PCB Boards -- Simple Machinery

[JohnerH]

If you hard wire the motor through a suitable DOL (motor starter) and if the PCB is some form of brake, you will just loose the braking function. So the machine will not be regulations compliant, and you can’t use it with employees. Typically for this size of machine before the PUWR regs came in, none had any form of braking. The regs are to prevent people getting injured because they became impatient waiting for the machine to slow down and stop and stuck their fingers in / too close.

@deema, No else but me and my wife will be using this machine and quite frankly it's a stop gap for me to board up the garage walls with pallet wood, once the garage is up and running I have the Wadkin RM big boy to take over.

Although potentially it might come in for small jobs.

It's unlikely that the board itself will spontaneously experience RUD, so there will have had to have been (an) external event(s).

It's perfectly possible that the resistors are fried because they were initially a bit underrated and long running may have shortened their life. Alternatively, an unexpectedly high main voltage (we get up to 250VAC here out in the country) or a big spike/surge (think: lightning etc.) or network provider issues could have taken the unit out of its safe operating area (SOA). The TVS on the input (the round beigey-orange thing) will only absorb a certain amount of energy - at a certain point they just stop working or in extreme circumstances, they explode leaving black soot everywhere. See the photos below of a blue one (Aqualisa shower mixer controller) and the remains of a beige one (cooker hood fan & light controller)...

Record Power don't have the manual available and I can't find it elsewhere - any chance you can scan & post it (it'll be useful for others too, no doubt). It may give some insight to the use of the 1-8 jumpers, which in turn may explain a lot about how that PCB is supposed to work. It's possible, for instance, that the board implements a "slow-start" rather than over/under voltage protection - pure speculation until there's a schematic.

Whatever happens, that PCB only contains cheap and still-available discrete components - no microcontroller or sealed-up magic - so it most certainly repairable.

My original point remains - just repairing the board without understanding its operating conditions is probably a waste of time - definitely need the whole machine checked.

View attachment 185194View attachment 185195

If I can fix it with help then I'm here for the learning experience,

Manual attached.

Just noticed the wiring diagram also!

 

[nickds1]

Thanks for that. Looking at the wiring diagram (SLD) and the PCB a bit more, the PCB, 4017 and associated pin header may be to do with timing the disconnect of the start capacitor. The SCR would, in that case, be delivering half-wave mains to the starter cap & winding until the timer expired (SCRs auto-turn-off when the current through them drops to zero).

As mentioned, it'd help to have an ID on all the "Q" components and also the spade connectors onto the PCB (which ones are 1-5?).

What make you think the capacitor is OK? Has someone tested it?

If the start capacitor is bad or permanently disconnected due to a PCB fault, then you would indeed see the motor shaft just wobbling and not starting. i.e. the symptoms are pointing to a cap or PCB issue. As other have said, re-wiring without the PCB and using a standard start cap disconnect method - there does not appear to be a more usual centrifugal switch on this motor so maybe use a "potential starting relay" - may be simpler in both the short and long term.

 

[Spectric]

I know breaking is needed, but again, this machine isn't getting sold

Why when the later machines do not have this feature, my PT107 just slows down under it's own inertia.

If I hard wire this thing with a PCB, what can realistically go wrong?

I assume you mean without the PCB then the answer would be a lot less.

 

[JohnerH]

Thanks for that. Looking at the wiring diagram (SLD) and the PCB a bit more, the PCB, 4017 and associated pin header may be to do with timing the disconnect of the start capacitor. The SCR would, in that case, be delivering half-wave mains to the starter cap & winding until the timer expired (SCRs auto-turn-off when the current through them drops to zero).

As mentioned, it'd help to have an ID on all the "Q" components and also the spade connectors onto the PCB (which ones are 1-5?).

This will take time and more pictures, but it can be arranged. Thank you for the help

What make you think the capacitor is OK? Has someone tested it?

Yes, it beens tested with 2 different capacitors from new and also, when I hard wired it directly to the mains it started and when chaged the poles it started in the other direction. Both indicating good capacitor.

If the start capacitor is bad or permanently disconnected due to a PCB fault, then you would indeed see the motor shaft just wobbling and not starting. i.e. the symptoms are pointing to a cap or PCB issue. As other have said, re-wiring without the PCB and using a standard start cap disconnect method (there does not appear to be a more usual centrifugal switch on this motor) may be simpler in both the short and long term.

