EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: panoss on March 10, 2017, 11:45:29 am
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Hi everybody.
I have the above mentioned crt TV.
Won't power up.
I have lost the remote control, but if I remember correctly (haven't used this tv set for 3 years now), when I opened it with the remote control, the red LED would light up and then would shut off.
I suspect the power supply.
Here (https://elektrotanya.com/daewoo_cp185l_cp185g_chassis_tv_sm.pdf/download.html) is the service manual (wait about one minute till the download link gets created).
Any hints are welcome, I'm going to open it tomorrow, Saturday.
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I opened it and found the fuse (f801) opened (open circuit).
This might mean a shorted component, right?
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Is the fuse a regular glass thermal fuse? If it is, it could be a shorted component, however, this does not mean that there is a shorted component. Fuses can age and the actual fusable link will burn at a lower current than rated. This sounds like an older TV, has this fuse ever burned before?
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Is the fuse a regular glass thermal fuse? If it is, it could be a shorted component, however, this does not mean that there is a shorted component. Fuses can age and the actual fusable link will burn at a lower current than rated. This sounds like an older TV, has this fuse ever burned before?
It's not a regular glass fuse, it's a strange fuse, in the beginning I thought it's a diode bridge, this one:
(http://www.newark.com/productimages/nio/standard/4463305.jpg?01AD=3j3qDJGjWjhmdJMV0G4CDkrvTYUFK81DwAIdOZV-5mGyUF1c6YNEiRA&01RI=BF7DC44358F99B5&01NA=)
It hasn't burned before.
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Just like over at BadCaps, rule #1, you're going to have to post some decent photos if you really want the best help quickly. :)
I'm sure it is possible to get it running again unless it is a shorted flyback or something but also remember that Daewoo is pretty much the worst of the cheap Korean crap. They tend to use terrible quality everything in the products they make. :)
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Just like over at BadCaps..
You caught me! :D
Haven't found any short circuit.
I have classical glass fuses, 250V 3,5A and 250V 5A.
Should I try one of these?
EDIT: I also have 2A, 250V. Maybe two of them in parallel?
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Haven't found any short circuit.
I have classical glass fuses, 250V 3,5A and 250V 5A.
Should I try one of these?
EDIT: I also have 2A, 250V. Maybe two of them in series?
Do you know the fuse current rating? This looks like a micro fuse from Eaton and is available from Mouser. Link of spec sheet for similar type below. Perhaps you can order from Mouser or find similar delay fuse in standard glass type.
http://www.mouser.com/ds/2/87/Bus_Elx_DS_OC-2590_ETF_Series-477632.pdf (http://www.mouser.com/ds/2/87/Bus_Elx_DS_OC-2590_ETF_Series-477632.pdf)
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The fuse is:
Buss SR-5
T 4A 250V
I guess it's 4A, slow burn.
(I corrected from 'series' to parallel)
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The fuse is:
Buss SR-5
T 4A 250V
I guess it's 4A, slow burn.
(I corrected from 'series' to parallel)
Ok, wrong spec sheet before, here's new link to Cooper Bussman spec.
http://www.cooperindustries.com/content/dam/public/bussmann/Electronics/Resources/product-datasheets/Bus_Elx_DS_4347_SR-5_Series.pdf (http://www.cooperindustries.com/content/dam/public/bussmann/Electronics/Resources/product-datasheets/Bus_Elx_DS_4347_SR-5_Series.pdf)
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I would bring it up on a dim bulb with a new fuse (or the fuse temporarily jumpered but ONLY while on the dim bulb) and check for voltages, etc. to be sure there are no shorts.
To make the simplest possible dim bulb tester you basically just need an old extension cord, a bulb socket and one or more different wattage standard tungsten (or halogen) light bulbs. None of that new-fangled CFL or LED rubbish. :) I would expect a 60W, 100W (or at absolute most a 150W) would be about right for your TV but the thing does have a 4A fuse in it, though I highly doubt it doesn't actually draw anywhere near 4A, especially since Greece is 220v/240v, isn't it?
What is the nameplate wattage rating of your set, anyway?
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I would bring it up on a dim bulb with a new fuse (or the fuse temporarily jumpered but ONLY while on the dim bulb) and check for voltages, etc. to be sure there are no shorts.
I thought that with a bulb in series, the voltages would be lower than normal, because of the limited current.
To make the simplest possible dim bulb tester you basically just need an old extension cord, a bulb socket and one or more different wattage standard tungsten (or halogen) light bulbs. None of that new-fangled CFL or LED rubbish. :) I would expect a 60W, 100W (or at absolute most a 150W) would be about right for your TV but the thing does have a 4A fuse in it, though I highly doubt it doesn't actually draw anywhere near 4A, especially since Greece is 220v/240v, isn't it?
Yes I have such a tester laying somewhere around, I had made it with an incandescent light bulb (from my first tv repair, so I'm not a total newbee :)), I think 60W.
Yes, the voltage is 230V.
What is the nameplate wattage rating of your set, anyway?
You mean what is written on the back of the tv set? It's 49 Watts.
I will try it with the 'tester' tomorrow, I hope at least I get some measurements (and no explosion :D).
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I replaced the fuse with two glass fuses in parallel (they 're 250V 2A each) and did the test with the light bulb (60W incandescent).
The bulb was fully lighted, the tv didn't power up.
So, I suppose, the short circuit remains (??).
I measured voltage at pin 1 of I801, it was 25V and was not steady, it was dropping, 24, 23, 22, 21...
I don't know what this measurement means, as I have the light bulb in series with the tv.
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I made some progress!!!
I removed the posistor.
(with the light bulb connected)
I powered it up:
the tv seems to start up(!!), the bulb is in the beginning not lighting.
Then the light of the bulb increases and tv starts to 'fade' (like working with less and less power).
This circle continues repeatedly, the light increases - decreases.
So I guess the defective component is the posistor!
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I connected two lamps in parallel (60W||40W like having a light bulb of about 15W) and...turns off and on with lower frequency.
Edit: I connected it without any lamp, works fine (I hope it lasts)!!!
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From this (http://eu.mouser.com/ProductDetail/Bussmann-Eaton/SR-5-25A-AP/?qs=2W5sgKM%2f370ZeSwgsS0KuQ==), I read:
Fuse Type: Time Delay / Slow Blow
So Time Delay = Slow Blow, right?
So it can be replaced by a simple glass fuse slow blow, right?
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I found out that the posistor can be checked with an ohmmeter:
pin 2 to 1: 580 Ohm.
pin 2 to 3: 15 Ohm.
These mean my posistor is ok.
So, final diagnosis: the fuse just died.
Parts replaced: C832, C834, fuse. (C832 & C834 replaced even though they seem ok)