Repair / Troubleshoot an IN-18 Blue Dream

[Paul Atkin]

Hi All,

I have an IN-18 Blue Dream that has run happily for 6 years in a dust free display case.  During that time, I had just one tube go bad with an apparent gas leak.

I have been operating it on a timer so it only powers on every evening which has also worked fine.

Just a few days ago, the tubes didn't light up when expected.  I powered it up on a second 12V supply (confirmed working) but no joy.  The LED's light up, but on initial inspection it seems I have lost the internal 170VDC power.  I am not a specialist and have no schematic so I was wondering if anyone has skills or knowledge to help me troubleshoot this.

Thanks in advance

Paul

[Nick]

Hi - welcome to the group.

The designer of this clock, Dieter, hangs out here so may be along shortly to help out...

Cheers

Nick

 

[Paul Atkin]

Hi Nick, thanks for the welcome.  I had a maiI from Pramacin and I also sent a mail direct to Dieter.  He has replied so I will share what I have learned so far in case it can be of use to anyone else.

First point is that my clock had run flawlessly on the same power supply for 6 years.  I run it at selected hours on a 7 day timer, around 40 hours per week (so about 12,000 hours running in total with 5 of the original tubes - had one with a gas leak that I replaced about 2 years ago).

I sent a mail to Dieter and he was very helpful to diagnose the possible issue within 36 hours.  He gave me some points to test the voltages as per the red text on the attached image. Based on the results I got he strongly believes it is IC03 on the PCB (yellow circle) which is a UCC38084 current mode controller in an SO-8 SMD package .  It can be replaced with a UCC38084D, UCC38084DR or a UCC38084DG4. 

It was likely taken out by the 12V power supply which I found was dead so I am guessing that when it died, it sent a spike into the clock.

Unfortunately, he is not prepared to make a repair on the board and I as am in rural Japan so I'd need to ship it somewhere in any case.  I don't think I'll be able to find anyone locally that will do the job.

I have some soldering experience but have never tried reworking SMD chips.  If I was going to attempt this I would need a hot air station but I don't do enough to warrant buying anything fancy.  So I am thinking to take my time and try to learn a new skill.  I saw a report from Dave at EEVblog who rates the simple 858D rework station good value and seems to work well enough for small jobs. 

https://www.youtube.com/watch?v=vva2t21sOAs

If anyone knows of another cheap unit I'd love to hear - I really don't want to spend much at this time.

I have a few old boards laying around that I could hone my skills on before attempting a hack at the Blue Dream.  If I find it too challenging, I might contact here again

If I manage to get this running again, I am going to use the best quality 12V supply and a shitload of capacitors!!

Paul

[Paul Atkin]

Sorry, I forgot to post the PCB image

On Wednesday, December 12, 2018 at 7:03:45 PM UTC+9, Paul Atkin wrote:

[Jeff Walton]

You could easily replace this with a solder iron.  

- Simply use a small wire clipper and cut the leads next to the body of the old part.  

- Then unsolder the leads from the board, one at a time and use a tweezer or equivalent to remove the remains of the old part. . 

- Use some solder wick across the pads on the PCB to remove excess solder to get them ready for the new part

- Use a flux pen or equivalent on the pads 

- Place the new part on the pads until it is lined up over the pads and tack one corner on each side. 

- Check the alignment and use your flux pen again across the pads

- With a clean, small solder iron tip, carry a small amount of fresh solder and drag the iron across the leads slowly to let the flux and solder wet the pads on one side at a time. 

- Repeat on the other side 

- Too much flux won't hurt!  The flux and solder resist on the PCB will generally prevent a solder bridge. 

- If you need to re-do anything, get one side right first before starting on the other. 

- YouTube is your friend if you want to study the technique.  The part that you are looking at replacing is not difficult for you to start with. 

You can do this! 

- Jeff

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[Nicholas Stock]

Hear hear Jeff, wise words.

Nick

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[Paul Atkin]

Thanks so much for the support, including the private replies.  I have ordered some replacement chips, I have some old boards at home I will try this out on before I commit to the repair job.

Cheers, Paul

[lokn...@gmail.com]

Yes, that is the way to do it.

Get a flux pen

Kester 83-1097-2331 Organic Water Soluble Liquid Flux Pen for Lead-Bearing and Lead Free Alloy, 0.33 fl. oz. https://www.amazon.com/dp/B0089ERAY8/ref=cm_sw_r_cp_api_i_338eCb93ZEYR2

Sent from my iPhone

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[HuggerMugger]

I seldom post in thsi thread, maybe beacuse other kind of tubes (like amplifier tubes) or kind of electronics (synthesizers) occupies most of my time. And sad to say, the two glowing clocks I have near me are LED clocks, while my two nixie clocks are stored on the shelf with my CDs.

