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Old 9th Mar 2015, 12:36 pm   #41
David Goodall
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Default Re: Quad 34 Radio & CD input.

Thanks for all this excellent advice. I'm picking up the ICs today, and will get snipping this evening.
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Old 10th Mar 2015, 5:13 pm   #42
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Default Re: Quad 34 Radio & CD input.

Right then. The new 4066 is in with an IC holder. I also found two open circuit corroded tracks that I have repaired. I still have only one channel! I must point out that I have still to put the new 4016 in, as I had such a problem snipping the leads of the 4066. I thought I would wait to ask what kind of snipper I should acquire.
I have done some voltage tests. The left channel is the OK one. At pin 1 and 2 (Right channel) of the 4066 (IC2) I am getting 6.4 volts DC. Obviously on the working channel there is no DC. How sensitive are the HEF4066s to static? I was handling the pins somewhat, so maybe I've pooped it?
Anyway, snipping IC pins. Damn tricky without the right tool, whatever that is.
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Old 10th Mar 2015, 6:34 pm   #43
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Default Re: Quad 34 Radio & CD input.

Dunno if there's a right tool, but small oblique cutters with a fairly sharp point on one side of the head seem to work OK.

Static sensitivity depends a lot on handling conditions- sweaty mitts in the kitchen probably don't pose much of a hazard, but clean and dry conditions in the living room might be a different story. Especially if the carpet's artificial fibre.
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Old 10th Mar 2015, 7:13 pm   #44
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Default Re: Quad 34 Radio & CD input.

How about a wooden floor, with sweaty fearful hands? Sounds like I might get away with it!
I can't quite see how you could get to those pesky pins with the snippers shown. Perhaps I'm missing how to approach them?
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Old 10th Mar 2015, 8:02 pm   #45
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Default Re: Quad 34 Radio & CD input.

You can just about get in between pins from the top or if there's access, the side and snip themone at a time. If access is a bit tight, start at one end and be a bit brutal!
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Old 10th Mar 2015, 8:05 pm   #46
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Default Re: Quad 34 Radio & CD input.

Thanks for that. I think I was being a bit chicken about crunching away at my beloved preamp.
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Old 10th Mar 2015, 8:22 pm   #47
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Default Re: Quad 34 Radio & CD input.

I use cheap micro sidecutters like these: http://cpc.farnell.com/pro-s-kit/pa-...0mm/dp/TL08717

Chop the leads of the IC one-by-one, as close to the IC as you can.

The aim is to end up with 16(?) individual leads attached to the PCB, and the faulty chip (minus its amputated legs) in the bin.

You can then heat each soldered joint one at a time, and remove each amputated leg using a small pair of pliers.

Finally, clean excess solder from the board with desoldering braid, and clean off the fluxy brown mess with isopropyl alcohol on a cotton bud or piece of rag.

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Old 10th Mar 2015, 8:38 pm   #48
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Default Re: Quad 34 Radio & CD input.

Thanks Nick. I have just ordered some isopropyl alcohol on your recommendation. Are there any advantages to using desoldering braid over solder suckers?

And I've just ordered the PRO'S KIT PA-101 PLIER. Looks nice, and pointy.
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Old 10th Mar 2015, 9:12 pm   #49
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Default Re: Quad 34 Radio & CD input.

The Proskit stuff is cheap and cheerful, but good value for what it is. Don't try cutting anything except thin IC leads and thin copper wire with them, or the blades will become gouged and useless. The same thing from a top-name company is about 10 times more costly.

Braid vs. suckers? It's a personal thing. Suckers work very well in certain situations, but the cheap ones are useless, and the expensive ones lose their magic quite quickly. Braid is a very good tidying-up tool, but stick with the decent, branded stuff (e.g. Servisol) and keep it in a sealed container when not in use as the flux in it seems to go-off eventually. For the same reasons, don't buy vast spools of it if you're not going to use it all up in a year or two.

Common sense will help avoid ESD (static) damage. No nylon clothes, wooden floor rather than carpet, humid workshop (or kitchen etc.) and you should be fine.

Nick.

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Old 11th Mar 2015, 10:53 am   #50
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Default Re: Quad 34 Radio & CD input.

David,

I reckon it is IC1 that is the problem, so since you've not changed that yet I'm not surprised you still have no sound on the right channel.

As for the snipping and the tools - well, I agree with what others have said - couldn't have put it better myself! I use the type of cutter that Herald1360 shows in his post no. 43 for this type of job. Just try to cut the pins from the top of the IC if you can - it does not matter if you wreck the old IC; your priority is not to damage/lift the pcb tracks to the IC.

By the way can you tell us the serial number of the pre-amp please? It may help in sorting out what is the 'correct' circuit diagram for your unit.

Last edited by SteveCG; 11th Mar 2015 at 11:05 am. Reason: Added a final question
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Old 12th Mar 2015, 11:44 pm   #51
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Default Re: Quad 34 Radio & CD input.

Success! I had made sure all possible broken tracks were bridged, and replaced the 4066, but it wasn't until the new 4016 went in that both channels appeared. For that Steve, I think you get the cigar!
At the risk of this sounding like an acceptance speech, I would like to thank everyone that made it possible!
Steve, for sending me out to the shops with the right list, including the snubbber.
Merlinmaxwell for the HEF recommendation. John Caswell for his IC holder, and pin cutting tips. Radio Wrangler up there in Fife with his "Purple plague, and glassivation" overview. (I know Fife well. I lived in Glasgow for fifteen years.)
Vidjoman, for the keen eyed snubber bulge diagnosis, and corroded tracks. It pains me to say so, but I genuinely hadn't noticed the different colour channel notation, and it's really helpful! And finally Nick the Dentist, for the fault finding photos, micro side-cutter link, and desoldering braid, and isopropyl alcohol tips. The desoldering braid is awesome. I bought some a couple of years ago, but had never tried it. It actually completely freed all but 2 of the IC pins. I almost didn't need to cut. The solder sucker is now going to be used for mass removal. The isopropyl alcohol arrived this afternoon, and I can now see my soldering. Great product. I haven't been around for a while, as I'm restoring an old boat, but I'm glad it broke down now, as it's been such good fun fixing it, and talking with you all.
Dave.
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Old 12th Mar 2015, 11:48 pm   #52
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Default Re: Quad 34 Radio & CD input.

Steve, the serial number is 8585.
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Old 13th Mar 2015, 10:30 am   #53
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Default Re: Quad 34 Radio & CD input.

Pleased you've got it fixed. Can seem daunting at first. I've been servicing for too many years, over 55 in fact, and one of the first things I learnt was to use my eyes. An even older engineer said to me "use your eyes son and you'll save a lot of time" and how right he was. A few minutes looking will often show up where many faults are lurking.
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Old 13th Mar 2015, 11:59 am   #54
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Default Re: Quad 34 Radio & CD input.

I'm very pleased you got the pre-amp going - Quad gear is worth the effort !

Also thanks for the serial number. Quad have issued slightly different circuit diagrams for the pre-amps (and other equipment as well it should be said) as their production run(s) grew, and they amended things; but they do give serial number ranges for the circuit diagrams so you can get the correct one.
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