whole new repair / learning world... plasma! Yikes!

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

checked the suggested components for shorts and diode check the IC according to table. Found nothing wrong. :-( The "towel is in the air"....

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

thanks... its probably more likely that my soldering is "less than good" but I have checked the components listed in the three "blocks" in the TS guide that you posted. I usually check components by going from the pin to somewhere on the board for continuity in hopes that soldering has been successful. I potentially need to do a better job on cleaning off flux as it is all over the place and makes finding a "contact point" harder and possibly resulting in "false checks" as then one is pressing / scratching to make a contact which might not be there when the probe is removed which doesn't help. I will check the suggested list again... thanks.

[foxyUK]

Re: whole new repair / learning world... plasma! Yikes!

so, I ran some "pre_checks" on voltages with the SC board isolated from the sd/su boards along with sc50 test short applied. When power up, I still end up with a blink 6 code... :-(

Checking the voltages as suggested in the block3 all look correct / appropriate.

Vsus 214vdc
P15v 15.7
Vad 199
Vscn 147
16v_f 18
15v_f 14.7
5v_f 4.9

I then tried to measure the MID voltage, I couldn't get a steady reading and saw a reading of 201 during initial "auto range" along with others in the 120-140 range.... so it looks like the range of the MID (measured at the capacitors) is outside the range of things. :-(

6 Blinks is indeed consistent with the energy recovery mid voltage being out of limits. It should be very steady, only fluctuating by a few volts. Typical level is around 115v.
So... you need to check again IC502, IC522, Q531, Q551, Q451&2, D461&2, Q581, Q441&2, D481&2. (those little Ic's and driver transistor pairs being the favourites for incidental damage after an explosive event).
If you have changed any of them, check for pins that haven't actually been soldered to the board pads...quite hard to see. Associated resistors are also possible victims.
Good luck.

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

I was looking at getting one of those "far east" digital "modules" that are "standalone". Cheap ones can be had but most are only single channel and 10M. As a DIY hobby guy who does really get "dirty" much, it is hard to justify putting more in as the hobby is "sunsetting". Basically, the opportunities are only when I come across something different / interesting that cost nothing but time to look at and maybe save from the landfill.

I will likely look for a used card to see if I can get this set up or at least see what the difference is between it and a "tested card" (ie. so the listing says). :-)

[tom66]

Re: whole new repair / learning world... plasma! Yikes!

thanks... nice scope. As you say, my old 20 mhz "one legged" (probe) scope might be hard pressed to help. what frequency are involved / "chopped" with the voltage stuff. Can it be triggered with the"line" or do I need some isolation transformer?

The sustain waveforms could be conceivably monitored with a 20MHz scope with some loss of detail (but not much), but the issue is more that a digital scope lets you pause the waveform and look closely and shut down sequences etc. You cannot do this with an analog scope.

Further: I see that you used the "modify the cord" method for "isolation".... :-) I might have to try that although we are only dealing with 120v systems here so a "3/2" plugs are in the "tool box". Of course, not sure yet whether I want to go there yet.

Yes it's a bit naughty. I can say I would only ever do it with a plastic cased DSO, a full metal case with earthing represents a serious electric shock hazard as it will be floating hundreds of volts above earth. On a DSO you still have to look out for the BNC jacks etc which are also grounded and so could shock you, and make sure you don't plug anything else grounded into it, e.g. USB port to PC, as that will obviously disable your ground hack.

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

so, I ran some "pre_checks" on voltages with the SC board isolated from the sd/su boards along with sc50 test short applied. When power up, I still end up with a blink 6 code... :-(

Checking the voltages as suggested in the block3 all look correct / appropriate.

Vsus 214vdc
P15v 15.7
Vad 199
Vscn 147
16v_f 18
15v_f 14.7
5v_f 4.9

I then tried to measure the MID voltage, I couldn't get a steady reading and saw a reading of 201 during initial "auto range" along with others in the 120-140 range.... so it looks like the range of the MID (measured at the capacitors) is outside the range of things. :-(

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

thanks... nice scope. As you say, my old 20 mhz "one legged" (probe) scope might be hard pressed to help. what frequency are involved / "chopped" with the voltage stuff. Can it be triggered with the"line" or do I need some isolation transformer?

Further: I see that you used the "modify the cord" method for "isolation".... :-) I might have to try that although we are only dealing with 120v systems here so a "3/2" plugs are in the "tool box". Of course, not sure yet whether I want to go there yet.

Still further, I noticed your comment in the reference thread about the "30 series"... perhaps that's a bad omen for me.

[tom66]

Re: whole new repair / learning world... plasma! Yikes!

May be worth reading my thread here
https://www.badcaps.net/forum/showthread.php?t=63035

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

Thanks...... i think that means my ic724 is good.... readings of .59 which is in line with the "target" of .65v +/- .2. wish I was a bit slower taking it off the board... but I wanted to make sure it wasn't an issue with the "in-board" test.

