Grundig T5000 frequency problem

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zoso-yu
Schaut ab und zu mal vorbei

#1 erstellt: 15. Jul 2020, 16:00

Hello everyone, I’m a proud owner of Grundig 5000 system. Thanks to good people from this forum I’ve managed to repair everything, and everything is working.
Recently I’ve bought brown version of t5000 tuner (I have silver version) couldn’t resist. I’t had the well known defect with rectifer. I’ve changed the rectifier and tuner started to work again after many years. It has good signal and everything works but I found a problem because I’ve compared the two tuners. On very weak stations let’s say 101.00mhz my first silver tuner turns the tunescope to green because that’s the stations frequency and plays with little noise. The brown tuner does the same thing but on 101.02mhz. On 101.00mhz turns the tunescope to green but it has less noise on 101.02mhz and one red signal LED more. So it has 0.02mhz miss match. How can I fix that? It’s not noticeable on strong stations only on weak ones.
Thank you!

Bertl100
Inventar

#2 erstellt: 16. Jul 2020, 08:23

Hello,

a re-adjustment of the center detection would be necessary.
Adjustment point "b". However, if you do not have suitable tools in your hands you should not try to change anything on these adjustments.

Best regards,
Bernhard

zoso-yu
Schaut ab und zu mal vorbei

#3 erstellt: 16. Jul 2020, 12:08

Hi Bernhard, thank you for your reply!
So you think it’s the problem with discriminator?
Maybe I didn’t explain it right.
If the right frequency of the station is 101.00mhz the tuner lights up green tunescope light, but on 101.02 the tuner has one more red signal diode and less noise. As I’ve said that’s only on very weak stations. The tuner normally lights up mpx on 101.00mhz and on 101.02mhz. I have very precise multimeter and plastic adjustment screw drivers :).
So the problem isn’t on HF part of FM? On FM tuner almost every ferrite core is sealed with wax.

After a good comparison between two tuners the good one has a better reception on weak stations. So I think that’s the problem. I think that the FM head is out of tune a little. How can i tweak it? Turn the trimmer capacitors to max signal strength?

[Beitrag von zoso-yu am 16. Jul 2020, 17:51 bearbeitet]

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