Restoration Quad 303 restoration

[mygoggie]

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Content:
This is a new post inserted to list all of you who have donated towards the project.

Any project can either be tackled alone or people can start owning part of it by contributing. I simply love it when others find a project interesting and want to contribute in some form or way.

I asked Family_Dog to edit this post so that I can acknowledge those of you who are contributing. Without you I cannot complete the project. Thank you and I salute you!

Nchebe - redesign of the regulator and output PCBs into Gerber format.
Family_Dog - supply of the Saf Dem cleaning and anti-corrosion fluid and his patience for helping me start this thread.
JohnnyIC - supply of a variac
Rob of Pollocks - UV printing of plates

and then lastly, to all of you who have commented, offered advice and compliments in the various posts below, keep posting!

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Quad 303 restoration

I found this Quad 303 and this Quad 33 abandoned when my neighbour moved out.

Maybe I am crazy, but I think I will give the restoration a go.

It looks better on the photos than in real life. Quite bad corrosion on anything that is metal.

 

[mygoggie]

Is this the same one that you posted about regarding the BC transistors needed, or is this another find ? Good luck with the restore...results should be pleasurable!

 

[mygoggie]

Is this the same one that you posted about regarding the BC transistors needed, or is this another find ? Good luck with the restore...results should be pleasurable!

Jip, the same one ... just had time to find the parts first and now the work starts.

 

[mygoggie]

Pull those to5's and to66's and test the hfe, diode test, and junction resistances as well. Check diodes as well ( junction resistance and diode test). No point putting in new power transistors ( if needed) without making sure the driver/input stages are good. Those 40352 RCA to66's might be hard to find but can replace with TO220 packages. To5's are still available most places.

 

[mygoggie]

Looks to be an interesting project, the PCBs look fairly respectable. Would be interesting to hear of those power transistors still work


-F_D

The PCBs have had a too hot soldering iron on them. I will see if I can recover the damaged tracks. Will post some pics.

Looking at the power trannies up close in real life I shudder ... will start stripping on the new year. Maybe that will work some miracles.

 

[mygoggie]

Nice :rubhands:
I have two of these. One works ok after a re-cap.
It has a hum once powered up though.
But sounds amazeballs!
The other needs extensive work and might not be worth the expense.
I wish I could just buy a complete kit LOCALLY as it's a mission for me to source parts.

Subscribed.

I will post a parts list here. Maybe I can order two kits, one for you and one for me?

 

[mygoggie]

All the best with the restoration.

The mains transformer and the PCB's still looks o.k.

The power transistors would possibly even work after removal of the rust.

 

[mygoggie]

I will post a parts list here. Maybe I can order two kits, one for you and one for me?

Fantastic. Thank you very much.
That sounds like a plan. :dop:

 

[mygoggie]

The three board's underside. Do not look too bad. Nothing that a resolder and resin remover will not clean.

 

[mygoggie]

I had an hour this afternoon before the braai starts. Stripped the unit into parts. Glad I did it as I found a number of dead shorts due to poor soldering.

The aluminium ends will clean up nicely with soda blasting. The rest I will send in next week to be chemically cleaned and plated.

Anyone knows of a face plate template for silk screening purposes? Otherwise I will have to spend some time making one up.

One thing I cannot get loose is the voltage selector in the top left hand corner. Anybody has an idea how the selector comes loose from the female socket? It is stuck ....

 

[mygoggie]

I would hazard a guess and say it should pull out but has probably corroded and is stuck fast. Liberally soak it with Q20 for a while?

 

[mygoggie]

Liberally soak it with Q20 for a while?

I followed your advice and soak it in Wynns No. Five for about 30 minutes. Then I put a ring spacer over the round black selector and put everything in my woodwork vise. One jaw on the ring spacer and one jaw pressing on the small little round pin that protruded on the back of the socket. I carefully applied pressure and "crack" it came loose as you can see below.

 

[mygoggie]

So I have been reading and it is clear the solder to use on the connections and PCB must contain lead. Now I have some old solder here, but have no idea if it contains lead and if so the correct ratio.

Anyone with some advice?

 

[mygoggie]

If it is on the old red plastic reels, probably is lead solder. Unleaded is a bugger to use and requires a hotter iron tip, so if the solder melts easily and you can adjust your soldering iron tip to lower levels, it probably is leaded.

 

[mygoggie]

If it is on the old red plastic reels, probably is lead solder. Unleaded is a bugger to use and requires a hotter iron tip, so if the solder melts easily and you can adjust your soldering iron tip to lower levels, it probably is leaded.


-F_D

That is a Roger and a Roger. :2thumbs:

 

[mygoggie]

I tried to loosen the insulation plate stuck to the inside of the bottom plate by using acetone to dissolve the glue. All I achieved was to dissolve the paint and in the process made a startling discovery. The paint is metallic based as a million little pieces of glitter started to float in the acetone!

Next step is to take the to the glue :rubhands:

 

[mygoggie]

Old British craftsmanship, from the days when people took pride in producing a high-quality product :thumbs:


-F_D

 

[mygoggie]

Herman,

You might do well to browse through this UK forum:

https://www.vintage-radio.net/forum/showthread.php?t=137769&highlight=quad+303+restoration

and here:

https://www.vintage-radio.net/forum/showthread.php?t=137769&highlight=quad+303+restoration

They recommend using the original 2N3055 output transistors in place of modern components, for reasons of stability. I'm inclined to agree with this, the rust can be removed with a pot wire-mesh scraper (what does one call these things??). Their suggestion is to replace the power supply caps with higher value electrolytics (6800uF) as this will improve the bass response somewhat, equivalent capacity caps back in the days when the 303 was built were simply too large physically to fit.


-F_D

 

[mygoggie]

Found this site as well, in Dutch, but full of pics. Quad 303 about half-way down the page.

Revisie klassieke Quad apparatuur

 

[mygoggie]

Thanks Eric, much appreciated. Going to take it slow for a few days now as I have tick fever. Will spend time reading when I can.