Is a bad cap enough to cause a tuner not to work?

[mikay786]

Hi guys, scored this Panasonic DMR-XS350 tuner the other day which I thought worked fine. Plugged in and dvd / hdd recording playback were working fine but today decided to hook it up to dish and isn't getting a signal. Tried two cables which both work fine on other boxes, so not a cable / dish problem.

Anyhow got it opened up and spotted a leaky cap right off on the tuner board.

Is this a likely culprit?

[mariushm]

Re: Is a bad cap enough to cause a tuner not to work?

It should definitely be replaced and the other RJG capacitor seems like it's going bad as well. By the vent shape it looks like made by Elna but any low ESR capacitor should be fine (like Panasonic FM or Panasonic FR).

[tom66]

Re: Is a bad cap enough to cause a tuner not to work?

Yes, if the cap is for the +30V tuner line, it can cause a drop out of that bias voltage which can prevent the tuner working properly or make some channels inaccessible.

[mikay786]

Re: Is a bad cap enough to cause a tuner not to work?

Cheers will replace the 4 electrolytic caps with FR series.

Would be great if its just the caps, fingers crossed

Yea its completely not picking up a signal what so ever, just says astra 2 not found.

[tom66]

Re: Is a bad cap enough to cause a tuner not to work?

This is a satellite tuner?
Have you checked for the 13/18V LNB voltage (from shield to tip of coax connector)

[mikay786]

Re: Is a bad cap enough to cause a tuner not to work?

Yes freesat tuner

No but I know coax cable works fine as have another freesat box, plus tried in two different rooms with two different coax cables.

[tom66]

Re: Is a bad cap enough to cause a tuner not to work?

The LNB supply is generated by the box. If this is missing the LNB will not be powered and no signal will come down the coax.
The LNB signal is mixed with the DC supply.
13V selects one polarisation type, 18V selects another.
A 22kHz tone also selects a low or high band (depending on if it is present or not)

[mikay786]

Re: Is a bad cap enough to cause a tuner not to work?

Should I plug in coax cable then measure? Just on the metal housing?

Thanks that's good to know, is this the case with freeview too?

[vinceroger69]

Re: Is a bad cap enough to cause a tuner not to work?

if ive read toms post rite i think he means black probe on the tuners casing and red probe in the centre part of where you plug the coax in on the tuner and no you dont need a coax lead in (this is how i would test it)

[tom66]

Re: Is a bad cap enough to cause a tuner not to work?

Yeah, that's right. This only applies for satellite tuners (antennas are usually passive but satellite dishes use an LNB which requires a power supply.) You can insert a wire into the coax connector to make probing it easier.

[mikay786]

Re: Is a bad cap enough to cause a tuner not to work?

Awesome all sorted, seems to have done the trick with both tuners picking up signal / channels

Thanks

[tom66]

Re: Is a bad cap enough to cause a tuner not to work?

Just that capacitor then? Cool. Goes to show - Always replace bad caps on sight!

[mikay786]

Re: Is a bad cap enough to cause a tuner not to work?

Replaced 3 of them, the two RJG ones and the 50v one.

There was one other tiny 50v one behind the blown cap but I couldn't make out the uF on it at time of ordering so didn't bother with it.

Hope I don't live to regret it!

Cost me £15 in total to repair, £12 for a replacement remote and £3 for caps. So satisfying.