Philips 40PFL3505D/F7 Blows fuse when plugged in

[selldoor]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

Yes you MUST use the lamp to try and safeguard the new parts in the event that there is another shorted part that blew them in the first place.

No difference what so ever to the result - If you are repairing/testing many items then its worth building a budm connector as its much safer to use.

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

I have found two MOSFETs that I think will work. I am unsure which specs can be higher or lower and still be acceptable for this application so I tried to best match most of the specs.

I also did not know if ones with metal backs that are tied to one of the pins is ok as the board layout shows the heatsink tied to other things so I am going with a fully insulate one.

Here is the original part datasheet:




And the two potentials. Do either of these meet the originals specs in the important aspects to make them acceptable? Thanks

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

thanks selldoor

I had built the tester when you mentioned earlier in the thread, but then switched when I read another post just using the bulb clipped in as the fuse. Since it is the same I will use the new tester for this and future projects and quit blowing things needlessly.

[Agent24]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

Unless you know for sure you have replaced all shorted components etc, I would advise you use the light-bulb test at first.

There is no difference. Using a lightbulb wired to a socket is easier because you don't have to bugger about trying to connect a lightbulb to the fuse holder.

Make sure if you make a tester like Budm's that the switch and lightbulb are wired in the active line.

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

I again have some time to pursue this so I finally replaced the MOSFET Q601 and the zener diode D1208.

I plugged all other boards into the power supply and used the lightbulb tool and the 60W light bulb stays on at about a medium intensity. I have also had sometimes that it stays on bright for a few seconds, I can hear something what I would call faintly pulsing and then the light goes to the medium intensity.

I went ahead and started to check voltages for the output cables and other marked voltages on the board. All outputs that have specific voltage marked, except those on the cable to the inverter, 24V, are correct as are those marked on the board except the 345V. Those on the cables that are labeled with abbreviations I am unsure what they should be so I do not know if they are correct given its current state.

Due to what turned out to be my improper understanding of the accuracy of the MOSFET test I did I know believe the original MOSFET for Q601 is good. It appears that it does not turn on at the 3V my meter outputs. I made the attached circuit to test it and the replacements I purchased, which also failed using my orignal methodology, and they light up the LED so I assume that means they are good. All the other MOSFETS were able to be tested as I detailed before using my meter.

Therefore, I then took out Q601 to see if that would change anything, as I was instructed earlier in the thread, and the lightbulb does not light at all and the 345V that is marked on the board comes back.

I tried to take more parts off that I can test with meter or in a test circuit. And everything I test is good as far as I can tell. I can go into detail if it would help.

I am pretty much out of ideas as I really can't seem to understand the workings of this SMPS. My idea now, probably incorrect, is the problem lies in the feedback circuit or in one of the following, all of which I am uncertain how to diagnose/test:

IC1401 DUAL-PHASE PFC CONTROLLER HPA00651DR
IC1201 SWITCHING POWER SUPPLY MIP2F30MSSCF
IC1702 Zero voltage switching resonant converter controller TEA1611T

I hope it is something simpler, but I do not know where to go from here.


If you have any ideas as to what to test or look for next it is greatly appreciated.

Thank You

[ben7]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

The driver circuit (commonly the PWM control chip) for the MOSFET might be turning it on constantly, causing the fuse to blow. Check to see if there is any oscillating signal going to the FET. (If you use an oscilloscope, beware that you need an isolation transformer or else you will short out the mains supply (120VAC) and possibly damage your scope!)

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

ben7, thanks

As much as I would like I do not have an oscilloscope nor an isolation transformer.

The driver circuit (commonly the PWM control chip) for the MOSFET might be turning it on constantly, causing the fuse to blow. Check to see if there is any oscillating signal going to the FET.

I don't know how I would check with only a meter. Is there a way to test this without an oscilloscope?

