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oztules

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Joined: 26/07/2007
Location: Australia
Posts: 1686

Posted: 10:40am 01 Dec 2008

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You asked to see the innards of one of the boxes I am fixing for the mills over here, and how I fixed it. I don't quite know what you want so here goes.

This 115 unit controls when to let the blades rotate. If there is not enough wind, it keeps the brakes on, When an average (settable from the front bottom control) wind has been established, it releases it's relay to let the brakes off.

Providing no other unit disagrees (phase drop, voltage wrong, vibration etc etc, the blades start to turn. It monitors this as an average all the time, if it slips below the preset (as an average taken over about 20 seconds (ish), it puts the brakes on and waits.

The top dial sets the upper limit you will allow the blades to run in. If it exceeds this it stops immediately.

This one won't come on.... so we open it up to find out whats inside.

Note, the rotten #@#@(explicative deleted) ground the numbers off the two IC's... this makes it a bit harder.

After struggling with how it might work, I figured out the two IC's were simply lm358's. Tracing out the circuit around the devices led me to this conclusion, so with this in mind, I tested accordingly.

found the two outputs generated by the anemometer, the peak and the average signals. They were generated by one of the IC's. It went through some buffer stages (transistors) and wound up at the other IC.

Knowing it was a lm358 by now, it was simple to find the preset voltages from the pots on the front panel, in the -in inputs of either op amp. One for average, one for peak. It simply beat one preset against the average signal, and one against the peak signal (against the peak preset). The average signal went to +in, the preset to the -in, but the out didn't change when I pushed the average signal up... dead 1/2 IC. So replaced that 358.

Now we had the signals OR ing to an 14541 programmable timer chip (under that big electro). It was getting the signal, but not resetting and counting down. This turned out to be a shot capacitor. Replaced it and she all works again.

Here is the back of the board... at least you could see through it to trace the tracks to the component side:

Here is the preset area:

Now, what made this harder than it should have been, (apart from those devious devils grinding the numbers off the IC's), was that I had to turn this while I was searching for the signal paths...

I reckon it would have been comical to see... spin... measure measure... spin.. measure measure.

In the finish I used the heat gun on cold air to spin the blades, and interrupt the airflow with my elbow to simulate change.... such is life for the free serviceman I guess.

Is that what you were after?

..........oztules

Village idiot...or... just another hack out of his depth

Dinges
Senior Member

Joined: 04/01/2008
Location: Albania
Posts: 510

Posted: 01:27pm 01 Dec 2008

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Oztules said I don't quite know what you want so here goes. [/quote]
No special reason, just curious what was wrong and how you repaired it. I don't know about the others, but I derive a lot of satisfaction out of such stories. Feels nearly as good as repairing something yourself.

In this case I was especially surprized by the fact that you were not only already aware of the existence of such modules, but had actually repaired one...

Quote Note, the rotten #@#@(explicative deleted) ground the numbers off the two IC's... this makes it a bit harder.[/quote]
Hear hear. Fully agree with you there. When faced with such a repair job I get some satisfaction out of thinking up new ways to punish the bastard who did that or ordered it to be done. Usually it involves an object (e.g. a hot soldering iron) stuck in orifices that were never meant to have a hot soldering iron inserted in them.

Incidentally, much of my deleted rant in the other post (on the Breezy 5.5) was about actions like this and the mentality that gives rise to such actions. Information wants to be free.

[quote]figured out the two IC's were simply lm358's[/quote]
That would have been my initial thought too: either a 555 or a 741. In this case a dual opamp, apparently.

[quote]Here is the back of the board... at least you could see through it to trace the tracks to the component side: [/quote]
I find shining a strong light on the other side of the board helps when reverse-engineering such boards. Also much easier on the brain, instead of having to flip the board over 100s of times and visualizing it in mirror-image.

[quote]such is life for the free serviceman I guess. [/quote]
Your story reminds me of an (involved) repair I did for a mate earlier this year on his flatbed grinding machine. The neutral of 3-phase power in his shop had developed a faulty contact in the distribution (in his shop, hanging from the ceiling). This caused many separate defects in the machine (fortunately, *only* in this machine; if the loose neutral had been in another place of his powerlines, nearly all his machinery would probably have needed repair...). Much of the machine worked off single-phase 230V (i.e. was using just one of the three phases) and thus neaded a proper neutral; when the large (10hp?) DC motor that powered the grinding stone started, it pulled the (now floating) neutral so far in one direction that the other 2 phases were at 400Vac instead of 230Vac. And (surprize...) a lot of the electronics didn't like that. Several burnt out transformers, relays, etc. And, one control module similar as yours (timer though). Repairing that timer module turned out to be the simplest repair of all however, as only the rectifier bridge had become shorted. Easy & quick to repair. 'Normal' servicemen simply replace the entire module (at $$$). And takes weeks for a replacement module to show up. But with some creativity and effort, one can have such machines back running in a matter of hours; if you can find a *good* free serviceman of course, that is.

Also, having been trained/educated in an entirely different field, I derive extra pleasure from pulling such things off and repairing on a lower level (component level) than most service 'engineers' do nowadays. <grin>

Out of curiosity: do the systems you have to work on (the windgenerator control cabinet where that SP115 module came from) come with a complete schematic/wiring diagram? That's the one thing I really love about the industrial machines I get asked to repair: they usually have full documentation. That makes repairing it for someone like me, who is not a professional repairman, a much easier job.

Anyway, thanks for the story. Was a pleasant read.

A longwinded Peter.

oztules

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Joined: 26/07/2007
Location: Australia
Posts: 1686

Posted: 07:44pm 01 Dec 2008

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Glad you enjoyed it. I only enjoyed it when I pushed it back inside it's case and tested it again... and it all worked properly.

No circuits for the mill, but there is one coming I'm told. It's a few thousand miles away at his other place.

The Chinese inverters I have had to work on lately all use phenolic (or something like that) board. You cant see through with the brightest light. It is no go. I am useless at imagining in mirror image too, which makes it difficult.

.........oztules

Village idiot...or... just another hack out of his depth

Dinges
Senior Member

Joined: 04/01/2008
Location: Albania
Posts: 510

Posted: 08:13pm 01 Dec 2008

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Everyone needs to ask for help sometime. Your fellow islanders don't know half how lucky they are to have someone like you to help them with this kind of stuff. Tell them Peter said so.

Even if you can't... I bet they'll wait for you to solve their problem.

Now... if you could do small medical procedures and surgeries too... or would that be asking too much?...

oztules

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Joined: 26/07/2007
Location: Australia
Posts: 1686

Posted: 08:49pm 01 Dec 2008

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I can remove splinters and dispense aspro's. (although the guillotine could certainly do amputations...)

Does that qualify?

Village idiot...or... just another hack out of his depth

GWatPE

Senior Member

Joined: 01/09/2006
Location: Australia
Posts: 2127

Posted: 09:49pm 01 Dec 2008

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Hi oztules,

I am sure you could work out an arrangement with a ccd camera and a monitor to see both sides without turning things over.

Gordon.

become more energy aware

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