 

However, just a week ago I picked up a non-functioning DMM that contained 6 Nixie tubes (NL-848 and a single NL843) and I feel I should do something intelliget with the tubes.

As they are all part of the instrument I can desolder the sockets (woho!).

 

But hat to do with the tubes and are they attractive in anyway?

 

Got a preprogrammed clock-IC from PV Electronics and some NS5837.

 

/Magnus

Virusfritt. www.avast.com

[HuggerMugger]

Forgot the pictures.

 

The instrumt is “working” but showing rubbish. One of the tubes may be bad, but I have no appropriate mains cable  to verify that.

 

/M

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[Dan Hollis]

Not sure how rural you are, but you might look for makerspaces in japan
and take a visit to the closest one. Someone there should be able to help
you if they have electronics soldering stations.

-Dan

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[Kevin A.]

Start a new topic thread about this and I'm sure we can help!

[HuggerMugger]

Sorry!

I though I had this sent to the group ... <bad me>

 

/Magnus

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[Paul Atkin]

Well I am really not sure how this forum is supposed to work.  It seems that I cannot post to the last reply and my thread seems to have been hijacked.

However, I am pleased to say that thanks to the input from Dieter on diagnosing the failed IC03 (UCC38084D) I purchased some replacements from Mouser and decided to take the plunge and bought one of the (in)famous 858D hot air clones and after a bit of practice on some junk boards I felt confident enough to start the surgery.

Actually doing the job, was not difficult just a bit stressful.  After removing the old chip, I dabbed a bit of flux on the board pads from a flux pen and re-soldering went very easily.

All went well and as I plugged in the 12V supply to test the voltages, the neon colons were happily glowing.

The clock is now reassembled and back in its place in my showcase glowing as good as ever.

So once again, thanks to all who chimed in on this and a special thanks to Dieter for his very quick support.

On Wednesday, December 12, 2018 at 7:03:45 PM UTC+9, Paul Atkin wrote:

[gregebert]

Paul - Can you post some details about the hot-air soldering/reflow you did ?

I'm soldering my SMT devices manually by hand because my casual experimenting with a heat-gun got bubbled PCBs and very hot (and probably damaged) ICs.

[Terry Kennedy]

On Tuesday, December 18, 2018 at 7:29:36 PM UTC-5, gregebert wrote:

Paul - Can you post some details about the hot-air soldering/reflow you did ?

I'm soldering my SMT devices manually by hand because my casual experimenting with a heat-gun got bubbled PCBs and very hot (and probably damaged) ICs.

When doing assembly (as opposed to re-work) a few parts at a time, the idea is to pre-heat the board (usually via IR to the underside) to a bit below the melting point of the solder paste you're using, then use the air gun to melt the solder paste you put under the parts you're soldering. That way you don't need a ton of very hot air coming out of the nozzle, since that would end up overheating the component before the board got hot enough for the paste to stick to the traces. Re-work is a bit more of a mixed bag, since you may have components on both sides of the board and the parts you're trying to remove are usually larger than the ones you want to leave in place - people starting out tend to blow things like resistors / caps off the board while heating the part to be removed. Even with the exact matching nozzle on the air gun, that air has to go somewhere. Pre-heat also helps with this, though you'll likely want a lower temperature so any parts on the underside aren't at risk.

Preheating also helps with some through-hole rework - I do a lot of work on Cisco boards (8 to 12-layer) and things like power supply caps are connected to interior layers that are pretty slab-like. And Cisco doesn't seem to like to use relief areas arround those inner-layer holes 

[Paul Atkin]

As this is the first time I have ever done hot air work, I really don't feel qualified to answer, but...

The chip I was replacing was an SOIC-8 package closely surrounded by numerous smaller components that I was very wary of accidentally moving.  Initially I used the smallest nozzle (about 2.5mm) to try to aim the air just at the pins but it was too restrictive so I went up to a nozzle around 5mm diameter using 370degC with airflow set on 5 (out of 8)

Once I got the chip off, there was plenty of solder remaining on the pads so I only added some flux, positioned the new chip and started heating.  Only took about 15 seconds for the solder to start to melt then I held the heat for a little longer.

What I have read recently is that the two major conditions to adjust heating for are chip size and thermal mass of the board.  As the number of layers goes up the heating requirement goes up massively.

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[Nick]

Glad it's sorted.

We're not too religious here about keeping threads personal or totally on track + it all seems to sort itself out in the end... :)

Cheers

Nick