Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
|
#1
|
|||
|
|||
Hitachi TV Takes 10 Minutes to Work !
I have a Hitachi colour tv which is 20+ years old, it is not a "warm
up" tv, it usually switches on immediately. Just recently, when switching it on it has a very thin horizontal line, the rest of the screen remaining black. After leaving it on for about 10 minutes the whole picture immediately reappears. Sound is unaffected. Would anyone have any ideas as to what might be wrong...? |
#2
|
|||
|
|||
"Mike" wrote in message ups.com... I have a Hitachi colour tv which is 20+ years old, it is not a "warm up" tv, it usually switches on immediately. Just recently, when switching it on it has a very thin horizontal line, the rest of the screen remaining black. After leaving it on for about 10 minutes the whole picture immediately reappears. Sound is unaffected. Would anyone have any ideas as to what might be wrong...? Apart from the line now burned into the screen? N |
#3
|
|||
|
|||
The line does not appear to have burned into the screen. It's just a
thin line of white light. Though you can see movement in the light, as if the tv picture is still being shown on the thin horizontal line. Though as the line is so thin, it's not possible to see any picture, just the movement of the light. Once the picture reappears after 10 minutes, there is no line visible. The picture is normal. |
#4
|
|||
|
|||
"Mike" wrote in message ups.com... The line does not appear to have burned into the screen. It's just a thin line of white light. Though you can see movement in the light, as if the tv picture is still being shown on the thin horizontal line. Though as the line is so thin, it's not possible to see any picture, just the movement of the light. Once the picture reappears after 10 minutes, there is no line visible. The picture is normal. It'll burn into the phosphor pretty quickly if you use it like that, I would recommend unplugging the set immediately until the fault has been repaired, it's a simple fix so far. |
#5
|
|||
|
|||
Mike wrote:
I have a Hitachi colour tv which is 20+ years old, it is not a "warm up" tv, it usually switches on immediately. Just recently, when switching it on it has a very thin horizontal line, the rest of the screen remaining black. After leaving it on for about 10 minutes the whole picture immediately reappears. Sound is unaffected. Would anyone have any ideas as to what might be wrong...? vertical output section check for solder joint cracks around the vertical section. also, spraying component cooler on said components after which the TV has started to work may help in finding a bad semiconductor. -- Real Programmers Do things like this. http://webpages.charter.net/jamie_5 |
#6
|
|||
|
|||
Thanks Jamie!
I'll check for that... thanks |
#7
|
|||
|
|||
On 10 Jul 2005 04:20:18 -0700, "Mike"
wrote: Thanks Jamie! I'll check for that... thanks As long as you continue to use it that way, turn the brightness down every time before shutting it off. If it is digital on-screen menu controls you'll have to remember how many key strokes to get to brightness. Tom |
#8
|
|||
|
|||
Thanks Tom,
no there's no on-screen menu as the tv is over 20 years old. No remote control either... Shows how good Hitachi tv's are, as it's never given any problems before! |
#9
|
|||
|
|||
Is there any easy way of knowing where the vertical output section is?
I took the back off the tv, and was hoping it would be marked "vertical output", but it doesn't appear to be... It's a Hitachi CPT 2224 There's a small circuit board attached to the very centre of the back of the screen, there's two solder joints that look as if there's a hole going through them. They're marked GND and K1. Thanks! |
#10
|
|||
|
|||
Hello, Mike!
You wrote on 11 Jul 2005 04:40:13 -0700: M It's a Hitachi CPT 2224 M There's a small circuit board attached to the very centre of the back M of the screen, there's two solder joints that look as if there's a hole M going through them. They're marked GND and K1. Don't think that's it Mike, your looking at the CRT pins. The vertical oscillator section will be on the mainboard. I don't really recommend you try to fix this yourself, as you really need access to the solder side of the main chassis, and there are potential (no pun intended) problems concerning dismantling reassembly and safety that call for a bit of experience. Take it to a repair shop, at this point the repair is likely to be an easy one, but an inexperienced repairer could soon fix that. :^) Best of luck. With best regards, 3T39. E-mail: |
#11
|
|||
|
|||
Thanks 3T39
I was about to contact a repair shop, when I managed to find the vertical section on the motherboard. I gave it a clean with a cotton bud, as it was thick with dust. The tv's over 20 years old. Anyhow, it seems to be working now...! It was mentioned above about spraying component cooler on the components after the TV has started to work which may help in finding a bad semiconductor. Out of curiosity, what is this component cooler? Is it something like WD40? Or something completely different? |
#12
|
|||
|
|||
Mike ha escrito: Thanks 3T39 I was about to contact a repair shop, when I managed to find the vertical section on the motherboard. I gave it a clean with a cotton bud, as it was thick with dust. The tv's over 20 years old. Anyhow, it seems to be working now...! There is no way on earth that dusting the set will bring about a repair to this sort of problem. You have treated the symptom not the cause. If you are serious about getting this eert working `properly, *Take the advice given you and get the set in to a tech who will do the necessary simple soldering*. -B. |
#13
|
|||
|
|||
Mike wrote: Thanks 3T39 I was about to contact a repair shop, when I managed to find the vertical section on the motherboard. I gave it a clean with a cotton bud, as it was thick with dust. The tv's over 20 years old. Anyhow, it seems to be working now...! There is no way on earth that dusting the set will bring about a repair to this sort of problem. You have treated the symptom not the cause. If you are serious about getting this unit working properly, *Take the advice given you and get the set in to a tech who will do the necessary simple soldering*. It sounds like you may be out of your depth here. -B. |
#14
|
|||
|
|||
Hello, Mike!
You wrote on 11 Jul 2005 07:58:10 -0700: M I was about to contact a repair shop, when I managed to find the M vertical section on the motherboard. M I gave it a clean with a cotton bud, as it was thick with dust. The M tv's over 20 years old. M Anyhow, it seems to be working now...! M It was mentioned above about spraying component cooler on the M components after the TV has started to work which may help in finding a M bad semiconductor. Out of curiosity, what is this component cooler? Is it something like WD40? Or something completely different? It's possible that your probing with a cotton bud has moved the faulty joint and caused it to connect a little better, but I'm in no doubt It's still there. I say joint, because reading your posts, I think on balance it's a little more likely to be a bad, thermal sensitive, joint than a faulty component. But of course I could be wrong here. It's the solder side of this mainboard around the vertical oscillator that you need the magnifier, reflow any bad or cracked joints. Concentrate on the items that use most power ( big stuff, and anything fastened to a lump of aluminum) as these will fail first. The cooler mentioned earlier is basically a chemical with a very rapid evaporation rate in a spray can, so when a component is sprayed the evaporation carries away huge chunks of heat. With best regards, 3T39. E-mail: |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Anyone need ANY of these parts?? | Electronics Repair | |||
DIY electrical work after 1st January 2005 | UK diy | |||
scroll saw for metal work | Metalworking | |||
Kelton Balancer Review Draft--long | Woodturning |