[amsat-bb] Elevation meter Rotor YAESU G-5500 stopped working

[Robert]

Albert,

I had the same kind of failure...in my case it was the LM/MC 7806C 
voltage regulator. At Mouser in the USA, it is a $0.62 part.

https://www.fairchildsemi.com/datasheets/LM/LM7806.pdf

Your problem may be something different...but wanted to give you one 
more place to investigate.

73 de Robert K3RRR

------

73 de Robert K3RRR
K3RRR.com
@K3TripleR
YouTube.com/user/K3RRR

On 7/18/2017 7:47 PM, Norm n3ykf wrote:
> Albert,
>
> Take EXTREME CARE working on equipment that has power applied.
>
> You'll need a copy of the schematic. Preferably the one that came with
> the controller/rotator. There are at least two different power op-amp
> power supply layouts. One with a pass transistor and zener diodes, the
> other a 75L10 regulator.
>
> Unplug the control box.
>
> Remove the top cover. Remove the front two screws from the bottom
> cover. This will let the face (meters, circuit board and switches)
> free. (still wired to the rest)
>
> Get two books. Turn the front face down on top of the books, switches
> between the books. (to allow the assembly to sit level and not
> press/break the switches)
>
>
> MAKE SURE THE UNIT IS UNPLUGGED!!!!!!!!!!!!!!!!!
>
>
> Q4 is one half of a 4558 op amp pair(two on one chip, the other runs
> AZ output for the aux jack).
>
> Find Q4.
>
> You're mission is to check the various components making up the drive
> circuit for the EL meter for trouble.
>
> Could be:
>
> Shorted capacitor
>
> Open diode
>
> Short or open via other means.
>
> MAKE SURE THIS IS UNPLUGGED!!!!!!!!!!!!!!!!!
>
> Use an Ohmmeter to look for capacitors that aren't open (Should look
> close to it, at least the values in the circut. Electrolytics are a
> different story...) Look for open diodes. Meter anything reasonably
> accessable, starting from the wiper on VR2 on the back panel. Some
> things are best looked at with respect to ground, others point to
> point reading the components in between.
>
> DANGER!!! DANGER!!!! DANGER!!!
>
> This part of the test requires making power on voltage measurements.
> Here be dragons, or a trip to your eternal reward!!!
>
>   Locate L2 and L4. Those components (each in their seperate circuit)
> form the power supplies (rails) for the EL op amp. See C1 (the voltage
> output) next to L2? C2 likewise next to L4?
>
> Check the pins 8(C1) with respect to ground and 4(C2) of Q4. These are
> the power supply rails (should be +/- 12 volts or so).
>
> Before plugging it in to test, make sure no bare wires are touching
> things they should not be.
>
> Plug it in (you did leave the power switch on, didn't you??). Test
> away. UNPLUG IT AS SOON AS YOU'RE DONE!!!!
>
> Have fun and don't break anything. A fire here is a failure.
>
> Norm n3ykf
>
> On Tue, Jul 18, 2017 at 5:56 PM, Albert van Deursen <avdeur at home.nl> wrote:
>> Hi all,
>>
>>
>>
>> All of a sudden the elevation meter stopped working of my Yaesu G-5500 rotor
>> controller unit .
>>
>> No issue with the AZ meter. Rotor itself keeps on steering / working
>> without any problem in EL &AZ (via interface EA4TX ARS-USB) so all still
>> working fine (fortunately !)  for satellite work.
>>
>> Looks like a component failure in the controller unit  or the meter itself ?
>>
>>
>>
>>
>> A physical check (opening the controller unit) didn't show any anomaly.
>> Being a not too tech ham was wondering if any of you Yaesu rotor users had
>> seen this problem before / around ?
>>
>>
>>
>> Possibly anyone to hint/ indicate at a quick check in the schematic wire
>> diagram to where to start looking for this failure ?
>>
>>
>>
>>
>>
>> Thanks beforehand for yr appreciated advice
>>
>> 73
>>
>> Albert
>>
>> PD0OXW
>>
>>
>>
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