Denford Software & Machines

We have an Easimill 3, we left the machine switched on overnight and when we came in the next morning the machine was dead.
We checked all the power supplies and they seem ok but when we checked the test points on the PCB in the PNC3 we found we have no 5V but we do have 12V, could anyone give any advice as to what to look for or what could be the cause of our troubles.
In the PNC3 there are two Toroidal transformers does any one have any information about these as we have tried to contact the manufacturer for information but with no luck, Thanks Ian.

Hi,
I am an expert on all the early Denford controllers (Easimill,Easilathe & Triacs) as I worked for many years for the original manufacturer North East Electronics.
The 12 volts is used to power the CRT driver card & normally goes when the VDU card dies. To prove this, Unplug the white 4 pin plug on the power card (the one which goes off to connect to the VDU card behind the tube). If the 12 volt LED comes back on then the VDU card is damaged. If it stays off then the voltage regulation on the power card is damaged. This could be due to a number of failed components but the most likely will be one of the 2 transistors on the front of the card which are bolted to the chassis.

In any eventuality, I have service exchange, Power cards & video drive cards if needed.

Hope this helps..

Alan

You sound a very useful person to know any chance we could have direct contact details.

Contact numbers here:
viewtopic.php?f=54&t=2841

Im confident that the problem will be on the power card & not the Toroidal transfomer.

However, if you need to check it, here are the voltages you should expect on the transformer connector.

Pins 8 & 9 = 10vac
Pins 10 & 11 = 12vac
Pins 7 & 12 = 7.5vac


If they are OK, try This:

Unplug the 4 pin VDU connector..
If the voltage rises back to 5 volts then the VDU card is still faulty & is due to fail completely. This is because the circuit is designed to shutdown the 5v if the 12v is drawing too much current.

If there is no change , measure the DC volts between the 0v test point & Fuse F3 you should have approx 9 to 11 volts.
If its lower than 9v, then the fault will be either DB2, C7 or C8.
If its within the range then the fault is going to be the 5 volt transisitor. Its the lower one mounted to the chassis.


Hope this helps..

Alan

Alan, if possible could you contact me with referance to one of your service exchange power cards as we have made the changes you advised and now we have lost the voltage at F3 all together so it might be less painful for both of us to change the board instead.