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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 23rd Oct 2019, 11:00 am   #1
stewartrose
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Default Revox A700 End of tape sensor

Good Morning,

Could someone offer number to search for on Revox A700 End of tape sensor, or offer a place to buy one that is not Australia Please

All the best and thank you from Alan
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Old 23rd Oct 2019, 11:27 am   #2
Michael Maurice
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Default Re: Revox A700 End of tape sensor

The diode mentioned in the manual is MRD148. They don't appear to be available anywhere even Ebay doesn't list them.

I cannot see why you couldn't use any opto transistor. Cricklewood stock SFH 206 which could work, or BPW48N.

Before you do so, check that R69 hasn't disintegrated and C8 hasn't gone short circuit. Also check Q1 by substitution.
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Old 23rd Oct 2019, 1:02 pm   #3
stewartrose
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Default Re: Revox A700 End of tape sensor

Good Afternoon Michael,

I changed the transistor because it was EB short, I am getting 4.78v from the sensor, to R8 which is suppling a hi to the B of transistor pulling the collector down to zero...

Covering the sensor does nothing, so I am assuming it is duff

All the best from Alan
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Old 23rd Oct 2019, 1:37 pm   #4
stewartrose
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Default Re: Revox A700 End of tape sensor

Good Afternoon Michael,

The Sensor you suggested SFH 206 I can buy on ebay,

The other one I cant find...

But thank you for the information, most welcome

All the very best from Alan
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