Nixie Clock Cool Project- a few questions

[Dman777]

I have a 6 digit Nixie ZM5660 clock that I got from pvelectronics that is beautiful and super cool. Everything is perfect about it. However, since it is multiplexed there is one spot that has a very high concentration of heat. I want to place a fan underneath the clock to draw out this hot air, otherwise the life of the clock will not be as long as it will without the heat. 

I will be taking dremel and drilling a large area underneath the case and placing a fan against the case surface(outside of the case) to draw out the hot air. I will then wire the 12v fan to the power supply connectors. When done, I will be placing the clock case on two blocks so there will be about 3 inches of area between the bottom of the clock(with the fan) and the shelf it sits on. I addition, I will drill some small holes for cool air intake on the sides and on top. 

A few questions come to mind, please:

1) The case is only 3/4 of inch deep. Should I go for a 2 inch fan or 1 inch fan? Typically, a 2 inch fan will draw more heat out. But since there will only be able 3/8" of space between the fan and circuit board, I am not sure which would be more effective in drawing heat out.

2) The source of heat is in the center middle of the clock. If I place the middle of the fan directly underneath the heat concentration, will that heat just sit since it won't be above the blades but instead above the rotor? Should the fan be off center to the actual heat concentration?

3) I would like a fan with a good ratio of not to loud but move enough heat out. Not sure which would be a good cfm.

4) I don't understand why, the heat concentration is in the dead center of the clock, but the source of what I think is the source of the heat...the 7805 voltage regulator... is of to the side of the source of the heat concentration area. 

5) Do I need to worry about trace erosion from air flow and friction? On my old Xbox I had the fan running high in it and one of the traces eroded.

Here are some of the fans(Would like to stick with ball bearing) I have been looking at. I am big fan of Sunon:

1 inch:

http://www.jameco.com/1/1/2967-kde1203pfb2-8-ms-dc-brushless-tubeaxial-fan-bearing-type-ball.html

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_1708465_-1

2 inch:

http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?refineValue=Ball&refineType=1&langId=-1&position=1&productId=1950446&refine=1&catalogId=10001&history=6fqaemmj%7CsubCategoryName~DC%2BBrushless%2BFans%5Ecategory~3715%5EcategoryName~cat_37%5EprodPage~15%5Epage~SEARCH%252BNAV%401bnairch%7Ccategory~371530%5EcategoryName~cat_3715%5Eposition~1%5Erefine~1%5EsubCategoryName~DC%2BBrushless%2BFans%2B%252F%2B2.00%2522%2B%252850mm%2529%5EprodPage~15%5Epage~SEARCH%252BNAV%40dnogx9g3%7CrefineValue~SUNON%5ErefineType~1%5Eposition~1%5Esub_attr_name~Manufacturer%5Erefine~1%5EprodPage~15%5Epage~SEARCH%252BNAV&sub_attr_name=Bearing&storeId=10001&ddkey=http:StoreCatalogDrillDownView

Thanks,

-Darin

[JohnK]

"I want to place a fan underneath the clock to draw out this hot air, otherwise the life of the clock will not be as long as it will without the heat. "

 

Hot air 'rises' ie is pushed up by denser air. Pulling hot air down is not as effective as helping it go 'up'.

 

AND, wherever you are moving air, you need an IN and an OUT.

I was not sure about your description... if you do pull the air down as you say, can air get in to replace the air you are trying to move.... ie holes in the top?

If there are holes for the air to get 'in', then you better compare pulling and pushing  - use a thermometer.

 

If there are no holes for the air to get 'in' then you had better reconsider.

Blowing air / 'sucking air' around the case will help cool by conduction through the case - a litle.

 

John K

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[Dman777]

 I will drill some small holes for cool air intake on the sides and on top. 

The fan will be drawing out air from the bottom. I won't change that. With the heat dispersed, it will not be issue as it is in one concentrated spot.  I am more concerned with the questions I have in mind from the original post, please.

Thanks,

-Darin

[Nicholas Stock]

Darin, the clock may get a little warm, but I think you may be worrying overtly. The holes under the case allow air to circulate up and through/around the PCB and out the holes around the tubes by convection. If you do plan on adding a fan (I don't think this is necessary, but hey it's a free world), take into account that the circuit has a 500 mA polyfuse, so if you plan on adding the fan to the circuit side 12V rail make sure it doesn't draw more than 100 mA or so. 

Nick

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[Ron Walsh]

Have you contacted Peter (PV Electronics) about the heat issue?  I have used I think three of his kits, and I have not noticed anything getting particularly hot.  The first clock I built has been in operation for over a year now, and if the clock were to go down, I am sure my daughter would be on the phone asking me to fix it.

I think you may run into an issue with noise with such a small fan.  One thing you can do is run it at 7v and that may help with the noise.

Keep us updated on your solution.

 

...Semper Fidelis...

On Tuesday, October 7, 2014 11:30 PM, Nicholas Stock <nick...@gmail.com> wrote:

Darin, the clock may get a little warm, but I think you may be worrying overtly. The holes under the case allow air to circulate up and through/around the PCB and out the holes around the tubes by convection. If you do plan on adding a fan (I don't think this is necessary, but hey it's a free world), take into account that the circuit has a 500 mA polyfuse, so if you plan on adding the fan to the circuit side 12V rail make sure it doesn't draw more than 100 mA or so. 

Nick

On Tue, Oct 7, 2014 at 6:52 PM, Dman777 <darin....@gmail.com> wrote:

 I will drill some small holes for cool air intake on the sides and on top. 

The fan will be drawing out air from the bottom. I won't change that. With the heat dispersed, it will not be issue as it is in one concentrated spot.  I am more concerned with the questions I have in mind from the original post, please.

