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Old 29th Oct 2020, 2:03 pm   #10
DMcMahon
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Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 2,960
Default Re: Making a midi system cassette deck standalone

Largely in agreement with you Ben, but see why you have some questions marks.

As from your Post # 6 with bold comments:-

1. GND - Agreed
2. SSB TU (tuner controlled record remote?) - SSB out from the microprocessor (active low), can see the other SSB out on IC3 which is driven by a Remote Control signal but not easily able to see if it is Tuner controlled ?
3. 9.1v AC phase - Agreed, yellow via fuse F2
4. 14.5v AC (1) - Agreed, green via fuse F3
5. 9.1v AC Centre Tap - Agreed, Black 1A
6. 14.5v AC (2) - Agreed, green 1.4A
7. 9.1v AC 2nd phase - Agreed, yellow via fuse F1
8. ? Rectified -29v? - Very Unsure about this, it connects to the +ve side of the mD4 bridge rectifier, with the -ve side of the rectifier at -43.5V, with the regulator transistor mQ7 emitter being at -29V. With the 30V Zener mDZ2 connecting the transistor emitter back to the +ve side of the bridge rectifier. There is also a 10 Ohm pull down (to ground) resistor mR80 connected to the +ve side of the bridge rectifier. On the one hand I thought pin 8 may be close to -29V because of the Zener but the 10 Ohm resistor to ground confuses me ?
9. ? -29v? - Agreed, via inductor mL100
10. 5v? - Unsure, 5VAC from transformer (Orange 0.3A) connecting through to the 5.6V Zener mDZ3 via 100 Ohm resistor mR15 but the Zener cathode is at -29V so unsure of final voltage ?
11. 5v? - Unsure, 5VAC from transformer (Orange 5V) connecting through to the 5.6V Zener mDZ3 via 100 Ohm resistor mR14 but the Zener cathode is at -29V so unsure of final voltage ?

David

Last edited by DMcMahon; 29th Oct 2020 at 2:10 pm.
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