Author Topic: Quad 33 restoration  (Read 25891 times)

Offline mygoggie

Quad 33 restoration
« on: December 31, 2018, 10:41:38 AM »
This thread is about restoring the Quad 33 that was abandoned with this Quad 303.

Corrosion is really bad and I am a bit scared to open the lid ...









« Last Edit: December 31, 2018, 05:09:26 PM by Family_Dog »
Herman

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Offline Family_Dog

Re: Quad 33 restoration
« Reply #1 on: December 31, 2018, 05:15:43 PM »
Shot - looking forward to watching this :)

G'wan... Open the lid. Enquiring minds want to know!


-F_D



-Eric

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Offline mygoggie

Re: Quad 33 restoration
« Reply #2 on: January 01, 2019, 12:31:50 PM »
I was brave this morning and took the screwdriver to the Quad 33 ...

Before we proceed any further I will refer to the amp in the feminine as she has as many buttons and knobs as any woman I have ever met.

There she is laid open, surprisingly in a very good condition except some loose wires and shoddy soldering on the main PCBs.














As always I found a surprise in the case when I removed it!






I am going to have to work through the service manual to see how she comes apart. There are some areas that requires some serious derusting and cleaning.





« Last Edit: January 01, 2019, 12:34:13 PM by mygoggie »
Herman

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Offline Family_Dog

Re: Quad 33 restoration
« Reply #3 on: January 01, 2019, 02:05:05 PM »
I guess those pots could all do with a good soak and some cleaning. When done, try spread a thin film of Vaseline on the carbon track as lubricant. I used to do this 100 years ago when I was young and experimental, haven't done so for a while now but certainly going to try it when I get stuck into my AU-777 & AU-999.

Seems there are 5p DIN plugs fitted as after-market?


-F_D



-Eric

That Guy in South Africa...
*************************************
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Offline mygoggie

Re: Quad 33 restoration
« Reply #4 on: January 01, 2019, 02:40:30 PM »
I guess those pots could all do with a good soak and some cleaning. When done, try spread a thin film of Vaseline on the carbon track as lubricant. I used to do this 100 years ago when I was young and experimental, haven't done so for a while now but certainly going to try it when I get stuck into my AU-777 & AU-999.

Seems there are 5p DIN plugs fitted as after-market?

Any guide that you can recommend on cleaning the pots? How do I get the Vaseline in there?

Yeah, wonder what the reason was for the DIN plugs ... will figure that one out later.


-F_D
Herman

~ To heal the soul is to embark on a new journey. ~

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Offline Family_Dog

Re: Quad 33 restoration
« Reply #5 on: January 01, 2019, 03:35:19 PM »
I used to open the pots, simply by carefully bending the folded tongues open.

But check first, possibly some Kontakt Gold 2000 (Mantech) or Servisol spray might be all that's needed to do a good job. In which case don't open the pots, either of the above two sprays provide lubrication.


-F_D



-Eric

That Guy in South Africa...
*************************************
http://groups.yahoo.com/group/vintage_tube/
*************************************

Offline AudioEars

Re: Quad 33 restoration
« Reply #6 on: January 02, 2019, 03:48:05 PM »
If you look on line there is a great mod on the preamp pcb and a PSU mod'
It is reversible if you would like to keep the original design
Sound playback is way better than the original layout
All electrolytic caps will need replacing, my pots cleaned up nicely and are of good quality
Good luck and have fun

Offline mygoggie

Re: Quad 33 restoration
« Reply #7 on: January 02, 2019, 04:26:20 PM »
If you look on line there is a great mod on the preamp pcb and a PSU mod'
It is reversible if you would like to keep the original design
Sound playback is way better than the original layout
All electrolytic caps will need replacing, my pots cleaned up nicely and are of good quality
Good luck and have fun

Thanks, that's the idea with this one.
Herman

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Offline mygoggie

Re: Quad 33 restoration
« Reply #8 on: January 03, 2019, 04:02:54 PM »
I removed some boards today and there is a lot of work to be done it seems.

The front knob's locking screws are oxidised onto the knobs. I have now soaked it with Wynns No Five and will heat it tomorrow to see if I can crack the screws loose.





The power supply board needs some cleaning and obviously replacement of components and the change from 12V to 16V.







The two amplifier boards appear OK. One had work done on, will have to check what is what here.






The phone pre-amp board looks fine. Nothing a good cleanup and component replacement will not cure.







The main PCBs have problems. I need some help and/or ideas here. Some of the copper tracks and soldering tabs on the PCB are gone. Refer to the yellow circles.