Thanks,

-Darin

On Tuesday, October 7, 2014 8:18:59 PM UTC-5, Dman777 wrote:

I have a 6 digit Nixie ZM5660 clock that I got from pvelectronics that is beautiful and super cool. Everything is perfect about it. However, since it is multiplexed there is one spot that has a very high concentration of heat. I want to place a fan underneath the clock to draw out this hot air, otherwise the life of the clock will not be as long as it will without the heat. 

I will be taking dremel and drilling a large area underneath the case and placing a fan against the case surface(outside of the case) to draw out the hot air. I will then wire the 12v fan to the power supply connectors. When done, I will be placing the clock case on two blocks so there will be about 3 inches of area between the bottom of the clock(with the fan) and the shelf it sits on. I addition, I will drill some small holes for cool air intake on the sides and on top. 

A few questions come to mind, please:

1) The case is only 3/4 of inch deep. Should I go for a 2 inch fan or 1 inch fan? Typically, a 2 inch fan will draw more heat out. But since there will only be able 3/8" of space between the fan and circuit board, I am not sure which would be more effective in drawing heat out.

2) The source of heat is in the center middle of the clock. If I place the middle of the fan directly underneath the heat concentration, will that heat just sit since it won't be above the blades but instead above the rotor? Should the fan be off center to the actual heat concentration?

3) I would like a fan with a good ratio of not to loud but move enough heat out. Not sure which would be a good cfm.

4) I don't understand why, the heat concentration is in the dead center of the clock, but the source of what I think is the source of the heat...the 7805 voltage regulator... is of to the side of the source of the heat concentration area. 

5) Do I need to worry about trace erosion from air flow and friction? On my old Xbox I had the fan running high in it and one of the traces eroded.

Here are some of the fans(Would like to stick with ball bearing) I have been looking at. I am big fan of Sunon:

1 inch:

http://www.jameco.com/1/1/2967-kde1203pfb2-8-ms-dc-brushless-tubeaxial-fan-bearing-type-ball.html

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_1708465_-1

2 inch:

http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?refineValue=Ball&refineType=1&langId=-1&position=1&productId=1950446&refine=1&catalogId=10001&histor y=6fqaemmj%7CsubCategoryName~DC%2BBrushless%2BFans%5Ecategory~3715%5EcategoryName~cat_37%5EprodPage~15%5Epage~SEARCH%252BNAV%401bnairch%7Ccategory~371530%5EcategoryName~cat_3715%5Eposition~1%5Erefine~1%5EsubCategoryName~DC%2BBrushless%2BFans%2B%252F%2B2.00%2522%2B%252850mm%2529%5EprodPage~15%5Epage~SEARCH%252BNAV%40dnogx9g3%7CrefineValue~SUNON%5ErefineType~1%5Eposition~1%5Esub_attr_name~Manufacturer%5Erefine~1%5EprodPage~15%5Epage~SEARCH%252BNAV&sub_attr_name=Bearing&storeId=10001&ddkey=http:StoreCatalogDrillDownView

Thanks,

-Darin

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[Dman777]

Yes, I do not want to give the wrong impression. There is nothing wrong with the clock at all, it's a excellent clock with 100% A++ craftmanship. I am very happy with it. The heat is from it's native design using voltage regulation. I want to be proactive and use a fan to extend the life of it. At the very least, it would not hurt it to remove the concentrated heat area. 

Thanks,

-Darin

[Tidak Ada]

Are you aware witch component is due to the heat? I guess its the small SMD circuit, just behind the spacer or are it the two transistors , just left from the spacer (seen on photo clock4) ?

 

In case it is the SMD circuit it might be possible to make a copper heat sink that is fastened by the spacer and pressed by a little screw or spring through the case bottom to the IC that presses the heat sink to the IC. Make a vertical wing of about two inches broad and the height of the spacer at the backside of the print to rise the radiating surface. that must be enough. You will need to turn or grind off the spacer by the thickness of the copper or add washers of the same thickness to the other spacers to compensate.

Drilling some holes in the case, just above the heatsink would be wise.

 

Anyhow, I think the heat is a fault in the print design, leaving not enough copper to serve as a heat sink.

 

No noise and no electrical power needed

 

eric

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From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Dman777
Sent: woensdag 8 oktober 2014 3:19
To: neoni...@googlegroups.com

Subject: [neonixie-l] Nixie Clock Cool Project- a few questions

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[AlexTsekenis]

Darin,

I second blkadder's suggestion to contact the designer first. Check if this was intentional or if there is a fault.

Then, it is likely that the heat generation is from one single, power related, component. You could consider bringing this outside the case instead of adding fans.

From your pictures, the heat concentration is located at the high voltage section. The designer is aware of heat issues in this area as there are numerous vent holes there. It is likely to be that (transistor?) under the vent holes.

Alex

[Arne Rossius]

Hi,

Dman777 wrote:
> 4) I don't understand why, the heat concentration is in the dead center of
> the clock, but the source of what I think is the source of the heat...the
> 7805 voltage regulator... is of to the side of the source of the heat
> concentration area.

The 7805 only powers the electronics, which I expect draws very little
current, so the regulator will remain cool.

I think the heat source might be the MOSFET in the switching power
supply for the nixie voltage. Unfortunately it's the rather common, but
not very good MC34063-based design, you can see the schematic in the kit
instructions here:
<http://www.pvelectronics.co.uk/kits/LTC1040/LTC1040_v5.pdf>. They use
an IRFD220 MOSFET which has way too high R_DS,on for this application IMHO.

If you don't want to replace the MOSFET (which wouldn't look too good as
I don't think you will find a better replacement with the same
footprint), having a fan blow air onto it might indeed be a good idea if
you can stand the noise.


Best Regards,
Arne

[chuck richards]

Well one thing you could do would be to take a voltage
measurement at the input to the 7805 regulator.

