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Old 19th Sep 2021, 11:41 am   #28
ms660
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Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
Default Re: Ferrograph part missing?

Quote:
Originally Posted by sparkymike View Post
On record, an extra valve is used. Which one is that ?
Referring to the schematic, there's two, V6 and V5, the ECC82 (the bias/erase oscillator) and the ECC83 (the detector/amplifier for the record level meter) they both share the same HT feed which is switched in when in record by SW1-1c, the route from the main HT filter capacitor is via pin 6 of P3-SK3, SW1-1c, resistor R2 and pin 7 of P1-SK1, from that point the HT is fed to V6 via pin 4 of P4-SK4.

The bias is supplied to the tap on the record/playback head via capacitor C5, SW1-3c, pin 4 of SK3-P3 and the erase/bias link P8-SK8.

The record signal to the head from the amplifier is via pin 8 of SK1-PL1 and SW1-3a.

If that's any help.

Lawrence.
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