Maker Pro
Maker Pro

replacing capacitor in PSU

O

orange

Jan 1, 1970
0
I cannot find anywhere replacement capacitor (680 uF, 200V). Can I use
any other value for capacitance? I need two of them replaced
(identical), they are inside switching power supply, the biggest ones.
 
F

Franc Zabkar

Jan 1, 1970
0
I cannot find anywhere replacement capacitor (680 uF, 200V). Can I use
any other value for capacitance? I need two of them replaced
(identical), they are inside switching power supply, the biggest ones.

If you are running on 240VAC you could use a single 330uF 400V cap.


- Franc Zabkar
 
M

Michael A. Terrell

Jan 1, 1970
0
Franc said:
If you are running on 240VAC you could use a single 330uF 400V cap.


According to the header he's posting from Russia. Does anyone know
what the line voltage is there?

--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida
 
O

orange

Jan 1, 1970
0
OK, thanks all, I'll try ordering it from that site (unfortunately it
might get 'lost' in the customs )
BTW, I'm from Serbia and Montenegro and voltage here is 220V.
 
O

orange

Jan 1, 1970
0
I've ordered them from 'Debco Electronics Inc', very very cheap 2$ per
piece (other places want more than 4$), hope it will not be of bad
quality, and that it will arrive in a year or two, heh
 
D

David C. Partridge

Jan 1, 1970
0
Any capacitor of same value (or slightly higher) with a higher voltage
rating will do fine. As this is a switch mode supply remember to use 105
degree parts or you'll be replacing that part pretty soon.

Dave
 
S

Sam Goldwasser

Jan 1, 1970
0
me said:
bad idea.

No necessarily. If running a dual voltage (120/240 VAC) power supply
on 240 VAC, the input circuit forms a bridge rectifier with its output
across the two main filter caps (in series). The quesiton is what happens
with the centertap. If it's not used for anything else, then this approach
can work, but you'd have to trace the input circuit completely to be
sure it won't simply release smoke. :)

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.
 
me said:
bad idea.

In most switched mode power supplies, in 220V operation, the primary
capacitors are placed in series, so in that case the idea is actually
very usefull. You have to disable the voltage switch, of course.
 
F

Franc Zabkar

Jan 1, 1970
0
No necessarily. If running a dual voltage (120/240 VAC) power supply
on 240 VAC, the input circuit forms a bridge rectifier with its output
across the two main filter caps (in series). The quesiton is what happens
with the centertap. If it's not used for anything else, then this approach
can work, but you'd have to trace the input circuit completely to be
sure it won't simply release smoke. :)

In most PSUs that I've seen one could simply replace one of the two
caps with a single 400V type, link out the remaining one, and then
remove the two redundant wires going to the 240/120 selector switch.
Some designs may have MOVs in parallel with the caps, in which case
these should be removed.

By coincidence, yesterday I dismantled a Sony TV set which had a PSU
which was configurable for single or dual capacitors. The Australian
version of this set had a single 560uF 400V cap, and the other cap was
linked out. The PCB real estate allotted to the 400V cap was slightly
larger than for the 200V one.


- Franc Zabkar
 
F

Franc Zabkar

Jan 1, 1970
0
In most switched mode power supplies, in 220V operation, the primary
capacitors are placed in series, so in that case the idea is actually
very usefull. You have to disable the voltage switch, of course.

The switch is open in 240VAC operation so it doesn't need to be
disabled, but removing the two wires is a good precaution. I do it as
a matter of course whenever I open a PC PSU.


- Franc Zabkar
 
M

me

Jan 1, 1970
0
, so in that case the idea is actually
very usefull. You have to disable the voltage switch, of course.
an important note...
 
F

Franc Zabkar

Jan 1, 1970
0
, so in that case the idea is actually
an important note...

Not really. In a 240V system the voltage switch is open. I'd still
remove it, though, but for reasons of redundancy and added security,
not necessity.


- Franc Zabkar
 
J

James Sweet

Jan 1, 1970
0
orange said:
I cannot find anywhere replacement capacitor (680 uF, 200V). Can I use
any other value for capacitance? I need two of them replaced
(identical), they are inside switching power supply, the biggest ones.

You can use one of same or higher voltage and similar uF rating, doesn't
have to be exact.
 
Top