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Old 14th Jan 2019, 11:37 pm   #141
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Default Re: CRT is brighter to one side [Hitachi CTP213]

I did actually wonder if I had knocked one or some of them.

However, I don't know which, as there is about 12 of them all together. But I think the main ones would be the blue ones on the neck of the tube, or the off white one on the chassis itself.

Should they also be OK to change, with the TV turned on and the back off the set without a isolating transformer? (I should really get one soon)

Yet again - Just want to make sure.


Thanks
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Old 15th Jan 2019, 12:07 am   #142
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Default Re: CRT is brighter to one side [Hitachi CTP213]

There is unlikely to be a crack in the board.
The cracks I would be looking for are very fine and in the copper usually at the edge of the solder where a part has been replaced.
The copper comes away from the board and often cracks at the junction between the soldered bit and the plane copper under the usually green lacquer.
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Old 15th Jan 2019, 12:29 am   #143
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Default Re: CRT is brighter to one side [Hitachi CTP213]

I'll have a look tomorrow when I get home. I think there was some replacements done in the past, as the soldering looks slightly different to the usual precision soldering.


Thank you all for your help!
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Old 15th Jan 2019, 11:34 pm   #144
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Default Re: CRT is brighter to one side [Hitachi CTP213]

I've just had a look, and I think I've found a crack. I'm not 100% sure if it is a crack, I did think it could be some dirt but I got some IPA and a cotton bud, and cleaned the area and it didn't make a difference.

The crack is next to a capacitor I replaced, so could be because of this.

How would I fix it? Do I need to get another capacitor and keep the leg and fold it over, or is there another way?

Thanks
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Old 15th Jan 2019, 11:38 pm   #145
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Default Re: CRT is brighter to one side [Hitachi CTP213]

See Refugees post 137 on how to repair the cracked joint.
No need for a new cap at this stage, just resolder.
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Old 15th Jan 2019, 11:43 pm   #146
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Default Re: CRT is brighter to one side [Hitachi CTP213]

Sorry if this is a simple thing, but should I resolder the tracks, or the feed outs to the track, as I cut the remaining metal off the feed outs back when I replaced the caps.

Thanks for the fast reply!
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Old 15th Jan 2019, 11:53 pm   #147
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Default Re: CRT is brighter to one side [Hitachi CTP213]

Scrape away the solder-mask for a few mm either side of the crack. Either bridge with a nice smooth blob of solder, or if the crack has opened even slightly, preventing the solder flowing across, solder a little piece of tinned copper wire like a cut-off component lead across it. There's no need to disturb the capacitor

BTW, are you using 60/40 leaded solder? You should be, as lead-free solder will not work well on old equipment that was made with leaded, and your joints will be poor.
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Old 16th Jan 2019, 12:01 am   #148
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Default Re: CRT is brighter to one side [Hitachi CTP213]

I don't usually link to this sort of thing - too much clickbait and half-baked 'advice' from people who don' t really know what they're on about - but this shows quite well how to prepare the board trace prior to remaking the joint.
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Old 16th Jan 2019, 12:33 am   #149
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Default Re: CRT is brighter to one side [Hitachi CTP213]

Hi, thanks for the replies.

Ben - Thanks for the link, Iíll have a read of that after writing this.

Lucien Nunes - Thanks for your help - Itís really appreciated. About the solder, im not sure. I have a kit that was given to me so iím not sure which it is. I use the solder which is given in the kit.

I can have a look tomorrow to see if there is any information in the kit, but i donít think there is.

Thanks
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Old 18th Jan 2019, 11:01 pm   #150
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Default Re: CRT is brighter to one side [Hitachi CTP213]

Update:

PCB didn't have a crack, it was just some grime which looked like a crack.

I guess my next shot is to have a look at the resistor and diodes which were mentioned before my 1100 Man.

Thanks for your help
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Old 21st Jan 2019, 8:52 pm   #151
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Default Re: CRT is brighter to one side [Hitachi CTP213]

Hi,

I'm just about to test the components 1100 Man said to test, diodes, resistor and capacitors.

I was unsure of which to test for a diode as it's said CR703 has gone short circuit, but is then said to test CR103

Quote:
The most likely is that the diode CR703 has gone short circuit. It could also be C731 or C850 although these are both small value non electrolytic types so are not that likely to fail. You would need to test CR703 with a multimeter to confirm if it has failed.
Should I test CR703, or CR103.


