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Issues with Philips 27PT543S37A (SOLVED)   Goto page 1, 2, 3  Next  
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VictorVictor5



Joined: 10 Aug 2014
Posts: 12

PostPosted: Sun Aug 10, 2014 6:55 pm    Post subject: Issues with Philips 27PT543S37A (SOLVED) Reply with quote

Greetings all,

New user to the forum. Like this post:
http://www.riddledtv.com/forums/phillips-27pt543s37a-t935,highlight,l01.html

I had the same problem. What it was doing was, when first turned on for the day or after a couple of hours, I would lose sound and picture, but the power LED would still be on. I had to turn the TV off and on 5-7 times for the picture and sound not to cut out.

I did a ton of research on this, and (I can provide links if needed) it seemed as though the horizontal drive circuitry was bad. There apparently was a Horizontal drive kit from Philips for the L01.1U chassis that replaced the following components (which I replaced):

1-BU4508DX (Transistor)

1-BC547 (Transistor)

1-BC557 (Transistor)

1-47m/50v (Capacitor)

1-220m/35v (Capacitor)

I also replaced the BC33725 and BC32725 transistors since there was a burn mark at these points, and further tests on a transistor tester showed they were bad. So I sealed it up a couple of days ago and I thought I was good to go. But when I went to turn on the TV this morning, same issue, but I only had to turn it off and on once, not 5-7 times before the repair. This happened twice so far today. Mad Mad

I checked the service manual, and the error code told me to check for black current loop protection (device TDA6107/8, and items 7330, RCB amps, and the CRT). I can provide the service manual if needed.

Now, I know how to do circuit board repair, and probe needed points if someone tells me what to test, but this is my first TV repair. Any suggestions would be welcome.

Thanks!
VV5


Last edited by VictorVictor5 on Thu Aug 21, 2014 12:35 pm; edited 1 time in total
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JTS1957



Joined: 21 Jan 2009
Posts: 2286
Location: Far, Far Away

PostPosted: Sun Aug 10, 2014 9:34 pm    Post subject: Reply with quote

Does set shut down if CRT board is unplugged and insulated from rest of set's circuitry?
G2 setting is very critical.
Location numbers are easier to research.
VictorVictor5



Joined: 10 Aug 2014
Posts: 12

PostPosted: Mon Aug 11, 2014 2:50 pm    Post subject: Reply with quote

JTS,

So, since I'm a newbie at this, the CRT board is directly behind the tube (it's the little board), correct? If so I did not try that yet.

Is it ok to take pictures and post to see if I am on the right track?

Thanks!
VV5
JTS1957



Joined: 21 Jan 2009
Posts: 2286
Location: Far, Far Away

PostPosted: Mon Aug 11, 2014 4:36 pm    Post subject: Reply with quote

VictorVictor5 wrote:
JTS,

So, since I'm a newbie at this, the CRT board is directly behind the tube (it's the little board), correct? If so I did not try that yet. YES

Is it ok to take pictures and post to see if I am on the right track? YES

Thanks!
VV5
VictorVictor5



Joined: 10 Aug 2014
Posts: 12

PostPosted: Mon Aug 11, 2014 6:02 pm    Post subject: Reply with quote

JTS,

Ok great - give me a couple of days to post back (with work and everything). I definitely will. Thank you for your help thus far.

VV5
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VictorVictor5



Joined: 10 Aug 2014
Posts: 12

PostPosted: Tue Aug 12, 2014 6:43 pm    Post subject: Reply with quote

JTS,

Ok - if you go here
http://www.eecis.udel.edu/~samluk/PhilipsRepair

I put some pictures up. Sorry about the quality but my school doesn't have the best web hosting software, and on this system I can't PM you or attach images. Mad

Let me orient you - the first 3 are of the CRT PCB when looking at it from the front of the screen back (and the last one is bottom up). What do I unhook and test per your earlier posts?

The last three show the main board and the red arrows indicate what I replaced. Now, the 2 side by side are pretty much the same shot, I just tried to get more of the flyback bottom in one of them looking for this "G2" pot.

The last one is a face on of the flyback bottom, and the 2 red arrows are of things I replaced already (shown in the other 2 pics). Now, there's one thing on these set of pics that I replaced that currently isn't in view (closer to the front of the main board closer to the screen). If you need a shot of that let me know.

Hopefully these pics help - standing by for further instructions.

