Author Topic: repairing crt tv, start with recapping  (Read 14107 times)

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Offline xmetal

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Re: repairing crt tv, start with recapping
« Reply #25 on: August 30, 2019, 05:25:18 pm »
the red ones says 0.12j so there are 100pf/0.1uf with 5% tolerance?

I would say they are 120nF (0.12uF) 400V 5% caps.
« Last Edit: August 30, 2019, 05:27:52 pm by xmetal »
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #26 on: August 30, 2019, 06:18:35 pm »
ok meter says 11.5ohm good if<10uf so they are good too

i got two that the meter cant measure, the green one(cant read the value) and a yellow one 4n7j100. the rest seam ok to me.

i think i will do a testrun today or tommorrow, i got the ice spray but its flammable i dont know if thats a good idea on the back of my tv?
this north south module is a correction for the planar? tube. isit possible to bypass this module and hock my yoke directly in the mainboard without destroying something?
 

Offline Benta

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Re: repairing crt tv, start with recapping
« Reply #27 on: August 30, 2019, 06:39:25 pm »
It seems you're a bit in over your head here.
Like I said, start with the high voltage section, odds are your problems are there. Resolder everything.
N/S and E/W correction are secondary, don't start fiddling with that until the basic functionality is right, which is making certain that your horizontal deflection, high voltage generation and auxiliary voltage generation works 100%. This is all in one 15625 Hz transformer/circuit, by the way.

Pay special attention to the safety capacitors across the primary of the horizontal transformer. These need to be soldered 100% reliably.

Cheers.
« Last Edit: August 30, 2019, 08:46:01 pm by Benta »
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #28 on: August 30, 2019, 07:13:51 pm »
first time working on a crt:)
ok i will do that.

can you tell me where this cap is?
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #29 on: August 30, 2019, 07:41:49 pm »
look something was hidding under the plastic :)) i could spot 2 more but this was the worst of them
 

Offline Benta

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Re: repairing crt tv, start with recapping
« Reply #30 on: August 30, 2019, 08:44:32 pm »

can you tell me where this cap is?

It's the snubber network with LL02, CL04 and RL05. These make certain that the HVT does not produce too high voltages.

But you're already finding the relevant places for resoldering :)

 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #31 on: August 31, 2019, 04:05:14 pm »
i have found this parts, i will add a pic in the next post(size too big)

santa was here and brought my desolderstation :) i have found some black stuff looks like the big psu cap. in the pic bottom right*. i will update after i resolder everything

*the forum rotated the pic
« Last Edit: August 31, 2019, 04:11:23 pm by 2takt »
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #32 on: August 31, 2019, 04:09:13 pm »
so here are the safety parts
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #33 on: September 01, 2019, 08:45:58 pm »
i found 2 leaking caps the big psu cap had some brown crust on the underside and the other has even more. and it looks like this other is hooked to Audio 0V, like vk6zgo said.

so how do i find replacements for this?
the psu cap:
330 uF 385V  LL
057 90009
M HP 9320
40/085/56
Philips
ESR meter: 0,046ohm

the other cap:
1000uF 63V
85°C (VX)
9310(M)
Taicon
ESR meter: 0,021ohm

meter says caps are good low esr.

i got half of the board resoldered, hope i can finish it tomorow.
greetings
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #34 on: September 06, 2019, 09:50:09 pm »
hi i have finished the soldering today, and it works no problems :) thank you for your help!

i have attached the pics from the caps, i would like to get new ones. what do you guys suggest?
 