I am not sure which IC would be the one you are referring to. I am going to assume it is the HPA00651DR. It has a pin labeled PWMCNTL in its datasheet. On the schematic it goes to the TEA1611T pin labeled SD, shut down and as per the datasheet if over 2.33V it tells itself to shut down. I measure 3.78V on pin 19 of TEA1611T. I assume that would mean that anything relying on it will also not work.


I believe these are the datasheets for those two ICs.

https://cdn.badcaps-static.com/pdfs/...c0300e3fe8.pdf


If it helps I am getting 16.59V to pin 12 VCC of the HPA00651DR. And as I mentioned I get the marked HOT 17V on the board which feeds this pin.

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

I took some more measurements on IC 1401. These are with Q601 in
In parenthesis are the voltages shown in the schematic followed by what I measured and its pin designation in the datasheet

1 (1.0) 0.42 ZCDB
2 (6.1) 1.2 only when meter on as per below VSENSE
3 (5.8) 1.5 TSET
4 (6.1) 2.8 PHB
5 (0.6) 1.4 COMP
6 (0) GND AGND
7 (1.6) 0.6 VINAC
8 (4.3) 0.72 HVSEN
9 (0.2) 3.78 PWMCNTL This connects to pin 19 of IC1702 and as mentioned in the last post tells it to shut down.
10 (0) 0 CS
11 (8.8) 3.8 GDB
12 (17.2) 16.59 VCC
13 (0) GND PGND
14 (8.8) 3.8 GDA
15 (6.1) 2.8 VREF
16 (1.0) 0.42 ZCDA


The moment I clip my red meter probe to pin 2 it shows 1.2V and the MOSFETS, Q1601, Q1602, either or both, it is difficult to distinguish where the sound eminates as they are close together, changes and the pulsing of the light bulb increases seemingly in time with the sound frequency.

I am unclear how removing Q601 brings back the 345V. I seems like a red herring and the problem lies elsewhere? I can't seem to come to terms with the relationship between its position in the schematic and block diagrams and how it causes the 345V to be 70V when in, but if it is out to becomes 345V again.

[Agent24]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

I think, if the switching transistors are shorted or being turned on hard\incorrectly by the IC, it will load the main filter capacitor too much and drop the voltage, and the series lightbulb will prevent the filter capacitor from maintaining 345v due to its current limiting effect.

[budm]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

It looks like the Gate drive A and B (GDA, GDB) are stuck high, it should be high frequency pulses (KHz range) which your meter is not likely to show correctly.

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

Agent24

By switching transistors do you mean the MOSFETs that are connected to IC 1401, i.e. Q1601, Q1602, as pretty much all of the transistors proper and MOSFETS are lablebed as switching on the schematic? Or the MOSFET Q601, as I replaced this with a new one and that problem persists.

I can follow what you are saying but why does removing Q601 change this. I can't understand why its presence or not changes those things as it is seems to me to be in another unrelated part of the circuit. Am I missing the point by trying to figure what role if any it plays in the problem.?

budm,

If the GDA and GDB being stuck at a high frequency is that a fault of IC1401 or would it be being caused by something else?






I took out an tested, just to be certain, Q1601 and Q1602 according to the following site and the test circuit schematic I attached in post #25. http://www.sentex.ca/~mec1995/gadgets/mostest.htm

The both check good according to that site and light up the LED.

I took Q601 out again and either I did not remember correctly or was correct in my previous statement about the 345V and things changed again. Either way instead of 345V there is only 169V. Am I wrong in thinking that there should be some point at which 345V is created? I was assuming it would be right after rectification, e.g. on the cathodes of D1607, D1609 or on one of the pins on C1607.

I took some measurements with it out to compare things. I don't know if they are relvant with Q601 removed, but will share anyway.

On the COLD side:
I still have RL+5V and ALL+4.3V pretty much everything else is 0. The PWR RESET on CN1801 in now -2.4V.

