Jenny Reloaded problem :(

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1 year 7 months ago #7149 by Pacman223

lcc wrote: HI
i know that your clock has being running ok for some time
i can remember when i built one of these clocks i had trouble with the super cap it was solders to close to the board and solder had built up under neath it and shorted out stopping the clock from working just thought i would mention it just in case you had the same problem and it has only just started to give you trouble


Thank you for your input.. I wiggled the super cap further away from the board, and removed as much solder as possible, didn't have any effect. but I really appreciate your input, Thank you

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1 year 7 months ago - 1 year 7 months ago #7150 by Mr.Nixie
The ceramic disk are "normally" specified for 50 VDC but during the last time it looks that one batch of this types will fail (short circuit) after a long time of operation near to their voltage limits (47 VDC).
If t2 runs hot even with the replacemenr part it can happen that also C20 is faulty as it is also connected to the HV rail.
BTW: the clock will work even without C13 / C20.
If this will also not help unsolder the jumper H/I to disconnect the Gate of the MosFet from the PIC's PWM stage and see what happens than. I have also had a few PICs which has a continuously "high" on pin 13 instead of a regulated 50 kHz PWM signal. This "high" will cause nearly to "grill" the MosFet. Than you need to order a replacement PIC.
Last Edit: 1 year 7 months ago by Mr.Nixie.

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1 year 7 months ago #7151 by Pacman223
Juergen,

thank you very much for your suggestions. I'll take your suggestions and report back.

I'm ordering a IV-13 clock soon, I might ask for a new jenny Re-loaded pic chip to be inlcuded :) if I think it will help.

Thanks

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1 year 7 months ago #7152 by Mr.Nixie
No problem at all.
I am not sure if you have an osci. If yes unsolder the H/I jumper as described before and put the probe on pin 13 of the PIC. You should get a square wave signal of around 50 kHz with a duty cycle of 80 %. If you get a constant high, than the PIC is faulty.

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1 year 7 months ago #7153 by Ty_Eeberfest
I can sort of explain the 1.7K reading. Note that one end of R4 goes directly (same node) as the HV test point. You read about 0.7K from test point to ground. Other end of R4 goes thru 1K to ground. 1K + 0.7K = 1.7K.

So I think that mystery is solved and the reading is just a distraction from the real problem. The real problem being: why do you see 0.7K to ground at the test point?? Seems way too low a reading to me. Maybe time to look at C20 as Juergen mentioned. I didn't even notice C20 over there until I read his post.

Removing jumper H-I and scoping the PWM sounds interesting and I'd like to hear what you find.

Look into it later when the dust is clearing off the crater.

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1 year 7 months ago #7156 by Ty_Eeberfest
So what ever happened with this?

Look into it later when the dust is clearing off the crater.

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1 year 7 months ago #7157 by Pacman223
Thanks for following up.

My wife and family have been keeping me from working on it :(.. last Saturday I was all set to get some serious nixie clock work done (on Jenny and my own nixie clock design)... Wife and daughter were all set to spend most of the day at my in-laws.. and.. nope... in-laws called Saturday morning, and cancelled the party :(

hopefully soon I can get back to it.

I'm going to check C-20 I suspect if it is bad, that might be why I'm getting that reading... my other thought is I wonder if the pic chips is bad... would a bad pic chip mess up the high voltage->ground rsistance measurement?

I'm also worried that when I replaced t2, I messed up the board. but in my mind even if I did that, I should be able to solder a conection point to point to fix it..

I'm going to ask for a new PIC chip for this Jenny clock when I order the IV-13 clock, I'm thinking in a couple of weeks I'll have saved up enough for that clock :)

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1 year 6 months ago - 1 year 6 months ago #7162 by Pacman223
update!!!

ok I did some trouble shooting ... and nixie clock bulding .. see a different through. Here is what I have now.

across c20 is nearly 1k ohm
c20 looks ok.. but not sure that's a correct value or not.

(unplugged and before making any changes)
very high resistance between t2 and d6 (and L4 the diagram shows them connected)
from the diagram that's not right.. I'm guessing I messed up the t2 hole replacing ... so I soldered a small wire between d6 and t2... its hard to know which pins to use exactly, but I think I got it right.



when the clock is on.
all the pins of t2 read +5 voles (or nearly so.. 1 pin (the one connected to d6 reads slightly higher if I recall).

the clock is acting like its working, beeps when button is pressed, ect.. just the IV tubed still do not light up.

questions.

do these symptoms seem to indicate a bad pic chip? do you think I got the wrong pin on t2 connected to d6?

(hard for me to know which pin on t2 is supposed to be connected to d6).


I'll post a pic of the board with the added wire.
m
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Last Edit: 1 year 6 months ago by Pacman223.

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1 year 6 months ago #7163 by Pacman223
another image from the manual.. showing in red where I made a connection.. thinking that those two points should be connected.
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1 year 6 months ago #7166 by Ty_Eeberfest
According to the schematic it is the Drain of T2 that should connect to D6 and L4. According to the data sheet for T2, Drain is the center pin, not one of the outside pins. So I'd say your wire is in the wrong place.

Reading resistance across a capacitor isn't likely to tell you a hell of a lot about the capacitor itself. But if you are reading 1K across C20 what it does tell you is that *something* is pulling the entire HV network (D6 cathode, C5, C13, R4, R5, C20) to ground through 1K of resistance, which seems wrong.

Take a methodical approach as follows... shotgun approach will just get you and me both more confused! :unsure:

1) Pop IC2 out of its socket
1.5) read resistance from HV testpoint to ground.

2) Remove your jumper wire from T2 -> D4 for now.
2.5) read resistance from HV testpoint to ground.

3) Remove C13
3.5) read resistance from HV testpoint to ground.

4) Remove C20
4.5) read resistance from HV testpoint to ground.

5) Remove R4
5.5) read resistance from HV testpoint to ground.

6) Remove C5
6.5) read resistance from HV testpoint to ground.

7) Remove T2
7.5) read resistance from HV testpoint to ground.

After on of those steps the resistance from HV testpoint to ground should change suddenly and obviously. Probably it will go to open circuit / infinity (or some really high value). When that happens, stop. You have found the problem component (or at least one of them - could be more than one!).

Once you have that resolved we can talk about the possibility of a bad PIC. I think it unlikely but Juergen did say he's seen it happen. His advice about putting a scope (or even a frequency counter would help) on PIC pin 13 and/or T2 Gate is IMO great advice too. That would not deal with the issue of the HV being 1K to ground but it would tell you right quick if the PIC is okay or not.

Look into it later when the dust is clearing off the crater.

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