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Michael Maurice · 16th Jun 2019, 2:49 pm

Progress:

I fitted BC237's instead of the AC128 as they're pin-pin comparable. After sorting out a dry joint they work ok.

However I now have a fault on one of the tape tension units.

If you press <play, the LH motor starts up with very low torque then stops.

If you swap tension boards then the same happens to the RH motor when >Play is pressed.

I think they should both spin but with reduced torque.

I've changed the transistors both BC547's, I've checked the 4K7 preset and its OK and I've checked for dry joints.

I should add that FF and REW both work correctly.

So whats next?

16th Jun 2019, 2:49 pm	#7
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	Re: Philips N4450 Progress: I fitted BC237's instead of the AC128 as they're pin-pin comparable. After sorting out a dry joint they work ok. However I now have a fault on one of the tape tension units. If you press <play, the LH motor starts up with very low torque then stops. If you swap tension boards then the same happens to the RH motor when >Play is pressed. I think they should both spin but with reduced torque. I've changed the transistors both BC547's, I've checked the 4K7 preset and its OK and I've checked for dry joints. I should add that FF and REW both work correctly. So whats next? __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/