On the HOT side:
IC1201 WITH Q601
1 2.8
2 0
3 0.7
4 6.4
5 seemed to show over 1000VDC, it would flash something then go away
7 0
8 0


IC1201 WITHOUT Q601
1 1.8
2 0.3
3 0.7
4 4.4
5 randomly jumps between 2 and 26 or so
7 0.1
8 0.1

Drain of all MOSFETs Q1601, Q1602, Q601, Q1701 163V
Drain of Q1702 0V

Cathode of D1201, D1203 58V
Cathode of D1201, D1204 107V
Cathode of D1608, D1610 60V
Cathode of D1609, D1067, , 160V
Andoe and Caothode of D1604, D1606 160V

Pin 2 of L1603 L1604 169V

IC1401
1 (1.0) 0 ZCDB
2 (6.1) 0.9
3 (5.8) 0 TSET
4 (6.1) 0 PHB
5 (0.6) 0 COMP
6 (0) GND AGND
7 (1.6) 2.5 VINAC
8 (4.3) 1.9 HVSEN
9 (0.2) 0 PWMCNTL
10 (0) 0 CS
11 (8.8) 0 GDB
12 (17.2) 0 VCC
13 (0) GND PGND
14 (8.8) 0 GDA
15 (6.1) 0 VREF
16 (1.0) 0 ZCDA


I do not have and ESR meter so I cannot test properly, but I was wondering is there any chance all of this is being caused by a fault in an electrolytic capacitor?

Please let me know if there is anything I can check with my meager tools to help narrow down the issue.

Thanks again.

[Agent24]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

Agent24

By switching transistors do you mean the MOSFETs that are connected to IC 1401, i.e. Q1601, Q1602, as pretty much all of the transistors proper and MOSFETS are lablebed as switching on the schematic? Or the MOSFET Q601, as I replaced this with a new one and that problem persists.

I can follow what you are saying but why does removing Q601 change this. I can't understand why its presence or not changes those things as it is seems to me to be in another unrelated part of the circuit. Am I missing the point by trying to figure what role if any it plays in the problem.?

Sorry, I was speaking in general, rather than about any specific part in your circuit.

I did look at the schematic now, and as you can see, there is a path from the main +345V rail, through the primary winding of transformer T601, through Q601, and then to ground via the 0.75 Ohm resistor, R609.

To DC (which that 345V rail is), the resistor and transformer winding look like a short circuit. When Q601 is turned ON, the path between its Drain and Source becomes a very low resistance also, so there is basically a dead short between the +345V rail and ground.

However, if Q601 is working normally, it will be switching on and off rapidly. This creates quick pulses of current through the transformer primary, which in turn result in voltage on the secondary windings. Such fast operation does not blow any fuses etc and instead draws a constant and sensible current from the +345V rail.

BUT, if Q601 is NOT switching, and is just ON, then we have effectively shorted that +345V rail to ground, the current draw is very high, and the lightbulb's current limiting action comes into effect.


This will be the case for any switch-mode supply running from that main +345V rail.


I notice that Q601 does not appear to be switched by any IC, rather it seems (I think) to be part of an oscillator using Q602 and probably the feedback from the optocoupler, IC601. I am not sure how that circuit actually works.




From what I can see in your circuit, IC1201 is a switching IC and integrated FET which powers the standby rail (AL+4.3v)

IC1401 is the PFC controller which along with Q1601 and Q1602 generate the main +345V rail. This will be active when it receives a signal on Pin 9, otherwise the main rail will only be the rectified mains voltage which in your case is about 160 volts.

IC1702 is the switching controller for Q1702 and Q1703 which provide the backlight power supply.

And Q601 and Q602 (somehow) run the low voltage rails for the logic boards and the rest of the circuitry.

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

Thanks for the explanation

I am going to do a lot of assuming as my knowledge is limited

I think I understand, except

IC1401 is the PFC controller which along with Q1601 and Q1602 generate the main +345V rail. This will be active when it receives a signal on Pin 9, otherwise the main rail will only be the rectified mains voltage which in your case is about 160 volts.

