PET 2001 Monitor

[TheMatrix]

Hello,

can anyone help me to find a replacement for the monitor PCB part C28.
It's a 10uF/25V Non polarised. I can't find it anywhere.

 

[Hugo Holden]

You cannot replace that capacitor with any currently available new electrolytic cap, bipolar electrolytic. Their ESR is not low enough.

The better replacement is a film cap. Also if you lower the value from 10uF to 8.2uF it improves the scan linearity, center versus R hand side. But it won't help the L sided stretch, other methods can.

But you can fit a 10uF or 8.2uF film type as you see fit. But it pays (unlike the original cap) to use a higher voltage rated part at least 63V minimum but better a 160 to 450V rated parts because the physical construction is associated with a lower ESR.

If you want more information look at this article I wrote about PET VDU's:

https://www.worldphaco.com/uploads/RESTORING%20THE%20%20PET%20COMPUTER%209.pdf

These parts are available on ebay.uk and they will definitely work and are better than the original bipolar cap that was in there:

1pc CDE 930C 10uF (10uF) 250V 10% 930C2W10K Axial Film Capacitor | eBay UK

All of the goods are located in Taiwan. - Self healing.

www.ebay.co.uk

 

[TheMatrix]

Is the one on ebay better than what i can find on ali-express?

https://nl.aliexpress.com/item/1005005431840264.html

These are cheaper

 

[daver2]

One question would be why do you need to replace it?

Dave

 

[Gary C]

One question would be why do you need to replace it?

Dave

Its got a bulge the size of Norfolk on the bottom

 

[TheMatrix]

The original one is defect.
You can see in the picture (Blue capacitor from my post) that the bottom is expanded

 

[daver2]

Now I have a better computer to see the defect it is more obvious!

Dave

 

[Hugo Holden]

Is the one on ebay better than what i can find on ali-express?

https://nl.aliexpress.com/item/1005005431840264.html

These are cheaper

I wouldn't use those in this application where the peak currents are very high. Those caps have been designed for audio use, you will notice I did not select an audiophile capacitor.