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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 13th Feb 2020, 12:54 pm   #1
nicola.ghinassi
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Default Philips N4450 Reel to Reel Tape Player

Hello everybody, I'm new to the forum. I received a Philips N4450 as a gift, and I am proceeding to put it back into operation. I replaced all the belts, checked the contacts and circuits. Two problems: when I turn it on, there is a continuous background noise, I was unable to understand its origin. In addition, the REC key always remains on. Could it be the flip flop card and its transistors? Everything else seems to be working well. I am in your hands to ... find a solution.
Thanks in advance, Nicola
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Old 13th Feb 2020, 6:16 pm   #2
TonyDuell
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Default Re: Philips N4450 Reel to Reel Tape Player

A function 'stuck on' (like REC in your case) is very often due to the AC128s on the flip-flop boards.
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Old 14th Feb 2020, 7:54 am   #3
julie_m
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Default Re: Philips N4450 Reel to Reel Tape Player

BC327 will substitute OK for the AC128 in this case. It's a silicon device, but in this application only the PNP polarity is important.
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Old 14th Feb 2020, 9:14 am   #4
nicola.ghinassi
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Default Re: Philips N4450 Reel to Reel Tape Player

Thanks a lot for the reply, so I would say that I will proceed with the replacement of the AC128. The thing I noticed, when I start with the ON button, is that there is an annoying and continuous noise, like a bell trill, of which I can not find the origin at all. It is present both at standstill and when PLAY, FF, FW and PAUSE are started. In short, always .... any ideas? Thanks in advance, Nicola
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Old 15th Feb 2020, 6:26 am   #5
TonyDuell
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Default Re: Philips N4450 Reel to Reel Tape Player

There are two things that run all the time (when the machine is on) : The clock timer and the capstan motor.

You can disconnect the timer motor with the 2 push-on terminals next to it (these are 'live', so unplug the machine from the mains, disconnect the wires, then plug it in again). I seem to remember that the capstan motor is turned off in 'Amplifier' mode, so try selecting that with the slide switch.

Do either of those remove the noise?
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Old 17th Feb 2020, 3:07 pm   #6
nicola.ghinassi
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Default Re: Philips N4450 Reel to Reel Tape Player

I proceed to a check, as suggested. As soon as I have checked everything, I will let you know. thank you
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