You say when pin 9 recieves, I assume you mean interal from its own logic, as the datasheet seems to indicate it is an output.

The datasheet also says

"PWM enable logic output: This open-drain output goes low when HVSEN is within the HVSEN good region and the ZCDA and ZCDB inputs are switching correctly if operating in two-phase mode (see PHB Pin). Otherwise, PWMCNTL is high impedance."

Well the PHB pin is connected to the VREF so the seems to indicate that the IC is not being phase managed, thus only HVSEN and VSENSE is important for having pin 9 internally receiving the correct signal, correct?

However, it seems that in order to generate the 345V the PWM needs to work to tell the MOSFETS when to switch so they can generate the 345V and the VSENSE AND HVSEN rely on sensing 345V to tell the PWM to work. It seems like this is a bit if of circular logic, i.e. IC1401 is essentially relying on itself to function so that it can function. If you can clarify how I am wrong please do as I cannot see it.

As I read many of these Funai made TVs are damaged by lightning. Although I do not know what may or may not have occurred as it was a side of road special, I am wondering after reading about the VINAC and seeing how it had D1208 bad and given

That Zener D1208 is the protection if the AC line voltage goes above 140VAC ... this Zener is there to protect the standby power supply section which on 24/7 so it will see all the surge and spike on from the power line all the time.

if IC1401 was rendered defective and it is the cause of the problem?

However, if Q601 is working normally, it will be switching on and off rapidly. This creates quick pulses of current through the transformer primary, which in turn result in voltage on the secondary winding. Such fast operation does not blow any fuses etc and instead draws a constant and sensible current from the +345V rail.

The secondary output of T601 seems to lead to the outputs on CN1802, which are present and correct with Q601 in but not without. The leads me to think that Q602, along with a basic transistor meter check of it, is also good.

Thus, I do not see how the following is the case.

BUT, if Q601 is NOT switching, and is just ON, then we have effectively shorted that +345V rail to ground, the current draw is very high, and the lightbulb's current limiting action comes into effect.

And if that is not the case then, A: why does it act as if it were as you have described and B: does this not lead back to a faulty IC1401?

I notice that Q601 does not appear to be switched by any IC, rather it seems (I think) to be part of an oscillator using Q602 and probably the feedback from the optocoupler, IC601.

I pulled and tested all the optocouplers with the attached test circuit and they all light up the LED. I took that to mean the are good, correct?


Additionally, ShopJimmy has a repair kit and it mentions parts for a symptom of missing 345V. I assume that 'missing' could be 0V or not 345V, e.g. my 160V when Q601 is not allowing a short to ground and 70V when it is. I wonder how definitive their assessment of the fix is.

http://www.shopjimmy.com/magnavox-a1...repair-kit.htm

Of the parts listed to fix a missing 345V all but IC1401 I have tested and they are good as far as my tests can tell.

Thus, at this point I am leaning to IC1401 being bad as it seems to critical in having 345V and that many other things rely on it. Though I do not want to over look something that might be causing it to only appear bad.

From what I can see in your circuit, IC1201 is a switching IC and integrated FET which powers the standby rail (AL+4.3v)

If IC1201 controls AL+4.3 and I have that regardless of whether Q601 or 345V is present can I assume that it is good and eliminate it from the suspect list?

IC1702 is the switching controller for Q1702 and Q1703 which provide the backlight power supply.

And it is receiving the 3.78V from IC1401 pin 9 PWMCNTL which I believe invokes its shutdown, pin 19 SD, section 7.9 as per datasheet, and thus I do not get +24V to the inverter board. Does that logic seem correct?


Again many thanks for your time and assistance.

[Agent24]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

You say when pin 9 recieves, I assume you mean interal from its own logic, as the datasheet seems to indicate it is an output.

The datasheet also says

Well the PHB pin is connected to the VREF so the seems to indicate that the IC is not being phase managed, thus only HVSEN and VSENSE is important for having pin 9 internally receiving the correct signal, correct?

