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No Voltage for DTHC

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LuckyWeasel
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No Voltage for DTHC

Post by LuckyWeasel » Sat Aug 17, 2019 11:46 am

Voltage from torch for sure. Wired in a small meter after it quit working so I can see torch output directly. Changed PWM II module out on my CANDCNC with no change in results. Will not display any voltage on system with test switch operated on PWM units, Arc OK test works fine, so there are good communications. System was working fine with no changes to config.

BTA Plasma
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Re: No Voltage for DTHC

Post by BTA Plasma » Mon Aug 19, 2019 4:46 pm

Volts from the plasma cutter have a linear path.

Plasma cutter- Cable-PWM-cable-DTHC card-HUB-PC

So lets breakdown the components

Plasma cutter at 50:1 ratio @85 amps should be in the 3.4-3.55v when fired in the air or 176 tip volts, @45 amps with a 45amp consumable you should read 3-3.2 when fired in the air, @45amp fine cut you should read 2.4-2.6v when fired in the air

PWM test volt button should display 109-111 with the cable from the plasma cutter plugged in and 126v with it unplugged.

Depending on the firmware date it may NOT display volts if your volts are far out of the range of your preset volts from sheetcam.

So test the volts at PWM...checks out, ….test the volts with a meter at plasma cutter...checks out. Then the weak link may be the cable from plasma cutter to pwm. A quick test fire in the air checks the entire circuit.

tcaudle
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Re: No Voltage for DTHC

Post by tcaudle » Mon Aug 19, 2019 7:53 pm

1. Arc Ok is not part of the PWM circuit and has no part in volts reading. Its just two wires back to an input on the controller. The PWM can be totaslly non functional and the ARC OK will work as long as those two wires in the CAT cable are hooked up. The test light simply shorts across those two wires
2. Do as Matt suggests and follow it through the chain. The PWMII has a Blue LED on it that will show if its getting any input volts (even on test) and that shows the PWM circuit is alive and well.
3, Its possible that the DTHC is reading voltage just fine but it not displaying it on the screen . Screen display is though the RS485 comm channel (4 port hub) ; Same channel used by the Hub Utility to talk directly to the DTHC module.

LuckyWeasel
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Re: No Voltage for DTHC

Post by LuckyWeasel » Tue Aug 20, 2019 1:51 pm

Ordered a DTHC 5 card that should fix the problem. It would be helpful to have interconnect pinouts/signals for troubleshooting, but I am learning what they are. Will replace the 25 ft yellow cable with a tailored one to minimize noise and vulnerability. The system did hang up on torch firing now and then. Re-start everything and it would go away. Maybe new card will fix that too.

LuckyWeasel
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Re: No Voltage for DTHC

Post by LuckyWeasel » Thu Aug 22, 2019 1:23 pm

DTHC5 card fixed the problem.

Lampe101
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Re: No Voltage for DTHC

Post by Lampe101 » Wed Dec 02, 2020 3:41 pm

I've got this same exact problem. Controller just came back from CandCNC they said the dthc5 card was all tested and fixed up so I ordered a new pwm module. Hoping that fixes the issue

tcaudle
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Re: No Voltage for DTHC

Post by tcaudle » Sun Dec 13, 2020 10:24 am

Its always a good idea on units returned for repair that you include all of the modules. If you retune the PWM it gets tested with the unit . If we get no modules with it we just use our own in the lab and run the DTHC and motion tests that way. If you do return other things besides the main controller list them on the RMA form so it all stays together.

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