capacitor value help

us3rx · 7th June 2011, 07:07 PM

Hello all,
I'm needing some input on possible replacement values for an Arp pro/dgx bipolar power supply.
Can I use a different value than the 250mf cap spec'd for C5 and C1?
It seems to me that I could go higher without adverse effects, possibly might improve ripple?
I would also like to change out C6 and C7. I have a variety of caps available other than the ones on the power supply.
Currently only the +15v seems defective only outputting +6.25v dc.
When I set my VOM to auto it fluctuates between the ac and dc scales. AC reads 7.5v and then jumps to dc.
Is this a possible symptom of unfiltered output coming from bad cap (C1)?

nigelwright7557 · 8th June 2011, 10:38 PM

I wouldnt venture too far from the recommended capacitor values.

The noise on the output could be a capacitor.
There arent many I would change all electrolytics if it is an old power supply.

BZed · 9th June 2011, 12:24 AM

Check the doides. It sounds like you may have a bad one.

huibert34 · 12th June 2011, 11:47 AM

It is a ua723 voltage Ic regulator . http://www.datasheetcatalog.org/data...ents/ua723.pdf

So you have to check first the input input voltage accros Ci, I think some 20V DC,

After that, check the reference voltage of the ua723 = 7,23V , pin 5. If it is OK

Check the voltage accros the current limiting resistor , much lower than 0,6V, if not lower than 0,6V , than disconnect the output capacitor C4 is may be a short circuited and replace it

8th June 2011, 10:38 PM	#2
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	I wouldnt venture too far from the recommended capacitor values. The noise on the output could be a capacitor. There arent many I would change all electrolytics if it is an old power supply. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.

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9th June 2011, 12:24 AM	#3
BZed diyAudio Member Join Date: Jun 2009	Check the doides. It sounds like you may have a bad one.

12th June 2011, 11:47 AM	#4
huibert34 diyAudio Member Join Date: Jan 2011	It is a ua723 voltage Ic regulator . http://www.datasheetcatalog.org/data...ents/ua723.pdf So you have to check first the input input voltage accros Ci, I think some 20V DC, After that, check the reference voltage of the ua723 = 7,23V , pin 5. If it is OK Check the voltage accros the current limiting resistor , much lower than 0,6V, if not lower than 0,6V , than disconnect the output capacitor C4 is may be a short circuited and replace it

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