Denstep Controller with a Baldor Optmized controller board F391 Issue 2
We have 24 VAC going into the board and fuse F1 is good., but no +12 -12 +5 volts.
I have no schematic drawing and the link here to st.com doesn't work
Since all voltages are gone, I would suspect a component that uses all three voltages.
Anyone? The board is out of the CNC, I see no burned or charred parts.
The daughter board removed (Denstep with Red 7 seg display - atleast I think it's red, I haven't seen it light up yet)
And n voltages present either.
Spindle works as does the work light inside the enclosure.
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check the bridge rectifier and it's associated tracks.
Already pulled the two KBU8D's and they test fine with my DMM. I have two replacements and just to verify, I just now compared the old with the new.
I checked the tracks from the edge connector to the rectifiers, but not sure where the other sides go.
I checked the tracks from the edge connector to the rectifiers, but not sure where the other sides go.
As a side note looks like U16, the L4960 has been replaced at some point.
So that IC is suspect, but if it was replaced, then something else might be a cause,,,
So that IC is suspect, but if it was replaced, then something else might be a cause,,,
Is there any history of this type problem? When I worked as a repair tech in a mfr environment, I found a mfr problem where the silkscreen lifted up a little when the PC board was exposed to light. This created a short on the top layer of a multi layer PCB. I think they were 30 meg boards, double sided SMT and cost around 10K apiece. I pulled out the exacto knife, and under a microscope cleaned up the stray copper.
Anyway, this machine has had very little use, as it was in a school environment. And the L4960 voltage regulator needs replacing?
So I look at the L4960 data sheet, but the only way it shows to get +5 +12 -12 is with an L290 along side the L4960.
Really wish I had a schematic to look at.
Anyway, this machine has had very little use, as it was in a school environment. And the L4960 voltage regulator needs replacing?
So I look at the L4960 data sheet, but the only way it shows to get +5 +12 -12 is with an L290 along side the L4960.
Really wish I had a schematic to look at.
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Unfortunately there is not a freely available circuit diagram for the den step card.
They can be repaired by returning to Denford but the cost would probably cost more than replacing the card. If the multilayer board is damaged then the board would be up repairable.
The new board would be pin compatible. You can replace just the bottom power board or the whole unit.
They can be repaired by returning to Denford but the cost would probably cost more than replacing the card. If the multilayer board is damaged then the board would be up repairable.
The new board would be pin compatible. You can replace just the bottom power board or the whole unit.
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one of the dc supplies goes through the board to an inside track, i've repaired this on one board by working out where it needed to go and replacing it with an insulated wire.
There's a controller card on eBay for $500,, but I have no dongle, am I wasting my time?
What voltages does U16 (the L4960) supply?
Is the +5 taken from the +12?
Is the +5 taken from the +12?
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Don't want to distract your train of thought but ... the caps will be at about end of life, check the capacitors, they go open circuit when they degrade, especially the decoupling caps, dead short. I've had two go.
Tom
Tom