Ok. Page 31 of service manual talk about erase current. I thought that there should be a problem with the erase current. Technics says test the channels one by one and adjust them by using the same adjustment point and adjust the current to the desired value. Since there is only one adjustment point at the end I decided to adjust both of the channels at the same time. Also in the text Technics says measure voltage at point
A and there is also a figure numbered as 38 showing the test equipment connection. In the figure test equipment is shown as connected to the point
ER instead of point
A. I 've connected the voltmeter to point ER but I can't read something similar written in the manual then I switch to the point A and this point was giving me similar V readings asTechnics says in the manual. Before adjustment/measurement: Line in level controls to minimum, tape speed selector to 38 position, set the rec mode selector on and put the unit into rec mode.
- Bias selector position 1: Value read on voltmeter is around 65mv so erase current is 65mA for the given formula. Adjustment point VR501
- Bias selector position 2: Value read on voltmeter is around 71mv.Adjustment point VR502.
Bias selector position 3: Value read on voltmeter is around 78mv.Adjustment point VR503.
A
s a safety before touching to the adjustment points record the original Voltage readings for 3 bias positions for each channel Left and Right. If something goes wrong it is easy to go back. Here I don't have any Technics service so I did this trial and error job by using the service manual. I am a metallurgy engineer and I don't understand electronics can't change any parts by soldering etc. but I can measure and adjust things like this, so any kind of help is appreciated. If you think that I did something wrong please let me know. 2 months ago I have corrected my Nakamichi DRAGON s NAAC (nakamichi auto azimuth correction) problem by the help of WillyHermann Services.
Regards.
Ural