Rover Master STC meter fault - Help please

D

DishDick

Regular Member
My Satellite Setup
.
My Location
Gran Canaria
After having lots of luck with my Rover STC, I decided to buy a cheap back up one from a certain auction site. It appeared to work ok in the UK. On returning to GC I have tested it next to my other one and it’s far far less sensitive and won’t get up the NIT table etc on weak transponders. For example 10714 Noise margin on good meter 0db MER 7.3db on new meter -3db and 4.9db so no NIT. Took meter apart as it has another fault with the power lsocket which was a dry joint as I suspected. There is a heavily screened can where you connect your cable (sat, ter. or cable) I presume this routes the input to the correct tuner unit depending on the input frequency. I opened this and it was sticky inside, so I carefully cleaned it with WD40.

I re assembled, but still not working well. Any ideas anyone?
 
Perhaps an electrolytic capacitor dried/exploded and is not doing its function properly. Notice any brownish sticky liquid on the PCB around the capacitors?

Even if it is so and you exchange it, you would probably need to send it in for recalibration.

Cheers,
vma
 
No brown marks around the capacitors. Just given the first attenuator unit a WD40 bath, so when it has dried will refit and try. Also tried connecting directly to the meters satellite tuner, but no readings when I do that. This first atenuator box is quite complex and must do more than I thought. I have washed out some foreign matter out of the cable inlet socked, so fingers crossed.
 
Hi Dick ..
FWIW ..
I personally would never use WD40 for cleaning cicuit boards inside sensitive equipment ...
Its fine for high voltage stuff under the bonnet of a car ..or basic connections inside a motor case .....but small signal pcbs ..never..
It leaves an oily deposit behind which can also have a degenerative weakening effect on plastics and rubber..
For PCB cleaning always use pure alcohol or methylated spirit ..
This cleans all corrosion ..oily substances ..and residues ..and evaporates leaving nothing behind ..
Good luck with it ..but as already been suggested ..it does sound like leajing electrolyte from a capacitor ..
They dont always show any physical rupture or damge ... but can leak out from the base ..
Not always visible without removal and inspection..
rgds
VS
 
Reading your earlier post is indicative a fault condition which often affected the tuners of TVs ...
A leak at the seal ..aerial head end ..used to allow water to enter the cable and be drawn down a non solid air filled core by capillary action ..
..eventually this water found its way inside the varicap tuner unit ..often damaging the insides of the silver box ..beyond repair ..
Sometimes it was possible to open the simpler varicap units ..and again carefully clean with meths ..and a fibre pen ..
Never put WD40 inside the tuner..
rgds
VS
 
Hi VS, Have followed your instructions and cleaned thoroughly with pure alcohol.

Have opened second can (sat tuner) and there is corrosion in there, surprising as this is in the middle of the meter, and there is no corrosion around it. Going to get some more alcohol (and for the meter), give that tuner a good clean. Need to be careful as they has soldered 4 wires the thickness of a human hair on there.
 
Gently m8 ...very very gently ...
Use a strong magnifying glass ..or jewellers eyepiece ..whilst cleaning ..
rgds
VS
 
Wel, I have given it a good bath in alcohol. Don´t feel confident powering up tonight, will do tomorrow. Concerned about these tiny wires, they are un insulated and could potentially short out to points on the panel or the screening can. Not sure what to do about them.
 
DishDick said:
Wel, I have given it a good bath in alcohol. Don´t feel confident powering up tonight, will do tomorrow. Concerned about these tiny wires, they are un insulated and could potentially short out to points on the panel or the screening can. Not sure what to do about them.
Click to expand...

Odd that ..
I would have expected the tiny wires to be at least laquered...
If not they should be rigid enough such that they dont move against anything metal ...
Again ..use a strong magnifying glass to nake sure they are not touching anything they shouldn,t..
Then if it powers up ok tomorrow and works ...you could always give the wires and the imediate area a quick blast of aerosol laquer..

also very gently dab the treated area pre laquering to remove any loose crap and corrosion with a cotten bud..
best of luck
VS
 
VS I was considering sticking some insulation tape on the circuit board below the wires just to be on the safe side. What do you think? It looks like the wires connect various parts of the cb to the can, so the clip on screen touching the wires wont be a problem. Going to double check tomorrow with a meter.

Now it has dried, I still have some strong white blooms on the tuner panel. Dry cotton buds enough to remove these?

Thanks again VS
 
DishDick said:
VS I was considering sticking some insulation tape on the circuit board below the wires just to be on the safe side. What do you think? It looks like the wires connect various parts of the cb to the can, so the clip on screen touching the wires wont be a problem. Going to double check tomorrow with a meter.

Now it has dried, I still have some strong white blooms on the tuner panel. Dry cotton buds enough to remove these?

Thanks again VS
Click to expand...

Yes ..you could try gently rubbing with a dry cotton bud ..
If this doesn't work ..
Gently rub with a cotton bud dampened in alcohol ...and use a dry bud immediately to soak up the alcohol and residue..
In other words dont let the board dry naturally ..as the alcohol may have disolved something and has it in suspension..

..you see ..If I were doing this job ...
I wouldn't have soaked the board in a bath of anything ..
I would have cleaned the board 1 small area at a time..

also ...regarding the fine wires ..
move them as little as possible ..
At these frequencies they can be acting as coils in a tuned circuit ..
Moving them might make dramatic changes which might affect calibration..

..another good idea when doing this sort of job ..is to take photo's before you change anything ...to use as reference..

Last question ...
You are using pure alcohol ??
You can't use anything which contains impurities...
For example ..an alcohol based perfume ...or alcohol based drinks etc ..



rgds
VS
 
Pure alcohol (96%). There are tuning coils wrapped around very small ferrite cylinders about 1cm long and 2-3mm wide. I think the wires I am worried about are just connections. Yes may take pics in future.
 
VS, you were spot on, the tiny wires were laquered, as I descovered when I put my meter on them. Well its all assembled, but still performing the same. Still at least I didn´t make it any worse! Just fed up that I was ripped off again!
 
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