NAC 72 help please

The LH phono channel on one of my 72s makes a motorboating noise with its " new modified" 323 E cards fitted. The previous 322 cards didn’t make any noise.
Swapping the cards over does not move the motorboating to the RH channel.
It’s auditable with the volume pot at 9 o’clock and nothing being played. Disconnecting the P6 makes no difference.

Removing the outer sleeve, and the sound reduces significantly. Slide it back on, and it returns as the outer sleeve goes over the 323 cards. Really odd.
Any ideas?

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@Thegreatroberto - That’s weird… My 323 E’s in my 72 are just fine… But you probably didn’t want to know that… :crazy_face:

One for @Richard.Dane or @NeilS maybe…?

A weird one. Did it have boards fitted in that position before? Are the boards fully home in the pins? Could you post a picture showing the main board?

The OP - @Thegreatroberto - said he had 322 boards in that position before, which were fine.

Its almost like the links have not been removed, properly… Yes, need Main PCB picture.

Yes. My 72 only has one phono ( ex bnc) input. The cd input is a dun.

Or DIN… :rofl:

It is weird. The 323E’s are fully home. Previously I had 322 boards and they were, and still are OK.
I’ve made sure the remains of the links are nowhere near each other. Will upload a picture tomorrow.

When I was swapping the boards to fault find, I didn’t have the sleeve fully fitted. In order to turn up the pot, I had to slide the sleeve on to grab the pot. That’s when I heard the sound increase.
I’ve confirmed all boards are fully home. I’ve jiggled the gray cables from the RCAs to the main board just in case that changed anything. It didn’t.

Yep. Cd is din. This is a later 72.

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Exactly like mine… with 323 E boards in…

Can you post a pic of the Main PCB pls…? Wondering if the Links have not been removed properly.

Here we go…

I think I can see the Links (in 1st pic)… ?

I would be tempted to gently bend them out of the way. Maybe one leg is touching the Tracks on the 323’s…? But didn’t touch with the 322’s.

One for @Richard.Dane to confirm, though.

This transistor? Is very close to a power supply? This is the LH channel 323E card.

The RH similar transistor is not near this rail?

I’m clutching at straws now!

No. The little silver wires, above the Blue wires, in Pic 1.

Hang on…

I am concerned they might touch the 323 boards…

I would bend them straight - or ‘away’ from the 323’s - & try again.

They are , or were the links. Well broken!

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I’m going to let @neils advise here

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Looking at how the Links lie, I would bend to right hand top one to the right - like the other 3 are.

Its the only one which is ‘odd’. Maybe it can touch something, when to boards are trapped with the case fitted…?

Not convinced there’s anything wrong the 323E cards. Feels more like something with the 72. But no idea what.
Swapped over HCs, made no difference either.

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@Richard.Dane - Agreed… :slightly_smiling_face:

Its fine, without the case on…?

It’s a lot quieter. Thought the problem was fixed. But as soon as you slide the sleeve past the phono cards…

I thought this was going to be easy!

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