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Old 02-13-2018, 03:55 PM   #1
Ady2017
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Default Replacement capacitor

Hi all

Quick question. My old trusty CRT TV has got a bad cap. The original is 2200uF 6.3V and following a trip to my pretty useless local electronics shop, the closest match they had was a 2200uF 35V. It was cheap so I picked it up anyway.

I know you can fit ones of a slightly higher voltage but is 6.3V to 35V a bit too far and unsuitable?

Thanks
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Old 02-13-2018, 06:36 PM   #2
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Default Re: Replacement capacitor

The increase in voltage rating, of itself, is not a problem. But whether it is suitable (assuming it fits) depends on what the function of the capacitor is. If it's handling substantial ripple (AC) current the 35V part is likely to have a higher impedance and cause stability or noise problems or run hot and not last very long.
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Old 02-14-2018, 07:54 AM   #3
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Default Re: Replacement capacitor

Thanks for your reply. I decided not to use the 35V part but searched around and found the right part on an old power supply. After swapping it over the TV still had the same problem so although the cap was slightly bulged it was obviously ok. I am learning as I am going. Next step I need a more reliable way to test capacitors instead of putting a multimeter across them seeing if the resistance slowly rises.
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Old 02-14-2018, 10:29 AM   #4
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Default Re: Replacement capacitor

Maybe tell us the make, model and problem and we could help you.
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Old 02-14-2018, 10:30 AM   #5
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Default Re: Replacement capacitor

maybe one of these testers they test the esr etc of the capacitors too
https://www.ebay.co.uk/itm/Tester-GM...4AAOSwSypZAAVO
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Old 02-14-2018, 01:28 PM   #6
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Default Re: Replacement capacitor

Hi

Yes, the TV is a 28" JVC CRT TV. When you first switch it on, you get half the picture as a horizontal band and then after a few mins you just get single red/blue/green lines in the middle of the screen. After about 20 mins the picture come right and can stop on all night and run perfect. I have done some reading and I think it must be the vertical IC chip which is not working when cold. I have resoldered all the joints to the chip and have tried replacing a couple of capacitors anyway without any luck. I am a beginner at electronics repair but it makes sense. The IC chips are obsolete now from what I can see so I guess it is time for a new TV.

Thanks
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Old 02-14-2018, 01:33 PM   #7
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Default Re: Replacement capacitor

whats the ic part number? capacitors can look good but still be failed with low uf ratings or high esr as a test you can heat the area up with a hair dryer for a couple of minutes does the set then show a good picture?
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Old 02-14-2018, 02:04 PM   #8
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Default Re: Replacement capacitor

more likely its the screen bypass cap. something like 10-22 uf at 250 volts, near the flyback, or bad cap in the vertical output section.
Like I said post the MODEL NUMBER, should be AV-28????

Last edited by R_J; 02-14-2018 at 02:15 PM..
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Old 02-14-2018, 02:40 PM   #9
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Default Re: Replacement capacitor

Replace ALL the e-caps in the Vertical section (16V, 25V, 50V, etc). Re-flow the Vertical output IC pins and any suspicious cold solder joints in the Vertical section (be careful not to short out any connections). Look for Hi-Voltage e-caps. i.e. 160V, 250V (Not the main filter cap, as that is OK) and replace them, as well. There would be a 10uF 250V e-cap either on the CRT neck board or near the F/back Transformer in the middle-rear in the Horizontal section that may stand out. BTW the 2200uF 35V e-cap will work.
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Old 02-14-2018, 03:47 PM   #10
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Default Re: Replacement capacitor

Hi all

The model number of the TV is, AV-28F3SJ-BF.

I checked as many of the capacitors as I could with the Ohm setting of a multi-meter but as you say, I need to invest in a ESR meter to properly test them. When warm, the TV will work fine for hours on end and I often leave it on all night for the background noise. I did re-flow the solder on the connections to the IC but maybe they needed the solder completely removing and new applying.

This has been quite a learning experience but there is something about CRT TV's, they seem more like real TV's what I have grown up with. I even still remember when I way young, my dad had a big box of valves in the shed for the TV and used to have to swap the things when it stopped working.

