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mikey



Joined: 20 May 2013
Posts: 11

PostPosted: Mon May 20, 2013 8:22 am    Post subject: Toshiba 21S1ES No picture Reply with quote

Hello, I have a Toshiba 21" colour TV Model 21S1ES collected from scrap yard. Problem is there is sound (and menu display,volume,channel change ok) but no picture. This is my first time opening up a TV and try to fix it but do not know where to start and what to look for. I hope someone generous can point me the right direction and guide me what to do and in the process to learn on TV repair as a hobby.
The tools I have is a soldering iron,digital multimeter & capacitance meter.
Anyway, I am attaching two images of the problem TV board. Hope to get reply and Thank you in advance.
Smile


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JTS1957



Joined: 21 Jan 2009
Posts: 2340
Location: Far, Far Away

PostPosted: Tue May 21, 2013 4:15 am    Post subject: Reply with quote

http://elektrotanya.com/toshiba_21s1e_21s1es_21s1h_chassis_s3e.pdf/download.html
mikey



Joined: 20 May 2013
Posts: 11

PostPosted: Tue May 21, 2013 7:26 pm    Post subject: Toshiba CRT TV Model 21S1ES No picture Reply with quote

Hi, JTS1957 Thanks for the link which I had downloaded the service manual, but sorry to say I am a newbie in electronic not able understand the diagram from page 21 onwards.
Got two questions here:
1)From visual check on rear neck board, I saw slight brownish stain which I suspect can be the cause of no picture? How do I test to check if this area is function ok ?
2)How to perform voltage test on RGB colour on neck board circuit (to check for sufficient voltage feeding the tube) ?
I only have a digital multimeter; where do I put on test probe(red and black) on to do the test?
Just trying my best to diagnose what is the cause, correct me if I am wrong.
Appreciate for any suggestions and advice. Embarassed
JTS1957



Joined: 21 Jan 2009
Posts: 2340
Location: Far, Far Away

PostPosted: Wed May 22, 2013 6:50 pm    Post subject: Reply with quote

mikey wrote:
Problem is there is sound (and menu display,volume,channel change ok) but no picture.


So there IS or is NOT a lit screen? Menu display implies that you can "see" it - volume,channel change implies you could be "hearing" these change. Which route we take depends on this answer.

Stay away from "Service" and "Design" modes!

Brownish stain is flux. Usually won't affect operations.

You will also need some way to remove solder from a component to perform checks/replace. Cap meter, I assume, just checks their "Value"? Black probe on DVM will go to COLD ground (ie. Tuner case). Most HOT grounds will be in the primary side of the power supply and I will try to give you a convenient ground point if/when we get there.
mikey



Joined: 20 May 2013
Posts: 11

PostPosted: Wed May 22, 2013 7:27 pm    Post subject: Reply with quote

Hello again, thanks for prompt reply. My apology on unclear description.
There is indeed a lit screen of blue color when I press menu button on tv remote, able to adjust contrast,brightness, select channel, etc. FYI, I can select channel, can see volume level on screen, get full tv sound of the selected channel (hearing of audio part ok) except it shows no video (picture) of the channel.

Taking your advise I will stay away from "Service" and "Design" modes.
I am currently capable of using soldering iron to remove solder or bad parts from circuit board, have some experience remove bad electrolytic caps and replace new one to restore LCD monitor. Wonder if this will suffice to repair this TV. My cap meter can just check cap value "off circuit" type but I have a feeling this TV needs much more technical expertise to fix.
Thank you in advance & Appreciate any further guidance.
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JTS1957



Joined: 21 Jan 2009
Posts: 2340
Location: Far, Far Away

PostPosted: Wed May 22, 2013 9:52 pm    Post subject: Reply with quote

Please use the "Post Reply" button unless you mean to quote whole post(s). There is a Quote button above compose text window to post pertinent selection(s) {"quote" - highlight text - copy - paste - "/quote"} of a prior post. (if desired you can add: ="authorname" after first quote press). It drives me nuts wading through echoes of whole prior post(s).

Blue screen with menu when menu is pressed. Without pressing menu first, when a channel is selected does set also show a blue screen or is it a blank snow-free gray? Channel number confirmation indication is on screen?

