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paulf-2007
22-12-2018, 11:51
A new op amp arrived this morning for my little dot 1+ Replaced it and plugged headphones in. Crackly noise and on one channel. Put the original op amp back in, still the same. When I pulled the headphone jack about it came and went. I was using Spotify through a Najda dsp as the Dac, into akai integrated, pre out to headphone amp. So disconnect pre out cables from headphone amp and reconnect to integrated amp. Plug headphones into integrated amp headphone socket, still crackly and one channel. Ah maybe my headphones are playing up. Removed speakers from walnut cans ( grado 325 ) no problems I could see. I'm now thinking its the integrated amp balance control, connect iPad into tuner input and all good. Play vinyl into integrated all good. Oh bugger, maybe it's Najda dsp. So I sketch the inputs and outputs on the back of the Najda and note what is connected to which sockets as there are no labels. I then think to disconnect the analogue out from Najda to integrated amp aux in and connect direct to the headphone amp, all good. So now I have headphones working ok, integrated is working ok, Najda is ok, headphone amp is ok, I think I might replace the heavy interconnects that may be pulling on the RCA sockets. I don't believe they make any difference anyway.
Still haven't put the new op amp in again as my head hurts.

YNWaN
22-12-2018, 13:00
Your op-amp presumably plugs into a carrier socket? Check for dry solder joints and intermittent connections.

paulf-2007
22-12-2018, 13:07
It's working perfectly, I will swap the op amps again and see what happens. Although it pointed to the headphone amp it was still doing the same thing through the integrated amp headphone socket.

dave2010
22-12-2018, 13:26
For a second I thought you were going to come out singing and try to sell me car insurance. :lol:

paulf-2007
22-12-2018, 13:58
For a second I thought you were going to come out singing and try to sell me car insurance. :lol:
Wrong advert but had the little grey cells working

Jazid
22-12-2018, 15:12
You've tried twisting the volume and balance controls, and switching all The switches a few times I suppose?
After that I second the dry solder joint answer, or maybe a bit of dirt in the op amp socket?


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paulf-2007
22-12-2018, 15:49
You've tried twisting the volume and balance controls, and switching all The switches a few times I suppose?
After that I second the dry solder joint answer, or maybe a bit of dirt in the op amp socket?


Sent from my BLA-L09 using Tapatalkyes James tried twisting the balance control, it could do with some contact cleaner but not that bad.
Update, changed the op amp for the one recommended by Norman and the grado 325 sound the best they ever have. Flushed with success, I went about changing the stock valves for mullard cv1014 which entailed moving jumpers, I was led to believe but actually required extra jumpers fitted to j1 and j2. Checking that k1 and k2 were correctly positioned, which they were. I didn't have the extra two jumpers that would come with a new unit, although if I could find the box they may well be hiding there. I had some old ide drives in the office that I haven't got around to ditching and found two jumpers to use. All now working and sounding wonderful with new op amp and valves. I moved the headphone amp and the left channel cut out momentarily, so it turns out the 1/4" socket is iffy, I will get my tech mate to change it after Christmas.

paulf-2007
23-12-2018, 13:04
Squirted some contact cleaner in the 1/4" socket and shoved the plug in and out and round a bit, hope that does the trick.

Jazid
23-12-2018, 13:46
Gotta love that stuff!

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dave2010
23-12-2018, 14:30
Wrong advert but had the little grey cells workingIndeed - there's no comparison is there?

paulf-2007
23-12-2018, 22:27
After the contact cleaner, the moment of truth. Working perfectly, no noise or cutting out on one channel.

Light Dependant Resistor
23-12-2018, 23:25
You can avoid mechanical attenuation wiping surfaces altogether.

paulf-2007
24-12-2018, 12:15
You can avoid mechanical attenuation wiping surfaces altogether.
Not in an old jap crap amplifier you can't