[foxyUK]

Re: whole new repair / learning world... plasma! Yikes!

I was re-reading the panasonic guide (page 95) which deals with testing of components in block3... more specifically ic724 and ic795. I don't see how the test for these two different components can be the same. IC724 (5v regulator) has been Vin / pin1 and Vout / pin3 while IC795 (regulator?) has Vin / pin3 and Vout / pin1. Basically, the opposite of each other. Yet the "test result" uses the same + to - minus diode test setup on pins 1 to 3. My problem is ic724 appears to be wrong as the diode test is high in the stated direction but correct if you reverse the + -.

Can anyone confirm the diode test for a good IC724 (5v regulator BA178M05FP-E2)? thanks for any direction on this.

Yes, the guide is wrong. For IC724 pin 1 should be negative for the voltage shown. Reads about 1.5v for pin 1 +. Also, the centre pin 2 is not connected to the heatsink (the actual pin 2).

[and yes, there should be 3x 30F131 and 3x RJP30H2A on the SS board]

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

I was re-reading the panasonic guide (page 95) which deals with testing of components in block3... more specifically ic724 and ic795. I don't see how the test for these two different components can be the same. IC724 (5v regulator) has been Vin / pin1 and Vout / pin3 while IC795 (regulator?) has Vin / pin3 and Vout / pin1. Basically, the opposite of each other. Yet the "test result" uses the same + to - minus diode test setup on pins 1 to 3. My problem is ic724 appears to be wrong as the diode test is high in the stated direction but correct if you reverse the + -.

Can anyone confirm the diode test for a good IC724 (5v regulator BA178M05FP-E2)? thanks for any direction on this.

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

With all cables connected and SC50 shorted you will get a steady green light when you turn the tv on. ( no blinks ).

6 blinks means a problem in the sustain area which is almost certain the IC501 and transistor next to it. Just buy a SS board and get all parts you need from that board. Saves time and you got original parts.

Take the 30F131 and RJ30H2A from the ss board together with the small ic and transistor. So you know you got original parts
At the moment you are just gambling and guessing which part fails.....

I don't see any 30f131's on the ss board for this model of set. Am I seeing wrong?

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

I think / I hope I replaced the ic501 successfully (soldering isn't my forte). Moving on to block 3 checks, there seems to be an issue with ic724 which is a 5v regulator at the "top" of the board. The test from pins 1-3 shows a "capacitance" type reading while the diode check is in the 2+v as opposed to .65v.

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

After going thru the checks as outlined in the great guide that was "linked" by foxyUK, and focusing on IC501 as suggested by Moreno88, IC501 failed (shorted) the pin 3-7 check in diode mode. i haven't removed it yet. Just posting my "baby step progress".
All the checks in the first two "blocks" seem to be OK. But I see from the check list that I still need to recheck q606.

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

thanks... I will take a look at the guide.

On your problem, I suggested in another post that you look at reseating the sc to su/sd connectors / cables.

did you disconnect the su/sd boards from the panel during your work... then it is possible you have issues with those connections.

Further: at first glance to my unexperienced eye, the guide looks pretty good... people might want to grab it if they don't already have something like this.... before some "thing" happens to it.

[foxyUK]

Re: whole new repair / learning world... plasma! Yikes!

Do you have this guide, which describes many of the tests on these SC boards?
In theory it shouldn't be copied or distributed, but I figure Panasonic are probably no longer interested?
https://1drv.ms/b/s!AhyAtuUSxECNmmK-bZWYoxYi-hVu

Now, can someone help me with my poor picture after an SC repair (see post!)

[Moreno83]

Re: whole new repair / learning world... plasma! Yikes!

The SS board usually does not fail unless the SC board gets damaged and shorts out the RN part on the SS board.

They are cheap also!

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

thanks.... the strategy may work... assuming that I can recover the parts "well" from the board (you saw the picture of my current board... :-) ) and assuming that the board I find doesn't have issues especially with the 30f131's.

[Moreno83]

Re: whole new repair / learning world... plasma! Yikes!

With all cables connected and SC50 shorted you will get a steady green light when you turn the tv on. ( no blinks ).

6 blinks means a problem in the sustain area which is almost certain the IC501 and transistor next to it. Just buy a SS board and get all parts you need from that board. Saves time and you got original parts.

Take the 30F131 and RJ30H2A from the ss board together with the small ic and transistor. So you know you got original parts
At the moment you are just gambling and guessing which part fails.....

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

I "meter checked" all the buffer ICs (BD8693FVM-HVTR) on the SC board. I didn't find any shorts... probably doesn't mean much as the "in" and "out" could be open or at issue when powered.