However, it seems that in order to generate the 345V the PWM needs to work to tell the MOSFETS when to switch so they can generate the 345V and the VSENSE AND HVSEN rely on sensing 345V to tell the PWM to work. It seems like this is a bit if of circular logic, i.e. IC1401 is essentially relying on itself to function so that it can function. If you can clarify how I am wrong please do as I cannot see it.

Ah, I assumed myself that it would be an input.

looking again now, it seems IC1401 is actually switched on and off by the HOT+17V rail (presence or absence of it)

When a TV is in standby there is no sense in running the PFC circuitry, since all that needs to run is the standby supply with low power. So the PFC is usually switched on by a control signal from the logic board when you tell the TV to turn on.

BTW, I could not find the datasheet for IC1401 (can you upload it?)

As I read many of these Funai made TVs are damaged by lightning. Although I do not know what may or may not have occurred as it was a side of road special, I am wondering after reading about the VINAC and seeing how it had D1208 bad and given

if IC1401 was rendered defective and it is the cause of the problem?

If the set was struck by lightning or some other power surge there could well have been some damaged parts that did not fail immediately. It's plausible to say that IC1401 may have died now after just hanging in there for a little while.

Did you verify that IC1401 has that HOT+17V power rail supplied on Pin 12?

The secondary output of T601 seems to lead to the outputs on CN1802, which are present and correct with Q601 in but not without. The leads me to think that Q602, along with a basic transistor meter check of it, is also good.

Thus, I do not see how the following is the case.

And if that is not the case then, A: why does it act as if it were as you have described and B: does this not lead back to a faulty IC1401?

Well, if you are getting all correct voltages out of CN1802 then Q601\602 must be working for sure.
IC1401 has nothing to do with the operation of Q601, it only provides the main power rail to it.

But, since IC1401 gets Vcc from the HOT+17V rail, and the HOT+17V rail is derived from the HOT+20V rail, and that comes from T601... then IC1401 is not going to get any power if Q601 is not in circuit since T601 will not be doing anything.

And if IC1401 or its surrounding circuit is faulty somehow, it makes sense to say you only get the bright lightbulb when Q601 is in circuit, since it only gets power then.

It could even be that you have a bulb in your tester that is too low wattage, and it is preventing the PSU from running properly. I hesitate to say try a larger bulb as there may still be a fault though...

I pulled and tested all the optocouplers with the attached test circuit and they all light up the LED. I took that to mean the are good, correct?

While a working opto would light the LED in your circuit, so would one with a shorted\leaky transistor. To do a better test on optos you would also need to remove the power to the LED side of the opto and be sure your LED you have connected to the transistor side turns off.

Additionally, ShopJimmy has a repair kit and it mentions parts for a symptom of missing 345V. I assume that 'missing' could be 0V or not 345V, e.g. my 160V when Q601 is not allowing a short to ground and 70V when it is. I wonder how definitive their assessment of the fix is.

http://www.shopjimmy.com/magnavox-a1...repair-kit.htm

I would assume so too. But to be sure you could always ask them.

Of the parts listed to fix a missing 345V all but IC1401 I have tested and they are good as far as my tests can tell.

Thus, at this point I am leaning to IC1401 being bad as it seems to critical in having 345V and that many other things rely on it. Though I do not want to over look something that might be causing it to only appear bad.

Again, check the HOT+17V supply rail first

If IC1201 controls AL+4.3 and I have that regardless of whether Q601 or 345V is present can I assume that it is good and eliminate it from the suspect list?

Yes.

And it is receiving the 3.78V from IC1401 pin 9 PWMCNTL which I believe invokes its shutdown, pin 19 SD, section 7.9 as per datasheet, and thus I do not get +24V to the inverter board. Does that logic seem correct?

Probably, but can you upload the datasheets? I can't find them.

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

Thanks for your answers. I will look into them further.