The standard cap here would the compenents already there, right?

Why when the later machines do not have this feature, my PT107 just slows down under it's own inertia.


I assume you mean without the PCB then the answer would be a lot less.

Thought so...

 

[deema]

This has really peaked my interest. Great we have @nickds1 to guide us through the circuit.

We know the motor runs hard wired up, which suggests the cap is OK. If he’s run it for more than a few minutes the start cap would have given up if the usual manual disconnect in the motor wasn’t working. The wiring suggests just a single cap for run / start though.
Looking at the wiring diagram, I’m still thinking, probably incorrectly it’s a plugging brake system. The board has access to both coils which wouldn’t be needed if it just switched the cap.
I haven’t seen a plugging circuit before which is why I’m so interested in it.

 

[Spectric]

Newer braking systems use Dc injection rather than trying to reverse the motor which can be more stressful to the system.

 

[Sideways]

The detail that strikes me from the wiring diagram is how poor the industrial design concept is. It's a total kludge.
The design of the machine means a variety of guards are needed to make it safe and these need to move around between planing and thicknessing. The selector switch on the front really appears to be implementing a mechanical logic function to make sure the machine can't run unless the guards are in the proper position for each mode. Ugh.

Re: a DOL starter.
It needs to be 240V, not 415V because there is a coil inside and that is voltage sensitive.
It needs to contain a thermal overload relay. These are adjustable to cover a range of motor sizes, but their adjustment range is limited. Most off the shelf starters from screwfix etc are intended for bigger motors and may not adjust down low enough for a single phase machine of 1.5 or 2kW.

The tend tew11a6 is a potential budget option
https://tewltd.co.uk/product/axiom-dol-starter-single-phase-ac3-3kw-4hp-12a-240v-tew11a6/

It is rated upto 12A and should adjust down to 8.5A which is needed to match the motor in the RP planer (2kW in, 1.5kW out).
I installed one of this brand a few years back when they were stocked at toolstation (not any more) and I remember it as perfectly OK.

Incidentally, starters are pretty much all 3 phase devices. For a single phase motor you only use 2 of the 3 contacts inside.

 

[nickds1]

I'm most certainly not a motor control person, but as far as I can see a DOL is basically an NVR with added rather crude overload protection, plus it does nothing for single phase induction motor starting as there is no support for the second winding or capacitor.

 

[Spectric]

but as far as I can see a DOL is basically an NVR with added rather crude overload protection, plus it does nothing for single phase induction motor starting as there is no support for the second winding or capacitor.

The DOL is an industrial version of a no volts release contactor, the ones we find on many home workshop machines is a cheap alternative. All the switch does, DOL or cheaper version is to switch power to the motor and is not involved in starting the single phase motor which is done by capacitor or a startup winding with centrifugal switch .

Motor overload is a situation where a motor is drawing excessive current but not enough to trip the protective device so a thermal overload is used which can be adjusted to suit the power rating of the motor over a small range, so you need to buy the correct rated DOL to start with so it can handle your motor current. With industrial three phase you still get the basic thermal overloads with many motors but you will also come across more specialised protective measures for under / over voltage, loss of a phase and some also have an input that can sense motor winding temperature via a resistive device (NTC) located within the motor.

The design of the machine means a variety of guards are needed to make it safe and these need to move around between planing and thicknessing. The selector switch on the front really appears to be implementing a mechanical logic function to make sure the machine can't run unless the guards are in the proper position for each mode. Ugh.

That selector switch for modes is not needed, on the later machine you have two switches in series, one for each of the tables so if either table is lifted it prevents the machine running and once both tables are lifted and the extractor hood is lowered into position this operates a third switch to re-make the circuit. With the extractor hood lowered the drum is now shielded and " safe " . It is simple but effective and I suspect that the rspt 260 machine was Records early version of a P/T that was part of there design learning curve and the brake was included because they thought it was needed and other things like the mode selector switch had not been properly thought through. Then cost savings followed and more thought went into the design along with no brake or mode switch and from the looks off it other parts were made cheaper to end up with Records current line up with the startrite brand re badged to Record but with a one piece table.

They are also now selling the PT107 2 helical but then say a 4 spiral so are they confused, it is actually a spiral cutter block because all the knives are on the same plane wheras a helical the knives are not all on the same plane. The rspt 260 has just two blades which when you look at the rest of it being / looking better built you would have thought three or maybe four.

