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

[budwich]

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

The measurement stated in the summary is taken at the TPSC1 point referenced back to the TPVFG point on the board which I checked with respect to the screws on the SU/SD boards. Based on the guide, it appears the tpsc1 is in "spec"... but I have no experience to say otherwise. How can I check for shorted buffer IC?

[budwich]

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

budm... I went back to check the Vsus... related to your guidance about MID versus Vsus.

So, monitoring it during power on, it goes and stays at 215vdc while the led in on in the sc board. Based on what you said about the MID being high at 138 and supposed to be near / at about 1/2 of vsus.... that is a good area for potential issue.

To me it seems like either a regulator is not being controlled properly or maybe its "open circuit voltage" (ie. unloaded). Areas to look at???

[budwich]

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

well, the friend got the scope working... maybe. Its an old leader LBO522 20mhz scope. Hopefully, that has enough response what I need. He didn't do anything to get it working other than leave it plugged in and turned on for a while... so something needs to warm up somewhere. Anyways, its what I can use.

Suggestions as to where to start probing? There is only one probe at this point.

[tom66]

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

Show me what scope you got...also I'm not budm

[budwich]

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

oops... sorry tom66... watching to many threads... :-)

here is a face plate picture.

related to the circuit, during the first attempt fix which blew (physical) one fgd4536, that resulted in the q600 and q601 being lost (shorted) along with a blown 1ohm resistor all of which are associated with the sos6/MID stuff. These were replaced, along with all the fgd's in the sus/mid stuff (ie. 4). The set then worked with picture for about 5 minutes before two fgd physically blew again. I subsequently replaced the fgd's with 30f131's but q600 and q601 don't appear to be shorted so they were left as is. I am not sure how the MID circuit determines the "range" before it fires the sos6 but perhaps one or both are not quite right.

[budwich]

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

I decided to check a few other components in / near the Q600 / Q601 portion of the board even though those are not shorted (in board) and connections to the board and resistors in the area check out.

Doing in circuit diode tests on d609, d608, d674, and d673 appear to check with .54v. However, d618 appears to be shorted as it reads 0 in either direction. The diode "package" on all of these is 8313. Not sure why d618 would be significantly different "in circuit" as it feeds into q600 / q607 which should be both "open circuit" (unpowered state) so the "in circuit" diode test should be valid. D618 connects VSUS into Q600 which switches this towards the MID.

How does one cross-ref this to something that is orderable on ebay as 8313 does seem to be "complete" in its number.

[budwich]

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

It looks like the diode is RF101L4S based on reading thru the forum.

[budwich]

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

Good God look it that SC board. There's Nothing worse than having all active components soldered directly to the PCB

I didn't grasp the "full scope" of this comment at the time... but after looking at a couple of versions of this set and the SC boards, I see that some boards have the IGBTs mounted vertically and heat sinked. Not sure what choice panasonic made at the time to do it one way or the other, but now wonder if perhaps adding some thermal pads and stick a "bar of aluminum" across the main ones would help anything. Probably not easily accomplished unless some way to have it pressed against the back of the set.

[tom66]

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

I didn't grasp the "full scope" of this comment at the time... but after looking at a couple of versions of this set and the SC boards, I see that some boards have the IGBTs mounted vertically and heat sinked. Not sure what choice panasonic made at the time to do it one way or the other, but now wonder if perhaps adding some thermal pads and stick a "bar of aluminum" across the main ones would help anything. Probably not easily accomplished unless some way to have it pressed against the back of the set.

I think the design is fine. But Panasonic didn't get something right with the 30 series, probably related to the screws or some software/config issue with the drive. The 50 and 60 series are rock solid. And when the set is running the transistors are barely warm to the touch.

I think your scope may struggle with the task at hand. What probes do you have with it?

[budwich]

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

:-( while it is what is. Only one probe (friend thought he had another... but not yet). It a switchable 1/10X BK probe.

On the TV... thanks for the "run down" on the series... I guess I need to look in a different dumpster...:-)

I am hoping that the diode is the only item "broken" at this point... other areas that I "touched / worked" still seemed to meter test out.

[budwich]

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

I got some replacement fast diodes (RF101L4S). Removed the shorted one (indeed was shorted out of board also). Installed new one (D618). After rechecking things, powered up... same reaction from the set and 6 blinks still. :-( Rechecked the replacement diode, still OK. Need to recheck voltages to see if anything changed.

[budwich]

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

Before the diode replacement, these were the readings with:
TPSC1: 147vdc (VscnF) Ts schematic indicates 147V +/-3
TPVAD: 200vdc TS schematic indicates 200V+/- 5
V15F: 14.95vdc
V5F: 4.95vdc
MID voltage: 128vdc (chassis ground) - Troubleshooting manual indicates range 67-138.

After the d618 was replacement, these are the reading
TPSC1: 147vdc
TPVAD: 14.9 <<<<<< NOT GOOD... WHAT HAPPENED
MID voltage: all over the place... auto ranging meter having trouble catching it
saw 128... but also 165....

