Sanyo (No Power) DP26748

[Keshetisrael]

Namaste..

Well.. I am about to share with you, my First 'real' FULL TV Fix.

I figured I'd share the whole process, step by step and ask for help wherein I could use it (help others by following this Thread & commenting), right here on BadCaps.Net. Thanks for the Forum & the opportunity to share this with Ya'll

To start, I have to thank Tom for this site, and it having the Service Manual I needed for this TV.. DP26746 @ http://www.toms-service-manuals.com/

However, I have to notify you Tom, that 'view pdf' doesn't work..
I had to download it which is fine. here

I hope to learn as I go from those who help by commenting in this thread.

Whenever I get to a next step in the Process, I'll do my best to explain how I found 'the Next Step', and I'll ask 'The Forum audience' certain questions which someone just starting (like myself), might have.

Project: Sanyo DP26746 Manufacture date: Oct 2006

Pics: https://drive.google.com/file/d/0B3ICRe51lCaCeEVUV1BmQU90Y0k/edit?usp=sharing"
https://drive.google.com/file/d/0B3I...it?usp=sharing
https://drive.google.com/file/d/0B3I...it?usp=sharing
https://drive.google.com/file/d/0B3I...it?usp=sharing https://drive.google.com/file/d/0B3I...it?usp=sharing
https://drive.google.com/file/d/0B3I...it?usp=sharing
https://drive.google.com/file/d/0B3I...it?usp=sharing

Problem: T.V. won't Power On. No LED to Power Switch even?!
Safety: Step One!

Safety Question: Page 2 of Manual : Antenna Cold Check

:::: Should This Test Always be a necessary First Step? :::::::

https://drive.google.com/file/d/0B3I...it?usp=sharing

https://drive.google.com/file/d/0B3I...it?usp=sharing

https://drive.google.com/file/d/0B3I...it?usp=sharing

Safety Question II ::::
https://drive.google.com/file/d/0B3I...it?usp=sharing

1. An Isolation Transformer. What's the safest, Easiest & cheapest way of accomplishing this? Buy an Isolation Transformer? Does anyone have a schematic for making one for cheaper? Searching about this, I found this video.

I don't have an isolation Transformer, so for the purposes of continuing this project, I am going to just be 'extra' careful wherein I put my probes and only use my https://drive.google.com/file/d/0B3I...it?usp=sharing
https://drive.google.com/file/d/0B3I...it?usp=sharing, Rather than my https://drive.google.com/file/d/0B3I...it?usp=sharing

For safety, to start this project I have to take apart an electrical strip.. because the house I'm working in doesn't have 'earth ground' plugs! Just so you know, I myself put a 8 ft Ground Rod right outside my Bedroom and ran an #8 Ground wire into a four foot electrical Strip I got from Harbor Freight. problem is, I have too Much stuff on my work bench and it's too small for large Tv's.. so I've made my Bed, my work bench for TV's.. and put my oscilloscope.. well... On my Bed! :P 2 more days and I'll be working on a new WorkBench in a different room.

::::Safety precaution: Ground your Equipment, and make sure you keep one hand in your pocket when moving your test probes! ::::::

Ok.. Following the Troubleshooting Flow Chart for 'No Power' (Visually Checked for Bad Caps.. none found!)

https://drive.google.com/file/d/0B3I...it?usp=sharing

1. Is the Fuse (F601) Open ?
(Checked: Fuse is working, AKA: It shows Continuity! )

2. Is the Voltage 5v_STBY line supplied?
(Checked: YES!)

3. Is the voltage to all lines supplied?
checking this, I could hear the tv click on but without video. Then turn right back off. I noticed that the power was inverting from negative to positive. However, suddenly it stopped doing this. I can no longer get the tv even to click on.

So.. I'm stuck already. And mad at myself for sticking the probe around the board, and seeing the fluctuations. Now it won't power on at all. Great! Now what?!

[tom66]

Re: Sanyo (No Power) DP26748

I have an isolating transformer, but I've never used it. The antenna cold check thing will be something you should do if you intended to sell a TV, for liability reasons more than anything else.

A very good first step is to provide pictures of the boards in your TV. Clear, in focus, and as high detail as you can.

[Keshetisrael]

Re: Sanyo (No Power) DP26748

This TV is the Mother of All TV's for me.. if I can fix this then I'll move on to wanting to fix other one's. If I fail, I can't find my confidence to continue.. so this is a big TV for me.. though it's only 26" .lol

Anyways.. I was thinking about this last night, and I was completely thinking I blew up the power board, but this morning it powers on with a click again.. so that makes me feel good.

What I'm wondering, is it a good assumption to believe it could be the Video Board, because I can't get video at all, even after it clicks on till it clicks off. Not even the back light clicks on at all.. during those few seconds before it clicks off. So.. instead of going by the Trouble shooting Flow chart for 'No Power', should I goto the flow chart for 'no video'?

And Why hell wouldn't someone making a system manual, make it easy to look and see how many volts are to be going out of each leg of ever component? Ok.. maybe you can't answer this one..