 

[JohnerH]

The tend tew11a6 is a potential budget option
https://tewltd.co.uk/product/axiom-dol-starter-single-phase-ac3-3kw-4hp-12a-240v-tew11a6/

Hi @Sideways, thank you for the advice,

Looks nice and cheap...

@Sideways/@Spectric,

Would this be a good alternative?

RS PRO DOL Starter, DOL, 2.2 kW, 240 V ac, 1 Phase, IP55

It is rated upto 12A and should adjust down to 8.5A which is needed to match the motor in the RP planer (2kW in, 1.5kW out).
I installed one of this brand a few years back when they were stocked at toolstation (not any more) and I remember it as perfectly OK.

The above options (RS) would potentially not need any adjustments?

Incidentally, starters are pretty much all 3 phase devices. For a single phase motor you only use 2 of the 3 contacts inside.

I saw this, this motor has 3 contacts/wires, are you saying I would only need 2?

That selector switch for modes is not needed, on the later machine you have two switches in series, one for each of the tables so if either table is lifted it prevents the machine running and once both tables are lifted and the extractor hood is lowered into position this operates a third switch to re-make the circuit. With the extractor hood lowered the drum is now shielded and " safe " . It is simple but effective and I suspect that the rspt 260 machine was Records early version of a P/T that was part of there design learning curve and the brake was included because they thought it was needed and other things like the mode selector switch had not been properly thought through. Then cost savings followed and more thought went into the design along with no brake or mode switch and from the looks off it other parts were made cheaper to end up with Records current line up with the startrite brand re badged to Record but with a one piece table.

@Spectric, So am I to understand that this switch,

Isn't needed, it regulates whether it's on jointer mode or thicknesser mode.

They are also now selling the PT107 2 helical but then say a 4 spiral so are they confused, it is actually a spiral cutter block because all the knives are on the same plane wheras a helical the knives are not all on the same plane. The rspt 260 has just two blades which when you look at the rest of it being / looking better built you would have thought three or maybe four.

View attachment 185226

Possible upgrade when I finally have it running?

Thank you all for the help.

I haven't forgotten about the PCB photos (and connections), that's on tomorrow's todo...

 

[Spectric]

Isn't needed, it regulates whether it's on jointer mode or thicknesser mode.

What it does is nothing more than selects the safety inhibit switches, if you look at the diagram for the 107

these inhibit switchs A, B & C are not selected by any switch, they form a logic function that states for the contactor coil to energise you need ( A AND B ) OR C.

In planner mode with both tables down you have A AND B so it will run. Lift either table and it will not run because this exposes most of the cutter block so is prevented from running. With both tables lifted and the extraction hood in place covering the cutter block you do not have A or B but now have C which will allow it to run in thicknessing mode. What you need to check is how your switches operate as the manual shows only one table moved for thicknessing yet the wiring diagram shows two switchs in series that suggest the other table can be lifted but not neccessary, maybe maintenance. So do you have a safety switch that is operated only in thicknessing mode and another safety switch that is not operated in thicknessing mode because you have moved one of the tables ?

I saw this, this motor has 3 contacts/wires, are you saying I would only need 2?

Most of these DOL's are made for three phase where you have the three lives and no neutral, when using one for single phase you just use two of the contacts for live and neutral but make sure the coil is for 230 volts.

 

[Sideways]

Nothing wrong with the RS Pro one you point out, but like buying a £50k car, it isn't twice as good as a £25k model.
The overload always has to be adjusted and it is a graduated dial turned by screwdriver. Trivially easy for all that it is important.
if you are in a position to spend £100 on a starter for a machine worth £200, take a look at Crabtree at CEF electrical. They sell the thermal overloads separately so you can mix and match.

 

[Sideways]

as far as I can see a DOL is basically an NVR with added rather crude overload protection

Subtlties aside, a motor is a rather big crude mass of copper and steel.
Voltage spikes and the like don't affect them much, what they need protection from is a chap in a factory with a pallet full of resinous pine planks, banging them though the thicknesser one after another so he can get away home on time.
He might be taking a 3mm cut and the tables won't have been waxed to ease the load on the feed rollers.
The motor will be worked hard and will gradually heat up.
We just need to stop it before the varnish on the windings gets too hot. A simple but robust thermal overload switch is quite well suited to that.

If you have a VFD you can program much more precise overload protection but those contain processor chips with as much power as many early computers.