Offline Ysjoelfir

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Re: repairing crt tv, start with recapping
« Reply #35 on: September 09, 2019, 11:21:58 am »
The big one looks actually ok, the small one - not so. There is some corosion on the pins, so I would definitely exchange that one. The bigger one.... it depends. If you can afford it and find a suitable replacement, replace it.
Depending on the city you live in I could look in my cap stock pile if there is a fitting replacement waiting.
Greetings, Kai \ Ysjoelfir
 

Offline Benta

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Re: repairing crt tv, start with recapping
« Reply #36 on: September 09, 2019, 08:06:33 pm »
The big one's OK, the small one is leaking, which can be seen on the PCB.
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #37 on: September 12, 2019, 07:44:18 pm »
the big one also had a round(leaking) mark on the pcb.

i life in germany.

i couldnt find any detailed information(again) about this two caps. the thing i found was:
https://www.datasheets360.com/part/detail/tvx1h221m/381254941137251487/

how do i find out what caps i need for replacement. so i already know they are low esr, what else is important besides the uF and V rating


i did notice when the tv is turned on there is a really small flicker on screen(noticeable on letters) but is gone after 10minutes. is this a normal behavior when cold?

the image is a little bit curved on the sides, has this something to do with my repairing? i have the service manual so i can programm the picture to be square again. but have to check the "system voltage" first. it should be 148V, can you tell me where i have to measure?
 

Offline SparkyFX

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Re: repairing crt tv, start with recapping
« Reply #38 on: September 12, 2019, 08:15:52 pm »
i life in germany.
We too... check the country flags. Which city/area?

Quote
one last question i also ordered this cheap oscilloscop dso 138. the service manual says:
the chassis is isolated from line voltage. the isolation point is in the line section.
can i measure the chassis without a isolating transformer?
The BNC ground is usually connected to protective earth, therefore it is not isolated in the sense of running the device-under-test with an isolation transformer. In most cases, all BNC sockets on the front panel share the same ground, so whatever you touch with the probe ground is live on those BNC sockets -> horribly unsafe to work with, without further provisions.

Quote
how do i find out what caps i need for replacement. so i already know they are low esr, what else is important besides the uF and V rating
Capacity, voltage rating, temperature rating, the footprint of the part, obviously. ESR is usually somewhat defined by type of capacitor.

Quote
the image is a little bit curved on the sides, has this something to do with my repairing? i have the service manual so i can programm the picture to be square again.
Even if the pillow setting can be done in software, first sort out the line transformer issue. These deflection grids are probably not working as intended when hit by the beam (lines that are not on the screen probably end in them).

Replacing the leaked capacitors is probably a move in the right direction.
Support your local planet.
 

Offline Gyro

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Re: repairing crt tv, start with recapping
« Reply #39 on: September 12, 2019, 08:21:52 pm »
the big one also had a round(leaking) mark on the pcb.

Leakage marks... or just residue from board cleaning / normal environmental contamination? Hard to say but I think it is the latter - I can't see any sign of leakage around the terminal pins or bottom rubber, just marking on the end of the plastic sleeve.

It's worth at least thinking about replacing some caps after you've gone to the trouble of removing them but consider cost also. The caps around when that TV was built wouldn't have been the same as the ultra-low ESR ones used in compact, high switching frequency, SMPSs these days.

The factors determining capacitor replacements are capacitance value, voltage, ripple current (which effectively covers ESR too in these caps), temperature spec, and physical size / pin spacing. Remember that this is consumer equipment, the originals wouldn't have been exotic. With modern caps, you sometimes need to select a higher voltage part - simply to make the physical size big enough.

It's easy to 'see' picture defects in CRT TVs these days when you're used to modern digital LCD TVs. A bit of flicker on an interlaced screen is normal, as is a bit of curvature (which can probably be adjusted out if it really bothers you), I'd keep adjustments to a minimum.

The service manual ought to be specific on the voltage measurement points, often also marked on the PCB (with care!).
Best Regards, Chris
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #40 on: September 13, 2019, 05:23:41 pm »
i didnt see the country flags :) i life near kaiserslautern rheinland-pfalz.

i think i will stay away with my oscilloscope from the tv. i will train me on lower volt equitment first! and i have no isolation transformer

i will search for some spare caps, when i find something i will post it. so the only things that are importent is V uF and ESR. i will search for this over 100°C caps. i already read that i can go a little higher with V.

deflection grid, what is this in german? i think the picture was square befor i started working on it but i didnt look for it.. so i will get the leaking cap new and then we will see.

befor the pictures i cleaned the board with a vacuum, no liquids. the caps are a bit apart and there are other caps in between with no marks. the color looked the same(the small one had more gung so the colour was darker). on the underside of the pcb i found some black stuff(cap juice?)

i found other caps with "colored" legs but there was nothing to see if something had leaked.

i thought the same about the flicker, maybe it was this way. but it got away after 10mins and i used the program list of the tv, this shouldnt be an interlaced screen?!

yes the service manual tells me the points, i searched the schematics but couldnt find them. i think i have to look again. the system voltage should be in the psu area?


