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technics SA-400 FM Tuning indicator won't center

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jimkarl

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Problem statement - the Tuning indicator is not anywhere near center, quite a bit left (about 7 or 8 o'clock) regardless of dial position. It only centers when unit is off.

Background - I don't have the proper tools to be calibrating the FM circuit, no oscilloscope or freq generator so please postpone all the comments to that regard and focus or what I can do anyway without making the calibration worse than it is. I do have the service manual. In a environment where I test lots of receivers so it's not a coverage/antenna related issue. It's specific to this unit.

Action taken - Checked the electrolytic caps on the board, many out of tolerance so replaced all but a couple that were good tolerance and esr . No improvement to the tuning indicator as a result of the cap changes. It matters not what station I'm tuned to, FM mono or stereo, I cannot achieve center of this gauge (or even close). I tried a simple adjustment of the RF discrimator (T101 orange pot) by tuning to a blank section of the dial and adjusting. I could make the tuning meter WORSE, but not any better (more centered) even at extreme ranges on the control. I returned to the previous default position (where the meter is as close to the center as it ever gets - not!) . I tried this with and without antennas connected - no difference. Simply cannot get the dial closer to center.

Is there a specific part of the circuit (pic attached) that I should be re-checking component values that might be off enough to throw the meter left of center? Thanks in advance for the expert help!
 

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  • Technics_sa-400 FM Circuit.jpg
    Technics_sa-400 FM Circuit.jpg
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