For now

I believe these are the datasheets for those two ICs.

https://cdn.badcaps-static.com/pdfs/...c0300e3fe8.pdf

Thanks

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

Did you verify that IC1401 has that HOT+17V power rail supplied on Pin 12?

Yes, I have HOT+17V as measured at J1016, a labeled jumper on the top side of the board, leading to pin 12. I also did some transistor double checking with the attached circuit on a bunch of the transistors including Q1401 where the +17V emanates. They light up the LED when the switch was pressed. Also confirmed HOT+20V of 22.6V at R1441.

Well, if you are getting all correct voltages out of CN1802 then Q601\602 must be working for sure.

The correct voltages only show with a 60W bulb not 100W, see below.

IC1401 has nothing to do with the operation of Q601, it only provides the main power rail to it.

I guess that would mean even at 70V rather than 345V Q601 can still function and provide the means for the voltages seen on CN1802

It could even be that you have a bulb in your tester that is too low wattage, and it is preventing the PSU from running properly. I hesitate to say try a larger bulb as there may still be a fault though...

I have tried a 50W bulb and its pulsing is at a much slower frequency than the 60W.

With Q601 in again I have the voltages back I mentioned before, including HOT+17, and my supposed to be 345V is down from the 170V when Q601 was out to 70V with it in.

If I put my ear close I can hear Q1601 and Q1602 pulsing at a higher frequency, time rather than sound, than what I can hear from Q601. A 60W bulb, as far as my ear/eye connection can tell, is pulsing in time with Q601, albeit very fast, and not with the higher Q1601/1602.

With a 100W bulb used it lights up bright full on for a split second and the relay clicks on then off and the front standby LED flashes on once then turns off. Pressing the power button does nothing. The 345V line show 3.3V, there is no HOT+17V and the other voltages on the connectors are also gone or very low, I did not check everything as it appears there is still a problem. No diodes in the bridges, or fuse appears blown. When switching back to the 60W bulb everything is restored to its current status quo.

I thought that it was concluded that IC1201 was good as I had the ALL+4.3V standby when the 60W blub was used and seeing as that was gone with the 100W and I thought it would check the voltages on it with the 100W in. The thing that I found most interesting was when I had by black probe on HOT GND and touched pin 3, labeled CL, and the light bulb light up and the relay clicked on and off. Took me by surprise and am now confounded by this. Any thoughts as to why that happened?

( the closest thing I can find to a datasheet for IC1201 is in post #13 and this overview http://www.semicon.panasonic.co.jp/e...2F2Kx/#general )



In general how does the wattage of the bulb affect things. I thought that a higher wattage bulb takes away more current away from the circuit and a lower wattage bulb allows more into the circuit. If that is the case then I can understand why I get the readings I do with a 60W, but am confused why practically none are there with a 100W.

While a working opto would light the LED in your circuit, so would one with a shorted\leaky transistor. To do a better test on optos you would also need to remove the power to the LED side of the opto and be sure your LED you have connected to the transistor side turns off.

Would adding momentary contact switches seen in the amended attached circuit fulfill that requirement? I drew in two switches but am assuming that I only need SW1 and 5V can still flow/should flow to the transistor to allow for the more thorough shorted/leaky test, correct?

Thank You

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

Some clarification

In general how does the wattage of the bulb affect things. I thought that a higher wattage bulb takes away more current away from the circuit and a lower wattage bulb allows more into the circuit. If that is the case then I can understand why I get the readings I do with a 60W, but am confused why practically none are there with a 100W.

I now read that a lower wattage bulb provdes more resistance and thus limits current whereas a higher wattage bulb isn't as limiting and allows more into the circuit.

In experimenting with different wattage bulbs this is the result:

With a 60W the AC in is at around 48-50VAC. Everythings is has been mentioned, i.e. I am able to actually measure voltages on things. The relay clicks on when I switch the tester on and clicks off when I switch it off.

