Whitfield died?

[Mt Bob]

And what is the board upgrade ? The trace is still there I had to solder it to the center post where it was originally everything is so small for my 60+ year eyes I’m not sure I have the talent required. I will need to order more triac and inline fuses any recommendations on inline fuses, I’ve used several kinds over the years for ham power.

Just a newer board,usually the programming is a bit better or better cleaner burns,but,if was mine,and board fixable,go with the one you have.Although,some newer boards solder in pc board fuses to help protect the board.I would try to fix board again,if mine.

 

[Ssyko]

any in-line 120v 3or4 amp would work

 

[stellep]

Bugs, just curious.

What is the auger clearance with the new bushing?

Where are you sourcing the board component?

Soon you will win!

 

[Monica in France]

I've only just come across this fascinating thread!
I've been trying to correlate the 'touch board' and the printed circuit.
In general with success. But I don't understand what looks like two triacs for the auger motor control. One with a heat sink and one without. And it is the one without a heat-sink which blows.
This sounds wrong : so what is that other component ? A choke ? But its connections look like a triac or another power transistor config.

Taking the basic problem simply : all the electrics worked fine until the new auger motor was fitted.
After that we have a toasted triac and fuse for each trial.
The new motor is eliminated because it works for 15 minutes each time.
But what if the new motor is not the same rating as the original one : if the specifications have changed since 1991? I can not imagine any agent checking this < Looks the same – must be the same >.
Can I suggest two experiments after fitting Bob B's inline fuse in the auger feed wire ? ( Bob B : why not the unswiched side ?)
Run the old motor for 20 min – will it ?
Run the new one – does Bob's fuse blow ?

 

[Ssyko]

Bugs can you take a pic of the 2 auger motor labels. Im curious of the amps they are drawing.

 

[Mt Bob]

I've only just come across this fascinating thread!
I've been trying to correlate the 'touch board' and the printed circuit.
In general with success. But I don't understand what looks like two triacs for the auger motor control. One with a heat sink and one without. And it is the one without a heat-sink which blows.
This sounds wrong : so what is that other component ? A choke ? But its connections look like a triac or another power transistor config.

Taking the basic problem simply : all the electrics worked fine until the new auger motor was fitted.
After that we have a toasted triac and fuse for each trial.
The new motor is eliminated because it works for 15 minutes each time.
But what if the new motor is not the same rating as the original one : if the specifications have changed since 1991? I can not imagine any agent checking this < Looks the same – must be the same >.
Can I suggest two experiments after fitting Bob B's inline fuse in the auger feed wire ? ( Bob B : why not the unswiched side ?)
Run the old motor for 20 min – will it ?
Run the new one – does Bob's fuse blow ?

Monica,in case the problem is a rubbed through wire somewhere,You want fuse on power side befor eit feeds anything else.

 

[Monica in France]

Bob : good thinking.So as near to the circuit board as possible.

 

[Ssyko]

FOR REFERENCE. I keep going back to pg1 to reference the board

 

[Monica in France]

Silly idea perhaps , but what if you added a heatsink to that triac which is always burning out ?
I now see four triacs , two without heatsink for some reason , and a relay. ( Stovensons has an extra relay for the igniter).
Ssyko has labelled the two fans and the auger . What do the rest do ?

 

[Ssyko]

I been trying to trace them but its tough with a picture and no way to use a meter. That is what confuses me also Monica. 2 w/heatsinks and 2 wo/heatsinks. Now stovensons has the igniter control but Bugs doesn’t but both have the same amount of triacs. Now im guessing here but would they use a triac for something other than a motor control?

 

[Monica in France]

I'm surprised that the auger is using a triac : it must be speed controlled and not a duty cycle for which a relay would be more suited.
But 15 minutes sounds about right to toast a triac if you are overheating it.
what else could you use a triac for ?

 

[Ssyko]

Almost every stove board ive been into uses triacs for auger, fans/blowers control. My oooold lopi uses pots, thats one simple set up. But Bugs has 4 so my question is why arent all 4 heatsinked? are the auger motors drawing to many amps for the circuit? Old one wore out= draws to much. New one is made from diff mfg. and has a larger stack and draws more? Id like the board and motors to bench test.

I agree alot of these boards would benefit from relays! But they wouldn’t sell as many

 

[Stovensen]

Since monday the internet has been down at my place ( cables were ripped over by some heavy machines down the road. ) But now it's working again

There seems to be some confusion about the number af triacs on Bugs' and my control boards. They are absolutely identical ( except for a few 230 Volt components needed on my board ).
I can inform you with absolute empirical certainty that there are only three triacs on the boards... two are for the blower motors and both these have heat sinks, since the blower motors run continously and have a higher wattage ( draw more amps ). The auger triac is the one without heat sink. The auger motor only draws 0.41 amps @ 120 Volt/60 Hz and is only meant to run intermittently controlled by a recycling routine written inside the microcontroller.
The three triacs on my board are all manufactured by Motorola and all three have the type designation: MAC 228 A6 ( sensitive gate ).

