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Old 23rd Jan 2022, 7:31 pm   #1
Whaam68
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Default Quad 33 woes

Hi All
Iíve had this 33 for many years. I had refurbed it but the front edge of the filter section pcb had I later discovered had a hairline crack in the board which cut across several traces. As such it was unreliable even after bridging with wire and was put away. Having obtained some new filler epoxy thatís like a powder you fill gaps with and a setting agent that fixes it I thought Iíd give it a go. Anyway that seemed to work on the board which is now solid. I rebuilt the bridged traces with solder and continuity is good. Stupidly I also sprayed servisol into the switches and now none of the push switches on the filter side will lock in :0( Iíve blown hot air in to try and dry out the lubricating effects of the servisol but no joy. Itís an early unit 8776. Have I wrecked it? Any way to bridge the switch contacts to permanently set it to 5 or 7 k? At the mo all switches are out so not on cancel or any setting.
Thx
Mike
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Old 23rd Jan 2022, 7:52 pm   #2
Mooly
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Default Re: Quad 33 woes

Well done fixing the PCB

A few thoughts as cracked PCB's are a common occurrence in the repair trade. Firstly you should really bridge the cracked print with wire... now a resistor leg would be perfect. Just bend it 90 degrees, solder it across the break and snip... done. The reason is that solder cracks (well it can do) when used like this. It has no flexibility or strength.

Your resin is probably perfect for the job although another common option is super glue which seems to melt into the board and can be super strong when it does that.

I doubt the switches are wrecked, maybe gunge has been dislodged and is stopping the latch working. I'd be inclined to remove them and soak them in iso to clean any old lubricant out, then try again. I have bad memories of Servisol but for other reasons. There are other alternatives like Elecrolube.

Any switch/s can be linked out if you know the configuration. You would need to study the circuit diagram and see what parts were to be in circuit for the mode you want but I would try and salvage the old ones, they might end up better than ever if cleaned up properly. If you can't remove them then try iso blasted in with the straw and have a paper towel to soak the excess up.
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Old 23rd Jan 2022, 8:45 pm   #3
Whaam68
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Default Re: Quad 33 woes

Cheers Mooly
I will reinforce breaks with wire. The hardener That came with smelt just like superglue and seems strong. I just ohmed out the filter switch contacts pushing each switch in and think Iíve now found the right ones to engage the 5k filter which seems to sound good on my set up. Iíve temporarily bridged with wire. However testing has been delayed as now the power switch in the dual purpose volume control seems to have failed so Iím going to have to bridge that also and rely on plugging it in for power ďonĒ. This one is fighting me!
Regards
Mike
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Old 23rd Jan 2022, 9:44 pm   #4
Whaam68
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Default Re: Quad 33 woes

After a quick bypass of the power switch all now seems well. My ohming and bridging on the 5k filter seems to have done it. Iíll give the switches a day or so and if they start to Latch Iíll reverse it but if not I donít have the patience to strip the push switches down so Iíll leave well alone.
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Old 24th Jan 2022, 4:51 am   #5
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Default Re: Quad 33 woes

You might want to leave a note of what's been done inside the 33.

Your mod could give some future restorer, or your future self! a bit of a run-around without any clues.

I've tripped myself up a few times!

David
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Old 24th Jan 2022, 6:55 am   #6
Whaam68
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Default Re: Quad 33 woes

Good idea David will do!
I would never sell this with the pcb fix, in fact I struggle to sell any audio gear being more of an accumulator!
Iím using the 33 with a 405 where to my ears it sounds slightly nicer than my 44.
Mike
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Old 24th Jan 2022, 8:00 am   #7
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Default Re: Quad 33 woes

Have a look at the Dada site as there is a link there to the 33 service manual which shows how you can repair/rebuild the switches. I recently bought some Servisol for this very job but have read a few articles recently stating not to use a lubricant/cleaner and i think Quad say the same. I am part way through a Dada upgrade on mine. I was watching a good video on You Tube yesterday on this re-build plus cleaning up the push buttons and general refurb.
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Old 24th Jan 2022, 8:41 am   #8
Mooly
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Default Re: Quad 33 woes

Quote:
Originally Posted by Whaam68 View Post
..................... This one is fighting me!
I'm pleased to hear you are getting though. Its just typical that the power switch, not wishing to be outdone by the others, would pack up as well.

Good luck.
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Old 24th Jan 2022, 8:56 am   #9
Whaam68
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Default Re: Quad 33 woes

Quote:
Originally Posted by mikes08 View Post
Have a look at the Dada site as there is a link there to the 33 service manual which shows how you can repair/rebuild the switches. I recently bought some Servisol for this very job but have read a few articles recently stating not to use a lubricant/cleaner and i think Quad say the same. I am part way through a Dada upgrade on mine. I was watching a good video on You Tube yesterday on this re-build plus cleaning up the push buttons and general refurb.
Hi yes I did the Dada refresh on this a few years back and it worked well. I saw the youtube vid last night on dismantling the 33 switch gear...not for the feint hearted...lots of potential for losing unobtanium parts to the carpet monster!

