Naim 12/120 Service

STEP 2:

As per the above I think the 7824 regulator is faulty and that is why the preamp supply is not functioning. I see my options as follows:

1. Replace 7824 with new 7824 regulator
2. Replace 7824 with LM317 type regulator board from a SNAPS or simlar
3. Replace 7824 with Avondale TPR2 or ALW Superreg or similar
4. Remove 7824 and 3300uF capacitor entirely and get a BD SNAPS.

The cheapest option seems to be 1 and a new 7824 is about £1!

Options 2 and 3 would appear to offer significant performance gains and are something I would consider. Does anybody have a used regulator board of some type that they would be prepared to part with? The board needs to be fairly compact to fit inside the little 120 – say around 50mm by 50mm and I will need to form a bracket to mount it.

Once this is done I should have a cracking 12/120.

STEP 3:

I would like to remove the SOA circuitry from the 120. However all of the online guides I have seen for doing this are for the later Naim amplifier boards, not these old NAPA3/1 boards.

Would anybody know how I could identify the right components whose legs to lift from the following photographs?

STEP 4:

The power cable is a mini Bulgin type and is not great. I would like to fit a genuine Naim power cable with a Crabtree plug that I've got here. I'm wondering if it would be sensible to omit the Bugin 3A plug and hardwire the Naim power cable through a cable gland directly to the switch? I may also remove the switch as it is a bit aged and stiff. Could I just wire directly to the fuse?

I have some shielded DNM interconnect I am going to make a replacement SNAIC 4 with to compare to the old Naim SNAIC.

Is there any mileage to removing the fuses from the speaker circuits in this amp? I see these are not present on any other Naim amp from memory.

STEP 5:

I would like to try some simple mods to the power amp:

1. Input Caps
2. Feedback Caps

Can anyone advise what the best size and type to go for are? The Evox MMK that everyone raves about do not seem to be available. If anyone has a set of 4 suitable caps in their box that they would part with please let me know.

The way the boards are mounted on the 120 means that caps could be positioned on both sides easily enough if size is an issue.

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Naim 12/120 Service