Did the kit come with a schematic?

Fixed V surplus computer power supplies are basically throwaways and most of recent vintage do not have published schematics since they were not designed or expected to be repaired.

 

OK, you could be right. The RD6006 display indicates that the input voltage is up to par, i.e., 24 volts being delivered by the power source. So I will try connecting a different source.

So you know that the problem isn't the input voltage so to solve the problem you remove the known working part and replace it with a different one??

Third time of asking: does it go over 9V with no load?

 

The only real problem with less than 60 volts on the input is that the output will only go up to a maximum of (Vin - 1)Volt

59 volts coming out the front would be a lot more than I am likely to need, ever, so I would be glad just to get enough to deliver 17 furshlugginer watts.

 

So you know that the problem isn't the input voltage so to solve the problem you remove the known working part and replace it with a different one??

Third time of asking: does it go over 9V with no load?

Sorry, I thought I had answered that. No. It won't go over 9V with no load. 9 volts max. What does that tell you?

 

When we first tried to uses an SMPS supply for (BLDC) the spindle motor of a 5-1/4" hard drive (ca. 1980) we noticed that when trying to spin up the motor, the supply voltage would drop to it's knees and not bother to stop there. The problem was exceedingly poor transient response.

Hope that Pedant Engineer isn't reading this thread.

 

Dave Jones did give a fairly good review of it on his EEVblog on Utube...

 

Fixed V surplus computer power supplies are basically throwaways and most of recent vintage do not have published schematics since they were not designed or expected to be repaired.

It came as a kit. Some will include a schematic with expected voltages to help newbies troubleshoot an assembly problem.

 

Sorry, I thought I had answered that. No. It won't go over 9V with no load. 9 volts max. What does that tell you?

It tells me that it isn't just because you have some random piece of nichrome connected.
The input voltage is OK, the output voltage is not. Therefore the problem is with the bit between the input and the output.
There is no way for me to decide whether it is a faulty part or faulty construction. Maybe with a schematic and some measured voltages we might get somewhere. Otherwise I would just be guessing.

 

It came as a kit.

The "kit" for it is the Panel device and a bare chassis/box to hold everything. You have to supply the surplus computer fixed voltage switch-mode power supply to go into the chassis. It doesn't even include a power cord.
https://www.aliexpress.com/item/400...earchweb0_0,searchweb201602_,searchweb201603_
",this is only one enclosure and does not contain any power supply, "

 

Hope that Pedant Engineer isn't reading this thread.

He can read anything he wants. At least I was able to learn from other's mistakes and be part of the solution. In those days I was the "firmware" guy, and it was tweaking the startup procedure that was the initial solution, but better loop dynamics was the ultimate solution.

 

It tells me that it isn't just because you have some random piece of nichrome connected.
The input voltage is OK, the output voltage is not. Therefore the problem is with the bit between the input and the output.
There is no way for me to decide whether it is a faulty part or faulty construction. Maybe with a schematic and some measured voltages we might get somewhere. Otherwise I would just be guessing.

There was one step that I skipped, and that may be part of the trouble. The Youtube segments all show the assembler checking the input from the power source to and from the switch and the mains receptacle, then from the source to the connector at the back of the control panel. So I will include that step when I replace the fixed-voltage supply.

 

It could be defective or the results of my own error, but I don't know enough to troubleshoot it.

If it didn't come with a schematic, draw one and post it. We can help you troubleshoot.

 

Did it at least have a wiring/connection diagram? The PSU is typically AC on one end and DC on the other. Some of the computer PSUs have to have a load connected to have an output. Test the PSU outputs with a meter and post.

 

Sounds like one or both of the limits could be set.

 

If it didn't come with a schematic, draw one and post it. We can help you troubleshoot.

Draw a schematic of the control panel? I can draw schematics, but this device is two or three layers of boards, including a processor and a display, and it isn't really a PS, it's a buck convertor crammed into a pretty small space. Besides, I got it working right.

 

Besides, I got it working right.

What was the problem?

 

Did it at least have a wiring/connection diagram? The PSU is typically AC on one end and DC on the other. Some of the computer PSUs have to have a load connected to have an output. Test the PSU outputs with a meter and post.

I got it. The trouble may have been of my own making, or it may have been in the previous enclosed PS, but I took the whole thing back to square one, yanked the original enclosed PS, put everything back together with a different PS with roughly identical output, tested the connections between mains and PS and between PS and control panel. There was 24 vdc going from PS to control panel, so that was up to spec. I added a ground between the PS and the case, checked the connections I might have crossed up previously, and tried it again. I re-read the how-to instructions and punched in 20volts to the "V-set" display. It worked. I took it up to 22volts. That worked, on the display and according to my multimeter. I haven't tried it on the nichrome heater, but this is further than I got before. When I check out the previous enclosed PS I'll report the results.

 

What was the problem?

I wish I knew definitely. I just did it about an hour ago, and I haven't had time to go over the now-removed enclosed PS to see if that was the source of trouble. I will carefully put that all back together and see what it delivers. IF that one works up to spec, then the problem was in either my assembly or in my clumsy attempt at setting the control panel. In my opinion, both the PDF user guide and the RD6006 videos available give short shrift to the operating procedure. For a newcomer, the 2-minute-21-second video of setting and using the controls goes by pretty darn fast. It's like one of those speeded-up nuts & bolts sections from a YouTube assembly video.

 

I filled in all the blanks, and I still can't make it work. I had been operating without the CR1220 battery to run the clock, but since I didn't know for sure it was not there to maintain something else besides the clock, I finally installed a battery. At this point, the RD6006 is running off a known good enclosed (the other one)power supply, with a battery, and everything else is in place. So I start it up, check the display (looks good) and set it for offering 6 amps (the PSU's max) and delivering 22 volts. The display tells me it's set for Constant Voltage. So I have the banana plugs running to the nichrome wire element, which is ON, and I press the RD6006's Off/On button (which sends the selected V & A to the load). Result: the display tells me it's now in CC mode, the output voltage drops to 6.02vdc, output amps stays the same, and the wattage is around 39W. The wire gets warm enough to maybe burn a slot in a popsicle. Doesn't get red. I can hold my hand 1/4" away from it with no ill effects. I'm getting sick of this. If anyone there can think of a possible screwup on my part, or an error in my technique, let me know. Otherwise, it's going back to China. BTW, the possibly malfunctioning power supply wasn't malfunctioning. It's fine.

 

All of that is down to the nichrome wire, not the power supply. That wire has 6A flowing through it and that is the maximum the supply can provide but it is not enough current to make the wire as hot as you want it. You either need a thinner wire which will get get hot enough with 6A or you need a supply which can provide more than 6A.

Remember ohms law. That wire is about 6V/6A = 1Ω. You cannot change any one of those numbers independently of the others.