The fourth component, also in a TO220 housing like the triacs, is located close to the transformer and is a positive voltage regulator ( LM 7805 ) that supplies the microcontroller and its sourrounding components with 5 Volt DC

Overview, current consumption @ 120 Volt/60 Hz:
Combustion motor: 0.95 Ampère
Convection motor: 1.25 Ampère
Auger motor: 0.41 Ampère
Total: 2.61 Ampère

To this we must add transformer loss and the consumption of all the other components on the board. If the auger motor is restricted severely, it could easily draw more than the nominal 0.41 Ampère. I understand that Bugs is running the stove with a 3 A Fast acting fuse, since there's no igniter installed, so from this calculation we can conclude that a 3 A fuse is working on its limits in a restricted auger situation.

But why is the triac melted into a short every time the fuse blows? A possible answer to this question could be to know these exact informations: We need to know both the exact time for the climax in current rise through the auger triac and the exact time of the climax of the torgue produced by the auger motor. From what Bugs informed us in a previous post, the loud "bang" noise from the auger occurred simultaniously with the fuse popping. This information led me to conclude that the source of the issue was a restricted auger shaft.

Bugs: Try a 6 A fuse instead. Mine has been running with the same 6 A fuse since 1998. And note: The mains voltage here is 230 Volt, so any short circuits are even more destructive at this double voltage.
The damaged copper tracks are fairly easy to repair with thin copper wires taken from a piece of multicore cable.
And a new triac is only few $$

Good luck and take care. Keep us posted

 

[Ssyko]

Thanks Stovensen. glad your back on line

The fourth component, also in a TO220 housing like the triacs, is located close to the transformer and is a positive voltage regulator ( LM 7805 ) that supplies the microcontroller and its sourrounding components with 5 Volt DC

that helps me a lot. I am an amateur at electronics, and i try to learn as much as I can when someone with the knowledge speaks. correct me if i'm wrong with my assessment pic

 

[Monica in France]

If I follow Stovenson correctly he is saying that as the Triac is not causing the fuse to blow because when the fuse is replaced and the stove restarted ,it did not do so in the first place.
And there , I admit he has a very good point .
But unless we say that the blown fuse causes the triac to fry we are surely faced with a cause and an effect.

We need Bugs to confirm that the new auger is the same as the old one with a 0.41 amp rating.

 

[Ssyko]

If I follow Stovenson correctly he is saying that as the Triac is not causing the fuse to blow because when the fuse is replaced and the stove restarted ,it did not do so in the first place.
And there , I admit he has a very good point .
But unless we say that the blown fuse causes the triac to fry we are surely faced with a cause and an effect.

We need Bugs to confirm that the new auger is the same as the old one with a 0.41 amp rating.

your way ahead of me Monica.
I'm still confirming components on the board LOL I was thinking the auger was the culprit for the fuses blowing. I think the old motor was tired and brought the amperage draw to a spike when it bound up. yes we need Bugs to verify the new motor stats

 

[Stovensen]

But unless we say that the blown fuse causes the triac to fry we are surely faced with a cause and an effect.

We need Bugs to confirm that the new auger is the same as the old one with a 0.41 amp rating.

Yes, and we also need Bugs to confirm that the fuses all blow at the same time as the loud "bang". As I understand it, the bang can only be generated, when the torgue on the auger shaft is released very abruptly by the fuse cutting the power. Is it a "bang" or a "click"?
And remember: The winding in the auger motor has a quite high self inductance. If the power is cut when the phase of the alternating current is on its climax ( either + or - going phase ) a huge reverse voltage is induced in the coil... this could kill the triac instantly. Semi conductor based fuses are among the fastest acting types. Much faster than melting metal wires.

Edit, I just reread the last posts from Bugs and realise that the fuse and triac also blew after the auger bearing was replaced, so my theory about the restricted auger shaft cannot be the whole explanation.
Monica in Frances suggestion: That the issue is caused by higher amp-rating of new auger motor combined with an underrated 3A fuse, could be solved by replacing it with a 6A fuse.
I would guess that the reverse high voltage generated in the inductive load will destroy the triac in most of the cases, when the fuse blows??

