I have had many years experience calibrating my own Crown 2 track and pro machines like Scully, Otari and Ampex. I recently bought a RT-707 and downloaded the service manual. I started with solving all the tape path, tension and brake problems. I even installed roller guides on the tension arms but that is a subject for a different post in the future.
In the manual, the picture of the playback and record boards are not color and the VR numbers are not visible unless they happened to be against a white background. I think I have mapped out where the correct numbers should be except on the record board where there seems to be two VR-302 which should be right channel record level. One is next to VR-301 (left ch record level) but the other VR-302 is above that. What is it?
Enough background and now to my problem.
To adjust playback level while playing a test tape reference level, the manual says to measure the output with a millivolt meter with a 50K load resistor across the meter. I am using a 250 nanoweber MRL test tape. The manual says that I should adjust the PB level pot to obtain 450 millivolts on the millivolt meter. On one channel, the maximum I could get (on the backwards pots, by the way) was 240 millivolts and around 130 on the other channel.
On the input meter calibration there was no problem outputting 450 millivolts since there is no limit on the level one can input. But doing this will mean that the tape level will be about -10 VU on the meters. My meter cal pots were located on the left side of the board next to a transformer, not where they were pictured. It could be that my manual is for a different vintage machine.
I posted this on audiokarma but no response.
In the manual, the picture of the playback and record boards are not color and the VR numbers are not visible unless they happened to be against a white background. I think I have mapped out where the correct numbers should be except on the record board where there seems to be two VR-302 which should be right channel record level. One is next to VR-301 (left ch record level) but the other VR-302 is above that. What is it?
Enough background and now to my problem.
To adjust playback level while playing a test tape reference level, the manual says to measure the output with a millivolt meter with a 50K load resistor across the meter. I am using a 250 nanoweber MRL test tape. The manual says that I should adjust the PB level pot to obtain 450 millivolts on the millivolt meter. On one channel, the maximum I could get (on the backwards pots, by the way) was 240 millivolts and around 130 on the other channel.
On the input meter calibration there was no problem outputting 450 millivolts since there is no limit on the level one can input. But doing this will mean that the tape level will be about -10 VU on the meters. My meter cal pots were located on the left side of the board next to a transformer, not where they were pictured. It could be that my manual is for a different vintage machine.
I posted this on audiokarma but no response.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.