Re: Mayfair FT-305 Small Reel to Reel Check Out
Checked out the Play/Record switch wiring, had to partially remove to gain better access, also checked out the Microphone and earhone wiring all OK.
Did tests recording using small Sony mic, as expected still no sound on playback. Playing back the recording on another machine gave no sound apart from some tape hiss, so looks like the problem on the Mayfair is common to Playback and Record.
Sketched out most of the circuitry, not as easy as it sounds for such a simple machine.
From a few quick measurements nothing obviously untoward with the transistor voltages.
Used scope to try and check playback and record signals, found that signals or even just background noise disappeared through certain capacitors, also generally found that when probing around could induce some low level crackles out of the speaker.
Checking the capacitors concerned was surprised to find 3 are totally open circuit and a 4th very high capacitance (4,500uF verses 100uF).
So based upon these 4 capacitor failures will check out the remaining 6 or 7, they are all Echo.
David
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