I may try Mooly's IPA and straw approach as I have a bottle in the cupboard but if not for my use (home office) being stuck in one filter step isn't a big deal...the bass/treble etc all still work fine.

regards
Mike
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Old 25th Jan 2022, 8:04 am   #10
mikes08
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Default Re: Quad 33 woes

Could you dismantle inside a large plastic bag? Freezer type bag?
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Old 25th Jan 2022, 8:18 am   #11
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Default Re: Quad 33 woes

I'm curious how using Servisol on a push switch can cause malfunction. Clearly that has happened, but in decades' use on pots and many different kinds of switches I've never had a problem except for rarely, a slight 'gritty' feel afterwards. And that would subside after a further application. Strange, I'm curious..
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Old 25th Jan 2022, 9:13 am   #12
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Default Re: Quad 33 woes

The volume control with mains switch always fails with the mains switch failing. It did on mine. I suspect the contact snubber fails, and then the contacts erode.

I replaced it with one from Quad itself and the volume tracking was all over the place. I returned it to Quad for a refund and sent the tracking data to them.

The replacement looked nothing like the AB original. The original tracking was incredibly tight - and fortunately I did not toss it out.

What I did was lurk on eBay until I saw a NOS mono 1M AB pot with an identical mains switch, that cost hardly anything. I transferred the switch from that to the original pot.

Then I bought a new snubber from Farnell (the most expensive part of the exercise) and wired that it.

Problem sorted.

Craig
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Old 25th Jan 2022, 9:43 am   #13
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Default Re: Quad 33 woes

There is a firm that restores Quads and uses replacement AB-type pots. They get them from Blore-Edwards. The pots are made in Germany for BE. If you get stuck, drop BE a line.

NB - channel matching is supposed to be very good on the BE part. I'd like to try some for myself.
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Old 25th Jan 2022, 10:31 am   #14
Craig Sawyers
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Default Re: Quad 33 woes

The Quad supplied unit was identical to a Blore Edwards. It is not physically the same as the original very tightly matched unit.

Craig
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Old 25th Jan 2022, 10:33 am   #15
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Default Re: Quad 33 woes

Had problems with my 33 'intermittent switches'. Not for the faint hearted but i dismantled them for a thorough clean up and upon reassembly it was exactly the same!
Never did find the source of the problem but re soldering all joints on the boards cured it.
Switch boards do turn up on the bay from time to time.

Alan
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Old 25th Jan 2022, 10:47 am   #16
Craig Sawyers
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Default Re: Quad 33 woes

Quote:
Originally Posted by alanworland View Post
Had problems with my 33 'intermittent switches'. Not for the faint hearted but i dismantled them for a thorough clean up and upon reassembly it was exactly the same!
Never did find the source of the problem but re soldering all joints on the boards cured it.
Switch boards do turn up on the bay from time to time.

Alan
That sounds like a good idea. I have an intermittent problem in my 33 which could well be a dodgy solder joint.

Craig
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Old 25th Jan 2022, 11:13 am   #17
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Default Re: Quad 33 woes

Quote:
Originally Posted by Craig Sawyers View Post
The Quad supplied unit was identical to a Blore Edwards. It is not physically the same as the original very tightly matched unit.

Craig
That's interesting info. When I spoke to BE, they were praising the channel matching, 'as demanded by Quad'. I have yet to get samples out of them...

I've recently realised that the £12 Alps 'Blue' pot pretty much has the best overall L/R tracking of any modern pot. The TKD CP-2500 at 6x the price has 'image creep' below -50dB from full rotation (not in all cases, but it means around 1 in 3 or 4 have it, which is annoying for such an expensive part).
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Old 25th Jan 2022, 11:22 am   #18
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Default Re: Quad 33 woes

I have just changed out the filter board on a 33 due to a odd fault ( I had a spare) the switch bank has 2 shafts missing as the buttons were glued in and on removing them springs flew every where . If you want the board with the bank to make 1 good one from the 2 it is yours for the cost of post

Dave

Ps the board has a fault where power is on pins 5/6 poss a short cap
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Old 25th Jan 2022, 1:13 pm   #19
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Default Re: Quad 33 woes

I always found the 22 and 33 preamps difficult to use because the switching pressure needed necessitated holding the preamp down with the other hand otherwise the unit just slid backwards on the shelf! There are ways around it like a small wooden 'dam' fixed behind, or fitting them into a heavier custom made wooden box/rack which is what I did with my 22 setup.
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Old 25th Jan 2022, 1:25 pm   #20
Whaam68
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Default Re: Quad 33 woes

Just to report back time has not changed anything the filter switches are still U/S with no latching but at least itís still working with my bridging bodges. My main issue had been unreliability due to the cracked pcbÖ.used to have to gently push the cancel switch to get both channels which faded in and out and at least that is no longer a problem. Good to know there is an alternative to the volume/power switch I have bought other pots from B/E and will check that out. At some point I will probably give it another going over but pretty full on with work at the mo. I will look out for a spares unit but they seem to be fetching a premium these days.
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