I have been soldering up Viessmann kits and decided to share the experience... see
http://layout.mixmox.com/1/Viessmann-5291_kit

Thanks Dale,
good pictures and instruction IMHO,
encouraging for those who don't think they'll manage themselves.

/Lars

Dale, I've built several of these kits, and I purchased them for the same reasons you list on your website. They are fairly easy to assemble, and the instructions are in English, which is a bonus. Just don't get the zeneer diodes around the wrong way!! - and the values on the zeneers need a microscope to be able to read them!!

I've also assembled 3 of the 5290 signal controller kits, and these are somewhat harder. The circuit boards are double sided and the components are packed together quite tightly. You need to use a fine tipped iron, and make sure that the solder flows through to the other side of the board. The instructions are only in German, which doesn't help if you don't understand German, but at worst all you need to know is the German words for the various colours. The controllers I've assembled have worked OK, but they are not for the faint hearted.

All in all these kits are good value, but you need to have experience in assembling electronic kits, especially when assembling the 5290 controllers.

Thanks for your tips on your website. I can confirm that my experience in assembling the 5291 kits pretty much matches what you state on your website.

A word of advice from an Electronic Engineer:

Those IC sockets provided with that kit are bad news...
They don't provide sufficient "wiping action" when you insert an IC to clean the IC legs, and they don't "stay clean".

I suggest you go to your local elecronics enthusiast shop and replace the sockets with "turned-pin" type sockets, or -- better yet -- just solder the IC's directly into the PCB:
The IC's provided are generally robust, and are very rarely faulty...in my experience (as an electronic design engineer) you are better off soldering them directly into the PCB, and testing the unit aftewards. Just be careful if you do have to remove an IC...

BTW, it probably is worth investing in a simple anti-ESD work-mat and wrist strap, since they are very inexpensive now...and YES, ESD does matter.

Sorry Dale, I didn't mean to alarm you too much...
My experience as an electronic design engineer just said "avoid those suckers"...
Note:avoid...if you can safely remove the flat-leg IC sockets and replace them with "turned-pin" sockets, do so, but if they are already in place, then it's probably best to leave them there...
I work as as a Design Engineer, so I like to specify things right from the start...

If you have trouble with your IC conections try simply "wriggling" the IC in the socket.

No I am afriad my electonics knowledge is not that good. Open it up and see if you can see any components that are black or have that burnt smell.

Do you mean that the entire module is dead, or just one output?
The latter is usually due to a blown end amplifier transistor (the 8 square vertical ones).
It's a BD680, which is a standard type that can be obtained thru any electronics store.
I fixed a few decoders that way.

Frankie, I agree with Bart -- if an individual output is faulty it is almost certainly the output transistor. Make certain they are inserted the correct way round -- I assume the instructions show which way.

If the entire unit is dead, there are a number of possibilities:
* the decoder IC (U3/MC145027) -- getting hard-to-find now, certainly in the DIP16 package, but try an electronics shop
* if you have a multi-meter, check the voltage across U3 pin 8 (negative) and pin 16 (positive) when the decoder is powered -- it should be +5V to +18V -- I don't know the exact circuit, so I can't advise the exact voltage.
* double check the four power diodes (D3, D4, D5, D6) and the zener diodes for correct orientation.

And some general tips:
* go over all solder joints with the soldering-iron to ensure good connections
* check for solder bridges between IC pins
* check for broken tracks, or lifted pads (from too much heat when soldering)

Good luck!

Gents,
you made my day, I was able to fix a 5211 changing the BD680 and with Dale's tester I rapidly find out a positive answer to my job.
The components are quite inexpensive and since I have 4 of them to repair, it saved me a lot of money.
I owe you a beer in Rome!

David,
You do understand that electronic components run on smoke, don't you? The smoke is circulated around the tracks and inside the IC's.
When you overstress the transistor or IC, you let the smoke out, and it doesn't work anymore.
I have tried putting the smoke back in, but it is extraordinarily difficult...

Electronic design engineers say "if the prototype doesn't smoke when you test it, you could have used a cheaper transistor!"