Author Topic: Quad 303 restoration  (Read 5268 times)

Offline mygoggie

Re: Quad 303 restoration
« Reply #105 on: January 10, 2019, 02:19:04 PM »
Out to dry and yes @Family_Dog the nice smell of varnish is present.

Herman

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

Offline mygoggie

Re: Quad 303 restoration
« Reply #106 on: January 10, 2019, 04:16:46 PM »
It is amazing how long the block of iron stays hot. It is now 4 hours later and it is still hot to the touch.

First coat of varnish has dried so I moved the wire hangers to the opposite holes to turn what was up to down and what was down to up.

Dunked the transformer again and hanged it out to dry ...

Herman

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

Offline mygoggie

Re: Quad 303 restoration
« Reply #107 on: January 10, 2019, 04:19:57 PM »
I forgot to mention that when I wanted to use the tin foil today to line the baking tin, most of the foil on the roll has oxidised together. And I think this roll is only been in the cupboard for 10 odd months. No we do not use a lot of tin foil.

So yeah, everything here loves to rust ...
Herman

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

Offline mygoggie

Re: Quad 303 restoration
« Reply #108 on: January 10, 2019, 06:40:56 PM »
Two coats of varnish completed. Looking good if I may say so myself!





Tommorrow I will figure out a 60V load and then let the transformer run a bit and see what it does.
« Last Edit: January 11, 2019, 02:03:51 PM by Family_Dog »
Herman

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

Offline d0dja

Re: Quad 303 restoration
« Reply #109 on: January 11, 2019, 10:17:09 AM »
Nice work on the restore. Following with interest.

I think there's a permissions setting on your images stored on Google... some of them don't display as they need a google account sign-in.

Offline mygoggie

Re: Quad 303 restoration
« Reply #110 on: January 11, 2019, 11:05:43 AM »
Nice work on the restore. Following with interest.

I think there's a permissions setting on your images stored on Google... some of them don't display as they need a google account sign-in.

Thanks for the heads up. Will look into the images issue.
Herman

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

Offline Family_Dog

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Re: Quad 303 restoration
« Reply #111 on: January 11, 2019, 01:35:20 PM »
All pictures should be showing now...


-F_D



-Eric

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Offline mygoggie

Quad 303 restoration - Transformer
« Reply #112 on: January 11, 2019, 01:53:12 PM »
Time to gather some energy and go and see how the "new" transformer will perform.

First step is to check which primary terminals must be connected for a 220V input as found on my workbench. Referring to the above thread and this thread, I made up the following table for ease of reference.



I must therefore connect the two outer terminals to the mains feed which will be 220 VAC and install a bridge between the orange and pink terminals as shown below.




As per my understanding of the output windings, the outer two terminals are for a 50Hz AC system. I must therefore not connect the output wiring as in the image above but on the two outer terminal.

« Last Edit: January 11, 2019, 01:56:18 PM by mygoggie »
Herman

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

Offline mygoggie

Quad 303 restoration - Transformer
« Reply #113 on: January 11, 2019, 03:25:43 PM »
I took my time and checked all the winding readings and it all looked good.

So I wired the transformer up through my isolation transformer and my overload light bulb. Here it is standing all ready for the switch on  :thumbs:

Herman

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

Offline mygoggie

Re: Quad 303 restoration
« Reply #114 on: January 11, 2019, 03:46:38 PM »
First switch on I wanted to do without any secondary winding connections to make sure the voltages I read are within the requirements.

Today the mains supply voltage is once again crappy and the output of my isolation transformer is a little bit higher at 213 VAC than the previously measured 210 VAC as per this post.





I stood back and hit the on switch. Nothing happened ...  :faint:

So I listened closer to the transformer and I could detect a very faint hum. Wow, so much more silent than before. Excellent.

Time for measurement of the secondary voltage. As can be seen below it now measured 63VAC.




If we do a quick voltage ratio comparison between old and refurbished, we find the old Vp:Vs = 210/57 = 3.68.

The new ratio is Vp:Vs = 213/63 = 3.38.

This means we have a more efficient transformer. So who wants to calculate the percentage improvement of efficiency?
Herman

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

Offline mygoggie

Quad 303 restoration - Regulator board PCB
« Reply #115 on: January 11, 2019, 07:15:01 PM »
The regulator board was quick to do as it is fairly simple. One thing I realised is that the PCBs are not all the same length after completion of this design! So I failed PCB design 101 as I never checked this when I designed the output board layout.... tsk tsk tsk. I will have to resize that and move the tracks and tabs to suit. So you learn, so you learn.

Here is the regulator board. I think it is all good. Please check and let me know if you see any mistakes.



I will see about the extra tab for the multi turn variable resistor. Actually forgot about that on this board! :shh:
« Last Edit: January 11, 2019, 07:17:04 PM by mygoggie »
Herman

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

Offline mygoggie

Re: Quad 303 restoration
« Reply #116 on: January 11, 2019, 07:22:34 PM »
A quick update on the transformer. Good news, the transformer ran under no load for two hours and was only warm to the touch. In addition it is more efficient now! Tomorrow I will put a load on it and see if it gets hot.
Herman

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

Offline Family_Dog

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Re: Quad 303 restoration
« Reply #117 on: January 11, 2019, 08:11:48 PM »
There's a bug crawling on your PCB...   :giggle:

Just one thing - the bottom screw hole looks very close to the adjacent track?

Looks great, have you sourced PCB blanks yet?


-F_D




-Eric

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

Offline mygoggie

Re: Quad 303 restoration
« Reply #118 on: January 11, 2019, 08:43:26 PM »
There's a bug crawling on your PCB...   :giggle:

Just one thing - the bottom screw hole looks very close to the adjacent track?

Looks great, have you sourced PCB blanks yet?


-F_D

Yes, the bug is to sort the small bugs out ...  :clap:

Yes, the original is like that. I did move it a bit more vertical to get away from the topside of the hole.



No, I have not had the time to sit and really dig. I learned I should search for "phenol based single sided PCB" or "phenolic PCB".
Herman

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

Offline Family_Dog

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Re: Quad 303 restoration
« Reply #119 on: January 11, 2019, 08:46:31 PM »
Personally I would go with fibreglass for the boards. Looks better, is better and most certainly more easily obtainable. Also, the bug feel more comfortable on a fibreglass board, kinder to their little feet.


-F_D



-Eric

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