I don't see any further damage in terms of shorts or opens but obviously something very wrong since TPVAD is now very low and the MID voltages are moving all over the place (can't recall seeing this previously).

:-( Might have to throw in the towel.

[budwich]

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

redid the TPVAD... clearer eyes in the morning.
I was touching the wrong point on the resistor.

TVVAD 199.7vdc so it is OK.

Rechecking the MID voltage, it appears that the MID voltage never gets above 52 vdc although it is hard to know exactly as the "measuring / auto ranging" causes number "flashing". IF true, then that would appear to be too low / outside the normal range.

Any one know what would contribute to that low value when previously it was higher.

[budwich]

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

I continue to struggle on this... but making small progress maybe.

Looked at the control circuits involved hoping to find something... what I don't know since this is well past my understanding in terms of even block diagram operation.

Anyways, based on the previous attached block diagram for the SC board, I checked the components in and around the "sustain H" (? not sure what that does or should be).

I followed the track from IC501 (buffer IC for the Hor. sustain) up to Q501 which is just to the left of the IBGT Q402 (30f131). I cam across a resistor, R503 (small little guy) which is supposed to be 10 ohm (1/4w). It is reading 600ohms. :-(

Checked a bunch of other "similar" control circuits with similar resistors / layout and they all measure 10 ohms.

Of course, I don't have 10 ohms ...:-( Question: can I get away with 7.5 ohm?
Anybody familiar with these circuits / layouts... is the 10 ohm critical? thanks for any guidance before I blow some more things up... :-)

[budwich]

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

well the 7.5 ohm replacement didn't last long... with a whiff of smoke and it was "baked". :-(

It would appear that there is some issue with this circuit. The resistor (r503) feeds a transistor (Q501 - 3YDK4 CPH5524-TL-E) which feeds the gate of igbt Q403 and Q402. These IGBTs do not show any detectable issue with a meter (ie. short) and diode tests in line with the others. The gate resistance (in circuit) to ground "field" (above the igbts) is high at 47K and to chassis ground 300k. Trying to locate info and 3ydk4 / CPH5524-TL-E transistor array to determine its specs for testing.

[Moreno83]

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

Could you please take a decent picture of the FGD4536TM that you are using ? All those bangs are definately not good for the sc board.

You need to check the SS board also. Not sure about your model but the european models have a part called "RN1008" or something simmilar to that. It is next to the flex cable going from the mainboard to the ss board.

[budwich]

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

Here is a shot of the one that I had removed that were still "good" (ie. they didn't physically blow apart). As I mentioned, I did see a working picture for about 5 minutes before some of these blew up. Currently, I have placed some 30f131 on the board (are they "real"... who knows but they "operated" with the little "igbt" tester that was suggested on the forum).

Anyways, I removed Q501 as it was indeed shorted on the PNP side. these little suckers are no fun soldering in place. I checked all the other CPH5524-TL-E's and they appear to be ok and similar in readings. I haven't given the board another try yet as I am "praying to the electronic gods" that I get one step further without taking more components out... :-)

don't see an "rn1008" on the ss board... is it a igbt type device? I see a rcj330.... ?

[Moreno83]

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

So i read through the whole thread.

Im almost certain that you used fake parts in the beginning of the repair. Which is not your fault but real 30F131/RJP30H2A are very hard to find.
For repairs we use the FGD4536TM but unfortunately there are also fakes on ebay for this replacement part.
The result is that your board literally blows up because the replacement parts cant handle the load.

If you used the right parts your board would not blow but it would give a blinking code.

See the attachment.

RJP63G4 top left , is it short? Measure in diode mode for shorts.

You did not replace the IC501 + small transistor top right on the board? ( See circle )
This is the reason you dont see a light coming up and if this part fails you also get 6 blinks. After the first short this IC usually survives but you tried it a few times and im 100% sure it is dead.
DG302 probably wont read short but can also result in 6 blink , it is best to replace those after so many bangs.

RF1501 only reads short with shorted fets. If you have the original , use that 1 again , same for DAF30.

Im 100% sure you used fake parts because the 1ohm resistor + diode and other parts in that area blew up. I learned this the hard way also.

[Moreno83]

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

Your FGD4536TM dont look original to me.

Originals have a small hole in the middle , these are my FGD4536TM.
Also , you cant wash the logo of the part. When you clean it with alcohol the logo must be very clear.

check my pictures!

[budwich]

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

"holy mackeral"... :-)... yep mine don't have those "forge marks" although the "alcohol test" did seem OK.

you said: "You did not replace the IC501 + small transistor top right on the board? ( See circle ) "

I did check all of the "small transistor arrays" after I found the Q501 shorted. All others appear ok in terms of metering including the one you indicate.
Is there any on board check for IC501... I hate these small devices (in terms of desoldering / soldering) plus I am not sure I have a replacement at this point.

I have to check the other things that you suggested as I haven't rechecked them after subsequent failures although I do check the FETs/iBGTs to see if they have shorted.

you said "This is the reason you dont see a light coming up "... I do see the led on the board light for about 1-2 seconds before it extinquishes and the 6 flash code shows up.