Marantz 1520 Stereo Receiver Repair. Part 2. Final. 

Thank you, Simon. I could really use your advice on a couple Mid-80's. Sony STR-AV560, & 760 models. Synthesized FM receivers. I have 3. 2 of them have the same disease. They receive ok, but will not tune in Stereo, unless manually shift entry off one increment on the digital display. in other words, you have to detune to 98.55 manually, to receive 98.500 in Stereo. The readout is then showing incorrect, to receive stations in Stereo. Have 2 that do it, so it's something age-related. I'm familiar with some aspects of PLL, VCO's, etc., but not when they misbehave. Do not want to over-troubleshoot. Tuner is similar in design to your Pioneer tuner video. Same era.

@@Farmradio I just noticed the meter is off centre when the set is off!! Missed that one. Give L201 a slight tweak. That may pull stereo in better but will pull the tuning meter over too think. The off tune problem is quite common with age. If its a non Synthesised set like this, just to get the discriminator in rough alignment you would usually feed in a 10,7 MHz into the first IF and tune the discriminator core to zero the meter, If you look at the manual it should say about the final alignment part of the IF. The proper way is to wobulate or sweep the IF and adjust the discriminator for the best S curve. If the IF uses ceramic filters the process is different. In that case you usually feed in a known RF signal i.e. 98Mhz and adjust as before,

@@SoddingaboutSi Thank you. Yes this Marantz meter is "off" when powered off. Not messing with the mechanical adjust of this meter. Will leave well enough alone. The Sonys mentioned are totally different. Digital display PLL Synthesized units. I have studied VCO, & PLL circuits somewhat, but not when they get inaccurate. Sent you the service info on those in a separate email for review. Hope you get it. Thank you again.