Hey all!
I am restoring a Beocord 7000 and after Dolby Calibration, Record lever Calibration, PPM display level calibration I still have issues with right channel with higher frequencies.
I then changed all electrolytic capacitors (yes, all - Power, Signal and Control board) and issue is still there.
I also confirmed that if I inject 10kHz AUX signal it comes out without an issue on right channel too! Which points me to the tape head itself or circuit from head->amps? Amps must be good if AUX signal works....
SIgnal 1 - Yellow - Left
Signal 2 - Blue - Right
Azimuth and signals on Dolby level 400Hz (test point P15) are perfection (400Hz ANT Dolby level tape):
Now if I switch to 3kHz signal from tape this happens:
And on 10kHz from tape:
What would be cause of such thing? Bad head, some other caps (non elco)?
Thank you for any tips!
UPDATE:
Cleaning head - Since IPA did not do the trick I used Acetone which did help! A bit of Azimuth adjustment again and things are much much better!
Well done!
But I wouldn't recommed using acetone on tape heads.Not all heads will survive it, because acetone attacks certain types of plastics, used for insulating and casting in the coils.
Martin