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Random avionics internals

Had a look at my long gone Wheelen strobe box… heavy and bulky to say the least. The single strobe hole on the top of the VS fairing is now providing convenient space for sliding the Insta360 cam in.
Thinking about it this stuff ain’t that vintage since I suspect some of you still carry these kind of boxes in your aircraft… the homebuilt world is always more than one step ahead, and has been LEDized many moons ago

Love them huge condensers/capacitors…

ain't the Destination, but the Journey
LSZF, Switzerland

9845 date code = 45th week of 1998.

I posted a similar disassembly here. Similar age of both design and actual parts.

1970s components and construction.

I noticed right away that these two capacitors are in series and with no resistors distributing the voltage equally

which is basically crap. It means one will fail and then the other one will fail soon after.

But to do the job differently is not trivial. One would use surface mount technology but it is hard to get around the large capacitors. The construction is mechanically robust enough.

Mine was replaced years ago with LED wingtip lights. I posted the details somewhere here… The difference with uncertified is they are probably half the price

Shoreham EGKA, United Kingdom

@Dan Yes, I have one just like ‘everybody else’. My Whelen strobe and box are on the aft fuselage belly, I don’t pay any attention to them except to check they’re working every so often. My box weighs only 1.2 lbs and the strobe works and keeps working. It must’ve been replaced once as the manufacturing date is 1984, 13 years newer than the plane, or maybe the previous owner installed it. If the strobe were ever to malfunction on my plane, the plan might well be removal and a neatly installed patch over the hole. I’ve already removed the unapproved wingtip strobes that were definitely installed by a previous owner and I don’t need or want LEDs either. For night flying a rotating beacon and position lights are enough for my aircraft and purposes.

Last Edited by Silvaire at 03 Apr 20:50

L3 WX500 Series II Stormscope


I wonder what are the main chips.

The big one looks like a MC68321 which was sold into the printer sphere.

Very interesting. Thanks for posting.

Shoreham EGKA, United Kingdom

The big one with the sticker is Altera EPM7064LC84-10

smaller ones MC68331CEH16 and DSP56002FC40


That 3 terminal SOT23 package soldered on at an angle… it’s going to be either a diode or a transistor (probably a diode) but the silkscreen says it’s a resistor (R54). The things you can get away with in certified avionics!

Andreas IOM

Altera is an FPGA.
The 68321 is a processor which still sort of exists – popular 20+ years ago.
The 56002 is a DSP from around 1990. I did some work with one in 1991. Fascinating chips, 50MHz, 20ns per instruction, which was fast back then. These chips mostly died out when e.g. the ARM32 came in, at ~7ns per cycle and costing $5 and general-purpose, with decent C free compilers.

But yes all as expected for the 1990s era.

Yes; certification is just to get the paperwork. You can make any old crap afterwards, provided nobody finds out. So maybe not with an autopilot, which might kill somebody and then somebody might start digging

Shoreham EGKA, United Kingdom

PS Engineering PMA6000M audio panel

LKBU (near Prague), Czech Republic

If it’s an audio panel, why does it have a bunch of IF transformers? Looks awfully complicated for what is basically a few switches and some relays.

LFMD, France
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