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Author Topic: Capacitors - wrong orientation? (Read 4396 times)

Offline gflorez

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Re: Capacitors - wrong orientation?
« Reply #45 on: 2020.October.12. 09:32:13 »
Remember its first name: Damp Proof Course.

The first phases of development were strictly secret....

Offline Ep128

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Re: Capacitors - wrong orientation?
« Reply #46 on: 2020.October.12. 22:56:45 »
Remember its first name: Damp Proof Course.

The first phases of development were strictly secret....
THEN. :-) But there could have been photos, recollections at the time that could be put together before being ISSUE3. But we don't know ...

Offline gflorez

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Re: Capacitors - wrong orientation?
« Reply #47 on: 2020.October.13. 10:31:22 »
Not so long ago Tutus was honoured to ask Nick Toop some questions.

On his answer he narrates how painfully was his exit from Enterprise Computers LTD:

".....when I was constructively forced out of the company was one of the saddest periods of my life and I do not like to think about it.  I was also obliged to erase all personal copies of the design which is sad as I had various enhancements in mind and would love to be able to implement my design with these enhancements in a modern CPLD...."

This mean to me that all people involved on the project had such obligatory clause in their contracts.
« Last Edit: 2020.October.13. 10:34:49 by gflorez »

Offline Judge

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Re: Capacitors - wrong orientation?
« Reply #48 on: 2020.October.22. 19:57:47 »
I replaced the C9 capacitor on my 64/128 motherboard with a bipolar one. Working perfectly.

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Offline elmer

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Re: Capacitors - wrong orientation?
« Reply #49 on: 2020.October.23. 04:20:10 »
I replaced the C9 capacitor on my 64/128 motherboard with a bipolar one. Working perfectly.

Excellent, that is great to see. :)

I am very jealous of that beautifully clean motherboard! ;)

Offline Allf

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Re: Capacitors - wrong orientation?
« Reply #50 on: 2020.October.23. 07:56:27 »

Quote
I replaced the C9 capacitor on my 64/128 motherboard with a bipolar one. Working perfectly.
The electronics supplier in Poland currently only has a voltage of 6v3 (at a reasonable price) in stock, which I do not want to order. What is the voltage at the poles of the bipolar capacitance?

Offline BruceTanner

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Re: Capacitors - wrong orientation?
« Reply #51 on: 2020.October.23. 13:28:27 »
What is the voltage at the poles of the bipolar capacitance?
I put a 6.3v bipolar in my EP128, so far no problems. On an oscilloscope the voltages across it are exactly the same as with the original mono-polar (if that's the right word!) ie. goes briefly to 1V at power-up and then drops to a steady approx -1.25V - see my 'scope traces earlier in this discussion, I could observe no difference.

Offline Judge

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Re: Capacitors - wrong orientation?
« Reply #52 on: 2020.October.23. 13:56:21 »
Bruce was faster. :)  I measure -1150mV at the poles. My capacitor is a Nichicon 100uF 25v.
The output 12V is only 11.95V ... but still the picture is very nice.

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« Last Edit: 2020.October.23. 14:42:10 by Judge »
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Offline Allf

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Re: Capacitors - wrong orientation?
« Reply #53 on: 2020.October.23. 14:57:36 »
Thank you for your answers. I ordered 6V3 bipolar capacitors...

Offline Judge

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Re: Capacitors - wrong orientation?
« Reply #54 on: 2020.October.23. 21:07:41 »
I also replaced the C9 capacitor in my main machine with a bipolar one.

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The original capacitor was a Rubycon 100uF 10v, This capacitor is 99uF even after 35 years. The Japanese know something ... :smt023

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Offline Zozosoft

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Re: Capacitors - wrong orientation?
« Reply #55 on: 2020.October.30. 22:09:50 »
The original capacitor was a Rubycon 100uF 10v, This capacitor is 99uF even after 35 years. The Japanese know something ...
Yes, I have never found problems with this type of capacitors.
« Last Edit: 2020.October.31. 09:20:19 by szipucsu »

Offline dangerman

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Re: Capacitors - wrong orientation?
« Reply #56 on: 2020.November.08. 23:04:29 »
Huge thanks to Wolfgang for starting this thread and to everyone else for the comments. A while ago, when I repaired my Enterprise 12V, I was following the schematic diagram rather than the PCB markings and this thread explains why I kept blowing transitors!!! :cry: 

It never occurred to me that the circuit diagram was wrong. I have now installed C9 with minus to the left. Fingers crossed this will work.

Offline szipucsu

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Re: Capacitors - wrong orientation?
« Reply #57 on: 2020.November.09. 09:40:11 »
Fingers crossed this will work.
There will be no danger, man!
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Offline Zozosoft

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Re: Capacitors - wrong orientation?
« Reply #58 on: 2020.November.09. 11:02:35 »
explains why I kept blowing transitors!!!
One note: rare fault, but if the L1 are broken then the TR2 will dead again, and again... (I about after 5 transistors found the problem at L1...)

Offline dangerman

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Re: Capacitors - wrong orientation?
« Reply #59 on: 2020.November.09. 22:27:48 »
One note: rare fault, but if the L1 are broken then the TR2 will dead again, and again... (I about after 5 transistors found the problem at L1...)

Thanks for the tip.  I wound a new L1 myself so hopefully that will be okay.