Herman

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Offline mygoggie

Re: Quad 33 restoration
« Reply #9 on: January 03, 2019, 06:50:40 PM »
I felt like finishing the stripping of the Quad 33 today. Guess the pain pills are making me wild  :goofy:

Getting ready to heat the two knobs with the heat gun. I used a few layers of kitchen tin foil folded loosely to create a heat barrier and protect the underlying orange cover plate.

The right hand screw came loose in the clockwise (fastening) direction and I could get it loose by turning it back and forth for a while. The middle one now simply refused to budge. See why it is a her? So I reverted to violence  :angrywife: . I heated it some more till it was very hot and used a very short real life crow bar and simple levered it off the pot's shaft. The expansion of the knob moves the screw away from the shaft and it slid off easily.





And the front panel is removed!




The push buttons came off easily if you grip them with both hand's thumb and index finger and pull. No issues there.

The illuminated name plate is notorious for breaking when you remove it. I took one of my very very sharp woodwork chisels and slowly worked the name plate away from the front panel. It took some patience but it came off.

The next was the orange cover plate that is located below the knobs. As you can see above it is hold in place with four springsteel grip plates. An old trick is to take a small vice grip and pinch the plate on the short sides. This bows the plate and releases the catches from the stud and it simply slides off.

I desoldered the pots and removed them. Here the back wiper wires are desoldered.




I then discovered why there are two DIN sockets floating in the unit. Someone butchered the backplate and installed two headphone jack sockets. I will give it a think how to remove the back plastic plate and NOT break the brittle studs and try and save what I can.





Desoldering the main boards bridging wires proved why the PCB tracks are missing. Someone used non-lead based solder. I had to increase the soldering iron to 425C before the solder melted. A temperature way above what these old PCBs can handle.  :facepalm:

And there she lies in pieces. I will spend some time tomorrow to strip the back plate.



« Last Edit: January 03, 2019, 06:53:57 PM by mygoggie »
Herman

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Online bushtech37

Re: Quad 33 restoration
« Reply #10 on: January 03, 2019, 09:07:23 PM »
"Some of the copper tracks and soldering tabs on the PCB are gone"

Run point to point wiring, easier than trying to fix the tracks

Offline mygoggie

Quad 33 restoration - back plate
« Reply #11 on: January 20, 2019, 12:43:24 PM »
So tomorrow has come and tomorrow has become yesterday two weeks past. As per the Quad 303 restoration thread, I have been quite ill with a virus which remains a mystery.

This week is the week to get the metal parts cleaned and treated ready for painting. So I had to make a plan with the back plate and get it stripped.

As can be seen it was changed with the replacement of two DIN sockets with two headphone sockets.





The sockets were screwed to a plate which in turn was pop riveted to the back plate. To get to the pop rivets I had to remove the plastic backing cover which at 50 years of old is brittle. Especially the plastic pins that gets clamped by the metal hook friction clamps.

I set out to slowly ease the pins from the friction clamps. It took a while but at the end I got them all loose and could remove the plastic cover. It is important to know that the friction clamps cannot be removed from the metal back plate before the plastic pins are removed from the friction clips as they clamp through the hole onto the back surface as can be see here.





This means the complete plastic backing cover needs to be eased away from the metal back plate without skewing it and snapping the plastic pins off. So take your time, have a cuppa in between and do it in a controlled way.

And there the two plates are separated.





The one pin was broken off before I started disassembling the unit, so it needs to be glued back to the plastic cover plate. In addition the metal friction clip was snapped through on the one side. I will make a plan ...





Here the pop riveted and screwed down components have been removed. I need to figure out how to clamp the tube rivets down as these spin with the drill bit the moment you removed enough metal and the clamping tension disappears.


Herman

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Online bushtech37

Re: Quad 33 restoration
« Reply #12 on: January 21, 2019, 04:10:53 PM »
Use a flat ended punch of dia slightly smaller than the hole in plate and gently knock them through when the lip has been drilled off

Offline mygoggie

Re: Quad 33 restoration
« Reply #13 on: January 21, 2019, 04:26:31 PM »
Use a flat ended punch of dia slightly smaller than the hole in plate and gently knock them through when the lip has been drilled off

That is what I did with the ones I could get the lip off and it works great. The remaining ones just spins with the drill. Going to try a duck tape trick now and report back.
Herman

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Offline marantz123

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Re: Quad 33 restoration
« Reply #14 on: January 21, 2019, 04:51:29 PM »
The knurled-down in-side of the eyelets look easy enough to pry up and push the eyelet from the inside out...if its spinning, then its tension is already low enough to get a thin flat screwdriver or a craft blade under it to lift each wing.