MP 42HC56 SINOTEC 42 lcd

[dick_barton]

Re: MP 42HC56 SINOTEC 42 lcd

That diode provides the dc to give the V_15 (assume 15V) needed for a lot of the other IC's.
That seems awful low considering N501 requires VCC =12V min but has at least has 10V and if N502 has a 15V output then you would be expecting around 17.5V at it's input. Maybe worth checking C521.

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

That diode provides the dc to give the V_15 (assume 15V) needed for a lot of the other IC's.
That seems awful low considering N501 requires VCC =12V min but has at least has 10V and if N502 has a 15V output then you would be expecting around 17.5V at it's input. Maybe worth checking C521.

i replaced the Cap replaced no change in voltage

[dick_barton]

Re: MP 42HC56 SINOTEC 42 lcd

What voltage do you have on pin 3 (Vfb) of N501

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

What voltage do you have on pin 3 (Vfb) of N501

it goes from 0v to 9v then back to 0V and repeat

[dick_barton]

Re: MP 42HC56 SINOTEC 42 lcd

Reading the data sheet

A feedback voltage of 6V triggers overload protection (OLP).

This would indicate to me that there is a fault elsewhere which is switching off N501.

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

Reading the data sheet


This would indicate to me that there is a fault elsewhere which is switching off N501.

perhaps something else is in short i will have another look thanks

[dick_barton]

Re: MP 42HC56 SINOTEC 42 lcd

Data sheet attached.


Edit
Do you have 5V at C539

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

Data sheet attached.


Edit
Do you have 5V at C539

i see there is no resistor on R502 but doesnt look like there ever was on according to the circuit diagram there should be a 10k according to your data sheet that pin controls peak current limit should i put a 10k in and see if it works?

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

that been said i see n503 is also missing but the diagram recons it must be there

[dick_barton]

Re: MP 42HC56 SINOTEC 42 lcd

The data sheet does say it can be left open so I don't know.

This pin adjusts the peak current limit of the Sense FET. The feedback
0.9mA current source is diverted to the parallel combination of an internal
2.8kΩ resistor and any external resistor to GND on this pin to determine the
peak current limit. If this pin is tied to Vcc or left floating, the typical peak current limit will be 0.7A.

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

Data sheet attached.


Edit
Do you have 5V at C539

No there is only 1v there

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

Data sheet attached.


Edit
Do you have 5V at C539

not sure where that 5v comes from

[dick_barton]

Re: MP 42HC56 SINOTEC 42 lcd

I must admit I have absolutely no idea what is wrong and even I am going around in circles on this one.

N501 require 12V min to operate. It initially has capacitor C513 charging via R597 & R598 through an internal circuit. These resistors are connected to V_PFC.

The V_PFC voltage is generated by N507 but it needs V_15v to supply the IC's working voltage to generate the boosted V_PFC

V_15V is generated via T501 which is driven by N501.

If you lift one end of D504 will N501 charge C513 to 12V?

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

I must admit I have absolutely no idea what is wrong and even I am going around in circles on this one.

N501 require 12V min to operate. It initially has capacitor C513 charging via R597 & R598 through an internal circuit. These resistors are connected to V_PFC.

The V_PFC voltage is generated by N507 but it needs V_15v to supply the IC's working voltage to generate the boosted V_PFC

V_15V is generated via T501 which is driven by N501.

If you lift one end of D504 will N501 charge C513 to 12V?

No still 10v

[dick_barton]

Re: MP 42HC56 SINOTEC 42 lcd

Have you lifted R597 and R598 and checked they read what they are marked. You said you have already replaced C513, yes?

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

Have you lifted R597 and R598 and checked they read what they are marked. You said you have already replaced C513, yes?

Yes on both counts

[dick_barton]

Re: MP 42HC56 SINOTEC 42 lcd

You have 180V at the Vstr end of the two resistors, what do you have at the other end?

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

you have 180v at the vstr end of the two resistors, what do you have at the other end?

300vdc

[dick_barton]

Re: MP 42HC56 SINOTEC 42 lcd

It looks like your mains incoming voltage is low. Post #2 also from South Africa indicates 320V dc across C533 which would indicate an ac input voltage of 226V.

Can you check your mains input ac voltage. Is seems low maybe around 212V ac

[SonOfAnarchy ZA]

Re: MP 42HC56 SINOTEC 42 lcd

It looks like your mains incoming voltage is low. Post #2 also from South Africa indicates 320V dc across C533 which would indicate an ac input voltage of 226V.

Can you check your mains input ac voltage. Is seems low maybe around 212V ac

222VAC according to my multimeter