True that with a light load, the 7805 should run fairly
cool. However, the 7805 also runs proportionally hotter the higher
the input voltage is. For input voltages down around 11 or 12 volts,
it's not running very hot. But go up around 15 volts and over, and
that little dickens starts to heat up regardless of the DC load on
the 5 volt regulated side.

In my applications for the 7805, I always use a massive heatsink
usually in the form of a good-size aluminum plate. My earliest
nixie clock uses the .25 inch thick x 8 inch x 10 inch aluminum
base plate as the 7805 heatsink. The 7805 runs cool on that big
plate.

Most of those little chintsy thin aluminum heatsinks with the
fins don't really do much in the way of heat dissipation, I have
found. If you really want to take away some heat, a huge mass
of metal does the best job, in my humble opinion.

Chuck

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[John Rehwinkel]

If you really want to take away some heat, a huge mass
of metal does the best job, in my humble opinion.

For example, this 51-pound monster:

 http://www.ebay.com/itm/201187133796

- John

[gregebert]

Have you measured the power consumption of the clock ? The 6 nixies will consume about 2 watts, and everything else is dissipated as heat inside the case. That will give you a rough idea if you have a thermal problem.

If you are around 5 watts, then I'd say you're probably OK. My first nixie clock design draws about 5 watts, and everything including the tubes is sealed in a case with no heat problems.

If you are significantly over 5 watts, then I would look for ways to get rid of the heat; easiest is a small fan.

[jf...@my-deja.com]

My first question is “How hot is it?”  If you can keep your finger on it, it is probably OK, but you should use a thermometer instead of just saying “hot”.

 

My prejudice is that the only likely sources of excessive heat are the 7805 and the cpu, but they are both too far away.  The only components I see in the area are the two resistors; if one or both are the incorrect values (probably too low) they could be dissipating a lot of heat.  Check the color codes against the schematic, or get out your handy dandy ohmmeter (if you don’t already have one, digital multimeters are cheap at Harbor Freight).

 

I don’t think it is the heat source, but you can replace the 7805 with a pin-compatible switching mode regulator, available for less than $10 from http://www.ebay.com/itm/3-Terminal-5V-1A-Switching-Voltage-Regulator-Power-Supply-/261243604047?pt=LH_DefaultDomain_0&hash=item3cd3550c4f

 

[Terry S]

You're making some possibly unwarranted assumptions.

Have you measured the temperature? Electronics are designed to run at elevated temperatures. What leads you to believe that you need to cool the clock?

What makes you believe the fact that it's multiplexed has anything to do with the heat build up?

It sounds like you are going to create an ugly Frankenstein out of what is likely a proven design.

And you'll have to live with the fan noise and additional load on your 12v supply.

Simply venting the top of the case will likely cool the enclosure considerably IF that is needed at all.

PCB design - good PCB design (I am an expert in this area) -- can be made to draw heat away from hot components, but the warmest spot will still be the hot component. I suggest you revisit your assumptions about the source of the heat, and the location of the heat.

And "trace erosion" ???? Really? I've never heard of it, much less of having it caused by airflow. Other things can degrade traces, poor processing, chemicals, acidity, but airflow? MAYBE compressed air over the course of decades... MAYBE.

On Tuesday, October 7, 2014 8:18:59 PM UTC-5, Dman777 wrote:

[gregebert]

And "trace erosion" ???? Really? I've never heard of it, much less of having it caused by airflow. Other things can degrade traces, poor processing, chemicals, acidity, but airflow? MAYBE compressed air over the course of decades... MAYBE.

Perhaps he meant electromigration. It's been a major concern for IC design since the 1960's, and it is temperature-dependent. But on a PCB I doubt you would have high-enough current-density. 

[Dman777]

And "trace erosion" ???? Really? I've never heard of it, much less of having it caused by airflow. Other things can degrade traces, poor processing, chemicals, acidity, but airflow? MAYBE compressed air over the course of decades... MAYBE.

It was a known issue for a few(very small quantity) Xbox's...most of those modded and with high air current. I placed the motherboard on a scanner and magnified the scanned picture and saw the eroded trace with my own eyes. 

I don't think I could stick a heat sink on that tiny black circuit square, or the blue one ether. Also, drawing heat from it wouldn't do much good without a fan to displace the drawn out heat. 

I guess at this point I will use a fan. I would rather suck the air out than have a fan blow on it and spread the heat around. It's not a good idea to let it be...it's enough heat to warm the glass of those 2 tubes at the base, extremely warm the plastic,  and in time I am sure the heat would cook something on the circuit board that would cause a single point of failure. 

I'm not a fan of the idea of having a Frankenstein clock, but since heat is one of the electronics worst enemy, it's better that I protect my investment. Years down the road when the tubes and kits become more hard to find, I would like to have my clock still working. 

-Darin

On Tuesday, October 7, 2014 8:18:59 PM UTC-5, Dman777 wrote:

[Per Jensen]

On 09 Oct 2014, at 02:09, Dman777 <darin....@gmail.com> wrote:

And "trace erosion" ???? Really? I've never heard of it, much less of having it caused by airflow. Other things can degrade traces, poor processing, chemicals, acidity, but airflow? MAYBE compressed air over the course of decades... MAYBE.

It was a known issue for a few(very small quantity) Xbox's...most of those modded and with high air current. I placed the motherboard on a scanner and magnified the scanned picture and saw the eroded trace with my own eyes. 

There is absolute no thing as Trace erosion on an Xbox - that is pure rubbish.

There was some problems on Xbox boards where the etching of the board had been done improperly, leading to broken connections over time.

http://www.theisozone.com/tutorials/xbox/hardware-and-modding/trace-corrosion-repair/

This has nothing to do with high current or temperature.

// Per.

[Charles MacDonald]

On 14-10-08 08:09 PM, Dman777 wrote:

> It was a known issue for a few(very small quantity) Xbox's...most of
> those modded and with high air current.

