zenith a27b33w


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zenith a27b33w

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mike12086
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Sep 22, 2004, 7:14 PM

Post #1 of 22 (3375 views)
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zenith a27b33w	Can't Post

i have one of these tvs with the common green picture problem. i was reading online about resistor problems and read to check resistor R5102. i've looked all over both boards and canot find this resistor anywhere. could someone give me an idea on where to look for this resistor. also any other resistors i should check and their locations on the boards. thanks. also i do know that there is a good chance it is the picture tube but since i still have the tv i'll see if i can do the cheap fix before i just toss it.

thanks

mike

mel
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Sep 22, 2004, 10:23 PM

Post #2 of 22 (3365 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

R5102 is 47 ohm resistor on the CRT board off of the base of Q5102. You might want to check out www.FreeFlatScreens.com/default.aspx?referer=7509165 for an opportunity to earn a free replacement for this set with a little effort on your part.

mike12086
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Sep 23, 2004, 1:13 AM

Post #3 of 22 (3363 views)
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Re: [mel] zenith a27b33w [In reply to]	Can't Post

ok so i think i found it but just to confirm is it a little square on the back part of the circuit board??? if so how hard is that to get out and find a replacement? and if it is supposed to be 47 ohms than i think that it might be the problem
i just realised from the other post that the other post was for a big screen but in that post the r5102 says its 120k 1/2 watt so who is correct or are they different between big screens and tube tvs? not trying to sound like a jerk just dont want the thing to blow up if i put the wrong part in.

thanks

mike

(This post was edited by mike12086 on Sep 23, 2004, 1:51 AM)

mike12086
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Sep 23, 2004, 8:21 PM

Post #4 of 22 (3348 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

after searching around more i believe the resistor value to be 120k and if that is the case mine is way off. now can i replace it with a normal carbon resistor or does it have to be one of those little chip resistors and if it has to be the chip one where can i get one of them? if i can use a regular resistor what wattage should i get?

mel
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Sep 23, 2004, 10:16 PM

Post #5 of 22 (3344 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

Before you go any further, check for continuity between pins 6 and 10 of the CRT with the CRT board pulled. If you have any reading at all, the CRT is shorted and you need go no further. You can go to www.samswebsite.com and download Photofact #4186 for this model and get the exact info. I have been working from a schematic for a similar model and it has been my experience that Zenith makes very little design change between model years. My schematic shows R5102 to be a coupling resistor between the green amp Q2204 and green out Q5201 transistors and is a 47 ohm probably 1/4 watt resistor. If it a surface mount resistor in your set, we are obviously looking at different sets. A surface mount resistor can be replaced with a standard resistor if you are careful. I would use either a 1/8 or 1/4 watt. Good Luck. I would be curious about your final outcome.

mike12086
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Sep 24, 2004, 1:54 AM

Post #6 of 22 (3339 views)
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Re: [mel] zenith a27b33w [In reply to]	Can't Post

ok mel thanks alot but my question now is which pin is which, where does pin 1 start and then does it move clockwise or counterclockwise? i'll probaly end up getting one of those manuals if there isnt a short and the resistor doesnt fix it (i'm almost positive its the resistor because it reads .999k on my meter)(it is one of those chip resisors, at least thats what i think they are called, the thing is like 1mm by 1mm, so small) i turned the tv on today after it has been sitting for 1+ years; the problem seemed to be less frequent but it was still there.

thanks again mel

mike

mike12086
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Sep 24, 2004, 2:55 PM

Post #7 of 22 (3336 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

mel
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Sep 24, 2004, 11:39 PM

Post #8 of 22 (3328 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

Your last post implies that this is an intermittent condition. If so, the short may or may not show up when you check but it definitely eliminates the resistor as a suspect because if it is bad, the condition would be constant. Also, if that resistor is in the green circuit, you would have no green at all. The pin in the islated area is pin 1, the next pin counterclockwse is pin 3 and go from there.

mike12086
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Sep 25, 2004, 2:50 AM

Post #9 of 22 (3322 views)
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Re: [mel] zenith a27b33w [In reply to]	Can't Post

its not that the problem comes and goes it all depends on the picture (usually something with a lot of white or a bright color makes the screen turn green). i just did the pin test and it was non-conductive so thats a plus. i also checked the resistor again and it still measures .995k so i plan to go ahead and replace that with a regular resistor like u said before (47 ohm 1/4 watt) so i'll let you know what happens after that.

tanks again

mike

mike12086
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Sep 25, 2004, 2:07 PM

Post #10 of 22 (3318 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

another quick question: what is the value of R5103? i ask cause it is the only other chip resistor that looks the same (they are white chips). also some numbers have a M after them does that mean anything?