VV5
JTS1957



Joined: 21 Jan 2009
Posts: 2286
Location: Far, Far Away

PostPosted: Tue Aug 12, 2014 8:51 pm    Post subject: Reply with quote

Regarding pictures: http://www.riddledtv.com/forums/read-me-first-before-posting-t5.html#5641

I'm fully oriented with CRT televisions. Wink

1) G2 setting is very critical. Take a magic marker and mark the G2 control shaft and flyback in such a way as you can easily put the control back to its initial setting (this presumes that you haven't disturbed it yet). Rotate it counterclockwise 6 degrees at a time, a total of 5 times (30 degrees TOTAL), seeing if your set plays correctly after each attempt. You can return G2 to initial position and repeat in a clockwise direction.

2) Does set shut down if CRT board is unplugged and insulated from rest of set's circuitry? Isolate the CRT PC board from the CRT - They pull apart. Hold PC board above and below where white plastic (socket) and green plastic (CRT 'plug') connect. Being careful NOT to break either the board or the glass CRT neck, pull gently back (toward staircase in two of your photos) using a slight top to bottom 'wiggle'. Do NOT disconnect anything else. Place board so that no point(s) of it are in contact with ANYTHING. The farther away the better. If necessary, string or plastic ties can be used to hold it up or away.
The CRT is a picture tube that operates at very high voltages and contains a high vacuum. If cracked or broken, the CRT can implode (collapse into itself) and scatter fragments of glass. When working on or near a CRT, follow all safety rules and take every precaution against breaking the tube, especially at the neck where the tube is thinnest.

IF anything I've written is unclear - Ask for clarification BEFORE you proceed!

Location numbers are easier to research.
What are the location numbers of transistors: BC547 - BC557 - BC33725 & BC32725?
VictorVictor5



Joined: 10 Aug 2014
Posts: 12

PostPosted: Wed Aug 13, 2014 7:28 am    Post subject: Reply with quote

JTS,

Ok thanks for the reply. Sorry for making you go outside of the website to look at the pictures, but thanks to you I know how to submit them.

Ok, as per your request, location numbers of all the parts I replaced:

Transistor BC33725 - # 7461 on main board
Transistor BC32375 - # 7463 on main board
Transistor BU4508DX = # 7460 on main board
Transistor C557B - # 7443 on main board
Transistor BC547 - # 7540 on main board
Capacitor 47 uF/50V - # 2455 on main board
Capacitor 220 uF/35 V - #2405 on main board

Before I proceed I have 5 questions to make triple sure I don't screw anything up.

1.) Do you need me to verify anything on the above circuits? Like if the capacitance is ok or if the transistors are ok? I know they are new but sometimes we all get bad pieces. Do you need me to let you know of the Collector-Base Voltage and Base-Emitter Voltage of each transistor while power is off?

2.) About isolating the CRT PC Board from the CRT test - I imagine you want this unplugged before I turn power on to the TV, correct? May be a dumb question but you know what they say a dumb question is one that's never asked.

3.) G2 setting - Is the G2 potentiometer that big black object in my photos at the bottom of the flyback wire? I haven't touched anything with that yet. The only thing I've done with that board is put the new components in as listed above.

4.) G2 setting again - I take it it's a screw setting, and I take it a need to use a compass of some sort. Any special compass?

5.) G2 setting (one more time for now I swear Mr. Green) - outside of the set shutting off - the picture looks fine. Why am I adjusting the G2 voltage? What's the purpose of that (for my own sanity/knowledge)?

Thanks!
VV5
JTS1957



Joined: 21 Jan 2009
Posts: 2286
Location: Far, Far Away

PostPosted: Wed Aug 13, 2014 1:22 pm    Post subject: Reply with quote

From the questions you are asking I feel the need to go back and cover a few basics.
VictorVictor5 wrote:
"A" What it was doing was, when first turned on for the day or after a couple of hours, I would lose sound and picture, but the power LED would still be on. I had to turn the TV off and on 5-7 times for the picture and sound not to cut out.
NOW
VictorVictor5 wrote:

"B" same issue, but I only had to turn it off and on once, not 5-7 times before the repair. This happened twice so far today.

Is it STILL doing the same?

VictorVictor5 wrote:
I also replaced the BC33725 and BC32725 transistors since there was a burn mark at these points, and further tests on a transistor tester showed they were bad.

Burn mark? on the board? on one or both transistors? picture? What kind of transistor tester? Are you familiar with this tester's operation?

VictorVictor5 wrote:
I checked the service manual, and the error code told me to check for black current loop protection (device TDA6107/8, and items 7330, RCB amps, and the CRT).