Why should Microsoft's Hardware work any better than their software ;)

.it's enough heat to warm the glass of those 2 tubes
> at the base, extremely warm the plastic, and in time I am sure the heat
> would cook something on the circuit board that would cause a single
> point of failure.

Have you snooped around with an infrared thermometer? are there any
components that are too hot to touch? (watch out for the voltage of course)

if it is one warm part, you could also just epoxy on a SMALL heat-sink.
http://www.futurlec.com/Heatsinks.shtml


--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca Just Beyond the Fringe
http://Charles.MacDonald.org/tubes
No Microsoft Products were used in sending this e-mail.

[Terry S]

Dman clearly has ideas of his own about electronics, misguided as they may be. He asks plenty of questions here -- usually dominating the topic list -- that show exactly how little he understands about electronics.  If he wants to butcher up his clocks, let him have at it. If he chooses not to take advice from the knowledgeable assembled here, so be it. I, for one, am tired of reading his dribble.

[Nick]

OK, some basics on SMPS design:

1. All SMPS designs have losses, some more than others. This results is heat being generated and devices get warm. The two devices that may exhibit this are the switch FET and inductor.
   In a good SMPS, the FET will remain cool-ish and so will the inductor. This design uses an old-ish chip that is not very efficient, but should be good enough.
2. Do you actually have a problem? How do you know? In the light of point 1. above, your FET will get warm, but how hot is yours? Quantify the issue - is the FET at 30C? 40C? 50C? What voltage is coming out of the wall-wart when under load? etc.
3. If the FET is actually getting very hot, i.e. too hot to touch, it may be due to internal losses (RDSon for that FET is quite high, so it may get quite warm) or it may be a sub-spec FET.... 
4. Sometimes in SMPS designs, you can get RF oscillation - it may be that for some reason that is happening here... If it is, it is something for the designer to deal with, not you, and a fan etc. is NOT the answer.

...however the designer of that clock is a knowledgeable guy who has build a load of clocks- first thing should be to ask him.  Have you done that?

When tacking an issue like this, firstly establish whether you actually DO have a issue - speak to the guy that designed & built it. Remember that SMPSs are fickle beasts and sometimes misbehave and need care & feeding- judging by your apparent level of knowledge, this is not something you should do yourself - speak to the designer,

Secondly, forget about drilling holes and fans etc. for now - absolutely NO WAY should that be necessary - this is a proven design by a good supplier - if you feel its not right, SPEAK TO HIM !

Thirdly. a little knowledge is a dangerous thing - forget the random stuff about "electro-migration" - it simply is complete rubbish in this context. To quote from a recent Intel research paper:

"Electromigration (EM) remains a serious problem for the reliability of VLSI integrated circuits, and will become an even more serious issue as future IC's employ linewidths below 0.2 micron...."

Note the scale we are talking about here - 0.2 micron is one five thousandths of a millimetre, i.e. 7.9 MILLIONTH of an inch. The tracks on the PCB on that clock are at least 1000 times bigger - its a problem for VLSI chips running at high temperatures for long periods of time (typically many years), specifically mainly over-clocked CPUs. i.e. Forget about it.

So, like all engineering and other problems:

1. Establish whether you actually have a problem or whether what you are observing is expected behaviour.
   
2. Don't let your imagination wander out of the bounds of its experience. i.e. Keep it real - stick to facts, avoid speculation.
3. If indeed you believe that you have a problem, quantify the behaviour (measure temperatures, input voltage etc.)
   
4. Speak to the designer to resolve the issue - give him that data from item 2 - , and...
   
5. ... if that doesn't work, return the product for a refund (assuming you haven't done anything silly like drill holes & fit a fan).
   
6. That's it

HTH

Nick

[M.J.Sangster]

My guess is the heat is coming from the 7805 - they tend to generate heat with even modest current draw. I believe a simple linear voltage regulator is around 40% efficient - the rest goes to heat. The circuit uses 2 74141 type IC's, they draw a lot of current. If it was a problem (too much heat) the regulator would shutdown.

The power supply looks good, I'm guessing neither the FET or the inductor even get warm.

M.J. Sangster

On Tuesday, October 7, 2014 8:18:59 PM UTC-5, Dman777 wrote:

[Nick]

On Thursday, 9 October 2014 14:37:26 UTC+1, M.J.Sangster wrote:

My guess is the heat is coming from the 7805 - they tend to generate heat with even modest current draw. I believe a simple linear voltage regulator is around 40% efficient - the rest goes to heat. The circuit uses 2 74141 type IC's, they draw a lot of current. If it was a problem (too much heat) the regulator would shutdown.

The power supply looks good, I'm guessing neither the FET or the inductor even get warm.

The 74141s take 25mA each - being generous, the whole circuit may take 70mA including the alarm and GPS LEDs - the CPU is an ultra-low-power one and almost everything else is driven from the 12V rail - with 12V in, 5V out that's a 7V drop in the 7805 @ 70mA which is only about 500mW of heat - a 7805 in a TO-220 case hast a theta JA of 19C/W so the case will get to maybe 10C above ambient (perhaps a bit more as its in a case), i.e. its unlikely to get very hot at all (unless its oscillating, but it does have input and output 100n ceramics).

Nick

[M.J.Sangster]

It would be interesting to see which component is generating the heat. Dman777?

On Tuesday, October 7, 2014 8:18:59 PM UTC-5, Dman777 wrote:

[threeneurons]

I'm with the other guys. There may be nothing wrong with the unit, and its operating normally. Saying warm or hot, with no real numbers really doesn't mean anything. If you have access to a thermometer with a small "pointy" probe, then get us some numbers. F or C, doesn't matter, just as long as you relay the info correctly, and don't get them mixed up.