With a 75W the AC in changes. Sometimes it is at around 20VAC when I turn it on at around 54VAC another time I turn it on. The relay sometimes clicks two or three times before staying on. The bulb lights up and stays on. Measureable voltages are the same as with 60W for those checked

With a 100W the AC in jumps to 120VAC. The relay clicks on and then off and the bulb flashes on then off. I can't say exactly, but I have seen the relay and light going off at 15VAC, 60VAC, 80VAC various times I turned it on. Practically no voltages are measurable on the boards, as mentioned before I did not try to measure everything as it was obvious something was amiss. Nothing blows as far as I can tell and everything is back to normal when I switch to the 60W.

However, I still do not understand how with a 60W bulb, i.e. less voltage and current, everything gets power and I can test things but with the 100W bulb, i.e. more voltage and current, it is practically dead.

[Agent24]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

I guess that would mean even at 70V rather than 345V Q601 can still function and provide the means for the voltages seen on CN1802

Without the set running and hence a load on that PSU section it makes sense. It would likely need the full 345V to function properly under normal operation though.

Would adding momentary contact switches seen in the amended attached circuit fulfill that requirement? I drew in two switches but am assuming that I only need SW1 and 5V can still flow/should flow to the transistor to allow for the more thorough shorted/leaky test, correct?

Yes.

I thought that it was concluded that IC1201 was good as I had the ALL+4.3V standby when the 60W blub was used and seeing as that was gone with the 100W and I thought it would check the voltages on it with the 100W in. The thing that I found most interesting was when I had by black probe on HOT GND and touched pin 3, labeled CL, and the light bulb light up and the relay clicked on and off. Took me by surprise and am now confounded by this. Any thoughts as to why that happened?

I don't know why it disappeared with the 100watt bulb. But the fact that it does operate with the other bulb seems to suggest that it's working, just being interfered with by something else when you use the 100w bulb.

Your meter probably upset the function of the circuit somehow. While the meter does not have much of a load or affect on most circuits, in some circuits it can be enough to change the operation state.

However, I still do not understand how with a 60W bulb, i.e. less voltage and current, everything gets power and I can test things but with the 100W bulb, i.e. more voltage and current, it is practically dead.

Working on the assumption that the PFC circuit is faulty as budm said, if it's not giving proper drive to the transistors, it could be that under current limited conditions the PFC circuit doesn't try to come up, when you use the larger bulb it does try to start, then screws up due to the fault.

Really though it's hard to say (for me anyway)
Since none of these PSUs are designed for these current limited situations, it may be a result of a design itself responding to the conditions you have placed on it, maybe in conjunction with the fault or just the fault itself.

[Mad Capper]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

Problem solved!

Operator error. Or more precisely serious risk aversion and lack of understanding.

Though I hope that this can be a potential lesson for someone else who may be having some reticence. I guess if you get the proper volatges on the secondary side then it may not blow anything to shut off when plugged straight into the mains, it just may not work for other reasons requiring further investigation. As I mentioned I checked all transistors, MOSFETS, diodes, except the zener voltages on zeners, shunt regultators, shottky diode, optoisolators. All checked out good. Really the only thing I replaced that was definitely bad was D1208, just as so many others have done.


I only had problems with not enough current going in because of using the dim bulb tester. I worked my way up from 60, 75, 100, 110, 135, 150, 160, 175, 200W with a combination of bulbs then finally without the dim bulb tester. Along the way I double checked that the rectifying diodes did not blow and at some point did get that elusive 345V and a steady 4.3V for standby while the tester switch was still on. What threw me a bit is that this sets relay clicks on once plugged in and it seems to do a system check then shuts off. The standby LED on the front does not stay on until you actually turn the TV on rather than staying on in standby.


Thanks to all who help me, especially Agent24, I genuinely appreciate you willingness to help and all the time you spent assiting me.


Now, if I can find that damn remote.
Many thanks

[Agent24]

Re: Philips 40PFL3505D/F7 Blows fuse when plugged in

No worries, good to see you got it fixed!