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sententia replied to Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

in Troubleshooting TVs and Video Sources

06-03-2021, 03:54 AM
Re: Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

I was trying to desolder IC901 that was corroded and i may have shorted it due to overheating (probably).... It just wouldn't come off...

Either way the was a bit of smoke upon power on and got some nice fireworks after a min

I will need to take care of that before any further testing...

Thank you for the help!

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sententia replied to Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

in Troubleshooting TVs and Video Sources

06-02-2021, 08:10 AM
Re: Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

That resistor R634 was blown when the mosfet shorted...

It was replaced and is still good...

No output on the 24V either (it only connects to the inverter)

I do get 3.3 from 3.3VSB ...

:EDIT: Ok PSON needs to be pulled to Ground for the supply to switch on (the relay), but still no output except the 3.3VSB

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sententia replied to Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

in Troubleshooting TVs and Video Sources

06-02-2021, 07:15 AM
Re: Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

PSON does seem to turn on the power supply (relay does not click)...

There is no voltage on the 12v pins.

on the other terminal there is also an ON/OFF pin if that has something to do...

Thanks for the input!...

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Last edited by sententia; 06-02-2021, 07:28 AM.
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sententia replied to Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

in Troubleshooting TVs and Video Sources

06-02-2021, 06:18 AM
Re: Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

Anyone any input?

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sententia started a topic Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

in Troubleshooting TVs and Video Sources

05-31-2021, 01:17 PM
Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

Hello everyone!

I am trying to repair this power supply and i seem to be kind of stuck...

Mosfet Q603 was shorted, which also took out R634 ....

The small main cap C910 (33uf) had leaked and was off...

I have replaced both mosfets, the capacitor and the resistor and now have standby power but as soon as the relay clicks to switch on the TV i get 6 blink error led.... according to service manual its the 5V 12V supply error....

I cannot find any other damaged parts, does anyone have any suggestions or can point to a direction...

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sententia replied to HITACHI HVAC FS series RAS-10FS2 Power supply - identify diodes

in Troubleshooting Power Supplies and Power Supply Design

01-31-2019, 05:17 AM
Re: HITACHI HVAC FS series RAS-10FS2 Power supply - identify diodes

Thank you for your input!
Yep i just managed to see another digit using a microscope. So zener is "7 A3" which is 6.6V - 6.9V low leakage low, zener impedance.
The only datasheet i can find is from Edcon components.

I thought the diode was just general purpose, because it is used all over the board, and i was going to use a 1N4007! I will go with the UF4007....

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sententia started a topic HITACHI HVAC FS series RAS-10FS2 Power supply - identify diodes

in Troubleshooting Power Supplies and Power Supply Design

01-30-2019, 12:39 PM
HITACHI HVAC FS series RAS-10FS2 Power supply - identify diodes

Hello everyone!

I am trying to repair a power supply from the outdoor unit of an ac and i cannot identify a couple of diodes.

The one is the zener diode ZD17 which connects to the base of the transistor and another couple of diodes.

The other is a diode with blue dot that it is used all over the board.

The transistor is a 2sc3507.

Also the only think i can make on the zener diode is a very faint "A3" if that helps.

Thank you!...

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sententia replied to MasterVolt IVO 12/25-3 Marine charger - replaced power fet but now pulsating

in Troubleshooting Power Supplies and Power Supply Design

04-02-2018, 03:57 PM
Re: MasterVolt IVO 12/25-3 Marine charger - replaced power fet but now pulsating

I have removed the transformer to try to understand the windings and how the mosfets connect. The pins marked 1-2 are the Aux winding. Primary is pins 3-4 but on pin 4 there are 3x wires connected where the 3rd one goes to pin 5 of the transformer. That pin and winding is used to drive the 2nd mosfet.
Now on pins 6-7 there is a separate winding which seems to connect straight to the secondary's ground and circuits (i have striped a pad there but easy fix...)

It is not a standard...

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Last edited by sententia; 04-02-2018, 04:10 PM.
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sententia replied to MasterVolt IVO 12/25-3 Marine charger - replaced power fet but now pulsating

in Troubleshooting Power Supplies and Power Supply Design

04-01-2018, 04:12 AM
Re: MasterVolt IVO 12/25-3 Marine charger - replaced power fet but now pulsating

Hello!

I got this charger out of the pile,and removed the heatsink to get another look...

The situation is that the UC3845 gets in undervoltage lockout and it gets 8.0V on VCC so it won't start. I checked with an oscilloscope and it does output a pulse every couple of seconds but does not start.
If i supply VCC the chip outputs a signal and operates (without the mains connected).

Budm mentioned to check the application diagram......

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sententia replied to Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

08-07-2016, 12:04 PM
Re: Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

I have tested the charger with 3x 20w lamps for 10 hours. Now i have it running on batteries for 2 days and no problems...

I come to conclusion that it was a bad soldering problem....

It is also possible that i stressed the vertical board while repairing and flipping over the pcb. I also did the coil and transformer soldering again using lots of flux and new solder.....

Thank you capleaker for input, guidance and help! I really appreciate it!

