Sorry for my late reply. Actually I made some circuit modifications to the original schematic. First of all, I changed some capacitors to boost the low-frequency response to 15Hz. I modified BIAS regulator because the original circuit switch it off on metal position. Adding some capacitor for extremely phase compensation on the input corrects perfectly the phase difference to the high frequency signals. The DBX circuit on play was corrected, too. Since the original circuit has no individual level regulator (the level regulator is common both for dolby and dbx) it was small level difference on playing on dbx. That may corrects by record level dbx regulators, but at all, the record on the tape do not has equal magnetic level for both channels.
The main difficult component replacement was in the recording EQ, where I changed some values of the components for flat response in case of equal bias settings for both channels. The original circuit in my machine has small bias current on one of the channels to compensate the problems in the rec eq. So, when I fixed the rec eq, now the bias was corrected to be equal for both channels.
Adding a additional RC filter only for normal tape to the input of the REC AMP, fixes another problem – the original schematic does not have this circuit, thus the frequency response for normal tape has no good linearity. Adding the circuit makes the middle-range to be on same level with low and high range components.
Hi everyone i'm new to this forum .. hm and just found this old thread .. i'm not into repairing much .. more into sdiy .. whenever i'm lucky to make something work .. anyway i'm looking for this exact manual RS M233X so i thought if maybe someone can help me somehow .. thanks anyway hope you have a good weekend
greetings
Vladosh