Author Topic: NEVA 5225 Power Supply  (Read 438 times)

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Offline 09d08

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NEVA 5225 Power Supply
« on: November 24, 2018, 10:52:35 am »
Hi,

I'm trying to fix a rather old power supply. I saw two burned components on one of the two boards, one of them is definitely a resistor but I have no idea about the other axial metal one. The burned axial part is connected to the base and the collector of a BC547. I have just started to draw a schematic of the board so I'll attach the partial schematic and the pictures of the burned components. I hope someone has an idea what that axial one next to the resistor might be.

Thanks in advance
 

Online coromonadalix

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Re: NEVA 5225 Power Supply
« Reply #1 on: November 24, 2018, 02:18:24 pm »
maybe a zenner diode with the orange gold color on the photo ???  would fit the size of the part ?
 

Offline 09d08

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Re: NEVA 5225 Power Supply
« Reply #2 on: November 24, 2018, 05:51:30 pm »
It's larger than a regular zener diode and every diode on the board. I believe it's a metal axial capacitor but I'm not very sure.
 

Offline madires

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Re: NEVA 5225 Power Supply
« Reply #3 on: November 24, 2018, 06:13:30 pm »
Yep, a capacitor might be possible. BTW, I'd also check the Philips electrolytic caps since they are known to go bad.
 

Online coromonadalix

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Re: NEVA 5225 Power Supply
« Reply #4 on: November 24, 2018, 06:20:39 pm »
search for the : GPD3303SM  service manual  there is a similar circuit,  mosfet driven serial power supply, or any similar design

this one seems similar in some ways : http://powersupply33.com/transformerless-power-supply-fet.html

I would say  complete your schematic ... it would help to understand the circuit more ?
« Last Edit: November 24, 2018, 06:23:21 pm by coromonadalix »
 
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Offline 09d08

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Re: NEVA 5225 Power Supply
« Reply #5 on: November 24, 2018, 06:55:47 pm »
Yep, a capacitor might be possible. BTW, I'd also check the Philips electrolytic caps since they are known to go bad.

Their values seemed normal but I'll also check their ESR.

search for the : GPD3303SM  service manual  there is a similar circuit,  mosfet driven serial power supply, or any similar design

this one seems similar in some ways : http://powersupply33.com/transformerless-power-supply-fet.html

I would say  complete your schematic ... it would help to understand the circuit more ?

They indeed seem similar, I'll try to map the feedback portion and other parts involving the tl074.
 


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