P.S....

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sententia replied to Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

08-03-2016, 01:55 AM
Re: Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

I have put everything back together, i had to replace 4 electrolytics that i destroyed while removing them and 1 ceramic 102k 1kv which i replaced with a blue one 102 3kv (i think this one is 20% tolerance compared to 10% of the original ceramic). I redid some soldering connections on board and put it on test with the dummy load at 0.8A.

It has been operating for 10 hours without any problem and steady output.

I used my hot air station at 200c on the bottom side...

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sententia replied to How to test mosfets in parallel circuitry

in Troubleshooting Power Supplies and Power Supply Design

08-02-2016, 12:09 PM
Re: How to test mosfets in parallel circuitry

You can also use the millivolt range of you DMM (or diode testing), most of DMMs have, and measure the smallest voltage drop to ground while supplying a safe voltage (for that rail) from a current limited supply, 0.25A should be ok.

However this is to find the shorted one and not to check if a fet is good....

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Last edited by sententia; 08-02-2016, 12:11 PM.
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sententia replied to Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

07-31-2016, 12:23 PM
Re: Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

I read your thread, and just got what you are saying about heating up the board. No i haven't tried that yet, but i will as soon as i put some parts back after some more troubleshooting and shopping for a couple of ceramic caps.

All 3 channels act exactly with voltage output. Anyway in forced float mode they should all give 13.25V but it happens in all modes....

Now what i didn't know is that the mosfet i replaced is driven by a 2PCS01 PFC controller circuit through those...

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sententia replied to Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

07-31-2016, 05:39 AM
Re: Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

So far i replaced all TL431, replaced some caps just in case and tested many many resistors. The only thing that is a bit off is a ceramic 471K 1KV cap (marked in circle in photo) that measures 440pf. I don't know if that can cause the problem.

Also i remembered that the charger operates with just the batteries connected so i started to probe the optos and some other staff on board with safe voltage.
Almost everything i probe give a 50hz signal.

Moreover the charger...

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sententia replied to Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

07-27-2016, 03:15 AM
Re: Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

The fan does not run at all times. It kicks in when i increase the load to 1A or 1.5A and as soon as i decrease the load it switches off. The charger does have a sensor on the main transformer and on the secondary heatsink.

I have removed all 3 TL431 and did a simple test to check if they produce 2.5V, so they all look OK. However on board one of them gave only 1.9V reference but this could be, i think, because of resistor network or the fact that i used 5V supply to test it...

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sententia replied to Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

07-26-2016, 12:07 PM
Re: Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

Ok it went to 21V....

The transformer is quite hot at 58c, the fet next to it is at 50c, 1 out of 2 TL431 is significantly hotter than the other. I marked the in photo.... if that helps at all!...

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sententia replied to Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

07-26-2016, 11:23 AM
Re: Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

ooops i didn't post my previous message ......

I do use my variable current dummy load to test the charger, however only on 1 out of 3 channels. The charger can be used as a power supply on "FLOAT" mode where output voltage is 13.25V.

In front of the vertical board i have tested the two caps and both optos. All tested good.

Now about the resistors i measured. Some have normal code "51R0" etc and some have coding of "01B". I did check...

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Last edited by sententia; 07-26-2016, 11:26 AM.
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sententia replied to Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

07-25-2016, 08:17 AM
Re: Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

After removing some parts for testing, including those caps, and putting them back in the charger goes straight away to 20V.

So far i have tested the parts marked in the photo and quite a few resistors at the bottom of the pcb. Only the Y capacitor seems a bit off only by my "transistor tester" if i measure it with the DMM capacitance it measures ok, but i doubt that it is causing the problem. The are another 2x TL431 marked in the photo. I still haven't distinguished which parts...

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sententia replied to Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

07-24-2016, 11:44 AM
Re: Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

I have a difficulty identifying the feedback circuit.

On the first picture i have marked the track of PIN 2 which is the feeback of the 2845B ic on the botton side. It does not connect to the opto mentioned i think. The vertical board now has a TL494 and there is a TL431C as well there. I cannot understand which is for standby circuit and for main charger.

This power supply has a standby circuit which operates until power button is pressed and the relay closes.
...

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sententia started a topic Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

in Troubleshooting Power Supplies and Power Supply Design

07-24-2016, 09:56 AM
Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output

Hello everyone,

This charger had the bridge rectifier and mosfet (in red rectangle) shorted, so i replaced those and the main input filter caps as they were about 20% down of their capacitance.

I thought the charger was working good but after some time of being switched on the charger output high voltages around 20V and gets unstable. It detects the high voltage output and restarts. The heatsink that has the bridge rectifier and mosfet gets hot without any load. Although i haven't managed to find which of the parts on the heatsink is produced the high temp. Also the...

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Last edited by sententia; 07-24-2016, 09:59 AM.

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Philips 32PFL7403D/12 - Shorted mosfet -Delta DPS-182C Ppower supply

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HITACHI HVAC FS series RAS-10FS2 Power supply - identify diodes

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Mastervolt Chargemaster 12/35-3 Charger - Failed repair - erratic output