Thanks
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Old 21st Jan 2019, 9:47 pm   #152
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Default Re: CRT is brighter to one side [Hitachi CTP213]

"Should I test CR703, or CR103."

That would appear to be a typographical error on my part- sorry about that! CR703 is the suspected diode.

Have you now got a multimeter ?

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Old 21st Jan 2019, 9:51 pm   #153
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Default Re: CRT is brighter to one side [Hitachi CTP213]

I did think it was CR703, just wanted to make sure.

I do, and I have also tested R727, which is allowing no current through at all. - Replacement being ordered soon

I will now test CR703, and come back with my results.

Thank you for your help!
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Old 21st Jan 2019, 10:41 pm   #154
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Default Re: CRT is brighter to one side [Hitachi CTP213]

I don't know if I'm doing something wrong, but I cannot get a result from CR703, either.

I'm not too bothered about R727 not giving a result, as either way I'd like to replace it, due to the burn on it.

Any help would be appreciated as to how to get a reading/why i'm not.

Thanks
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Old 21st Jan 2019, 11:01 pm   #155
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Default Re: CRT is brighter to one side [Hitachi CTP213]

What setting do you you have your multimeter on and how are you actually testing the diode?

How did you test the resistor R727?

Nick

Last edited by 1100 man; 21st Jan 2019 at 11:02 pm. Reason: extra text added
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Old 21st Jan 2019, 11:12 pm   #156
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Default Re: CRT is brighter to one side [Hitachi CTP213]

My multimeter is on the diode setting with the diode symbol, and I have put red on the left side, black on the right, and visa versa with no luck either way.
Edit: This is on top of the PCB, where I can see the diode itself

I did the same with the resistor (switching wires over) but cannot remember which setting, I went through various settings.

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Old 24th Jan 2019, 12:05 am   #157
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Default Re: CRT is brighter to one side [Hitachi CTP213]

I think I will replace diode CR703 just to be on the safe side as I can't get a reading on the multimeter.

What type of diode would this be as it has no information in the service manual

Thanks
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Old 28th Jan 2019, 6:14 pm   #158
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Default Re: CRT is brighter to one side [Hitachi CTP213]

Hi

I thought I would link this thread to the now closed "What Diode?" thread.

"What diode?"
https://www.vintage-radio.net/forum/...d.php?t=153497

Quote:
Right, so the diode isn't crozzled? The resistor is? Do you know it's value, I think not if it's charred. Lawrence is your guy for that. As I said earlier, the diode is probably OK. Some confusion arose and it was assumed it was the RGB diode that had failed but that would result in an over bright raster. I think we all have a better idea as to which components have failed, but be aware when you restore your raster you will still have the shading. When you ascertain the value of the said resistor and replace it you "may" get your picture back. Have you no idea why it failed, because of where it is in the set it's unlikely to be a safety resistor, but not being terribly familiar with that model who knows.
The diode hasn't burned, the resistor had; which I got wrong in the linked thread as I mixed the two up and said the diode had burnt.

The resistor is a 1.8kohm metal oxide resistor. I have ordered a replacement, valued at 2watts which I was told should be okay.

How do I fix the shading? I was told replacing two capacitors would sort this, which I have changed, and that's when I had no picture.

Thanks

Ah right so it is the A1/screen diode, the confusion earlier was down to me, as I was under the impression it was the RGB 200v supply that was in trouble, my mistake.

Okay, do you know which A1 it would be from the list (See attached) as there are multiple.

Thanks

Thank you all for your help! It's really appreciated.
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Old 28th Jan 2019, 6:31 pm   #159
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Default Re: CRT is brighter to one side [Hitachi CTP213]

There is not enough context in that image for me to know what A1 means, I suspect there is a physical PCB layout diagram associated with it, with X-Y co-ordinates.

What we mean by A1 however, is the CRT first anode.
I don't blame you for misunderstanding the jargon which must be new to you.
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Last edited by rambo1152; 28th Jan 2019 at 6:45 pm.
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Old 28th Jan 2019, 6:54 pm   #160
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Default Re: CRT is brighter to one side [Hitachi CTP213]

Oh my mistake, I just get a little confused at times.

I don't know how to read schematics very well, I just find them useful for finding parts on the board more than anything.

My guess that diode could be CR092 or CR093? i could be very wrong.

Thanks.
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