Just because a TO-220 package can be, and is, commonly mounted on a heatsink, doesn't mean it needs one. Its particular use, and how much power its really using, will determine that. Also, how big of a heatsink, if one is needed. That's something the designer has to figure out.

I can go on a big rant about numbers, and quantifying data. That's something that seems not to be emphasized today. Numbers count ! I have a little money, and Bill Gates has money. You think numbers matter, in that example !?

I don't know squat about electromigration, other than it doesn't happen at the PCB scale (remember numbers). However, a PCB trace can carry only so much current. Too much, and it will simply act as a fuse. Don't think that's an issue on a nixie clock. Can't say, either way, on an X-Box. Maybe there was an excess current issue on one of the X-Box traces, and some fool heard a new big word ? I spoke the word "euphoria", here at the office, and one idiot overheard it, and misused it for months.

On Tuesday, October 7, 2014 6:18:59 PM UTC-7, Dman777 wrote:

[Paul Parry]

I have built lots of PV Electronics clocks 60+ and not had an issue with any of them. They are a sound design and very well thought out, Pete is a very exerienced guy and knows what he is doing. Yes, some parts may get a little warm, it is what they are supposed to do. It's like thinking there is a problem with a coffee maker, because it gets hot..

You have got a very nicely engineered clock, just be happy with it and not try and find an issue where there isn't one.

 

Regards,

Paul

 

[Sture Nystrom]

Darin,

Measure what you have for voltage from the power supply unit. If it is a
simple unregulated power supply voltage can be above 12V. Cheap power
supplies are often built of a transformer, four diodes and a capacitor.

Sture

[jf...@my-deja.com]

On Friday, October 10, 2014 2:16:47 AM UTC-7, Paul Parry wrote:

I have built lots of PV Electronics clocks 60+ and not had an issue with any of them

 

First, I do not think there is a real problem.  It looks like the case already has plenty of holes on the top and bottom, more than should be necessary for relatively simple consumer electronics operating at low frequencies.

 

If there were any serious overheating, there would be some discoloration on the pc board at the hot spot, espcially after hundreds of hours of operation.  However, if Darring built it from a kit, there could be a workmanship problem (looking at the pictures, there are details I would have done differently).

[Dman777]

Yes, the clock is 100% A++ quality. I do not want to give the wrong impression on this. It's the native behavior of the clock components in which I am looking to keep cool...even if others think it's ok for them to be hot.  

Thanks,

-Darin

[Dman777]

I was studying the area where the heat is trying to figure out where the heat is coming from, since there are no real components near the heat concentration. 

Using my camera and zooming in, I see some strange markings on PCB board surface and some brown/burn spots also. Could this have anything to do with the heat concentration? What are these from? I attached a couple of pictures.

Thanks,

-Darin

[Arne Rossius]

Hi,

Dman777 wrote:
> Using my camera and zooming in, I see some strange markings on PCB board
> surface and some brown/burn spots also. Could this have anything to do with
> the heat concentration? What are these from? I attached a couple of
> pictures.

The brown gooey-looking stuff is probably flux residue from soldering
the component (which is on the other side). The component warms up the
flux residue and it turns from transparent or yellow-ish to brown. This
is nothing to be worried about, but if you want to get rid of it you can
clean it off with some isopropanol.

By the way, is that the footprint of the MOSFET? If unsure, take a
picture of the same spot from the other side of the board. This would
confirm my suspicion that it is the main heat source.


Best Regards,
Arne

[Dman777]

That is a big relief....thank you. Here is a picture of where those right legs are exactly soldered to on the other side. From what I can gather, this would be the closet part to the heated concentrated area...although the heat area seems is a little more off to where the tubes are. Not sure if it's because the air is traveling out the circle openings?

Thanks,

-Darin

[jf...@my-deja.com]

On Friday, October 10, 2014 6:53:05 PM UTC-7, Arne Rossius wrote:

The brown gooey-looking stuff is probably flux residue from soldering
the component (which is on the other side). The component warms up the
flux residue and it turns from transparent or yellow-ish to brown. This
is nothing to be worried about, but if you want to get rid of it you can
clean it off with some isopropanol.

You are assuming Darrin used rosin core solder.  What if he used acid core?  That could leave leakage paths all over. 

[David Forbes]

Darin,

That is the MOSFET. It's been replaced, which is what the brown stuff on
the bottom of the board came from. That's residue from solder wick
braid, and from solder.

None of this stuff is the least bit problematic. If it was me doing the
work, I would have cleaned it off with isopropyl alcohol and a cotton
swab before shipping the clock.

Don't worry, it's not acid core solder. That looks different.

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[Dman777]

Thank you. I didn't build the clock myself....so I ask this question, why would the MOSFET of been replaced if it's a brand new kit?

Thank you,

-Darin

[David Forbes]

Let me put on my psychic goggles.

Please talk to the person you got the clock from before asking any more
questions about it here.

> <https://groups.google.com/d/msgid/neonixie-l/a2c3acbe-99f5-4b8a-ae6d-0673f2caeb89%40googlegroups.com?utm_medium=email&utm_source=footer

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[Tidak Ada]

What I see are very poor solderings!. Best would be to clean the print with IPA, as arne suggests. Then take a magnifier glass and inspect the solderings carefullyand resolder bad ones. Then again clean with IPA.

 

eric

---

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Dman777
Sent: zaterdag 11 oktober 2014 3:38
To: neoni...@googlegroups.com
Subject: [neonixie-l] Re: Nixie Clock Cool Project- a few questions

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[JohnK]

EEEk!!! Soldering is a skill... don't let him anywhere near it.

Inspecting solder joints is not easy, especially for novices.

 

I predict cooked board, delaminated tracks, overheated components....