 

[nickds1]

This has really peaked my interest. Great we have @nickds1 to guide us through the circuit.

Don't raise your hopes too much!

I've been sketching out the schematic as far as I can - it's difficult to get the colour codes for all the resistors and I'm pretty sure that one or more of the DO-35/DO-204AH cased small diodes may in fact be zeners. One of the TO92 devices is a 5V voltage regulator and as suspected, the 4017 is counting mains pulses with the jumper set determining how much it counts up to before resetting.

It's moderately horrid and the PCB was obviously laid out by someone out of their head on a bad trip. It's very poor.

When I have the IDs of all the little black TO92 jobbies, identification of the spade connectors (1 to 6) and clear views of the resistor values (the capacitors are no so important but their values would be useful), I can fill in the blanks.

Frankly, might be simpler to post the board to me!

 

[JohnerH]

As promised,

Pictures from the PCB.

I tried to get the best of connection, I'm getting some wire labels so I can map them out better and then take pictures, but thought I'd post this first.

 

[JohnerH]

Back of the board...

Please let me know if you want finer detail on any particular picture.

 

[Spectric]

the 4017 is counting mains pulses with the jumper set determining how much it counts up to before resetting.

With the 4017 decade counter, counting the mains pulses then it requires a clean edge rather than the sine wave and maybe only the positive half cycle. It looks like the components next to this IC on the opposite end to the pin selection could be what cleans up the clock input on pin 14, there is a small diode just in view which could be a zener.

 

[nickds1]

With the 4017 decade counter, counting the mains pulses then it requires a clean edge rather than the sine wave and maybe only the positive half cycle. It looks like the components next to this IC on the opposite end to the pin selection could be what cleans up the clock input on pin 14, there is a small diode just in view which could be a zener.

Not really - the 4017 clock has a Schmitt Trigger input, so it doesn't really need that clean an edge or fast rise/fall times - the inbuilt hysteresis takes care of that - it's a very old design, but a good one which is why it's still around after so many years - the CMOS 4000 series devices were introduced in the late 1960s by RCA and almost all are still available new.

I have determined most of the schematic from the photos of the top & underside of the PCB however many component values are not clear either due to being obscured or poor colour differentiation in the photos. I wouldn't place too much reliance on component proximity being an indication of functional association - the board has such a bad layout that stuff is all over the place.

Having the R & C values, plus and very importantly, the identification of the spade connectors, would really help.

I wasn't kidding when I said that sending me the PCB would be far faster. e.g. if the 4017 or the SCR are dead, it's something that someone with the correct test equipment should do. There may also be dry joints (particularly on the spade connectors) due to the vibration the board would have experienced over the years.

 

[Spectric]

Yes it is very old and takes me right back to when we had many discrete components that could easily be prototyped as they were through hole mount, now with much smaller surface mount components it is that much more difficult and made worse by not so good eyesight !

Looking at that board, I wonder why they used a socket for the 4017 and not direct mount, perhaps not to clued up with static and CMOS devices.

What this also shows is how OEM's have cut out stuff to reduce the cost over the years, that machine looks much more sturdy than some of the newer machines that have superceeded it.

I would agree that popping that board in a jiffy bag and sending it to you would be an easy option, I doubt he has a scope or signal generator laying around.

 

[nickds1]

This is my design & test bench at home from a few years ago - it's rather more modern now as I've moved some of the equipment from analog to digital...

The Tek 7904A has been moved to a new home as it was too big. The 2465A is still my scope of choice and the 2430A was a bit temperamental (probably because the workshop is cold overnight) and has been moved on. The other end of the workshop is the assembly & storage area - mostly Metcal MX-5200 stuff, PSUs and racks of components, and there is a machining area with lathe/mill/press etc.

The small board being intimidated on the desk is a Jim Williams design of an ultra-low-distortion oscillator - the Great Man himself helped me with some issues on that.

The big power amp to the right is a Perreaux 2105B class A 400W/channel into 4ohm. For years this used to either warm my coffee to a nice 60C or act as a space heater to keep frost out of the workshop! I rebuilt and realigned it and it was my reference amp for speaker builds, but I was told by Someone Who Must Be Obeyed that I had too many amps (really? 12 seemed good), so it was sold. Besides, I design and build my own amps, mostly valve...

I wrote up the rebuild of one of my current amps at https://nick.desmith.net/Electronics/QUAD_upgrades.html