60pb660v flogging a dead tv-shop visit req

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

I hope that you are measuring for shorts using the resistance mode on your meter and NOT the voltage range.

Yes definitely in ohms beep mode (600 ohm range) all the voltages are there apart from 18v my mate double treble checked he was in continuity mode.

One thing he did note was that ic200 may have blown again vcc pin6 is reading / beeping with ground pin 4

[R_J]

Re: 60pb660v flogging a dead tv-shop visit req

How can you measure 2.5v on both sides of D205? The anode is connected to the transformer so it will be a/c voltage, the cathode will be DC voltage.
Again, whats the number on IC203? It looks like it should be a 15 volt regulator and it supplies the +15v VF voltage
This ic203 also supplies the voltage for the feed back optocoupler.

Did you check R213? I can only go by the SJ picture I have and it looks like a 4.7k resistor, are you saying it is a 47k?

[R_J]

Re: 60pb660v flogging a dead tv-shop visit req

Yes definitely in ohms beep mode (600 ohm range) all the voltages are there apart from 18v my mate double treble checked he was in continuity mode.

One thing he did note was that ic200 may have blown again vcc pin6 is reading / beeping with ground pin 4

Please don't rely on that @%^# BEEP. it means nothing. most meters BEEP between 0 and 150Ω. so if pin 6 BEEPS and it's 140Ω it could be good. If it BEEPS because it is 10Ω it is bad. So Please provide the resistance reading in OHMS and not BEEP!

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

Please don't rely on that @%^# BEEP. it means nothing. most meters BEEP between 0 and 150Ω. so if pin 6 BEEPS and it's 140Ω it could be good. If it BEEPS because it is 10Ω it is bad. So Please provide the resistance reading in OHMS and not BEEP!

He checked ysus pins to chassis again his meter is reading OL (600 ohm range) on every pin apart from ground (0.4)

[R_J]

Re: 60pb660v flogging a dead tv-shop visit req

Has anyone checked or replaced the optocoupler? If the feedback voltage is less than 1.4v the ic will be oerating in Skip Cycle Mode. What is the voltage on pin2?
Earlier I asked about the trace that runs under R209, one end connects to R212, does the other end connect to the ic200 ? and if it does which pin?

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

Has anyone checked or replaced the optocoupler? If the feedback voltage is less than 1.4v the ic will be oerating in Skip Cycle Mode. What is the voltage on pin2?
Earlier I asked about the trace that runs under R209, one end connects to R212, does the other end connect to the ic200 ? and if it does which pin?

R212 looks like it should be connected to pin 6 but the track is damaged- I will get him to solder a wire from pin6 to the resistor, will look at octocouplers again.

Pin2 has 0 voltage ( ic200)

[R_J]

Re: 60pb660v flogging a dead tv-shop visit req

I would make sure that is where the trace goes before soldering a wire.
Pin 2 should have about 4 volts which is supplied by and internal 8k pullup resistor, I dont know why it would be 0 volts, you checked the pins and there was no short so it should have voltage on it.

At one point you found that R213 was open and you had 10 v on pin3 (r209), was the ic changed after r213 was replaced?

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

I would make sure that is where the trace goes before soldering a wire.
Pin 2 should have about 4 volts which is supplied by and internal 8k pullup resistor, I dont know why it would be 0 volts, you checked the pins and there was no short so it should have voltage on it.

At one point you found that R213 was open and you had 10 v on pin3 (r209), was the ic changed after r213 was replaced?

Yes the ic has been changed 3 times most recent after the smd resistors where blown- r213 was still reading ohms a bit charred so it was replaced.
Q202 the 5n60 has been replaced several times. But Im only getting 205v on the centre pin nothing on the Rhs pin whereas I was getting 2 volts previously. The octocouplers were removed from the board and tested by my mate he said they read fine.

I will wait to see if leg 6 is indeed connected to r212. Thanks again for your help. Yes there are no shorts on the pins of ic200

[R_J]

Re: 60pb660v flogging a dead tv-shop visit req

Whats the Rhs pin? do you mean the GATE pin? If you had 2 volts on the gate, the fet would be turned ON, taking 205v to ground via the R213 (POOF). There should be drive pulses coming from pin 5 of ic200 that drive the gate of Q202
What value did you use for R214?

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

Whats the Rhs pin? do you mean the GATE pin? If you had 2 volts on the gate, the fet would be turned ON, taking 205v to ground via the R213 (POOF). There should be drive pulses coming from pin 5 of ic200 that drive the gate of Q202
What value did you use for R214?

Sorry I meant the Rhs source pin. The smd resistors were replaced by smd resistors with the same value r214 was replaced by a 100 code which is a 10 ohm and r209 was replaced with a 102 - 1000 ohm both are fine . On r213 I was getting 205v on one side and 137v on the other side of the resistor..but I can't get it checked until i get the tracing confirmed between r212 and pin 6.

R206 was open and replaced r217 was charred but still reading 2 ohms but still replaced.

