[color=#0040BF]Hello.
I have constructed the K8004 kit, which I intend to use to control a variable heatsource to prevent dew formation on a telescope. The supply voltage will be 12v DC.
When I set it up to test, following the instructions in pt 14 of the manual (using a 12v DC voltage) with RV1 RV2 and RV3 initially set at their midpoint, I could not read a voltage across the LOAD terminals. adjusting RV1 fully CW then gives a reading of 2.5v at the LOAD terminals. Adjusting VR2 and VR3 appear to make virtually no difference.
Could you suggest anything I should check before testing again please? I have checked the solder joints, and all appear to be clean and firm. I am expecting to be able to set the output voltage to 12v. Or have I misunderstood the test, and this is what I should expect with the test resistor supplied?
[color=#0000BF]Hi,
Thanks for replying. I am an amateur when it comes to electronics, so… I assume you mean instead of the resistor in the test. I have now done that, with a bulb rated at 14V 200mA. It lights, but not to its full intensity. I am still getting a reading of about 2.5v across the load.
Should I use a different rated bulb?[/color]
[color=#0000FF]Aaah sorry, forgot that piece of information. Yes, adjusting pot RV1 allows me to dim the bulb, but I cannot get it to light at full intensity (i.e. as it would at 12v) It only illuminates as I described (i.e. weakly) when RV1 is fully wound CW. [/color]
[color=#0000FF]I’m sorry - I don’t even understand what that means.
I have tested it exactly as illustrated in the manual (pt 14, on P7) - the test voltage is a 12v DC source (from a sealed lead acid cell, which is fully charged). I have then done the test substituting the light bulb for the 4k7 test resistor as you asked me too, with the result as described.[/color]
[color=#0000FF]OK. I have solved the problem
It appears to have been a poor connection between the vref post and the pcb. Resoldered and all now works as it should.
Thanks for trying to help.[/color]
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