Burnt Spot on Mini Controller

I've not seen this (and I have some mini's I've used for 10 years), but I'd probably try gluing some (double layer?) Aluminum foil inside the case, (a sq. 1"?) centered over the source of the heat. This should help to spread out the heat, so the spot doesn't appear.

Anyway, just a thought.

I'd drill some air holes in the bottom of the case to start with because there's no air flow in the case as-is, I looked at fitting a thin aluminum strip covered by electrical tape across the top edge of the case right over the two diodes. I just opened one up and there's room for almost an 1/8" thick by 1" by 3.5" metal strip (a PC backplane cover is almost the perfect size if you hacksaw the end off). The problem is that there are lots of sharp solder tails you would have to grind down with a dremel tool - otherwise they would surely punch through even black electrical tape and short the PCB.

Since this part of the page talks about replacing the diodes, it gives the part numbers. The parts needed are an 18V zener diode and a 1N4002 diode. It may be possible to find diodes with a larger body that can dissipate better then the ones they use, but I'm not expert enough to recommend any. I don't think that will help much because the heat generated will probably be the same. The diodes in the MC look too small and cramped together to take any sort of add-on heat sink. Ideally, you could put dab of thermal paste on them that put them into contact with small piece of aluminum but that's got to be done with surgical precision.

I think the safest bet would be to drill air holes in the bottom of the case right at the location of the diodes and then figure out where to put a hole or two on the top of the case. The heat of the diodes will create a convection air current that might be enough to dissipate the heat better than an unmodified case.

-- Bobby G.

PC overclockers use a heat sink paste that's also a glue to add cooling to various support chips. You could use it to glue a bit of copper wire to each diode to wick away some heat. There's room to mount a small spiral coil of copper wire on the PCB board.

Looking again at the circuit board it looks so spacious and simple that even

*I* could work on it. Desolder the diodes, and move them to the wide open real estate towards the other end of the board. I don't think the added length of wire will affect the circuit much.

When they are off in the corner they'll be really easy to heat sink without the solder tail problem. Also, you can mount them on the *bottom* of the heat sink, thus greatly increasing heat transfer away from the spot on top of the case. I'd still drill the air vent on the case bottom. Just like modern PC's, you can build the most efficient heat sink ever, but it doesn't matter unless the heat extracted has some place outside to go.

I'll bet with a little handiwork (and providing you could pull 12VDC from somewhere on the board), this fan:

might work (Type 1204KL 25mm SQ x 10mm (0.98" SQ. x 0.4")

If you mounted the MC on higher rubber feet than stock, you actually would have the room! (And the only chopped, raised and turbocharged mini-controller in existence!) It almost looks like the standard 2" fan found in drive bay coolers would fit.

The switch side of the mini controller is here

and here's the component side:

Vcc is 17.5 volts DC so you could power it from the circuit board. Might ha ve to upgrade the fuse wire, though.

If you're really determined to cool those beasties:

:-)

You've reminded me that there's something to be said for the old BSR chocolate brown and black color scheme. Like the Spartans wearing red cloaks to conceal any wounds to their enemies, brown and black devices won't show scorchmarks!

They made those cases in black - I have an IR controller and an RF repeater that are the same factor as the mini-controller in fade-resistant black FWIW, most of the older white Powerhouse stuff I have is fading to a sickly yellow green, at least anything that gets exposed to direct sunlight. The

20 year-old brown BSR modules are still brown! Unfortunately, several have died just this year so I suspect even those stalwart modules have a limited life span. I still have a dozen or so more left working, so maybe those were just the "premature" failures. :-)

Happy cooling!

-- Bobby G.

I cant believe I'm the only one experiencing this. It takes a few months for the discoloration to appear, but every single MC I buy has done this (or maybe I'm the only one who cares :-).

My AC is 110V, kind of on the low side from others I know. Normally

120V is common.

It looks like a 1/2W zener to me. My plan was to go find the same voltage (I now know its 18V) in a 1W zener. I think I'll also try your suggestions and try to put a heat sink on it, maybe a piece of un-etched FR4 PC board. It'll take several months to know if it works though.

dickm

Might be worth checking what your mains voltage is in case it's excessively high.

It's happened to most of my MC's, too. Even the white keys over the diode area have become discolored.

I don't think mains voltage is the culprit. There's just too much heat building up in the case in that one area as designed.

The current flow and the heat generated and trapped in that area will still be the same. I doubt changing it will affect the temperature problem much. It's a heat dissipation issue and it's remarkably similar to PC heat problems. You can have the biggest heatsink with the highest RPM fan in the world in your PC case, but if you don't eject that heat from the case, your CPU will still fry.

I don't think it would take much venting to improve the current zero airflow. The heat sinking will wick the heat away, but you still need to dispose of it. Check the overclocker's newsgroups to find the heat sink glue. They use tons of it. :-)

I suggest, if you have a digital thermometer with an outdoor probe, that you take a reading from the area above the case before and after the mods. It's warm to the touch now. If it's even a few degrees cooler, the case should not discolor as much as in the past - although the whole case will fade over time anyway.

-- Bobby G.

Sadly over the past several months I've felt my tabletop controller getting warmer and warmer. Then a few days ago the red LED would never turn off and simply stays on.

Nothing ever operates now.

I figure I'll go back to RS and make an effort to replace it. But what could have possibly died?

I checked most all of the diodes and resistors for proper operation and resistance readings. What now?

I have a scope and I have a feeling that even though this is about 1 year old the heat has been a problem since day 1. That much heat on the outside means a lot more heat inside.

I'd like a schematic, tips on typically what fails and what fails due to heat. Then we'll go from there.

I'll follow up with repair tips, solutions and measurements.

Thank you

andre

aj aj aj at re di ff ma il do tc com

Thanks ================== dicko wrote:

snipped-for-privacy@rediffmail.com wrote in news:1124300295.122595.322980 @o13g2000cwo.googlegroups.com:

OK, I''ll bite. What is the point of this attempt at hiding your email address when the address is in the From: header of your posting?