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Old 9th Dec 2021, 11:45 pm   #60
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Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 5,408
Default Re: Grundig TK27 - Low audio output

Originally Posted by Phantomrose1999 View Post
I fiddled with the same switch to make sure all contacts open and close and I got my bias back

The bias voltage at the head is 182v PP. this canít be normal ?

Itís at 41khz
Yes the Bias record signal can appear large especially when Peak to Peak monitored, i.e. 64V RMS (for 182V Peak to Peak) does not sound that high.

Checked my TK 27L, Record Bias at the head |(white wires) was 180V Peak to Peak at around 55kHz (very similar to your 54kHz at Post 42).

Erase signal at the Erase head (red & blue wires) was 23V Peak to Peak.

Bias signal at output of the Bias Oscillator coil (blue wire) was 460V Peak to Peak.

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