Hi Suzy, did you wash the board yet, if so how did you was it? Soapy water. I’ve got an old marantz that is filthy. Any advice greatly appreciated.
Also: Somebody has previously replaced the caps here with the wrong values.
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Just isopropyl and a little scrubbing brush, then mopping up the gross stuff with cotton buds. It’s a lot cleaner than it was but by no means good yet.
I’m not slavish with replacing caps - I make a snap judgement as to whether to increase the capacitance, or voltage, or just chuck a poly one in.
I’m not slavish with replacing caps - I make a snap judgement as to whether to increase the capacitance, or voltage, or just chuck a poly one in.
I ordered new trim pots, as I couldn’t adjust the bias or offset. With the new trim pots I still couldn’t set the bias in one channel. Turns out the Vbe multiplier in that channel had popped. Luckily I had a spare 2SD669 for replacement.
So that’s it. I promise. A whole bag of new caps, some replacement transistors, and new trim pots. It’s better than new now.
Just for fun I put a 1KHz tone in at 60V peak out, and had a look on the spec-an. It barely manages 0.01%. Needs more OLG. I’m not going to do that.
So that’s it. I promise. A whole bag of new caps, some replacement transistors, and new trim pots. It’s better than new now.
Just for fun I put a 1KHz tone in at 60V peak out, and had a look on the spec-an. It barely manages 0.01%. Needs more OLG. I’m not going to do that.
Hi Suzyj,
Firstly thanks for all the useful info on this amp repair. I'm trying to bring my 3240pe back to life as well.
A question on idle current adjustment if you have a moment. Service manual calls for solder bridge removal on R471/R472, and then replace solder bridge once adjustment done. Can you confirm what this solder bridge looks like? Is it simply a solder trace between the resister leads? This unit was doctored in the past and I can't be sure it was bridged correctly. I can't find a reference pic anywhere.
Hello Mark,
I've found that in the NAD, the solder bridge tends to look like a nasty blob across two traces (pic attached of a 3225PE).
Once you have sorted your bias out (remembering to allow plenty of time for the amp to warm up and stabilise), make sure you resolder the bridges!!!
I found out that it is easy to forget after reassembling the amp, only to have to strip it again to replace the vaporised 1 ohm resistors!!
I've found that in the NAD, the solder bridge tends to look like a nasty blob across two traces (pic attached of a 3225PE).
Once you have sorted your bias out (remembering to allow plenty of time for the amp to warm up and stabilise), make sure you resolder the bridges!!!
I found out that it is easy to forget after reassembling the amp, only to have to strip it again to replace the vaporised 1 ohm resistors!!
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Yup it was just a couple of pads bridged, though on one side of mine a pad was missing due to some really crap soldering. I mounted some 1Ω resistors underneath, replacing the ones on the top side, and then bridged across the resistors themselves.
I really like my 3240PE. Now that it’s fixed properly it’s a lovely, capable amp. I can see why they have such a bad rep though, as if anything ever goes wrong with it you’re unlikely to find someone with the ability to fix it properly, and there are lots of ways to “fix” them such that they make noise but have god-awful distortion at high level.
I really like my 3240PE. Now that it’s fixed properly it’s a lovely, capable amp. I can see why they have such a bad rep though, as if anything ever goes wrong with it you’re unlikely to find someone with the ability to fix it properly, and there are lots of ways to “fix” them such that they make noise but have god-awful distortion at high level.
I too have just acquired a NAD 3240PE. I have read with great interest these threads. My amp works fine but there is a fault with the soft clipping. When switched on the left channel is distorted. I know it's definitely not my speakers and in truth I would never drive this amp so that soft clipping would be required. However, owing to my OCD, I would like it fully functioning and would be grateful if you could give me some pointers where to look. Although I have repair shops near me I would like to have a look myself first. As again, my OCD is a source of perturbation when it comes to trusting said repair shops. Having said that, if SuzyJ was nearer I would happily have her look after it.
Also, can someone please recommend the best contact/pot cleaner. I've read that de-oxit is harmful to carbon tracks. I always used to use Philips 390ccs but that isn't available in the uk any longer.
Thanks in advance,
Nigel
Also, can someone please recommend the best contact/pot cleaner. I've read that de-oxit is harmful to carbon tracks. I always used to use Philips 390ccs but that isn't available in the uk any longer.
Thanks in advance,
Nigel
That was very much the symptom that mine was displaying. At low level it was fine, but wind the wick up and it distorted badly. Mine was due to a popped driver for one of the PE transistors.
Have you got a cro? An image from that would be terribly useful.
Also totally understand the OCD thing. I’m an absolute terror for my techs. Every chassis has to be held in with the correct bolts, every fibre and cable has to be routed just so. All board rework is done with sn62 solder and RMA flux, and cleaned afterwards. I’ve actually chucked no-clean fluxed solder in the bin. Pity help you if you use sticky tape on rack doors. But I like reliable gear and that’s the way to get that.
Have you got a cro? An image from that would be terribly useful.
Also totally understand the OCD thing. I’m an absolute terror for my techs. Every chassis has to be held in with the correct bolts, every fibre and cable has to be routed just so. All board rework is done with sn62 solder and RMA flux, and cleaned afterwards. I’ve actually chucked no-clean fluxed solder in the bin. Pity help you if you use sticky tape on rack doors. But I like reliable gear and that’s the way to get that.
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