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power supply sometimes works
I've got problem with one PSU. Its occasionaly working.
Sometimes when I turn the switch ON nothing happens and then when I turn it OFF, for a sec it starts and (normally) shutsdown immediately. what could be the problem? It is very old Amiga 2000 switching PSU, similar to PC (+12V, +5V..etc). please help |
orange wrote:
I've got problem with one PSU. Its occasionaly working. Sometimes when I turn the switch ON nothing happens and then when I turn it OFF, for a sec it starts and (normally) shutsdown immediately. what could be the problem? It is very old Amiga 2000 switching PSU, similar to PC (+12V, +5V..etc). please help The supply may require some minimum load on one or all outputs to function. mike -- Return address is VALID but some sites block emails with links. Delete this sig when replying. .. Wanted, PCMCIA SCSI Card for HP m820 CDRW. FS 500MHz Tek DSOscilloscope TDS540 Make Offer Wanted 12" LCD for Compaq Armada 7770MT. Bunch of stuff For Sale and Wanted at the link below. MAKE THE OBVIOUS CHANGES TO THE LINK htremovethistp://www.geocities.com/SiliconValley/Monitor/4710/ |
it behaves the same, load or no load, sometimes it works but its pure
luck |
Bad filter caps in PS...
kip "orange" wrote in message oups.com... I've got problem with one PSU. Its occasionaly working. Sometimes when I turn the switch ON nothing happens and then when I turn it OFF, for a sec it starts and (normally) shutsdown immediately. what could be the problem? It is very old Amiga 2000 switching PSU, similar to PC (+12V, +5V..etc). please help |
Check your heat sink & the heat tranfer cream, it could due to poor
heat tranfer to the heat sink, i have this problum also. |
Startup resistors gone high in value?
"kip" wrote: Bad filter caps in PS... kip "orange" wrote in message roups.com... I've got problem with one PSU. Its occasionaly working. Sometimes when I turn the switch ON nothing happens and then when I turn it OFF, for a sec it starts and (normally) shutsdown immediately. what could be the problem? It is very old Amiga 2000 switching PSU, similar to PC (+12V, +5V..etc). please help |
orange wrote:
it behaves the same, load or no load, sometimes it works but its pure luck It`s probably going to be a failing electrolytic in the mains side of the chopper circuit - I dont have a diagram but I`d expect it to be in the region of between 1 and 10 uf. Be aware that there are dangerous voltages around there, maybe even when it`s unplugged. Ron -- Lune Valley Audio Public address system Hire, Sales, Repairs www.lunevalleyaudio.com |
I have uploaded hires (1Mb each) photos he
http://orange.users.sbb.co.yu/Amiga/psu/P7180008.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180009.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180010.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180011.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180012.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180013.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180015.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180016.JPG could you tell me which one capacitor is most likely to be the cause? |
Pull then all and change them if you dont have an ESR Meter.
kip "orange" wrote in message ups.com... I have uploaded hires (1Mb each) photos he http://orange.users.sbb.co.yu/Amiga/psu/P7180008.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180009.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180010.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180011.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180012.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180013.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180015.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180016.JPG could you tell me which one capacitor is most likely to be the cause? |
To start with blow out the **** from the PS..