 

John K

Australia

----- Original Message -----

From: Tidak Ada

To: neoni...@googlegroups.com

Sent: Saturday, October 11, 2014 5:48 PM

Subject: RE: [neonixie-l] Re: Nixie Clock Cool Project- a few questions

What I see are very poor solderings!. Best would be to clean the print with IPA, as arne suggests. Then take a magnifier glass and inspect the solderings carefullyand resolder bad ones. Then again clean with IPA.

 

eric

---

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Dman777
Sent: zaterdag 11 oktober 2014 3:38
To: neoni...@googlegroups.com
Subject: [neonixie-l] Re: Nixie Clock Cool Project- a few questions

I was studying the area where the heat is trying to figure out where the heat is coming from, since there are no real components near the heat concentration. 

Using my camera and zooming in, I see some strange markings on PCB board surface and some brown/burn spots also. Could this have anything to do with the heat concentration? What are these from? I attached a couple of pictures.

Thanks,

-Darin

...clip....

[Dman777]

What do you mean by resolder the bad ones? If there were bad ones, wouldn't the clock not work? Also, how can you tell that the MOSFET has been replaced?

Thanks,

-Darin

[threeneurons]

Because most of the guys, that have responded, had soldering irons in their hands, when the only place they had hair, was on the top of their heads. The solder traces, and solder mask, can get a little beat up during a "rework". Also the excess of chemical residue, both flux, and whatever they use in Solderwick, which I believe, is also some form of flux. Yeah, a cleanup would have been nice.

Even though, I've held a soldering iron, almost daily since, I was ~12-ish, and I'm 55 now, my rework leaves its mark. My mother worked as an assembler for some 30 years. And a rework assembler most of that time. If she had done the rework, you would never had known. Up until only a few months before her passing, she would still critique my soldering work. 

I don't know why the FET was replaced. Either it was bad "out-of-box", or the assembler put it in backwards initially. Getting a bad part, use to be rare, but now there's a whole controversy on questionable parts sources, out of China. As I get older, I notice myself making mistakes, that I wouldn't had made in my 20s or 30s. Those 4-pin DIP FETs can easily be mounted incorrectly. Especially if your eyesight has deteriorated.  

[Instrument Resources of America]

    As a side note I've had a ""soldering iron"" in my hands since I was about 10 ish and I'm now 67. My dad did not have much in the way of tools, much less any soldering tools, but he did have an assortment of screwdrivers, who doesn't? (Anyone see where this going yet???)  I would sit at the kitchen table, screwdriver tip resting in the flame of one of the burners on the kitchen stove, and when it got hot enough would do my soldering. Thanks for bringing up the fond memories. Oh for the good old days. LOL         Ira.

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[JohnK]

"I don't know why the FET was replaced. Either it was bad "out-of-box", or the assembler ..."

 

Or it was just a late-arriving component and no problem at all.

 

AND, way back at the beginning..."otherwise the life of the clock will not be as long as it will without the heat."

 

Whilst in general terms less heat = greater life, if it is running within design specs the tubes will go first. [NOTE - as many have said so far..... hard facts ie numbers are needed]

 

John K

 

 

[Dman777]

After doing research, I see that 

from: http://www.fda.gov/ICECI/Inspections/InspectionGuides/InspectionTechnicalGuides/ucm072859.htm

The more active the flux the easier a solder connection can be made and the fewer rejects that occur. However, if not properly removed after soldering, active fluxes can lead to corrosion and electrical failures.

 What is the best way to remove the flux? If it's a chemical, do I just wipe down that one side of the pcb board that is flat and leave the other side alone?

Thanks,

-Darin

On Saturday, October 11, 2014 2:03:52 PM UTC-5, johnk wrote:



[Instrument Resources of America]

I usually use a tooth brush and isopropyl alcohol. Then air dry, or use compressed air if the circuitry is not static sensitive.   Ira.

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[Charles MacDonald]

On 14-10-11 04:44 PM, Instrument Resources of America wrote:
> I usually use a tooth brush and isopropyl alcohol. Then air dry, or use
> compressed air if the circuitry is not static sensitive. Ira.

When I worked repairing computers, we used to use Tric. Too bad that is
now banded as a carcinogen and a greenhouse gas, it took the flux off
likkity split.


--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca Just Beyond the Fringe
http://Charles.MacDonald.org/tubes
No Microsoft Products were used in sending this e-mail.

[David Forbes]

On 10/11/14 4:48 PM, Charles MacDonald wrote:
> On 14-10-11 04:44 PM, Instrument Resources of America wrote:
>> I usually use a tooth brush and isopropyl alcohol. Then air dry, or use
>> compressed air if the circuitry is not static sensitive. Ira.
>
> When I worked repairing computers, we used to use Tric. Too bad that is
> now banded as a carcinogen and a greenhouse gas, it took the flux off
> likkity split.
>
>

Yeah, it's too bad. I had high school classmates who were killed by it,
from living near the missile factory in Tucson and getting cancer.

I'm very grateful for water-soluble flux these days. It's much safer.

[jf...@my-deja.com]

On Saturday, October 11, 2014 1:31:07 PM UTC-7, Dman777 wrote:

After doing research, I see that 

from: http://www.fda.gov/ICECI/Inspections/InspectionGuides/InspectionTechnicalGuides/ucm072859.htm

The more active the flux the easier a solder connection can be made and the fewer rejects that occur. However, if not properly removed after soldering, active fluxes can lead to corrosion and electrical failures.

 What is the best way to remove the flux? If it's a chemical, do I just wipe down that one side of the pcb board that is flat and leave the other side alone?

Thanks,

-Darin

 

Proof that a little knowledge is a dangerous thing. You should never need a "more active" flux when soldering electronics. You should only use a good rosin-core solder (Kester or Ersin, for example), which should work fine with new parts. When I have trouble wetting old parts from my junque box, I use a rubber eraser to remove the oxidation. The residual flux can be hygroscopic undeer very high humidity conditions, but I have never had this as a problem at under a few kilovolts; sometimes, I used IPA to remove the excess flux, but this was only for esthetics.

