Hello,
My unit recently stopped working, and it is probably a solder joint. I can measure about 36 volts across the tube, which is about 1/10th
of what I would expect. Should I focus on the IC chip, or does anyone have an idea of what pins to inspect?
Correction, after replacing the batteries and testing the connections, I now get about 0.3-0.45 volts. About 1/1000 of what I need.
It is clearly a solder joint issue or perhaps the HV chip. I will do some more visual inspection, and then do some re-soldering. Things look clean, though.
I will check the schematic and use a multimeter, and post what I find. BTW, the correct voltage is showing across the J6 pulse points.
Thanks,
Nick
Kit stopped working, low voltage
Kit stopped working, low voltage
Last edited by nbrand on Thu Dec 15, 2011 1:21 pm, edited 1 time in total.
Re: Kit stopped working, low voltage
Hi Nick,
What kind of meter are you using to measure the voltage, and are you using a 1 GigaOhm in series with it as described in the PDF instructions?
Do you hear a faint whine from the speaker when you turn the kit on? Are the batteries fresh and tested at 1.5V each?
What kind of meter are you using to measure the voltage, and are you using a 1 GigaOhm in series with it as described in the PDF instructions?
Do you hear a faint whine from the speaker when you turn the kit on? Are the batteries fresh and tested at 1.5V each?
Jeff Keyzer
http://mightyohm.com
http://mightyohm.com
Re: Kit stopped working, low voltage
Hi Jeff,
Happy holidays and thanks for the reply.
I had posted a reply, but I was not logged in so it was lost. This is an abbreviated version...
Once I got the schematics, I started to understand the design a bit. It looks like a 555 timer is triggering voltage pulses
that are being multiplied by inductor L1. As I am getting zero voltage across TP2, and no sound upon start-up,
I decided to look there.
I checked the Vcc and GND pins on the 555 timer. No voltage reading. After inspecting the board again,
I replaced the chip with a spare I had, and voila - 3 volts! Unfortunately, I do not have the low-power 555 [TLC555CP] as a spare,
so the device is still not working. However, it does prove that the 555 was blown. I may have a short somewhere.
I will order some replacement chips and then see if I can investigate the short before I blow it up again.
The 555/inductor is a clever design, although probably not as reliable as a Cockcroft–Walton (CW) generator, or multiplier
which are typically used in a geiger counter. I am not sure what the mini processor is doing, as I do not know how complex
it is to trigger a LED/buzzer upon signal. If so, it is overkill. Of course, there may be some more complex logic processing going on.
I will post again after I get some replacement chips, in about a week.
Thanks again for all the assistance!
Nick
PS. I agree that a v2 should have pads for all points. When it worked, it did chew through batteries quickly, so perhaps a larger
capacity, or external supply.
Happy holidays and thanks for the reply.
I had posted a reply, but I was not logged in so it was lost. This is an abbreviated version...
Once I got the schematics, I started to understand the design a bit. It looks like a 555 timer is triggering voltage pulses
that are being multiplied by inductor L1. As I am getting zero voltage across TP2, and no sound upon start-up,
I decided to look there.
I checked the Vcc and GND pins on the 555 timer. No voltage reading. After inspecting the board again,
I replaced the chip with a spare I had, and voila - 3 volts! Unfortunately, I do not have the low-power 555 [TLC555CP] as a spare,
so the device is still not working. However, it does prove that the 555 was blown. I may have a short somewhere.
I will order some replacement chips and then see if I can investigate the short before I blow it up again.
The 555/inductor is a clever design, although probably not as reliable as a Cockcroft–Walton (CW) generator, or multiplier
which are typically used in a geiger counter. I am not sure what the mini processor is doing, as I do not know how complex
it is to trigger a LED/buzzer upon signal. If so, it is overkill. Of course, there may be some more complex logic processing going on.
I will post again after I get some replacement chips, in about a week.
Thanks again for all the assistance!
Nick
PS. I agree that a v2 should have pads for all points. When it worked, it did chew through batteries quickly, so perhaps a larger
capacity, or external supply.
Re: Kit stopped working, low voltage
Can you explain what you mean by "pads for all points"?nbrand wrote:Hi Jeff,
PS. I agree that a v2 should have pads for all points. When it worked, it did chew through batteries quickly, so perhaps a larger
capacity, or external supply.
Jeff Keyzer
http://mightyohm.com
http://mightyohm.com
Re: Kit stopped working, low voltage
Jeff,
My mistake. It just seems that some of the pads are especially small, which did not allow
for a solid solder connection. The batteries points in particular, but there are other critical points
where a larger pad would of made things easier. The layout is very good, so there seems to be ample
space for more contact area.
Nick
My mistake. It just seems that some of the pads are especially small, which did not allow
for a solid solder connection. The batteries points in particular, but there are other critical points
where a larger pad would of made things easier. The layout is very good, so there seems to be ample
space for more contact area.
Nick
Re: Kit stopped working, low voltage
The next revision of the design will address this with larger pads for many components.
Thank you for the feedback!
Thank you for the feedback!
Jeff Keyzer
http://mightyohm.com
http://mightyohm.com