Are A/V jacks in front or back working with a dvd / dvr?
mikey



Joined: 20 May 2013
Posts: 11

PostPosted: Thu May 23, 2013 9:03 am    Post subject: Reply with quote

Hi, to answer your question on without pressing menu first, when a channel is selected , the TV set show blank snow gray. The channel number confirmation is shown briefly on screen (e.g. the No. 3 if channel 3 is chosen)
I retest just now got TV channel sound clear but still no picture.
I recheck on TV tuner for any damage or dry joint but found nothing suspicious. During testing, I also try knocking on side of TV tuner hopefully
to get some picture but still none.

The A/V jacks are at the back of TV is working with a DVD player, I have tested the DVD player working only with sound but no picture.
Hope this info is useful for further trouble shooting & Have a Good Day ! Smile
JTS1957



Joined: 21 Jan 2009
Posts: 2340
Location: Far, Far Away

PostPosted: Thu May 23, 2013 12:15 pm    Post subject: Reply with quote

Your photos (and service literature) both show a jack pack on both the front and back of the TV circuit board.
Since the schematic seems to indicate that the insertion of plug(s) into a jack works a built-in switch, you would need to try both front and rear to be sure a switch is not stuck in the open position when a plug is removed.

DVD video also blank snowy gray?

If your set has the "Monitor Out" jack, can you feed it to the video in jack of a properly working TV and get a picture? Also does your set have a "Text" feature and is it also defective?
mikey



Joined: 20 May 2013
Posts: 11

PostPosted: Fri May 24, 2013 8:24 am    Post subject: Reply with quote

Hi,

Yes I noted both front & rear of TV got audio & video jacks.Glad that you are helping me out. When I connected a DVD player to the problem 21" TV set, I got audio of the said DVD but black screen. To be sure I selected the correct input I also test the DVD player connect to a working 14" TV and got both audio and picture fine.
I retried again just now after shut off everything, connect only DVD player RCA audio & video cable to input side of the problem TV which is at the rear side. First I switch on the TV, see nothing but dark black screen and just hiss sound. Then I switch on the DVD player, insert a good DVD disc, press play. From TV speaker, I heard clear good sound but still dark black screen. I switch to input side of front jacks still same result.

As per your suggestion, I did another test to see output of the problem TV, I connected RCA jack audio & video output from this problem TV, select a working channel (got sound no picture) then output to a input section (input jack RCA audio & video) of a working TV (14"), but the working TV (14")show blue screen, got sound but no picture.

For your next question, I am not aware of "text" feature and do not know how to use. Maybe you kindly point me out which button on remote to use.

Thank you for your guidance.
JTS1957



Joined: 21 Jan 2009
Posts: 2340
Location: Far, Far Away

PostPosted: Fri May 24, 2013 9:37 pm    Post subject: Reply with quote

So to recap, you appear to have a NO VIDEO (has menus, has audio) condition. Although when screen is blue color/black/gray or screen blank/snowy is a little confusing - no matter.

Since this manual covers more than one set, your set may or may not have ALL the features covered on the schematic. I'm just trying to cover all possibilities. I'm also presuming you have TV set correctly for your location. I've been unable to find a block diagram of the connection paths INSIDE Q100 nor can I locate VT01 on the SCHEMATIC. There doesn't appear to be a pin to voltage chart so main schematic only shows pin ID and VCCs.

Although its tempting to see if the sets internal test pattern(s) are working (pg7, item 7), I believe they are relying on same path as the OSD (On Screen Display) which you say is working.

The good news is that at Q100 you are getting audio (and presumably video) from all three (Tuner and Front/Back jacks) inputs.

Since with a DVM you can't check for any "signals," (you would need a oscilloscope), the only confirmations you can make are for VCC's and DC voltage measurement "changes" of various points. Connect DVM black lead onto the tuner case/cover - Red lead to point under test. If you touching joints at the IC (Q100) itself is too dangerous as far as accidentally slipping and shorting to adjacent pads or pins, see if you can visually follow the foil trace to a safer joint.

With set ON and DVM set for DC, let's start with confirming appropriate VCC is arriving at the following:

5 Volts DC at Pin# 9 / #25 / #36 / #44 & #55

9 volts DC at pins #29 & #49
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