Hi,
I am new here and I am glad to have found this forum especially for vintage TVs.
I've been looking for an early color TV from the 70's for quite some time and now I got a nice Hitachi CNP865 for the very beginning.
It ran for a fairly short time but after a few minutes of operation the picture moved up more and more. In addition, the previous owner had removed a burst capacitor on the convergence board without replacement and then changed the convergence settings.
When I opened the device, I found some leaking capacitors on the Deflection Output PCB and replaced all of them. Then I replaced some capacitors on the convergence PCB, PAl and Signal PCB as well.
Until now the unit was running fine except for the convergence which has to be corrected naturally since there was a missing capacitor.
Because many of the electrolytic capacitors were defective I wanted to change all the electrolytic capacitors on the Power PCB. After the first 10 pieces I tested the TV again.
But now the picture tube stays off after switching on and the sound does not work anymore. (But the picture tube still heats!)
I checked the capacitors several times with the circuit diagram and the values and polarity +/- are correct. Also all plugs are plugged in and no cable is torn off.
Now my question is, before I solder the old capacitors in again, can this be caused by a defective on/off switch?
As a reminder the device has two on/off switches: One is the main switch on the right side for the tube heating and the other one on the front which switches on the picture and sound.
The last time I had it on, I accidentally switched it off directly from the right main switch. Maybe the front switch got damaged? (would make sence that sound and picture is not working while the tube is heating)
Or could this be a completely different defect?
And here is a completely different question for the owners of such TVs (With these channel buttons).
Unfortunately, not all the channel buttons click into place anymore, which is why I would like to clean them.
Is it worthwhile to disassemble the control panel or are the buttons not repairable if they do not snap in anymore?
I only ask because it looks like it is extremely complicated to remove the control panel and tuner and get them back in again.
Best regards,
Basti
Welcome to the forum.
You have checked your work and it’s seems ok, I presume the capacitors you used were from a reliable source.
Its very likely a broken wire due to the flexing after all these years untouched.
Some straightforward voltage checks should find the problem, the PSU in thecCEP-180 is a linear regulation so no complicated Switch mode type.
Does the degaussing circuit operate when switched on?
I only have a circuit for the CEP-180, I don’t know how different they are.
Frank
I only have a circuit for the CEP-180, I don’t know how different they are.
I have just purchased and made available the full HITACHI CNP865 (inc other models see below) manufacturers service manual in data library. For those with access, to request, who wish to help Basti with his fault.
But now the picture tube stays off after switching on and the sound does not work anymore. (But the picture tube still heats!)
Like nuvistor, I believe you may have accidently introduced a man made fault. I assume you have the same service manual? Page 7/8 covers what checks to perform for a no raster scenario. Pages 11/12 for no sound.
Here's a snip of the relevant section, So others without data library access may assist you.
p.s.
I believe you're our first member from Germany, a very warm welcome to you ?.
You may find this brochure of interest, its even in your native language https://www.radios-tv.co.uk/hitachi/
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Hello again,
Thanks for the welcome and the tips!
The brochure is also good to have!
I have the complete service documents and I didn't know if it was ok to share them. I have now also found the documents for the troubleshooting. (These were not included in the German documents but as I have now seen in the English ones).
I will now check a few things and while I'm at it I will measure the new electrolytic capacitors (they are from a credible source but you never know)
I will keep in touch if there is any news again!
Sorry for the double post, I can't edit my previeous post.
I have now found the problem! It was a small hair fine wire on the "T701" Horizontal Hold Transformer that came loose. It was so thin and broken at the soldering point that I completely missed it. Now the sound and picture is working again! ?
Last but not least there are the buttons that do not snap in anymore. I just don't know if the panel is held by these nuts or if it is necessary to remove the complete front. The cross-head screws do not hold the panel. Unfortunately I don't have a proper screwdriver with nuts attachment yet.
best regards,
Basti
A few turns undoing that nut, probably another at the bottom and slide the unit to the left and lift out, that what it appears to be. I can’t remember if the buttons will still be in place or lift out with the tuner.
Well spotted on the fault.
Frank
UHF Only, UK version of that set is the CNP-190.
I wouldn't worry about capacitors too much. There's a lot of mis-info on the web about it. According to the web, most anything over 5 years old needs every cap replaced, where my 40 year old CNP-190 only has had three replaced in total. One to cure blue droop on convergence board, one to improve brightness range due to low rail volts on the timebase gen board, the other was the 4.7uF 450V on the line board in the field o/p stage to prevent transistor failure.
Hitachi used United Chemicon, and some Rubycon which are pretty good quality caps even now. Don't forget, 40 years ago, the ESR of caps wasn't anywhere near as low as it is now for say a 100uF 35V cap, you well may be replacing stuff needlessly.
Good quality equipment made before say, 1990 don't need blanket cap changes, only new crap does!
One thing to do as it does cause trouble with these sets, replace all the fuses in the thing with the right values and types. the 40 year old ones can sometimes fail just because they are 40 years old, and one gives some very strange symptoms when failed (uncontrollable and rather low +B rail, but the set still works poorly!)
Also, keep an eye on the 2SC458 if you get no colour or IF issues, Hitachi made, (odd shaped) ones go bad.
Push button units do go bad. Replacements were difficult/impossible 30 years ago, symptoms are drifting off tune and buttons not locking.
I bought the slightly later CNP192 when they first came out, 1973 or thereabouts. Had it for 10 years or so and gave it to my father in law who had it another 10 years, only fault it had was a faulty tuner. We sold a lot of the CNP192 sets and that was only only stock fault I had with them. I used a local company who did tuner repairs, once fixed they didn’t give any more trouble.
Frank
CNP865 is a PAL-1 chassis set. UHF-only version is CNP860, PAL-2 equivalent is CNP190/195.
Still working on my CSP680 which has had two losses of HT and a loss of colour so far, but these sets are interesting.
"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"
