HI, my name is Anders Lundgen and i need your help.
I have recently finished building my nixie clock, and have come upon a problem. I carefully soldered all the components on the two boards step by step and ticked the boxes as i went along, i then bought a power supply that was rated 12vAC. (I checked the voltage on the powersupply to be sure that it actually was a 12v unit.) It first measured 15v, but went down to 12v under a small load.
I then connected it to the nixie clock, and nothing happened. I started to go through the troubleshooting tips in the booklet. I measured the voltage over C2 and C4, they were approximately 5VDC, i then measured the voltage from the metal part on VR1 to the cathode on D6, and only got from 20 to 39VAC.
I then started checking all my solderpoints but didn’t find any that looked bad. I then started measuring the solderpoints with an Ohm-Meter to check the conection between the solderpoint and the components legs, they were all fine. I re-checked all the components positions, and could not detect a single component being wrongly mounted. I even started to measure the contacts between components to make sure that everything was connected according to the schematics supplied with the kit, and still could not find anything wrong.
I have however not been able to measure the function of the transistors or the higher ohm resistors due to lack of instruments. (I only have a Fluke T5-600 electrical tester).
I however noticed something strange when measuring the voltage over the input jack. It was only 8Vac which should suggest that there is a short circuit somewhere. And the diodes in the rectifier also get pretty hot pretty fast. However the fuse does not blow since my power supply only delivers 500mA.
I suspect that there might be a faulty component somewhere on the board, but i have not been able to discover it.
Is this a known problem with a simple solution? or do I need to send the clock to you for repairs?
Definately a problem in the HT power supply section.
Did you mount the MOSFET as indicated in the manual and NOT against the PCB, as this could lead to a short?
The MOSFET is mounted with the M3 screw from under the PCB, the MOSFET has one M3 Nut underneath it and one above it. This is all in accordance with the instruction-manual.
Is it possible that the MOSFET is faulty in some way? Or should i continue to measure the continuity of my circuit? (Please note that I am unable to measure the components themselves)
Difficult to say without being able to examine your assembly.
You could remove the MOSFET and measure continuity between the center and right pin. If you measure a low impedance in either direction, the device is faulty.
As for as we can see, soldering and component placement looks OK.
Unfortunately we cannot check the transistors for type.
If an assembly error is not at the cause, we suspect the MOSFET, MOSFET drive transistors and/or the PIC.
Should you have a doubt about the PIC, you can return it for inspection/exchange to:
I just measured the MOSFET with a borrowed multimeter, and with my own to make sure the values were the same. I only got one reading, and this was between the source(right leg) and drain (middle leg) with the Positive probe on the source and the negative on the drain. The result I got was 460-Ohm. However I do not know if this is considered a low impedance.
And I did another test for the MOSFET (test was found on 4qdtec.com/mostest.html.
I first connected the meters negative lead to the source, and the positive to the drain, this measured OL. I then connected the positive to the gate to open it, and measured the drain again, and it showed approx 145ohms. Then the gate was closed by shorting the gate and the source legs through my finger.
I also found a specs sheet for the irf830 which suggested that the “rDS(ON)” should be 1500ohms, however I do not know if that was what I have just measured. It it is, then it is safe to say that the MOSFET is probably faulty in some way.
I also unsoldered T2, T3 and T4 and checked them.
T2 and T3 both showed the same characteristics when measured with an ohm meter- They showed approx 710-ohms with the positive probe on the middle leg and the negative on the right or left leg.
T4 showed 646-ohms with the Negative probe on the middle leg and the positive on either right or left leg.
I also connected the Power supply to the board when the MOSFET and three transistors had been removed so I could measure the voltage over the transformer, it showed 15 volts which should suggest that there is no load on it, ergo the short-circuit has been removed which should suggest that the short circuit was somewhere in the circuit that involved the MOSFET and the three transistors. I might be totally wrong on this assumption since I am not too experienced in dealing with this type of circuitry.
Is there an accurate way of measuring the function of the IC with a multimeter?
Vel417 I am very grateful for all your help so far. And I would just like to ask for one more thing.
Is it possible for you to send me a new IC? since this is almost certainly the faulty component. I have bought new transistors and MOSFETS and the VR1 myself and have changed all of them but the problem still remains, so it has to be the IC (or the PCB, but that is highly unlikely).
Can you send one without me sending the old one back to you?
And if so, where can I supply my address to you without posting it on the forum?
In the Assembly Manual that came with my kit (H8099-B1), there is no M3 hardware nor any instructions to attach the MOSFET and regulator to the PCB. The pdf file of the manual at velleman.be (H8099IP-1) instructs to attach the components to the PCB with M3 screws.
My kit does not include any mounting hardware for these components.
Most likely, you have an early version of the kit, which did not include the bolts and nuts.
You can add them yourself or you can simply bend the MOSFET and regulator, but keep in mind that it may not touch the board.
If you cannot get hold of them, we can mail the necessary parts, if you supply an address.
[quote=“VEL417”]Most likely, you have an early version of the kit, which did not include the bolts and nuts.
You can add them yourself or you can simply bend the MOSFET and regulator, but keep in mind that it may not touch the board.
If you cannot get hold of them, we can mail the necessary parts, if you supply an address.[/quote]
I had just finished mounting both components as I wrote that yesterday. The components have been mounted in this fashion:
There may be enough room to fit a mica insulator between them and the board if you feel this is required. Let me know if the mounting as shown is appropriate, and/or if my solution with the mica isolators is acceptable, and I’ll order the mounting screws. If the components have to be raised enough to fit a nut between them and the board (as the previous poster has done) I may have to replace the MOSFET and the regulator as their leads have been cut to fit.
This is an awesome kit to build, so much fun, it is quite soothing to observe the clock in function with the soft glow of the nixie tubes. I’m happy I saw your earlier message about the limited availability of this kit, ordered one promptly after seeing it.
The semiconductors may not touch the board, because they could create a short between the metal part and a track of the PCB.
A mica can help.
Next, there is the heat issue.
It is better to either bend the semiconductor to say 45° or to place the bolt and nut
This will provide better cooling than a mica.
I’ve the same problem with the power. The Mosfet becomes very hot. I measured the voltage over C2 and C4, they were approximately 5VDC, i then measured the voltage from the metal part on VR1 to the cathode on D6, and only got from 20 to 39VAC. I’ve checked everything and couldn’t finds something wrong. I don’t know if there is found a solution yet.
Most likely an assembly problem.
Sorry, this forum does not allow picture uploads
If you can provide LINKS (e.g. by using a free online picture base) to HI-RES and SHARP pics of your assembly (both solder- and component side)
then we can take a look and provide some feedback.