kip "orange" wrote in message ups.com... I have uploaded hires (1Mb each) photos he http://orange.users.sbb.co.yu/Amiga/psu/P7180008.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180009.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180010.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180011.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180012.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180013.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180015.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180016.JPG could you tell me which one capacitor is most likely to be the cause? |
orange wrote:
I have uploaded hires (1Mb each) photos he http://orange.users.sbb.co.yu/Amiga/psu/P7180008.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180009.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180010.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180011.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180012.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180013.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180015.JPG http://orange.users.sbb.co.yu/Amiga/psu/P7180016.JPG could you tell me which one capacitor is most likely to be the cause? It would be my guess that it`s one of the little orangey ones with the black stripe under the silver heatsink, The type visible in pic 0011, right on the edge of the board. Also look for one similar near the chopper transistor - That`ll be the one on the black heatsink I reckon. You`d really need to check all the electrolytics with an esr meter to be sure. First off I'd get all that crap out of there if I were you, and remember that there might be a charge stored in those 200 volt smoothers. Ron -- Lune Valley Audio Public address system Hire, Sales, Repairs www.lunevalleyaudio.com |
On 18 Jul 2005 01:23:43 -0700, "orange" wrote:
I've got problem with one PSU. Its occasionaly working. Sometimes when I turn the switch ON nothing happens and then when I turn it OFF, for a sec it starts and (normally) shutsdown immediately. what could be the problem? It is very old Amiga 2000 switching PSU, similar to PC (+12V, +5V..etc). please help Serious question: Have you tried replacing the switch? |
ok thanks all, I was going to clean it thoroughly but since
electrolytics can leak I thought experienced users might see signs of leakage if not cleaned, I was also hoping it might be the switch, but after checking with ohmmeter it works ok. err, what exactly is esr meter? My voltmeter can check capacitance (but I need to desloder them and put in special place for checking probably because of cable capacitance, right?) and it can see if capacitors are shorted. I can check resistance between various points, if that could be of any help for solving the problem? |
Why don't you just replace the filter caps and end your misery.
kip "orange" wrote in message oups.com... ok thanks all, I was going to clean it thoroughly but since electrolytics can leak I thought experienced users might see signs of leakage if not cleaned, I was also hoping it might be the switch, but after checking with ohmmeter it works ok. err, what exactly is esr meter? My voltmeter can check capacitance (but I need to desloder them and put in special place for checking probably because of cable capacitance, right?) and it can see if capacitors are shorted. I can check resistance between various points, if that could be of any help for solving the problem? |
OK, kip, but which ones ARE filter caps? Please have a look at photos
and tell me.. |
Ok, I'll start replacing them all. But before I try finding them, could
you tell me what does '4700/16 V1' on capacitor mean? what is the capacity and voltage ? ( http://orange.users.sbb.co.yu/Amiga/psu/P7190003_up.jpg ) |
Thats a 4700/16 Volts
kip "orange" wrote in message oups.com... Ok, I'll start replacing them all. But before I try finding them, could you tell me what does '4700/16 V1' on capacitor mean? what is the capacity and voltage ? ( http://orange.users.sbb.co.yu/Amiga/psu/P7190003_up.jpg ) |
and 4700 is 4700 microfarads?
|
yep
"orange" wrote in message oups.com... and 4700 is 4700 microfarads? |
"orange" wrote in message oups.com... ok thanks all, I was going to clean it thoroughly but since electrolytics can leak I thought experienced users might see signs of leakage if not cleaned, I was also hoping it might be the switch, but after checking with ohmmeter it works ok. They can leak, but usually they fail without any visible signs. That wave of caps made with bad electrolyte did tend to bulge and leak though. |
unfortunately, somethings terribly wrong :(((((
I have replaced all caps except the two BIG ones (680uF, 200V) and one small 1,5uf 50V; couldn't find replacement for them (actually I got 1uf-could it replace 1,5uf?) I also connected a car light as load for 12V, but 5V was with no load. The power supply (again) sometimes works, BUT instead of 12V I get 7V while car light is connected. when its disconected, voltage goes up to 10V it seems that there is no solution but to modify new atx psu :( |
"orange" wrote in message oups.com... unfortunately, somethings terribly wrong :((((( I have replaced all caps except the two BIG ones (680uF, 200V) and one small 1,5uf 50V; couldn't find replacement for them (actually I got 1uf-could it replace 1,5uf?) I also connected a car light as load for 12V, but 5V was with no load. The power supply (again) sometimes works, BUT instead of 12V I get 7V while car light is connected. when its disconected, voltage goes up to 10V That's normal, with no load on the 5v the 12v won't regulate. |
you were right, when I put load on 5v it works :)
still sometimes it won't start, I'll try to find replacement for those 2 big ones 680uF 200V, hope it will solve it |
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