MC-32 failure

Just went today to fly (I fly on a regular basis) and when switching on, the first sign that made me feel strange was that the volumen of the radio was a bit low. On switching on the receiver and doing the pre-flight check, it was obvious that none of the switches was working. Failure was found on a bad contact of the switch general board on the ribbon that connects it.
Has anybody experienced such a situation?
Would it be wise to change ALL the ribbons,, as they seem to get bad contact on the pressure points at the female contactors on the boards?
Happy Flying
Jose

Jose,
probably contact got lost due to previous vibrations or so.
I recommend to detach the plug and spray a contact cleaner into it. Also pure alcohol would fit.
Then connect / disconnect a few times again.
Kind regards from Switzerland
Jürgen

Hallo Jürgen

Thanks a lot for your input. Yes, it's a good idea, cleaning contacts with a non residue board cleaner and reinsert it.

I've been thinking about the failure causes and due to simplicity my thoughts end always in the same "scene" ... I'll explain...
The ribbon goes into a female receptacle which has a safety catch. This acts pressing the ribbon in a transverse line against the contacts. On removing the ribbon, if the male contacts are observed, there is a linear depression just in this place, and depression means that there it is becoming thinner. It may be possible that when the ribbon adapts to the pressure, it may deform and get thinner and loose positive contact to the female portion. I will try to do some micro photos this evening and post them to show the groove on the male part of the connector ribbon.

In my case, the "field repair" was done just reversing the ribbon. Both male ends have a slight different length and this forces that when changing the direction, the pressure lines lays in a different (new) part of the male connectors, thus reestablishing the correct contact.

If this may be a probable contact failure, I would change perhaps on a yearly/two year basis all the ribbons in the MC32 to avoid an "in flight" failure, as this is a fairly easy task to do, given some time, relaxing music and a cold beer

Jose

Jose,
I don't have a MC-32, just a MC-20. But I never heard about serious problems with flat cables in Graupner transmitters.
Of course a picture would clarify the situation. And I could interrogate German speaking friends about.
Kind regards Jürgen

Jürgen N. schrieb:

Jose,
I don't have a MC-32, just a MC-20. But I never heard about serious problems with flat cables in Graupner transmitters.
Of course a picture would clarify the situation. And I could interrogate German speaking friends about.
Kind regards Jürgen

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OK, Jürgen
Vielen Dank, es ist sicher eine gute Idee (not easy for me to write in German )
As it is an early MC32, it may be showing now some issues that newer ones still not show, or maybe the strip is a not very "thick" one...
I've contacted my dealer already about the issue and most probably, Graupner tech service will have something to say, they have been most helpful till now (that's good)...

As said, this evening I'll try to do some photos which will give a clear idea.
Once more, just in case for any MC32 user, symptoms are in this particular case:
-Low volume on switch on tones
-None of the switches is operative

Lesson... Perform ALWAYS a preflight check!!!

Well, here are the photos...

This is the strip connecting the main switch board:



And this is a close up of both ends where the Groove is clearly seen with the naked eye:



This could lead to the propper contact failure. On changin the strip direction, a new surface is used, but probably, cutting 1/2 mm each end would give another couple of year service to the same strip.

In the meantime I'm trying to get some replacement strips, but seems that it may not be very easy since Graupner problems... let's cross fingers, I really like the 32, it's a beautiful radio in concept...

I posted your question in the most capable forum for these specified questions in Germany:

http://www.gh-lounge.de/forum/mc-32/1650-flachkabel-problem-bekannt

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But to read it, you have to be registered. Do not hesitate to do so, even it is mostly in German.
I will keep you informed.
Kind regards Jürgen

Thanks a lot Jürgen
Did not know this forum. Will have a look, no problem un reading/understanding German...
Alles beste
Jose

These "strips" have also been used in the MC24 and are working normaly over decades. I can't imagine that they should be the reason after such a short time in use...

Viper2097 schrieb:

These "strips" have also been used in the MC24 and are working normaly over decades. I can't imagine that they should be the reason after such a short time in use...

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Yes, I have a very old used and abused MC-24 that still works like new, and that makes this failure very strange for me too...

...probably the girl assembling the device ate a fat fish with fingers before?
Regards Jürgen)

Any idea what the surface material is on the connector? Does not look like silver since it did not turn gray or black and certainly does not look like gold.
Cheers
Walter

WalterH schrieb:

Any idea what the surface material is on the connector? Does not look like silver since it did not turn gray or black and certainly does not look like gold.
Cheers
Walter

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Yes, Walter. it looks more to some metal like tin (Sn) or similar, and clearly isn't gold nor gold plated copper track

Tin has the tendency to creep.

http://en.wikipedia.org/wiki/Creep_(deformation)

Therefore, for example, it is not admissable to tin wires that are meant to go in luster terminals.

Maybe this kind of deformation over time lead to problems.

However, since the same contact structure apparently is used in the MC24 without any known problems, I would simply say you have had a case of bad luck.

Julian Holtz schrieb:

Maybe this kind of deformation over time lead to problems.

However, since the same contact structure apparently is used in the MC24 without any known problems, I would simply say you have had a case of bad luck.

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Yes, I'm pretty sure that the deformation under female connector's pressure lead to the failure. I may be having a replacement strip, but still unsure if they will be sending it to me through the local (>2000Km away) technical service.
I just opened my MC24 and yes, there are also a few strips, but they look quite different, also the connectors; both seem not as flimsy as the ones used in the MC32 ... Preisgünstiger? They has to bring an awaited new product at a precise cost with "all" the expected functions... quality has to loose somewhere or somehow...

If one looks inside a Jeti Duplex, the cables are almost absent inside, this reduces the number of conectors to less than a half... this was a more intelligent approach, I think...

Hallo Lagunero,

as the MC-24 was build from famous JR-Propo and the MC-32 from SJ, so it could be that the stripes only looks the same, but perhaps are not from the same quality as from JR. Noboday knows...

Taking a look in the newest radios from WEA, JR or Jeti you will see hardly no cables inside; everything is clean inside; so less connectionsmean less possibility of having problems. Also hall sensors and 2 HF moduls in the TX (see WEA, Jeti) are modern art and especially 2 HF independent working HF moduls are giving more safty.

I would send your MC-32 to Graupner/SJ service to replace all strips, to check connections and making a complete function check. Then you are sure and you will have a good feeling.


Regards

PW

www.jeti-forum.de

Thanks PW

Yes, the strips and strip connectors are definitely not the same quality as before, not bad, but not the same. For now, I'll change the strips, but slowly I will have to think over and look for an alternative as I want safety and reliability; a Jeti will cost a fraction of a 6m ASH26, or maybe almost the same as a high-end F3F or F3J glider (without servos!) ... so, no point in risking any of them

Cheers
Jose