mel
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Sep 25, 2004, 10:13 PM

Post #11 of 22 (3309 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

According to my schematic, R5101, R5102 and R5103 are all the same value (47 ohms). Incidentally, try setting your ohmmeter on the X1 scale for making measurements of less that 100 ohms. You will get a more accurate reading that way.

mel
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Sep 25, 2004, 10:47 PM

Post #12 of 22 (3308 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

On closer examination of my tech package, I believe that we are looking at the same configuration because it does show R5102 as surface mount resistor on the CRT board. It is connected directly to the base of Q5102 and is between that and the collector of Q2205 on the main board. You will not get an accurate Ohms reading with this resistor in circuit because there are other components in parallel with it. It is more likely that one of the transistors has failed than the resistor and I have had to replace a video amp (Q2205/4/6) on more that one occasion although I don't remember it being for the same symptom that you describe.

mike12086
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Sep 26, 2004, 12:29 AM

Post #13 of 22 (3304 views)
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Re: [mel] zenith a27b33w [In reply to]	Can't Post

thanks mel,

my meter is an auto-ranging one. i'm at work now so i picked up a component tester to check the transistors now the only question i have about them is how will i tell what the base leads are on them or do they go in order? i asked about the other resistor because it was close in number and same color and i measured both and got the same reading, and now that u mentioned it i did notice another little surface mount object (a resistor like you said) right next wired parallel on the board. i also bought some resistors so maybe i'll play around with that but what u said and my reading between those 2 different parallel resistors makes me think that isnt the problem. also if you know what is supposed to be the total resistance on that parallel circuit?

thanks again mel, i REALLY appreciate it

mike

mike12086
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Sep 27, 2004, 12:58 AM

Post #14 of 22 (3277 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

ok so i bought a transistor checker and checked all 3 trnsistors on the crt board (Q5101,Q5102,Q5103). is it possible that they are all bad becuase all of them read the base correct but read that there is 2 collectors?

mike12086
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Sep 30, 2004, 3:17 AM

Post #15 of 22 (3255 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

???

brucebee29
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Sep 30, 2004, 5:06 AM

Post #16 of 22 (3253 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

you have a bad contact somewhere on CRT little board. this problem always happen in some Zeniths when they stay on for many days... your resistor is ok, you don't need change it.

brucebee29
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Sep 30, 2004, 5:07 AM

Post #17 of 22 (3250 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

no.

brucebee29
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Sep 30, 2004, 5:08 AM

Post #18 of 22 (3249 views)
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In Reply To

sorry in my last post I reply no about this message.

brucebee29
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Sep 30, 2004, 5:14 AM

Post #19 of 22 (3249 views)
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Re: [mel] zenith a27b33w [In reply to]	Can't Post

In Reply To

hi,

did you try that link? did you get anything free? or this is just one more scam websites of the net :)

mel
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Sep 30, 2004, 5:20 PM

Post #20 of 22 (3241 views)
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Re: [brucebee29] zenith a27b33w [In reply to]	Can't Post

I checked it out before I signed up for it so I felt comfortable in signing up. The guy who introduced me to the site says that he has now received his free TV so I have no qualms about recommending it to others. I still need two people to join to qualify but I'm getting there. Since it has not cost me any money and I enjoy participating in giving advice on this site (I am retired after 40+ years in TV repair), I figure that it is worth the effort and almost everyone can use a new free TV, especially those whose current set is giving them headaches.

mike12086
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Sep 30, 2004, 5:56 PM

Post #21 of 22 (3239 views)
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Re: [brucebee29] zenith a27b33w [In reply to]	Can't Post

In Reply To

you have a bad contact somewhere on CRT little board. this problem always happen in some Zeniths when they stay on for many days... your resistor is ok, you don't need change it.

what do u mean by bad contact? just a bad solder joint somewhere? this tv, when it was in use, was on for days on end and when it was off it would only be off for a few hours if that.

mel
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Oct 1, 2004, 9:55 PM

Post #22 of 22 (3225 views)
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Re: [mike12086] zenith a27b33w [In reply to]	Can't Post

I'm baaack. The transistor elements are marked on the board as E, B, and C. You will not be able to test them in circuit because they are in parallel to other circuits. The contacts that the other guy was alluding to are probably R5126, 7, and 8 which are high wattage resistors and the heat generated will deteriorate the solder. However, if R5127 were to become unsoldered the green cathode would have low voltage resulting in a green screen runaway which would be constant. There are only 11 components in the green output circuit between pin 20 of the video processor and the green cathode of the CRT and to me the most likely candidate is Q2205.

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