Another question.. it says on the bottom of the flow chart for 'no power', to 'Check 'Power Failure' Circuit. Sanyo DP26746

Namaste... Need to start listing my Fixes..at the bottom of my name too!

I've Fixed: 3 LCD Monitors, 2 Video Cards, 2 motherboards, 2 Televisions.

I'm a computer guy, trying to add Android phones, Game Stations & Televisions to my skills.

[newtothis]

Re: Sanyo (No Power) DP26748

Ok lets start with some good pictures of the boards and close up shots of any connectors, PSU is a good place to start

[newtothis]

Re: Sanyo (No Power) DP26748

Lets start with the connector from PSU to Mainboard... Check pin 7 with your DMM on 20v DC.

[Keshetisrael]

Re: Sanyo (No Power) DP26748

Ok lets start with some good pictures of the boards and close up shots of any connectors, PSU is a good place to start

You can't see the Pictures listed in my original post? I do believe I gave all of the pictures.. but if there's a better way .. please let me know..

[newtothis]

Re: Sanyo (No Power) DP26748

Yeah i spotted them afterwards, just used to seeing uploaded pics... check that pin in my previous post

[Keshetisrael]

Re: Sanyo (No Power) DP26748

Here are some Pictures:
Power Board
DP26746 MainBoard
mainboard connectors

Service Manual

If you need anything else.. just ask.. thanks for your comments.. now.. onto the 20v connector you were talking about..

[newtothis]

Re: Sanyo (No Power) DP26748

Set your DMM to 20vdc and ground the black probe to the chassis (spare screw hole is good) and red probe to PIN 7 of the connector (K6R) ... Give me your reading

[Keshetisrael]

Re: Sanyo (No Power) DP26748

I don't have an earth ground on this TV.. only two prong plug.. does the Chassis actually work as a ground? If I count up.. pin one is at .0001 if I count down it's .0001.. also....HMM

I just changed my meters because it didn't seem right.. my other meter reads 5.11 v

[newtothis]

Re: Sanyo (No Power) DP26748

yes chassis is still ground,

5.11 volts is right.

OK, can you go across the pins 1 at a time and take readings for them... reply back like this,

1 = 24v
2 = 24v
3 = 0v

etc etc

[Keshetisrael]

Re: Sanyo (No Power) DP26748

K6R > Power Board to Mainboard

8. 0
7. 5.11
6. 0
5. 0
4. 0
3. 0
2. 0
1. 0

[newtothis]

Re: Sanyo (No Power) DP26748

Ok so you have standby voltage but no other lines present.

PSU definitely at fault there

Can you check diodes D1630, D1633, D601 and D670

You will have to desolder and lift one leg of the diode from circuit to test, Use diode setting on DMM

[Keshetisrael]

Re: Sanyo (No Power) DP26748

ok.. let me ask you .. if you were doing this, would you remove the whole board? Then unsolder & Test, each of them; one at at time?

I ask this because it appears the first diode you mentioned is on the underside D1630 (I can see it listed on the 'Foil Side') but not on the other side. And since the Diode test doesn't require power it seems the easiest route.. what have you found?

wow.. turned over the board and there's a big dark spot on it.. where it obviously blew..

[Keshetisrael]

Re: Sanyo (No Power) DP26748

Maybe I jumped to a wrong conclusion.. because I just cleaned it up some and it looks a little better. what is all this orange fluid spill or whatever it appears to be.. do you know? And the Diode is a very small black surface mount component. Since there's no legs.. how do you go about checking this diode?

[newtothis]

Re: Sanyo (No Power) DP26748

What was in place there... Dxxx?

Be either flux or varnish

[Keshetisrael]

Re: Sanyo (No Power) DP26748

You mean that darkest spot.. R678 on the other side of the board. I turned it over and that Resistor is Glued Completely. Here's a pic for D1630 which I'm suppose to test.... seeing the brownish discoloration.. under this resistor, should I just continue with the original diode tests and ignore that? Do I remove the whole SMD diode completely, and test them one by one?

[Keshetisrael]

Re: Sanyo (No Power) DP26748

Telling me it's definitely a power board issue, is this where most people would go and directly buy the power board, and stop searching? Because I'm not trying to learn to fix Televisions as much as trying to figure out how to always find the problem with them. Once I can do this confidently, the repair shouldn't be a problem. Learning the Right Troubleshooting path & tips is my hope. So, Thanks again for sharing and being patient.

[Keshetisrael]

Re: Sanyo (No Power) DP26748

I also noticed you skipped straight to Diodes, rather than pointing me to CPU (1C801), IC (IC802, Ic 1803), Crystal (X801), Transistor (Q1609, Q1610, Q1611,,QQ602,Q670) found on the Flow Chart... Do Diodes go out more often, is that why you pointed me to them first?

[newtothis]

Re: Sanyo (No Power) DP26748

Where i have had no power across a board but still had the 5v stby i found open diodes.

Can you just run a check on that resistor to make sure