ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hello all radio experts.
What could cause blurry sound on analog BM1100 FM turner? It occurs on whole band, on all presets and on manul as well.
blah-blah and photographs as needed
If the sensitivity is fine, I would take a closer look at the detector."Uneven" detection can give a muffled sound.
Martin
Sensitivy quit ok. I dont know if muufled is exact, more like water in headphones.
Do you mean stereo detector? What is AGC?
(as you see, turners are not my specialites)
The detector is the circuit that "picks" the programme signal from the IF (Intermediate Frequency) and sends it on to the amplfier (thestereo decoder if fitted).AGC is Automatic Gain Control. Using the IF signal strength as reference, it sets the amplification at the front end tocompensate for stronger and weaker stations.
Water could be one way of describing the sound from a bad detector.Bad filtering in the power supply could also cause programme signal problems. Has the Beomaster been recap'ed?
Yes it is recapped (power second time now, and properly this time) Only noticealbe different value is 160 >220 in turner section but I think it is morely for filtering power rail.
AGC adjustment made by book does not have any difference. I haven´t much time for this lately, maybe on mid-winter break.
If you are sure that the sensitivity is fine, but the AGC line does nothing, the problem could be with the AGC, but that rarely affectsprogramme sound quality.Is the AGC line negative or close to ground?Else I would suspect one of the transistors at the front end.
AGC clearly affectsto sound but I cant measure it, maybe I do something wrong?
Checked front end tr's (BF194) they are ok. Found one broken trace at R47, but stil sounds like getting overload to preamp when stereo.
Pre amp works ok, tested with CD