Tuner repair

[Jane]

I found a discussion here about using a Eardatek tuner. I have few pcs but they seem to be faulty.
The tuners are a part of a satellite tuner board - in a repair shop tuners are not repaired - only PCB board ,if there is no LNB voltage(13/18V) that is made in PCB board.
If there is LNB voltage and yet no signal then tuner board is throw out with tuner, which is a pity.
Has anyone tried to repair a tuner like that made by Eardatek ( or ALPS )?
Can anyone suggest a method how to repair them?
Here is a a picture of Eardatek

EARDATEK.JPG (383 KiB) Viewed 6299 times

and here is a picture of Eardatek and ALPS tuner( used with a board). Eardatek replaced ALPS tuner and is used in the same way - so pins should be the same as ALPS

PICT0369.JPG (508.12 KiB) Viewed 6299 times

[G4GUO]

I have never repaired one of those devices but I suspect it might be the LNA "low noise amplifier"
that has gone (chip bottom right hand corner). You should be able to test that by using a signal generator
@ 1 GHz, inject a signal into the main LNB input and then measure the output on the 2nd LNB
connector which is usually connected to the output of the amplifier. If there is little or
no signal present at that connector the chip has gone and will need to be replaced.

A heat gun, tweezers and a steady hand and you should be able to replace that chip.

I am only guessing.

[Jane]

Thank you for your reply.
Yes, it could be the first step( starting from LNA , from singnal input).
Can you please recommend a signal generator?
Is this
http://www.ebay.com/itm/138MHz-4-4GHz-U ... SwcL5XMAk9

good enough?


The SMD IC ( Low Noise Amplifier alias transistor booster) is marked GT.
Do you have any idea what model is that? Or what compatible LNA can be used?( it is a 4-pin-IC).
Thank you

[G4GUO]

I have no idea about the LNA part. I am sure Google can help but I expect they are all the same.

If you don't have a signal generator you could just loop the signal from a working satellite
system through the broken tuner and then use a satellite finder to measure the received power.
If there is little or no signal present then the LNA is probably broken.

[Jane]

Thank you for your reply.

I tried to measure the signal coming from the coax.cable( from satellite dish - LNB )- inserted into input connector of tuner but It did not work.
Can you please explain what you mean by
loop the signal from a working satellite system ?

And do you think that signal generator from Ebay would be OK for my testing?
Thank you for help

[G4GUO]

Most tuners have two connectors on them.
One connector connects to the input of the tuner's LAN the
other connector is connected to the output of the tuner's LNA.
It allows you to daisy chain receivers. It will also allow you to test the
LNA to see if it has gain by connecting the connector on the output of the
LNA to another receiver.

Yes you can use that signal generator but don't overload the input to the LNA
as you might damage it.

You still need something to measure the output of the LNA.

Using the method I suggested you can do the testing without the need
for any test equipment.

[Jane]

Thank you for the explanation.
And can you please suggest a device I can use to measure the output of LNA?
I tried https://www.ownta.com/sunkko-2400-multi ... ter-1.html
but it did not seem to work well.
Thank you for your reply

[G4GUO]

The ideal tool would be a spectrum analyser however you should be able to use the signal strength meter
on a working receiver.