If you screwed everything up by using an acidic flux, there will be unexpected leakage paths. Even if it kinda works initially, it is doomed to die a slow death due to corrosion. I do not know of any safe way to completely remove the residual acid. 

[Instrument Resources of America]

tric.= trichlorethane ?? Ira

[Terry Kennedy]

On Saturday, October 11, 2014 12:56:37 PM UTC-4, threeneurons wrote:

Even though, I've held a soldering iron, almost daily since, I was ~12-ish, and I'm 55 now, my rework leaves its mark. My mother worked as an assembler for some 30 years. And a rework assembler most of that time. If she had done the rework, you would never had known. Up until only a few months before her passing, she would still critique my soldering work. 

All rework leaves its mark. As long as it works well (both right away and after extended use), it's good. Extra points for not causing needless damage (lifting traces and then repairing), but normally this is all inside the case and out of sight. Here's my most recent work, removing and replacing 2 66-pin TSOPs on a Cisco switch. More info here for interested parties (and larger versions of the pictures).

[JohnK]

trichloroethylene more likely... sweet green death !!

I fought for many years here to have cigarettes, this and a bunch of other
chemicals banned in government workplaces - I wasn't popular.

John K
Australia



----- Original Message -----

[JohnK]

Oh c'mon! You really left pin 17 U72 looking like THAT!

 

:-)

John K

[PS  :-))  :-))   ]

----- Original Message -----

From: Terry Kennedy

To: neoni...@googlegroups.com

Sent: Sunday, October 12, 2014 5:12 PM

Subject: Re: [neonixie-l] Re: Nixie Clock Cool Project- a few questions

...clip...All rework leaves its mark. As long as it works well (both right away and after extended use), it's good. Extra points for not causing needless damage (lifting traces and then repairing), but normally this is all inside the case and out of sight. Here's my most recent work, removing and replacing 2 66-pin TSOPs on a Cisco switch. More info here for interested parties (and larger versions of the pictures).

[threeneurons]

That's some pretty damn good work ! The only way I can see that a human got involved, is by looking at the soldering.

My mother was not technical. She didn't know how any of the stuff, she worked on, functioned. But she was an meticulous old European lady, who took great pride in her work. To her, it was a reflection of herself, so she took the extra time. And her supervisors knew well enough not to tell her otherwise, or they'd get that scolding, that I got as kid.

She retired before surface mount pitches got really dinky. I know the exact day. The day of the Sierra Madre Earthquake. That was her scheduled last day, but she cut it even shorter. The quake was in the morning. They evacuated her building just after the quake. When they gave the "all clear", and let them back into the building. she just said good-bye, and drove home.

On Saturday, October 11, 2014 11:42:09 PM UTC-7, Terry Kennedy wrote:

On Saturday, October 11, 2014 12:56:37 PM UTC-4, threeneurons wrote:

... My mother worked as an assembler for some 30 years. And a rework assembler most of that time. If she had done the rework, you would never had known.... 

All rework leaves its mark. As long as it works well (both right away and after extended use), it's good. Extra points for not causing needless damage...

[Nick]

On Sunday, 12 October 2014 07:42:09 UTC+1, Terry Kennedy wrote:

Here's my most recent work, removing and replacing 2 66-pin TSOPs on a Cisco switch. More info here for interested parties (and larger versions of the pictures).

Nice job Terry. Did you cut off the pins of the old chips? I've found that the cleanest way to get them off and not damage the board if I'm not worried about destroying the chip I'm removing... either fine snippers or a Dremel...

Of course, having a Metcal QX2 (or similar) with the correct head would be quicker and neater, but that option costs about USD 5,000 !

Nick

[Terry Kennedy]

On Sunday, October 12, 2014 1:32:01 PM UTC-4, Nick wrote:

Nice job Terry. Did you cut off the pins of the old chips? I've found that the cleanest way to get them off and not damage the board if I'm not worried about destroying the chip I'm removing... either fine snippers or a Dremel...

Of course, having a Metcal QX2 (or similar) with the correct head would be quicker and neater, but that option costs about USD 5,000 !

I have an Aoyue 968 and a magnifying stand, but I find that when removing these large chips when there are smaller parts nearby, there's too much collateral damage as smaller components get blown off the board. Also, there's no TSOP 66 nozzle for the 968.

In this particular case, I used a razor blade and cut the leads off right at the package, then cleaned up the remnants from the board. This is complicated by the massive power and ground planes on Cisco boards, where the pins soldered to those require a lot of heat to get them up. That makes wicking impractical for either pin / chip removal or "flood" rework (where you just blob solder onto the pins and board, then suck up the excess with braid) - you'd be going along just fine, and then the braid would stick to the board when you hit a power or ground pin.

TSOP 66 is about at the limit for me to do by eye without magnification. Here's an earlier rework on a chip with a more manageable pin size / spacing (yes, that is hand-soldered):

[David Forbes]

No magnification? You nuts.

I bought a wonderful Bausch & Lomb stereo zoom microscope ten years ago,
and can't do anything surface mount without it. It's also very handy for
inspecting DIP perfboard builds, to make sure nothing's shorted and
everything's soldered.

I regularly hand solder .5mm pitch TQFPs, and occasionally .4mm pitch.

On 10/12/14 11:36 AM, Terry Kennedy wrote:
>
> TSOP 66 is about at the limit for me to do by eye without magnification.
> Here's an earlier rework on a chip with a more manageable pin size /
> spacing (yes, that is hand-soldered):
>

[John Rehwinkel]

On Oct 12, 2014, at 2:53 PM, David Forbes <dfo...@dakotacom.net> wrote:

> No magnification? You nuts.
>
> I bought a wonderful Bausch & Lomb stereo zoom microscope ten years ago,

I'm with David. I bought a cheap Chinese stereo zoom boom microscope several years back, and find it indispensable.

