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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 18th Feb 2017, 10:54 pm   #21
BillTweedy
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Default Re: No sound from Ferguson 3258 tape recorder

Lawrence, thanks for the information about the S1 switch. I haven't read many circuit diagrams lately but did transistor theory in the early 70's at college. I'll post back when I try your suggestions.

Many Thanks
Bill
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Old 18th Feb 2017, 11:06 pm   #22
ms660
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Default Re: No sound from Ferguson 3258 tape recorder

No worries Bill.

Lawrence.
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Old 18th Feb 2017, 11:12 pm   #23
BillTweedy
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Default Re: No sound from Ferguson 3258 tape recorder

Just one last query before I call it a day, there are a couple of thermistors (X1 and X101) on the base connections of VT10 and VT110. From the one I can see is the coloured paint on the body peels off when you touch it. I'm not sure that's a fault but I thought I'd just mention it.

Thanks
Bill
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Old 18th Feb 2017, 11:21 pm   #24
ms660
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Default Re: No sound from Ferguson 3258 tape recorder

If they are disc types then those types of thermistors have been known to fall apart if they've gotten too hot. Somewhere in the manual there should be something describing the quiescent current set up which should give the quiescent current figure in mA's, use that figure as a guide when doing the tests.

Lawrence.
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Old 18th Feb 2017, 11:34 pm   #25
BillTweedy
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Default Re: No sound from Ferguson 3258 tape recorder

They look flat, rectangular and about 1/2 long. In the manual they are listed as 25-42ohms , Mullard type VA1077. No mention of the quiescent current from what I can see.

Bill
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Old 19th Feb 2017, 1:00 pm   #26
JohnBHanson
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Default Re: No sound from Ferguson 3258 tape recorder

Measure the voltage across R61 or R62. Using ohms law you can work out the current
V=IR therefore I=V/R as R is 0.5 that means take the voltage, double it and that will give the current. You will need a digital voltmeter to do this.
You can do the same on the other channel.

PS - the 0.5 ohm is likely to be two 1ohm resistors in parallel
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Old 20th Feb 2017, 10:00 am   #27
BillTweedy
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Default Re: No sound from Ferguson 3258 tape recorder

Thanks John,

I have to leave it for a couple of days but when I do I am going to put a couple of breaks in the PCB to the left and right of point 58 on the circuit diagram, that's if I can work out where it is on the board.
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Old 20th Feb 2017, 11:39 pm   #28
BillTweedy
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Default Re: No sound from Ferguson 3258 tape recorder

I have just found this information in my manual (see attachment) and I think this is where I must put my meter as suggested by Lawrence in an earlier post. All I have to do now is to find where this link is on the circuit board.

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Bill
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