Faulty Spa/Jacuzzi Controller - Possible Capacitor Issue??

Hi, I am new to this forum and I make no pretence to know my way around small electrons (as opposed to the big ones that drive conveyors and crushers!!!) Hoping someone might be able to provide me some guidance. I bought a second hand spa (2010 Sundance Optima) and installed it two months ago. It ran fine until last week then the controller display started flickering. Usually switching the power off and on again a minute or so later got her running again, however two days ago i got a frozen display (what Sundance call the dreaded Watchdog error and their recommendation is to call one of their service techs and open your wallet up wide!!!) and have lost all ability to operate the spa. I opened her up and checked that there was power to the control board, removed and checked all fuses, checked all terminations/junctions were clean and tight, checked transformer output and checked the back of board for dry solder joints and having no luck, then got on the internet. Apparently these boards are prone to capacitor failure. Attached photo 669 shows overall board and 668 shows the six round caps and what i think might be a (failed?) crystal which i will come to. Caps C8 and C17 (which i have subsequently removed) are 3300uF 35V and show a yellowish brittle non-conductive gunk around their bases. The top of these two caps appears flat. C5 and C58 are 10uF 50V and C33 and C57 are 150uF 35V and these four at least visually look ok. There is also a silver device shown in photo 680 which i assume is a crystal and it too has a similar yellowish brittle gunk around its base. It is labelled ECSX/V, 12.00 - 20, china. I do not have the ability to test these caps or crystal. My questions are:
1) is the yellow gunk a fair indication of shot caps and a shot crystal?
2) if C8 and C17 are shot i'm guessing it would be sensible to replace all caps?
3) should a crystal leak this yellow gunk?
4) I've tried to find this crystal as a replacement part on the web and i can't get an exact match with the coding on it. Can someone distill this coding down to something i can order please (Sundance don't appear to sell this as a spare part)
5) Is this yellow gunk likely to do any damage to other components that it touches?
6) what is the mode of leaking this gunk? I'm guessing it fluidises when its warm or hot and solidifies when it is cold?

Many thanks in advance for your assistance!!

Welcome to ETO.

Electrolytic capacitors do contain some rather unpleasant "gunk", and one of their failure modes includes squirting this gunk out all over the circuit board.

However in this case, the gunk which can be seen is simply glue, and adhesive to give machanical stability to the large capacitors.
I guess that someone thought that this circuit board would be subject to a lot of vibration and added the glue to minimise the components shaking and breaking their solder joints.

From viewing the pictures, I can see no obvious problems with your capacitors.

Crystals do not contain gunk. The best ones actually have a vacuum inside.
The crystal on your board is a 12MHz crystal, it is most unlikely that there is anything wrong with it.


JimB

Check ICs U48 and U12. The second and fourth pics show what looks like micro-cracks/stress-marks in their tops.
For those ICs with legible markings to identify them, get their datasheets and check that there are expected voltages on the supply pins.

I agree about the 'gunk' it's simply glue applied during manufacturing. However I don't agree about imaginary 'micro cracks' in IC's, it's not something which happens.

However, one point of note, there's a Dallas real time clock 'module' on the board, and I'm fairly sure it's one that has an internal battery - it might be as simple as the battery in the module has died?, it really depends on how the system software is written.

alec_t said:

Check ICs U48 and U12. The second and fourth pics show what looks like micro-cracks/stress-marks in their tops.

Click to expand...

Nigel Goodwin said:

However I don't agree about imaginary 'micro cracks' in IC's,

Click to expand...

I have seen IC packages crack slightly due to overvoltage/overcurrent, as well as blow the tops off completely!

In this case I think we are seeing traces of the clear varnish which appears to have been applied to the surface of the circuit board.

JimB

JimB said:

I have seen IC packages crack slightly due to overvoltage/overcurrent, as well as blow the tops off completely!

In this case I think we are seeing traces of the clear varnish which appears to have been applied to the surface of the circuit board.

Click to expand...

Exactly, if there's a crack in a chip it's pretty obvious, and catastrophic - and only really applicable to 'power' chips.

Several of the ICs are in sockets - it might be worth removing and re-seating these in case there is a bad connection, and applying a little contact cleaner if you have some.
Also, I'm sure I speak for everyone when I say that I appreciate the OP's clear description of the problem and well-labelled photos. An excellent example!

<EDIT>
Actually, only looks like a couple of sockets. The large square thing with NXP on it is a "PLCC" package - ideally you need a tool to remove them, unless anyone has a favourite track they can suggest for doing so?

tomizett said:

Also, I'm sure I speak for everyone when I say that I appreciate the OP's clear description of the problem and well-labelled photos. An excellent example!

Click to expand...

Agreed!
JimB

Some say the goop when goes brown becomes conductive & causes problems.
If that is true then its likely to cause trouble esp around the crystal.
Power caps tend to, but not always bulge when they are on the way out.
Nige is probably right about the real time ram, does the thing show the time?, does it stay correct if you cycle the power?

Nigel Goodwin said:

However, one point of note, there's a Dallas real time clock 'module' on the board, and I'm fairly sure it's one that has an internal battery - it might be as simple as the battery in the module has died?, it really depends on how the system software is written.

Click to expand...

I think Nigel is right about the clock chip. Those things are ticking 10 year time bombs. The company I used to work for sold data collectors that used these and as the first units. As the units reached about 10 years of service, the phone calls about dead data collectors started rolling in.

It may not be just a simple matter of replacing the chip to restore service. Those chips have battery-backed RAM. Depending on what's stored in that RAM, it may be game over when the battery dies.

The RTC is available from numerous sources. If you want to play around, I found:

Many thanks for the helpful replies. Plenty to ponder here.

Jim, the adhesive explains why i had some trouble getting the caps off - amazing what you can fix with a big enough hammer and chisel!!! I wouldn't have thought that vibration would have been a problem for this board but i guess it's cheap insurance.

Alec, i dont think they are cracks - there is some laquer spread liberally around and upon closer inspection, that's what it appears to be.

Tom, have given IC U13 a bit of a wiggle in its socket - bit nervous about taking it out because my understanding is that static can damage these things. Not brave enough to irritate NXP though!! Might try that as a last resort.

Dr Pepper/JonSea/Ylli, the display does have a clock. This gives me the opportunity to buy a new soldering iron!! Thanks for the videos on how to work around this.

And thanks also for the comment re clear description. My background is retired mech engineer (mining) and i always found that going a bit extra to provide the best clarity possible gave the bst chance of engaging people and getting a satisfactory outcome.

If i can fix this, i'll post what the solution was. The "correct" way is to repair/replace one item at a time and test the result, but i am a bit loath to put the board in and out of the spa a number of times (my knees aren't quite as young as they used to be!!!)

Cheers
Halsey