As for power and ground planes, I've run into that myself. I sometimes have to switch up to a different iron for those leads. When I'm designing my own PC boards, I put in thermal reliefs to avoid that pain.

- John

[Instrument Resources of America]

The Dremel with a one inch round diamond wheel works wonders.  Ira.

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[Terry Kennedy]

On Sunday, October 12, 2014 2:53:47 PM UTC-4, nixiebunny wrote:

No magnification? You nuts.

I have a photographer's magnifier which I use to inspect the work when I'm done to make sure I don't have any solder bridges.

I do have a rework table with magnifier, but I end up taking off / putting on my eyeglasses when switching from using the magnifier to just eyeballing the work, so I do it all without and then inspect with the little round magnifier. 

[Instrument Resources of America]

I often use a jewelers loupe, of around X10 magnification, or a pair of those head worn magnifiers purchased from Harbor Freight Tools, (A.K.A.' the adult male toy store')    Ira.

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[Joe Croft]

Now for my two cents. I have not looked at the schematic due to time issues, but I know I ran into issues driving a standard mosfet with a logic level gate signal. It got hotter than blue blazes! If the gate signal only goes to 5 volts, you must use a mosfet that will turn on fully at this level otherwise, it acts like a power resister.

-joe

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[Nick]

On Monday, 13 October 2014 13:34:05 UTC+1, joenixie wrote:

Now for my two cents. I have not looked at the schematic due to time issues, but I know I ran into issues driving a standard mosfet with a logic level gate signal. It got hotter than blue blazes! If the gate signal only goes to 5 volts, you must use a mosfet that will turn on fully at this level otherwise, it acts like a power resister.

Not the problem in this case - there is a 12V driver for the FET - generally, a FET may be considered as a voltage controlled resistor - if its fully on, then is DS resistance is Rds(on), which in this case is about 800milli-ohms - this is the lowest DC resistance the FET will exhibit.

If the FET is not fully on, then its DC resistance will be greater, leading to far greater thermal losses, i.e. it'll get hotter... In an SMPS, its vital that the switching device is either fully on or fully off, and not ever somewhere in its linear region - its being used as a switch, and should be driven in a way that ensures that's exactly what happens... Logic-level FETs are available which, as their name suggest, switch at lower gate voltages, but they also tend to have a low Vds and so are not suitable for simple HV boost converters (there are other, more appropriate, topologies should use wish to use these sorts of devices).

However, that's not what's going on here (if, indeed, anything at all untoward is happening...)

Nick 

[John Rehwinkel]

> If the FET is not fully on, then its DC resistance will be greater, leading to far greater thermal losses, i.e. it'll get hotter... In an SMPS, its vital that the switching device is either fully on or fully off, and not ever somewhere in its linear region

I was thinking along those lines too - perhaps some flux residue provides a little bit of leakage. Since the FET is high impedance on its gate, a little leakage could turn it partially on, leading to heat. I haven't looked at the schematic either, but if the driver circuit doesn't turn the FET off solidly, this could happen.

- John

[threeneurons]

Speaking in general terms, and not on this kit in particular:

Yes, driving the FET on a boost switcher, directly from a uC IO pin, is a bad idea. Not only, are they not fully driven ON, but you can kill the uC. I've actually done it. I think Nick warned us about this, many, many years ago. There is capacitive coupling from the drain to the gate. If the uC gets a "reset", while that FET is ON, or more destructively, when It just turned OFF, the HV pulse can couple over to the gate. Normally, it sees a relatively low impedance load, from the circuit driving the FET. But at "uC reset", all IO pins revert to inputs, presenting a high impedance. In short, use a FET driver, either one "off the shelf", or made up of both sourcing and sinking transistors, that always present a low impedance. Like I said I killed a couple of those 8-pin Tiny12 uCs, driving an IRL640 FET, directly. Its a logic level FET. But they died (the uC) by me just resetting the circuit.

But this particular clock kit, does not do this. It has a separate MC34063 based power supply. I refer to the circuit used, as a MKII design. The FET is not driven directly from the MC34063, but thru a push-pull PNP/NPN emitter follower pair of transistors. There is also the MK1.5 design, which uses the MC3406s's own transistor to pull the signal up, and an added PNP to drag it back down. Both the MKII and MK1.5 have active drive, both sourcing and sinking. There is also the MKI design, with passive pull down (a simple resistor), but I'd avoid that one for all but the lowest amount of power delivery. Though the MKII, and MK1.5 are old designs, using a really old chip, they are adequate for most nixie clocks applications. They should only get modestly warm delivering 25mA or less. I've tested some to 45mA (at 170V), and they can get quite "toasty", at just around 65C, at the coil.

Here's the manual of the kit in question:

http://www.pvelectronics.co.uk/kits/LTC1040/LTC1040_v4.pdf

The schematic, is on the last two pages of the 30 page document.

As stated by many earlier, there is probably nothing wrong with the unit, and what is observed, is the just the normal expected amount of heat. Maybe the OP could slap a thermoelectric cooler on the FET. I'd just leave it alone.

[threeneurons]

Its a 3x2 (or is it 2x3 ?) multiplexed design. There are three anode drivers, with two tubes ON, at any time.

My only faults with the design, is that there are no resistors across the base to emitter, on the PNP anode drivers, and no mid-pull resistors. This means there is a possibility of "ghosting". Both by the anodes staying ON too long, and overlapping into the next cycle, and small amounts of leakage current slightly ionizing the nixie tubes.

I bet he "fixed" the "anode overlap" in software, by using extra long blanking periods. Only six extra resistors !?