Philips Discoverer

[ben]

I know I may be stating the obvious here, but I think a few more basic checks might be worthwhile.
try to get hold of another UHF device - a video would be ideal (not least because you can use its scart socket to connect a freeview or dvd to this tv cheaply and safely) and a new coaxial cable to link it to the tv. Then try to tune in. An 80s vcr would be ideal, the sort with a TEST switch on the rear, giving you two clear white bars as an unambiguous test signal!

I mention this just to eliminate the possibility that the game console or its cabling is the root of all this, seeing as the tuner voltages are ok and the resistors mentioned earlier too....
If all else fails, I think I have a tuner unit on a scrap chassis here, albeit a PAL B-G standard.

[Red to black]

Hi Ben,
The problem with doing what you suggest, is that this set is a live or half mains chassis,
if the O/P plugs an earthed aerial in this way he will damage the PSU, and if it it isn't earthed he will create a dangerous electrical hazard to himself and others.
This set has no AV inputs.

My first move as an engineer, would have been to eliminate the isolated aerial socket, because I have an isolation tranformer, and then straight into voltage measurements.

The O/P is new to servicing TV's and I was making him aware of the dangers of this type of chassis, as I was unaware of his technical ability, and didn't want to be responsible for any injuries either to himself or others (safety is paramount).
Also he learnt a lot more by checking things methodically and safely

The original poster has put a request on the wanted forum for a replacement tuner and would be grateful to receive the offer of one, it wouldn't matter if it was a B/G one as the circuitry for VHF selection is not present on this set, and besides it is the IF that determines the sound spacing.
Cheers,
Baz.

[Red to black]

Hi again Ben,

I apologise if I have misread your post above, I thought you were suggesting to feed the tuner directly, bypassing the Isolator/aerial socket (it is getting late )
After re-reading your post I assume you meant try a different signal source ?
I should of asked the original poster if his games console worked OK on another TV via the same cable, or maybe try, like you suggest a VCR with a different RF lead.

I did get the O/P to do the cold checks first though, as this was safer and relevant to the fault, and gave me a quick assessment of his technical skills (No offence meant martynmcg, you did well) , before diving into voltage measurements on a live chassis.

It is extremely difficult to give guidance on fault finding on a forum especially when potentially dangerous voltages are present as well as the TV concerned is a Live chassis type, and you are not sure whether the person you are trying to help has the technical ability to work safely (something we engineers take for granted a lot of the time). Then there is the fact this part of the forum is open to the general public.

I hope this goes some way to explain why I posted the way I did.
Cheers to all,
Baz

[ben]

Don't worry Baz. Perhaps I should have mentioned that the video (or whatever) should be connected to the Tv aerial socket as-is, just in case there was any question.
I was trying to say that it would be worth another go at tuning the set in to a different device, just to narrow things down by elimination. Wouldn't be the first time a bad coaxial cable or faulty UHF modulator in the source device was responsible for a problem situation. We've all been caught out this way I'm sure!

[martynmcg]

thanks for all the advice, i am close to giving up on fixing it for the moment though as i when i put the tv back together i bougth a new coaxial cable and used my sky box instead of a games console and to my suprise it actually worked, the picture was there and looked great for a minute and then i was back where i started, snow on the screen and it has stayed that way ever since.

[ben]

I seem to recall there was an afc pot (or was it a coil/slug)? caused tuning drift on these. But check the supply voltage to the tuner is constant first

[Red to black]

Hi again,
Do as Ben says and measure the voltage across Diode 6702, you should have 33 volt's across this.

Your tuner may be faulty, Sideband requested the number (see label on tuner)
in the parts wanted column, as different types were used (see mod sheets I posted earlier).

Don't give up!, Ben also said he may have a tuner.
If req. I will have a look through my service data (later) and see if there are any known faults (other than the special reference diode/regulator mentioned above) for tuning drift/afc faults etc.
There are plenty of people on here to help you

Cheers,
Baz

[Leiraider]

Help!

I need to find the user's manual of the TV Philips GR1AX or 37KV1242/10B. I forgot how to tune the channels.
I browsed a lot and didn't find it. If anyones has it in Portuguese I apprecciate, otherwise english will do.

[AC/HL]

Hello & welcome.
Is the one in post 10 any help?

[Maarten]

Is the 37KV1242 a 3-button set?

[ben]

Originally Posted by Leiraider

I need to find the user's manual of the TV Philips GR1AX or 37KV1242/10B. I forgot how to tune the channels.
I browsed a lot and didn't find it. If anyones has it in Portuguese I apprecciate, otherwise english will do.

As Maarten says, we need to know how many buttons are on the set. There were two common versions of this chassis. You may also need the remote control if the three key version. Post photos if unsure.

I have user manuals in English and at least one in Spanish.