Thanks again.
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Old 02-14-2018, 04:15 PM   #11
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Default Re: Replacement capacitor

Try replacing C801 10uf/250v and maybe C905 10uf/250v (on the crt neck board)

Last edited by R_J; 02-14-2018 at 04:18 PM..
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Old 02-14-2018, 04:52 PM   #12
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Default Re: Replacement capacitor

Thanks for this. It doesn't look like something the local electronics store (Maplins) keeps so I will order a couple and give them a try and will let you know.
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Old 02-17-2018, 11:22 AM   #13
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Default Re: Replacement capacitor

I have just replaced the 2 10uf/250v caps in the telly. One was C627 on the mainboard and the other C902 on the crt neck board. It has made no difference and the problem still persists. It must be the vertical IC chip, TDA8359J.

There is also something else on the main board that I do not recognise but looks like it has been getting hot as the board is quite discoloured around it and it is not connected to a heat sink. There must be 15-20 legs on the component.
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Old 02-17-2018, 11:33 AM   #14
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Default Re: Replacement capacitor

https://www.ebay.co.uk/itm/TDA8359J-...sAAOSwMl9aXhue

for capacitors you can open a account with rs components they are very cheap and have free delivery and no minimum order offers but if you want too use ebay this seller sells genuine Panasonic capacitors at a reasonable price as maplin ones wont last very long as only general purpose capacitors

https://www.ebay.co.uk/itm/Panasonic...pFYC0lUmNtpYdg

Last edited by vinceroger69; 02-17-2018 at 11:39 AM..
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Old 02-17-2018, 12:03 PM   #15
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Default Re: Replacement capacitor

Have you checked the voltages on the vertical ic, what are they (pin # - voltage)
I didn't quite understand the actual problem, I thought the rgb lines were the only problem.
You say the picture is compressed top and bottom when it is first turned on?
I must not have been using the correct schematic, the vert ic does'nt match in this one. must be a different chassis
I also made a typo. It should have read C601, not C801 but that would be to correct lines near the top of screen only.

Is there a chassis number somewhere? Is this circuit look right
You may have a low +50 volts to the ic, C620 may be badif that is the case.
If +14v_vert is low, C625 could be bad
Attached Images
File Type: jpg crt_vert_problem.jpg (37.6 KB, 6 views)
Attached Files
File Type: pdf Deflection.pdf (111.8 KB, 6 views)

Last edited by R_J; 02-17-2018 at 12:45 PM..
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Old 02-17-2018, 12:59 PM   #16
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Default Re: Replacement capacitor

Yes, the picture is compressed when you first turn the TV on and then it goes to just BGB lines and then comes normal. The 2 10uf 250v caps I changed were the only 2 in the TV. It looks like my set is a slightly different revision of the service manual as the vertical IC has a different number of TDA8359J (I hope I have located the right component).

Just trying to work out what the other component is. It looks similar to the vertical IC but is bigger and has more legs but it is no connected to a heat sink and there is no means of attaching it to one anyway. It is in close vicinity to the vertical IC so might be something to do with it.
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Old 02-17-2018, 01:01 PM   #17
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Default Re: Replacement capacitor

Now that you have done all that. I would replace the Vertical Output IC. As e-caps and cold solder joints have been replaced and fixed.
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Old 02-17-2018, 01:01 PM   #18
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Default Re: Replacement capacitor

Quote:
Originally Posted by Ady2017 View Post
Yes, the picture is compressed when you first turn the TV on and then it goes to just BGB lines and then comes normal. The 2 10uf 250v caps I changed were the only 2 in the TV. It looks like my set is a slightly different revision of the service manual as the vertical IC has a different number of TDA8359J (I hope I have located the right component).

Just trying to work out what the other component is. It looks similar to the vertical IC but is bigger and has more legs but it is no connected to a heat sink and there is no means of attaching it to one anyway. It is in close vicinity to the vertical IC so might be something to do with it.
https://www.promelec.ru/pdf/TDA8359J.pdf
whats the part number of the other ic then we can look at a data sheet

Last edited by vinceroger69; 02-17-2018 at 01:03 PM..
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Old 02-17-2018, 01:06 PM   #19
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Default Re: Replacement capacitor

I uploaded a different pdf, is this one correct?
It is from this manual: https://elektrotanya.com/tv_chassis_.../download.html

Last edited by R_J; 02-17-2018 at 01:08 PM..
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Old 02-17-2018, 01:09 PM   #20
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Default Re: Replacement capacitor

That is the frustrating thing about the other IC. The numbers are worn off of it so I can not find out what it is. I will study the schematics you sent tonight and try and work out what the thing is. What ever it is, it has been getting hot.
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