 

[Ssyko]

BUGS!! where are you? lol

 

[Stovensen]

BUGS!! where are you? lol

Lol

Until Bugs shows up with some more info, we can keep the discussion alive. Right now I'm going to contradict myself.
I made this assumption:

I would guess that the reverse high voltage generated in the inductive load will destroy the triac in most of the cases, when the fuse blows??

If this is correct, then why does the triac not get blown when it switches the auger motor on/off?

 

[Ssyko]

The winding in the auger motor has a quite high self inductance. If the power is cut when the phase of the alternating current is on its climax ( either + or - going phase ) a huge reverse voltage is induced in the coil..

would this be similar to a capacitor unloading? if so would that make the blowing of the fuse and triac simultaneous and instantainious. not after 10-15 min of running

 

[Stovensen]

would this be similar to a capacitor unloading?

Good point, Ssyko! Capacitors and inductors ( coils ) have totally similar behaviours ( transfers functions ) when they are charged/discharged. The difference between them must be noted, though: The voltage rise on a charging capacitor follows the same exponential curve as the current rise on a charging inductor.
A charged capacitor is in a static state ( electrostatics ) The voltage is present with the terminals disconnected from the charging source.
A charged inductor is in a dynamic state ( electrodynamics ) The current is present only with the terminals connected to the charging source.

The real "magic" happens, when a charged inductor with a running current is disconnected from the DC source: It responds conservatively by generating a reverse much higher voltage with respect to the polarity of the DC source. Mystical, isn't it?

When a charged capacitor is connected to a short circuit it responds by generating a very high current in the opposite direction af the charging current.

if so would that make the blowing of the fuse and triac simultaneous and instantainious. not after 10-15 min of running

Remote troubleshooting is difficult. If only we could have seen/heard what happened, when Bugs' stove blew the fuses, and also have measured the current running through the board, things might have been easier.

A couple of years ago I made a video of what the auger voltage looks like on my stove. You can see that the motor gets the full line voltage ( 230 V/50Hz ) directly from the triac. What the oscilloscope cannot show is the exact moment when it switches on and when it switches off. Does this happen when the line voltage crosses zero? If so, the current should also be zero, and this would be harmless for the triac.
If the triac is switching in the phase climaxes, wouldn't this generate the destructive reverse voltage? I really don't know, to be honest.

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[Ssyko]

A charged capacitor is in a static state ( electrostatics ) The voltage is present with the terminals disconnected from the charging source.

This I learned long ago and it knocked me cold, (school of electro shock)

A charged inductor is in a dynamic state ( electrodynamics ) The current is present only with the terminals connected to the charging source.

this i did not know. and could this explain the time delay in blown fuses vs auger run time?

The real "magic" happens, when a charged inductor with a running current is disconnected from the DC source: It responds conservatively by generating a reverse much higher voltage with respect to the polarity of the DC source. Mystical, isn't it?

FASINATING!

Does this happen when the line voltage crosses zero? If so, the current should also be zero, and this would be harmless for the triac.
If the triac is switching in the phase climaxes, wouldn't this generate the destructive reverse voltage? I don't really know, to be honest.

there would have to be some sort of timer in the circuit or prom to calculate zero voltage and trigger the triac. which is possible (i have yet to get into any of the prom code on stoves). IF it is in the code and the first blown fuse and fried triac very well could have damaged the prom and its coding. I think i hurt my brain.lol


AWSOME VIDEO!! im looking into this in the near future (broken link removed)

 

[Monica in France]

hey folks - Keep It Simple !
I think zero volt triggering is to reduce interference more than anything else.
if these sorts of problems cause that triac to be toasted then think what could happen with a power cut.

If we assume that the rest of the board is still ok , and that is partially confirmed by the 15 minutes before the fuse goes, then we only need a reason to explain the 15 minutes of it actually working. And to my mind a heat build up is nice simple solution.
When that triac gets very hot something happens to blow the fuse. After that it is a simple short circuit and not generating heat.
The noise heard by Bugs is this something blowing the fuse.
I would add that heat sink , not make the fuse bigger.

I enjoyed hearing the pellets falling in the burner in that video !

Where are you Bugs ?

 

[Mt Bob]

Well,an Endland pellet stove can blow the fuse,after warming up,when one of the motors gets too hot,and is what I suspect,is bugs problem,just poor design it takes out the triac.Europeans have much cleaner burning pellet stoves,and furnaces,but also have much higher restrictions.I prefer simple.As we say in the car business,more bells and whistles are just more things to break.

 

[Ssyko]

Sorry we did get a lil carried away. Keep It Simple Stupid (KISS). Im sure the components are overloading because of amprage draw, old auger was just plain tired and had a jam to boot, poof! Now the new motor we need bugs to verify it’s voltage. Amperage, specs match the original or if it is an aftertmarket that is higher amperage