Re: [GrizHFMinimill] Re: Mill controller woes



Thirty  years ago when my company imported a lot of electronics from China (Hong Kong), most double side PCBs made used plated thru holes and a good solder joint should have been made. Probably a bad board, boards these days aren't hand soldered but are soldered by using a wave soldering machine. The Plating process could have been poor or the board wasn't preheated enough prior to the wave soldering. Your board would have tested fine until the eventual joint failure.  Failures do occur and these kind are harder to catch. Most Chinese manufacturers then  accepted a 5% failure rate as a satisfactory rate. My contracts called for a 2% QA failure rate as being acceptable...... had to work with them to keep it that low....
 
I f found that if you had long term on going contracts and repeat business you got better results.  One contract was for only 10,000 items. The manufacturer sampled to make sure that all shipments met QA requirements and just set aside the bad units and didn't fix them. Then shipped these bad units in the final container, they got their money, we got the duds. That was 30 years ago, I hope things have gotten better! The other company gave us good service because we were buying 40,000 items per month and had overlapping contract for various items and they tried to keep us happy!
 
I don't know how many of these controllers they have made, but 5% of 50,000 (assumption) boards would be 2,500 bad controllers. I don't think there have been anywhere near that number of failures. YMMV
 
Bob
Sent: Tuesday, September 06, 2011 8:58 PM
Subject: [GrizHFMinimill] Re: Mill controller woes
 
 

I have an earlier X2 about 12 years old. I went through 2 controller boards in 12 months and built my own after that. I don't know what happened to the first board but suspect a power surge. The replacement board stopped working within a week due to a dry solder joint on the large inductor coil. I could see that the bottom pad had a good joint but the top pad takes all the power and had vaporized by arcing to the inductor leg. I'm suspicious that there was no solder on this pad.This would have been hand assembled in China and the technician soldered the bottom pad but would've found it difficult to reach the top pad with the iron. The Quality Assurance on these controllers is poor although if you analyze the circuit it has all the necessary features of a good controller.

--- In mailto:GrizHFMinimill%40yahoogroups.com, "v_flad" <flad@...> wrote:
>
>
> Chuck,
> I had a simular problem with the stock control board. I found a KBLC board on ebay, and havn't looked back. much better control, and more power. I adjusted max to 115VDC, on a 110 motor, and it works real well. I have the extra power if I need it. It cost me about 15 bucks, and an afternoon.
>
> Good luck to you!
>
> vFlad
>



__._,_.___


Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe

__,_._,___