulding which holds the PCB, there's certainly nothing at all sooty-looking anywhere. (I should perhaps add that while I certainly would not call that PCB housing "hermetically sealed" it IS pretty well protected from the ingress of fine wood dust and general carp and is generally well closed up).

When finished my write up WILL cover all the mechanical aspects of getting the machine apart (including removing the motor, which as I suspected before starting removal was NOT necessary!); and I have taken a number of pix of the electronics (mainly to help me reassemble).

But after all that's posted (as said, I'm aiming for mid next week at the latest) I'll be pleased to answer any queries. But when it comes to invisible electrons wizzing silently and mysteriously along wires and through unknown components, just don't expect much in the way of any sensible answers!

Again, thanks for all the interest and help and encouragement.

 

[MorrisWoodman12]

I can see no obvious component failures in any of the pictures @AES has supplied. I can see however a daughter board with black conformal coating at the bottom of the last picture. It obviously has a couple of integrated circuits/ICs/chips on it and presumably a few other surface mount components. If that has blown in some way then there is no repair. Most likely failed components though are the heatsinked transistors.

 

[okeydokey]

Good luck and fingers crossed the new pcb is the fix

 

[AES]

Good luck and fingers crossed the new pcb is the fix

Again, thanks to all who have shown interest and help in fixing my Excalibur Scroll Saw problem.

In a previous post I said that I'd post a "Procedure" on how to get the PCB out of the machine (once I'd found out how to do it, 'cos I couldn't find anything anywhere on the net to help).

Well I've now done so, and I guess because I've "meticulously" referred every removed part to the Parts List and Diagram, AND because I've also listed all the tools & sizes needed, I've ended up with a potential post which in draft comes to almost two full A4 pages.

Frankly I think that unless anyone on here already owns, or is thinking of buying one of these machines, the whole thing is a VERY boring read and would soon stop being of even passing interest to anyone not owning this machine (or similar).

So I THOUGHT that it should NOT publish that detailed "how to" here, but rather post separately on the Scrolling & Scroll Saws section.

That would mean that this thread will again remain silent until I've fitted the new PCB (due this week) and seen that a new PCB was indeed (or not? the fix?

What do you all think please?

 

[MorrisWoodman12]

Is it possible to post your tome into the How-To's section of this forum. Mind you I don't know how-to do that.

 

[Spectric]

When you look at that PCB it just jumps out as being very old technology and crude, yes it is simple and works but when will these machine OEM's embrace newer technology based around a processor. A small DSP would have a very small footprint and not only provide many options for motor speed control but also protection from many fault situations and therefore offer protection rather than component failure. Once they have the board it could easily be used across a wide range of machinery just by using different software / firmware. Take this up a level to larger machinery and they could then use a three phase motor across the product range and offer speed control where needed, plus you don't need the starting capacitor and will get smoother power delivery with more constant torque, especially if you embrace field orientated control.

 

[Sideways]

Much truth in that.
That board is doing less work than the variable speed control built into the trigger of your power drill and the tech is about as old as I am !
Oddly, about the only positive justification for sticking with something that dated would be to to make it easy to replace a component

 

[AES]

Is it possible to post your tome into the How-To's section of this forum. Mind you I don't know how-to do that.

Yup, will do (when I find out myself)!

 

[ajs]

Much truth in that.
That board is doing less work than the variable speed control built into the trigger of your power drill and the tech is about as old as I am !
Oddly, about the only positive justification for sticking with something that dated would be to to make it easy to replace a component

I'm surprised to, seems done on the cheap to avoid the need to step down the voltage. It appears to connect the motor directly to the mains for up to a quarter of the mains cycle, it's that duty cycle which allows a 60V motor to be used (240 ÷ 4 = 60V).

I've sketched out how it seems to work in the attached photo, connect it to mains for only e.g. the rising portion of the positive half of the mains cycle.

However that has some drawbacks. The power factor will be utter crap. The saw will need to make at least six strokes up and down carried by it's own momentum, even at the lowest speed. More significantly the entire circuit is exposed to peak mains voltage, insulation including motor windings need to accommodate that. The same goes for the speed controller pot - there will only be some lower voltage across it along with the rest of the control electronics, but regs state it should be a safe condition even if live and neutral are reversed, I suspect it would actually be at the mains voltage level in that case and I doubt it is mains rated.

Curious now, going to have to hang a scope across the motor on my Diamond to see if it's the same...

 

[Sideways]

Transformers are physically big, costly to make and costly in copper compared to switch mode power supplies. I absolutely get why manufacturers avoid them wherever possible.

I'm too lazy to try and reverse engineer the schematic from @AES 's very decent photographs but I did suspect something similar to you when I went looking for the classic four diode bridge and didn't find it. There's one bigger diode labelled D1 hiding behind the two blue + black wires and the inline plug+socket, so yes, the circuit maybe drawing power for little more than a quarter of each cycle.

 

[AES]

Thanks for your continuing interest chaps. Sorry but I am just not able to comment at all on any of the last 3 posts about the electronics (I know enough to know when to keep my mouth shut)!

But assuming you're correct about the electronics being old-fashioned, I wonder if any of you can hazard a guess as to why?

I ask that question in the light of the fact that A): This machine IS generally reckoned to be amongst the leading makes in scroll saws;
B): AND in the light that having had a decent mech eng training, I DO feel qualified to comment that after the stripping exercise nothing has changed my initial feelings and impressions of the high build quality of both the machine itself and all the fasteners used.

Just as a couple of examples, the machine "main frames" (quite complicated shapes and bends) have been fabricated out of mainly 7 to 8 mm steel plate, very neatly welded then cleaned up. AND there is not a single burr, a ragged edge, mis-shaped opening, nor a mis-drilled hole!

And as just a second example, the paint finish (high gloss black) is "perfect - either electro-static powder coated then baked, or sprayed and stove enamelled (I can't tell which). Whichever, even on the unseen internal areas, coverage is 100% and flawless. I've seen worse finishes on a new car! And from the mechanical design, specification, and assembly viewpoints, I could go on all day about the VERY high standards maintained throughout.

In short, this machine should NOT have failed within anyone's lifetime. I certainly did not expect it to.

So again my question: If it's EXCELLENT from all those points of view, then why on earth, according to those that seem to know their onions, is the electronics a bunch of carp? Doesn't make any sense to me, and in view of the cost when new 8 years ago, and the new price today, it CANNOT be because the bean counters have been getting at it.

Anyway, I have nearly finished the full write up on how to remove the PCB (and a separate one on how to remove the motor). I'll post those separately - at the suggestion of MorrisWoodman12, in the "How To" section of UKW, rather than here. As it's a detailed write up and must be dead boring reading for anyone who doesn't own one of these machines.

Will be posted before the end of this week (before I disappear out of reach of my PC for a week starting next Sunday).

Cheers