fixing tvs for a hobby

[slag]

Beware, incoming wall of text:

I dabble with Lawnboys and other small engines in the spring, boats and jetskis in the summer, and now, my fall/winter passion, DLP TV's.

I picked them because they are relatively cheap to pick up when broken, have a good picture, and haven't been all that hard to fix. Here's what I've fixed so far.

Last year I picked up a Mitsubishi 62725 tv. It had a ton of blown caps that, after replaced, ran flawlessly and has been our main movie watching TV in the basement (until this weekend, but thats later on).

Last week I found a 62525 in the paper for $35.00. Spent about 4 hours on it total, taking the chassis out, pulling it apart, replacing the obviously blown caps and groups of others that are prone to failure. Then I put it all back together, and gave it to sister so we have something to watch over Thanksgiving at her house.

While shampooing the carpet in my basement this weekend, I blew a breaker at my house and my TV wouldn't turn back on. The famous blinking green light of death!! Its been working great for over a year, but I took the chassis back out of it and replaced 14 SMT caps (Surface mount), that are known to go bad, even though they looked good. I put it back together, crossed my fingers, and its been working fine.

I just picked up another 62725 this weekend thats sitting in my garage, and am supposed to get another tomorrow night. I've been paying between $35.00 and $100.00 for the broken TV's and hope to be able to start flipping them for around $250.00 - $300.00 for a 62 inch TV. They look great and are huge. I suppose if I cant sell them, I might make an eyefinity display on my computer room wall

oh, one last thing. I had a 50 inch Samsung given to me (responded to an ad in craigslist), that turned off after 30 seconds. After a bit of research, it looks like all it needed was a new lamp. $74.44 later, I popped the new lamp in and have been watching it all weekend while I was working on other things on the first floor. Trying to decide between keeping it or the 32 inch LCD in my front room, both look really good.

 

[kornphlake]

good for you, I thought the TV repair tech had gone the way of the Dodo. I'm surprised with people being so energy conscious and environmentally aware these days more people don't try and repair a TV instead of sending it to the dump. When my 10 year old CRT let out the magic smoke I opened it up to look for something obvious and found nothing, I don't have strong electrical engineering skills but I did look for a repair man, I was only able to get a response from one and he said it would cost more than the price of a new television for him to fix it.

 

[slag]

good for you, I thought the TV repair tech had gone the way of the Dodo. I'm surprised with people being so energy conscious and environmentally aware these days more people don't try and repair a TV instead of sending it to the dump. When my 10 year old CRT let out the magic smoke I opened it up to look for something obvious and found nothing, I don't have strong electrical engineering skills but I did look for a repair man, I was only able to get a response from one and he said it would cost more than the price of a new television for him to fix it.

I wish I had more electrical knowledge and understanding of how to actually troubleshoot the problems. Right now I rely on my 40 watt weller soldering iron and the knowledge of others who like to share their information out on the web. I would like to have a capacitor tester, and have found the schematics to make one, but haven't gotten that far yet. For now, its easier to buy a large selection from digikey or mouser and just replace what might be bad.

 

[A5]

I wish I had more electrical knowledge and understanding of how to actually troubleshoot the problems. Right now I rely on my 40 watt weller soldering iron and the knowledge of others who like to share their information out on the web. I would like to have a capacitor tester, and have found the schematics to make one, but haven't gotten that far yet. For now, its easier to buy a large selection from digikey or mouser and just replace what might be bad.

You're doing it right so far - the caps and lamps are the main failure points for these things. Caps are an easy place for manufacturers to cut corners and still have the TVs fail outside of warranty. You probably won't be able to do much beyond cap replacement without schematics and a supply of the chips used on the boards (aka more effort than it's worth).

Also, make sure you have the TV unplugged for a long time before working on it to make sure the power supply capacitors are discharged for safety reasons.

 

[Modelworks]

Capacitor tester isn't necessary. Circuits that fail because of the capacitor are pretty easy to spot unless you move into some really sensitive components like RF circuits. Using a 40 watt iron is risky , you need temperature control . If a boards traces start to lift because of the excess heat you can end up having to replace the board.
The minimal equipment I would list that someone needs is:

Temp controlled soldering iron - to prevent circuit damage.
Digital Multimeter - AC/DC/ohms/current
Analog multimeter - AC/DC - Can show transients and spikes better than digital which takes too long to adjust to fluctuations.
sharp test leads for meters - prevents the probe sliding off a test point
Isolation transformer - for safety. Prevents contacting a hot circuit . Also prevents loops from harming test equipment.
cord with light bulb for testing power related issues. - basically an extension cord with a light bulb in series with one wire. If the device you are testing somehow shorts then the light bulb will glow brighter but nothing will blow.


That would be the minimum , if you have the budget add:

Logic Analyzer - doesn't need to be fancy, just something that can display I2C channels. I2c is used by onboard micros to control many of the functions. You can get a pretty decent hobby version for about $45
http://www.seeedstudio.com/depot/preorder-open-workbench-logic-sniffer-p-612.html?cPath=75

SMD Hot air rework station, makes SMD work much easier