Re: Thomson 55UA7706 LCD TV startup problem?
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Zener has a 18V value. If this zener breaks, then also FSFR1700 fails and need to be replaced, no empti place here! Although it may seem to work even without this zener it not work without a zener.
Now this TV works again.
SMPS
Member
Last Activity: 12-04-2020, 05:44 AM
Joined: 08-16-2020
Location: Peipsiääre
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Re: Thomson 55UA7706 LCD TV startup problem?
Yes, this is weird but - I was measured this maybe tens of times and compared to others and this is clear that this zener is defective. I dont know why? Also, first time I have this fault but lets see when new IC is in place and also new zener.
I have now 17V, 18V and 24V SMD zeners too. I think that maybe I`ll try then 18V here?Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
I finally got new PSU chip and now is still only one problem - this damaged zener.
Like as I say some time ago, I was measured all components which located near this FSFR1700XSL chip and clear is that this D404 (some kind of zener) is damaged BUT - how can I be sure what value zener this must be?
I draw this part of PSU zircuit and measured all little SMD parts, this circuit is below and there is also componets values which I measured.
Now - how I can calculate this D404 value? Or rather what does...Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
OK.
I once thought that I marked with a dot, not a comma... My country also have a comma for this kind of separation, but I get previously resented that I used a comma and tried to prevent now
Anyway I need to figure this zener value out now and new inverter or ICs. I drew a diagram but i will only get the component measuring device tomorrow or the day after tomorrow, so if i get it done maybe it will give some overview to find out the value of the suitable zener. OK, lets seeLeave a comment:
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Re: What's this transformer for and how to find in on aliexpress?
This transformer seems more like gate driver transformer for powerful converter IGBTs or FETs.
If this device where this transformer is, is known manufacturer product then you may find replacement transformer but if not then you can make it yourself if you know how to make it.
But if this smps operate 70 or more kHz then you need take very special care. If you want only replicate - exactly same wire and turns of windings exactly same direction, core must be same shape and material N87, N97, 3C94,...Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
Look next answer
Yes, I wrote this but there is +41.45[COLOR="Red"]m[/COLOR]V , not 41.45V. There is over 1000x lower value this +56V rail.
Then is only possible that inverter itself is bad, this OZ9998, all other semiconductors is good. And If you need I can take picture this zener measurements - virtually [url]https://i.ytimg.com/vi/GwRyAGgpbPg/maxresdefault.jpg[/url] but I have 1000ohm resistor and adjustable supply, if I now get new THT zeners from manufacturer...Last edited by SMPS; 10-07-2020, 08:25 AM.Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
Yes, below is new, do they help?
This 24V comes to inverter board from psu pin no. 10 (marked red). And yes, I have 22.92V before but after disconnect/reconnect this 14pin cable, I dont have this anymore, also, no standby.
Because (also question 4) ) one technician suggested to measure C401 22uF/50V voltage and there is 1.6V, they told that I must check this part of circuit, I then measure this SMD components and find this zener conducted both ways, soldered it off and checked...Last edited by SMPS; 10-07-2020, 02:54 AM.Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
I think that this maybe is also not good but I have night and my phone cam is not good to make better pictures.
And if I want take a picture to whole pcb, i cant take it very close
There is limit also if I take many shots closer and put them together.
And LED is this: [url]https://www.aliexpress.com/i/33023939915.html[/url]
If I search from google all this PCBs (all markings which there is) then I only get different e-store etc, no topics, no information which I need. Some...Last edited by SMPS; 10-06-2020, 06:22 PM.Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
OK.
Moment ago I did it - disconnect this black cable to inverter board and connect it back, there is no standby anymore after connecting back.
If I reconnect TV to mains there is only one very short blink in this standby - maybe because I try to replace this zeners today earlier.
Yes, there is no image and yes, i did not connect anything to input (HDMI or nothing) - maybe this is why not sound or nothing.
I have tester to test LEDs, they give me very weak light and I have also new stripes I connect...Last edited by SMPS; 10-06-2020, 04:27 PM.Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
---HOW it is possible if I disconnect socket where is also this low level signals? (where there was an explanation?) What picture I see then? If there is blank screen - do i need to connect something? No, there is NO any picture if I watch torchlight, I say it - i also feel like a buggy that i have to do things over and over again that i've already done it.
This cable is wery strongly in connectors - i can say that I haven't encountered ribbon cables so hard before and that's why I suspect they can't be caught in...Last edited by SMPS; 10-06-2020, 02:17 PM.Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
Want to EDIT last post but I cant
OK, last post here - no help and seems like there are not even like-minded people
Anyway, replaced this broken zener with 18V THT component but no change.
If before red standby light came on then now it stays off - broken zener=standby, new zener=no standby and no power.
I cant any information nor google, nor yandex, nor other search engine - why this zener is here? what they do here? What happen if they are too high or too low values or what happen...Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
Nobody
I searched with different methods to maybe find some circuit diagram or fragment but nothing, in this PSU board is printed also: 40-E461CD-PWD1XG
But google says - no circuit diagram or even fragment this FSFR1700XSL part.
There is multiple PSUs which use same IC but all are little different - and I dont know what zener I can use to replace this D404 (measured, shorted) - there is also D402 and D403 and they are both 18V zeners (measured).
What happen if I connect this...Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
OK.
Haven't tried it yet but main PSU contains a FSFR1700XLS resonant converter switch [url]https://cdn.badcaps-static.com/pdfs/cd66314fef8bf5f7ba38c8f141f56ce1.pdf[/url]
Found that there is one zener diode in this circuit part which is shorted, it is not exact circuit like Philco PH48S61DG (service manual page 14) but there may be some reference, this part of this main PSU produces LED driver +56V which I dont have. Hope that this FSFR1700XLS itself is good but I cant see any marking in this shorted zener (D 404...Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
Sorry for delay.
Image from rear side, at below.
Quick measurement from T-CON fuse shows that this fuse is in good conditions (continuity test).
I haven't done this 24V circuit test yet but I will soon. How long can i turn on the tv without this 24V node? Can it damage the power supply if there is no load in this node longer time?
If I connect a relay between this 24V wire and turn on the relay (from aux power) a few seconds after turning on the TV, will it not damage the power supply itself?
...Last edited by SMPS; 10-05-2020, 04:59 AM.Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
You mean this in red circle?...Leave a comment:
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Re: Thomson 55UA7706 LCD TV startup problem?
Here it is.
This is inverter board.
I try this method but can you tell me - what is the purpose of this 24V node? 56V seems backlight power (72 LED in one strip, 4 groups 18 LED per group) but for what is this 24V purpose?
EDIT: No image if I illuminate the screen from different angles with a flashlight, I forgot this to mention in the first post....Last edited by SMPS; 10-04-2020, 12:51 PM.Leave a comment:
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Thomson 55UA7706 LCD TV startup problem?
Hello.
My first post here.
I apologize for the typos because English is not my native and I haven't learned English in my school years. I have tried to learn it myself but probably I still make many of mistakes because reading written language and trying to communicate are two different things..OK, hope that these mistakes are forgiven
My concern is as follows:
I need help finding a service manual for Thomson 55UA7706 tv. Or - which may be the cause when the TV is in standby mode and the screen stays blank when you try to turn it on (even no backlight... -
Re: New Members - please post your introductions here
Hello.
I am new at this forum. I have read it a few times and got help here also.
I am from Estonia.Leave a comment:
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