Nac52 tape out channel dead

Have a really weird one here. My NAC52 is only putting out a signal on 1 tape out channel. This happens on all of input 4 5 and 6. Same for 2 different cables tried. Some years ago I had a headphone amp connected and it worked fine using either of the 2 cables tried above with both channels. Yesterday I connected a tape deck and only get one channel for recording. Deck works fine in another system. I’ve checked everything I can imagine even that the link boards are properly in place. Any ideas or theories would be welcome.

My initial thought was whether the tape boards were perhaps loose on one channel, however, if it’s affecting all three in/outs then that would be too much of a coincidence. It may be worth opening up and checking though, just to be sure. Otherwise, on the big olive pre-amps while faults are rare, it’s usually optocouplers or relays that can fail if there’s an issue. Perhaps @NeilS has a better idea here.

Yes, it’s so odd that I’ve ordered another ‘cheapy’ cable just for a triple test. I’ve already wiggled the cards and inspected the pin locations and all looks good. There would be no reason for them to come loose anyway. The inputs haven’t been used for about three years so it’s difficult to imagine a cause. A trip to ClassA is on the cards as I’m smitten with my new deck and need to make it work in my system.

That’s a good idea. Darran should be able to get to the bottom of it.

When you said “There would be no reason for them to come loose anyway” that’s what i thought but it’s exactly what happened to my NAT01 tuner. I was listening to it one day then all of a sudden the sound went dull and the volume very low. The frequencies all shifted picking up very few radio stations and in mono. This stayed like this for about 3 years then i decided to have a look inside, made sure the daughter boards were seating right, put it back together and it burst into life. The 01 was never moved from its position.

Each input has a pair of record out relays & each tape output also has a pair of output relays. So, if you have checked more than one input & all three tape outputs are missing a channel, I’d say there is a fault in one of the tape output buffer stages.

I’m pretty sure that output 4 has no plug in board option, so if that’s not working correctly I think you can rule out an interface pin alignment issue.
Worth trying your source with a different input if you haven’t already, as that may point to a faulty tape out relay (specific to one input).

Hope that makes sense!

Regards
Neil.

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Thanks Neil, makes total sense to me. Good point on input 4 as well. I’ve also tried sources via 2b (prefix) and 3 (dac) so Problem definitely beyond my skill set. I’ll book a trip to ClassA in for the end of the month. This has however reminded me that the variable input boards are still in place so I might pull them as surplus to requirements as I believe some say that this can improve sound quality by removing The extra draw on the PS. Selling them might also cover some of the repair cost if they are still in demand :slight_smile:

Hi Paul,

Pulling the 528s will indeed reduce the current draw, but do bear in mind that unless you replace them with 526s, you will lose the use of that particular input. Some motherboard revisions have link wires that can be reinstated, but that would involve a soldering iron.

Regards
Neil.

Unfortunately, I think the demand for NA528 boards is minimal, as most replace them with NA526s or link wires.

Your right. There is a pair on the bay for £30 asking price so not a pot gold then. I’ll keep them in the spares box :).

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