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

How can you measure 2.5v on both sides of D205? The anode is connected to the transformer so it will be a/c voltage, the cathode will be DC voltage.
Again, whats the number on IC203? It looks like it should be a 15 volt regulator and it supplies the +15v VF voltage
This ic203 also supplies the voltage for the feed back optocoupler.

Did you check R213? I can only go by the SJ picture I have and it looks like a 4.7k resistor, are you saying it is a 47k?

Yes i am certain it's a 47k resistor, measures 47k and one of the bands looks like a purple / blue to me. Sorry ic203 part number is 8g416ne3 or it could be e78g416ne3 - I can't find this ic on the net.

[R_J]

Re: 60pb660v flogging a dead tv-shop visit req

R213 will have 205 volts (Vs) on one side, the other side connects directly to IC200 pin6via J71. The ic200 internaly takes that (137v )voltage and uses it to supply the VCC. That seems to be ok, the ic is drawing about 2ma

That ic203 number does'nt seem to make sense, It should be a sot-89 package and likely is a 78L15 maybe. I trace its output to P151 pin7 which is 15VF

[Agent24]

Re: 60pb660v flogging a dead tv-shop visit req

The first thing I did was check for shorts i.e with the board in place place probe on chassis and one probe on each pin - nothing. I also ran it probe against mosfet etc still nothing. D556 read 203v and 137 v the other.

Not all nodes in a circuit, and hence pins on a component, are referenced to ground. You will not find all shorts by checking between pins and ground.

To test an individual diode for being shorted, it's better to check across the diode itself, not from each pin to ground.

[Agent24]

Re: 60pb660v flogging a dead tv-shop visit req

Can we get some photos of the board in its current state at all? I wonder if there's something being overlooked.

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

Not all nodes in a circuit, and hence pins on a component, are referenced to ground. You will not find all shorts by checking between pins and ground.

To test an individual diode for being shorted, it's better to check across the diode itself, not from each pin to ground.

Yes I've seen that for example the diodes individually tested but in regards to the board in question we are trying to confirm the trace from r212 to pin 6 so stuck at the moment.

To be on the safe side ic200 is going to be replaced again- the only short there is is between pin 4 and pin 6 but I think this is how it's designed to function(?)

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

Can we get some photos of the board in its current state at all? I wonder if there's something being overlooked.

Will get some uploaded but it's a mess

[R_J]

Re: 60pb660v flogging a dead tv-shop visit req

To be on the safe side ic200 is going to be replaced again- the only short there is is between pin 4 and pin 6 but I think this is how it's designed to function(?)

The answer is NO. The ic can not function without the vcc pin at 10 volts. There can not be a short on pin6. There is one electrolytic on that pin, make sure it's not shorted. The pdf explains how the ic operates.

This circuit is really quite simple. It is not unlike any other smps, instead of a power cord, ac bridge main cap etc. it runs from the power supplies Vs voltage so the primary and secondary use a common ground (no hot side)

I am not sure about q200 & q201, they may be used to control ic200 but I don't know where they connect to the ic.
J96 supplies +5 volts, it connects to r201/202 then to r203 and the base of q200. I suspect q200/201 might be there to turn off ic200 if the +5 volts was missing as a protection.

In this case a picture is not worth a 1000 words, a schematic would be nice but I doubt you will find one.

Don't be too concerend about the 18 volts from D203, You need to have the (around 20v) from D205. that is what supplies the regulation and feedback circuit (ic203,ic204,opto) Once you have this voltage the 18 will also be there.

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

The answer is NO. The ic can not function without the vcc pin at 10 volts. There can not be a short on pin6. There is one electrolytic on that pin, make sure it's not shorted. The pdf explains how the ic operates.

This circuit is really quite simple. It is not unlike any other smps, instead of a power cord, ac bridge main cap etc. it runs from the power supplies Vs voltage so the primary and secondary use a common ground (no hot side)

I am not sure about q200 & q201, they may be used to control ic200 but I don't know where they connect to the ic.
J96 supplies +5 volts, it connects to r201/202 then to r203 and the base of q200. I suspect q200/201 might be there to turn off ic200 if the +5 volts was missing as a protection.

In this case a picture is not worth a 1000 words, a schematic would be nice but I doubt you will find one.

Don't be too concerend about the 18 volts from D203, You need to have the (around 20v) from D205. that is what supplies the regulation and feedback circuit (ic203,ic204,opto) Once you have this voltage the 18 will also be there.

Thank you will keep you update once ic200 is removed should be able to see where the track goes - to pin6 etc thanks again

[thuss]

Re: 60pb660v flogging a dead tv-shop visit req

My mate cant tell if R212 goes to pin 6 for definite (100%) - its all burnt underneath the chip (Ic200) - If anybodys got a board laying about confirmation of pin6/pin5 to R212 would be really appreciated.

Pin 2 goes to the octocoupler but the track looks broken- if someone can confirm if pin 2 connects to the octocoupler would also be appreciated

[Agent24]

Re: 60pb660v flogging a dead tv-shop visit req

If the board is burnt under the IC you may be having problems with carbon causing leakage and messing with the circuit.

You need to clean up the board well and scrape away any burnt sections, run wires to replace traces as necessary.