 

Offline 2taktTopic starter

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« Last Edit: September 13, 2019, 05:41:59 pm by 2takt »
 

Offline Gyro

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Re: repairing crt tv, start with recapping
« Reply #42 on: September 13, 2019, 06:56:00 pm »
i think i will stay away with my oscilloscope from the tv. i will train me on lower volt equitment first! and i have no isolation transformer

Good plan! Stay far away from the TV with your scope - a handheld DMM should be all you need for a CRT TV.

I thought the same about the flicker, maybe it was this way. but it got away after 10mins and i used the program list of the tv, this shouldnt be an interlaced screen?!

yes the service manual tells me the points, i searched the schematics but couldnt find them. i think i have to look again. the system voltage should be in the psu area?

I would be surprised if the TV suddenly switched to non-interlaced when the program list is up, I think it will probably always be interlaced.

Regarding the 148V measurement. Looking at your partial schematic in reply #28, it is the signal named 'USYS', the only place I can see it is on Pin 8 of the line output transformer, LLO1 (makes sense as it is the regulated HT line feeding the line output stage). The LOPT isn't the safest place to measure it though, you should be able to find it in the PSU area (not on the partial schematic photo).
« Last Edit: September 13, 2019, 07:00:47 pm by Gyro »
Best Regards, Chris
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #43 on: September 13, 2019, 07:46:37 pm »
ok this helps me. i have added the rest of the schematics. would DP56 be a good measure point?

i should measure from the underside? because its near the line output transformer
 

Offline Gyro

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Re: repairing crt tv, start with recapping
« Reply #44 on: September 13, 2019, 08:17:02 pm »
I don't know if you have safe access to the underside of the PCB when it is operating. If so, then CP54 looks like the biggest target. Harder to mis-identify.

Please don't do it if not confident in your ability.

The safest way, after checking that the capacitor is discharged, is to solder on a pair of wires and attach these to your meter probes (and insulate) before powering the TV. Your hands are then free.
Best Regards, Chris
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #45 on: September 13, 2019, 08:28:30 pm »
i dont want to get near the 31kv when its on, so the upsite i wouldnt do. i will check it tomorow if the cables are long enough for rotating 90° but your suggestion is great! i think i go with yours.

negative i can get from the shielding? the neckboard has a black ground cable that goes the shielding of the mainboard
« Last Edit: September 13, 2019, 08:31:41 pm by 2takt »
 

Offline Gyro

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Re: repairing crt tv, start with recapping
« Reply #46 on: September 13, 2019, 09:06:41 pm »
negative i can get from the shielding? the neckboard has a black ground cable that goes the shielding of the mainboard

Probably (without tracing it out). If measuring at CP54, you can simply measure across the capacitor - or at least continuity check between CP54 negative and the shielding first.
« Last Edit: September 13, 2019, 09:08:29 pm by Gyro »
Best Regards, Chris
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #47 on: September 13, 2019, 09:38:48 pm »
ok i will update the result tomorow
 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #48 on: September 14, 2019, 06:56:04 pm »
i got 148.3 v on start up and it goes up to 148,5. this should be good?
i do a longer testrun right now.

 

Offline 2taktTopic starter

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Re: repairing crt tv, start with recapping
« Reply #49 on: September 14, 2019, 08:09:10 pm »
still on 148,5v

i added a pic so you can see its just a little off

the first line is displaying green red and black flickering. it disappears when i zoom in.

 


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