G-box fix....

[Vipersan]

Had to take a break from all other issues to fix my Alshat Gbox..
It became unresponsive to the remote..
Didn't power up from standby on receipt of a command from any receiver..
It would sometimes overshoot position requested..
It sometimes moved on it's own with no prompting..
So I had to take it apart ...
First time of opening ..
build quality is crap...justified in calling it Alshat I think..
one of the box closure screw pillars inside decided to shear off when being unscrewed ,,
Fault traced to 470uf 50v capacitor,,
Fully dried out of electrolyte ...
Nasty glue holding it to the PCB made unsoldering and removal tricky..
Replaced cap and all is well ..
No power applied with it disconnected from the motor on Carl ..thus no realignment necessary ..
Now working just fine.
Usually I repair such things to earn a living ..but figured I'd share this one with you guys..
Don't attempt repairs of this kind unless you are confident.
...it's the one with brown staining on top ..just behind the motor spring clip connectors.
rgds
VS

 

[Lazarus]

Brown staining is never good.

 

[Terryl]

Brown staining is never good.

I use a good amount of Clorox (1/2 to 1 cup) to remove the brown stains, if they don't come out then it's a trip to Walmart for a new set.

 

[Huevos]

VS, have you seen how much power those things use just in standby? Can you think of a simple mod to only power it up if there is voltage on the co-ax?

 

[Vipersan]

VS, have you seen how much power those things use just in standby? Can you think of a simple mod to only power it up if there is voltage on the co-ax?

Sadly Huevos ..
No such thing as a simple mod on these units ..
Simply because they are transformer based power supplies ..not pulse width modulated /switch mode psus..
Sorry buddy ..
No simple answer to that one...
rgds
VS

 

[Mickha]

How long have you had this G Box Vipersan?
The only model I was able to get was a Superjack V-BoxII, even though I ordered a Moteck, which don't seem available anymore.
I even had to move my DECT telephone, to stop the known interference, as the quality isn't great.

 

[Vipersan]

Good question mate ..
bought from new to drive my H180 ..
So perhaps Ged (Digi247) can remember ..
I'll try a search to get a rough approx.
rgds
VS
Searches dont go back far enough any more ..
I'd guess 2 to 3 years old maybe

 

[Mickha]

I should imagine the V-Box II, I have, wont last much longer than that !!!!!!!!

 

[Huevos]

The only model I was able to get was a Superjack V-BoxII

WoS do them. Looks like the Clarke-Tech and the Alsat G-boxes are one and the same.

 

[Vipersan]

I finally fixed the G-box unreliable operation ..
The electrolytic caps leaking were the prime cause of bizzare operation ..moving the dish unprompted ..and incorrect selection of diseqc position etc..
but NOT the sole problem..
For a couple of weeks after changing the 470uf ..and the 1000uf cap for good measure ..the gbox did work correctly..
errr ..more or less ..
Occasionally not coming out of standby mode when the receiver was turned on ...
and not responding first time to a channel change ..
So today I set about fixing it fully..
The 'staying asleep' problem was diagnosed to the hot glue often used in shyte construction of electrical gear these days ..
experience taught me to remove where possible this unneccesary gunk as it will brown and become conductive in hot environments ...and guess what ..
The manufacturer uses it as an extra but un-needed brace where the control pcb is connected to the motor/psu pcb ...
speading it quite liberally over pins of the risc microprocessor...
Out came the control pcb and all traces of the brown discoloured now conductive glue removed..
Once clean the control pcb ewas refitted using leaded/flux solder ..replacing the unleaded solder.
This makes for stronger more reliable joints and negates the need for glue as a brace.

OK the G box now comes on EVERY time the receiver is turned on ..
ie doesn't stay asleep in standby ...nor popping off to sleep unprompted.
But still I have an issue with selection of certain channels ...
Often the dish remained unmoved ...so diagnosed the Gbox as insensitive..
So located a coupling cap that supplies the 22khz signal to the control board ..
10nf ..and upped it by a factor of 10 to 100nf ..
Now we are cooking with gas ..
The Gbox is reliably responding to commands and moving the dish to the correct selected position ..and doesn't go to sleep unpredictably during an operation.

Here are a couple of before and after pics of the baked hot glue and a photo of the cap changed in value to 100nf..
Maybe this will be useful info to Gbox owners ..
The Gbox COULD have been a definitive product ....IF the manufacturers had not skimped on quality components and cut corners by using glue..
Perhaps why they stopped making it ????
..did it get a bad rep ? ..

rgds
VS

 

[Huevos]

What did you remove the brown stuff with?

 

[Vipersan]

What did you remove the brown stuff with?

Scraped away most of it using a scalpel ...sewing needle ....and tweezers ..
Then a fibre pen ..
,,,and finally cleaned with ISO alcohol ..and an old toothbrush..
rgds
VS

 

[Vipersan]

Got to the root cause of this problem I think..
Shyte build quality ...the transformers are the cause of failurr imo.
Anyone who knows how transformers work will understand this.
All secondary loading was temporarily disconnected...and mains power applied.
Within an hour the transformer was warm to the touch..
This should NOT be the case.
The situation worstens if the secondaries are reconnected and the box remained in standby ...thus a small current being drawn.

Ok the new Cbox arrived this morning ...
The unit plugged in but left in standby...ie small current load..
the lid removed and the transformer touch tested ..
it remained cold to the touch.