When was Error Code present? "A"? or "B"? (or both?) see your quotes above.

VictorVictor5 wrote:
Before I proceed I have 5 questions to make triple sure I don't screw anything up.

1.) Do you need me to verify anything on the above circuits? Not at this time. Like if the capacitance is ok or if the transistors are ok? I know they are new but sometimes we all get bad pieces. Do you need me to let you know of the Collector-Base Voltage and Base-Emitter Voltage of each transistor while power is off? With the power "off" there will be NO voltages. - When the time comes, you will put a DVM on DCVolts, place it's black lead on the requested reference [usually Hot or Cold ground] and take a reading at the point(s) requested.

2.) About isolating the CRT PC Board from the CRT test - I imagine you want this unplugged before I turn power on to the TV, correct? May be a dumb question but you know what they say a dumb question is one that's never asked. I want you to try setting G2 FIRST. - but to answer your question: Unplug TV; Unplug CRT board and isolate it so it won't short to anything; Plug in TV; Turn power ON.

3.) G2 setting - Is the G2 potentiometer that big black object in my photos at the bottom of the flyback wire? I haven't touched anything with that yet. The only thing I've done with that board is put the new components in as listed above. FOCUS adjustment is at top / G2 is at bottom.

4.) G2 setting again - I take it it's a screw setting, and I take it a need to use a compass of some sort. Any special compass? Control = Pot = Potentiometer = Variable resistor. Since you seem to have trouble envisioning 'degrees,' let's try an 'analog clock.' I want you to mark the G2 control at 12 o'clock and try the TV each time you turn it 1 minute CCW ending at up at 11:55 (then return to 12 and do the same CW to 12:05). Of course, we have no way of knowing where the control is at to begin. It may already be within 5 minutes of being fully CCW (unlikely, but possible), so do NOT force it beyond its limits.

5.) G2 setting (one more time for now I swear Mr. Green) - outside of the set shutting off - the picture looks fine. Why am I adjusting the G2 voltage? What's the purpose of that (for my own sanity/knowledge)? Service Manual Page 101: Other supply voltages are provided by the LOT. It supplies +50 V (only for large screen sets), +13 V, +8 V, +5 V, and a +200 V source for the video drive. The secondary voltages of the LOT are monitored by the 'EHTinformation' lines. These lines are fed to the video processor part of the UOC IC 7200 on pins 11 and 34. This circuit will shut 'off' the horizontal drive in case of over-voltage or excessive beam current.
VictorVictor5



Joined: 10 Aug 2014
Posts: 12

PostPosted: Wed Aug 13, 2014 2:15 pm    Post subject: Reply with quote

JTS,

Apologies on my lack of clarification.

Ok. Case "A", where it was shutting off 5-7 times until a steady picture and sound, had the following error codes: 11 10 5 4

According to the manual: Error code 11 we already discussed, Error code 10 was the Tuner (Tuner I2C identification error, check items 1000 and 7482), Error code 5 is TDA95XX (POR 3.3 / 8V Protection, check 7200, 7560, 7480) and Error code for MSP34X5TDA9853 (MAP I2C identification error, check 7831, 7861).

Now I did some research on case "A" and even verified it with a local repair shop that it needed a Horizontal Repair Kit. There is a brown burn mark at 7461 and immediate vicinity (if you need another picture of it let me know, it should be on the ones I posted), so I knew (and in researching on the Internet) that 7461 and 7463 needed to be replaced as well.

The transistor checker I used at school is a BK Precision model 510 transistor tester. I am familiar with the functionality - the tech explained how it worked. Turns out 7461 and 7463 were bad. From what I remember 7443 and 7540 were either both good or one was bad/vice versa (still have the old parts if you need me to check). The only problem was when I replaced the BU4508DX one of the legs came off of the old one, but again still have the old parts).

So, for Case "A" all I thought I needed to replace were the 5 pieces in the Horizontal kit, along with 7461 and 7463 and I thought I was solid, and I didn't check the other parts (yes I'm probably going to get grief, but I am new at this). Sealed it back up, hooked everything up, cleared the error codes, and 2 days later it does the same problem, but now instead of 5-7 times to get a steady picture, it's 1-2 times (so this is Case "B"). Needless to say it doesn't do it as often as Case "A".

Now, the error code I see (as of this post) is Error code 11 (and it even does 11 blinks on the LED, did not notice (was not paying attention) the blinking with Case "A" if that matters.


Standing by for further instructions. I am not touching anything until I get the go-ahead.

Thanks!
VV5
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