Now back to the older Gbox.
The transformer is coated in a laquer ..which obviously coats and isolates the laminates but in close proximity..
I believe the laquer is acting much like the brown gunk removed from the pcb ..ie becomes resistive over time..and partially shorting together the laminations of the transformer.
The upshot of this ..is that the transformer runs warm ..and eventually hot.
This effect is caused by the magnetic eddy currents within the transformer core and laminations...
Eventully causing saturation and thermal runaway.
,,and the heat generated inside the unit causes all the other failures already sorted..

The only cure is to replace the transformer with one of a better build quality..
A genuine 240v transformer would ease the problem by having more volts per turn on the primary.
Sadly most imported crap uses a rating of 220-230v ....which runs the transformer slightly harder than we in the UK are used to.
I have an old NEC model 2025 stand alone positioner from the 80s ...with a physically similar transformer..
This may be my saviour ...as I can hopefully graft it into the Gbox case.

I ask again ..why do we put up with underated shoddy crap with built in life expectancy and destined for failure ?
Because manufacturers dont give a fook once they have your hard earned....and can save pennies on the manufacture.
Joe public demands ever cheaper ...so they cut corners ...and hope to sell you another in a couple of years..
It is just another example of the 'Throw away world in which we live'
cest la vie
Thank higgs I stockpile old and broken equipment.
We deserve better ..but we wont get it.

For reference hunt down the 'Lightbulb conspiracy'...watch and absorb.
I aint makin' this up.
rgds
VS

 

[Vipersan]

Now this is interesting ..
whilst rooting amongst my loft for a suitable transformer/postioner ...I came upon an old Philips unit from the Dmac days..
It is an addon unit which is a positioner in it's own right but needs control from a suitable receiver.
An SCC 209
Obviously this cannot be used as is ..but a nice square box with nothing on the front save a power led ..
On the back
Mains in 240v
A din socket 7 pin labeled optical antenna control ..? (remote control addon possibly)
A socket labelled 'antenna positioner 4 pins' ...but on the pcb behind the sockets is stated ..'D2BUS Interface'
The a 5 pin molex type socket
pin 1 = motor +
Pin 2 = motor -
Pin 3 = square pulse (skew control)
pin 4 = gnd
pin 5 = +5v

Motor rating on the socket
Ouput 36v DC 2.5Amp max

So ..maybe the electronics of the Gbox could be fitted inside ??
All the supplies I need are there ...and switch mode power supply to boot ...

Before considering the hybrid ...
what kind of current is drawn by a jack or H to H motor ..
anyone ?
My thinking is ...perhaps 2x G box internals can be fitted ...and I'll be able to have one box do AZ EL ...
my dream positioner ..
But I cannot exceed the 2.5 amp limit or may damage the SCC209.
Got my juices going thats for sure..
rgds
VS

 

[Topper]

Got my juices going thats for sure..
rgds
VS

As if they needed any encouragement

 

[purplemarina]

Had to take a break from all other issues to fix my Alshat Gbox..
It became unresponsive to the remote..
Didn't power up from standby on receipt of a command from any receiver..
It would sometimes overshoot position requested..
It sometimes moved on it's own with no prompting..
So I had to take it apart ...
First time of opening ..
build quality is crap...justified in calling it Alshat I think..
one of the box closure screw pillars inside decided to shear off when being unscrewed ,,
Fault traced to 470uf 50v capacitor,,
Fully dried out of electrolyte ...
Nasty glue holding it to the PCB made unsoldering and removal tricky..
Replaced cap and all is well ..
No power applied with it disconnected from the motor on Carl ..thus no realignment necessary ..
Now working just fine.
Usually I repair such things to earn a living ..but figured I'd share this one with you guys..
Don't attempt repairs of this kind unless you are confident.
...it's the one with brown staining on top ..just behind the motor spring clip connectors.
rgds
VS

The last few days ive been trying to realign my dish after it overshot a position, sometimes it responds or dosent move or moves a lot! I took my Gbox apart and found the same as vipersan, a bulging capacitor and the beginings of a brown stain. is it worth up rating the cap or just change it with a better quality one?

 

[purplemarina]

carried out vipersan's mods, luckily there was no glue to scrape off although there was some under the radial cap?
put it back together, it turns on and no smoke.
wont get time to play further until new year, so cant yet say its a success yet.

 

[Vipersan]

carried out vipersan's mods, luckily there was no glue to scrape off although there was some under the radial cap?
put it back together, it turns on and no smoke.
wont get time to play further until new year, so cant yet say its a success yet.

That under the radial cap is usually baked electrolyte leakage ..
..and yes ..always replace with the same capacitance rating in UF ..but up the voltage rating if you can physically fit the larger cap ..
ie 470uf ..but if 35v ..use 50v ..
if 50v ..use 60v or even 100volt ..
But be warned ..a large increase in voltage rating usually equates to a physically bigger capacitor.

rgds
VS

 

[purplemarina]

carried out vipersan's mods, luckily there was no glue to scrape off although there was some under the radial cap?
put it back together, it turns on and no smoke.
wont get time to play further until new year, so cant yet say its a success yet.

Gave this a through testing today All OK Then i caught the cable with my foot and the box hit the concretefrom the 4th step of the ladder i balanced it on, i was doing it outside on the play dish. after taping it to the step i retested again it still seems ok at the moment,
a valuable lesson was relearned.