UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Television and Video

Notices

Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

Reply
 
Thread Tools
Old 31st Jul 2022, 11:01 pm   #1
Jan Zodiac
Pentode
 
Join Date: Sep 2021
Location: Aabenraa, South Jutland, Denmark.
Posts: 117
Default 1961 B&O Capri 17" height problems

Hi all,

I just finished, or almost finished, restoring a small Bang & Olufsen Capri 607 tv. As I was adjusting the picture after assembling (it had been taken totally apart), I had problems getting the picture height correct. The control is adjusted fully to one end, and the picture is still too high. The control is the 1M trimmer, located between the PL84 vertical output valve, and one half of ECC82 (osc.). It is turned all the way to the 1M resistor going to ground.

All capacitors are replaced, as well as resistors that was out of tolerance. HS marked resistors are carbon film types, and they all have the correct value.
DC values around PL84 are correct, although I did of course not measure the plate voltage due to large spikes. The supply voltage is the correct 180V. The valve was tested and 100% OK. I swapped the valve for a new one to be sure, but it didn't change anything.
I should mention that the the scan coil assy (is it called yoke?), was replaced with another one some time in the past. I believe it is a correct replacement though, since both width and linearity can be adjusted within limits.

My question is, can I lower the value of the 1M resistor going to ground, at the lower end of the trimmer to solve this height problem? Or is there something else I should pay attention to?
What does the VDR between ground and the 0,47M resistor at the top of the trimmer do? Is this to stabilize picture height? I read somewhere that VDR resistors wear out over time, and their value would rise. If this should be the case, the signal at that point could be larger than original, resulting in problems getting the correct height.
It is a bit confusing, since everything is connected in a feedback loop.

Could something be done around PL84 instead maybe? Like changing the working point a bit with another value of the cathode resistor? Or would this just result in distortion, giving problems with linearity?

Sorry for the bad pictures of the schematic. I don't have a scanner, so I took sections with the camera instead.

Kind regards,

Jan
Attached Thumbnails
Click image for larger version

Name:	Diagr. 2.jpg
Views:	62
Size:	102.1 KB
ID:	261926   Click image for larger version

Name:	Diagr. 3.jpg
Views:	50
Size:	86.8 KB
ID:	261927   Click image for larger version

Name:	Diagr. 4.jpg
Views:	33
Size:	62.5 KB
ID:	261928  
Jan Zodiac is offline   Reply With Quote
Old 31st Jul 2022, 11:23 pm   #2
staticmind
Tetrode
 
Join Date: Sep 2019
Location: Aalborg, Denmark
Posts: 94
Default Re: 1961 B&O Capri 17" height problems

Hi Jan,

Maybe I can be of any help, as I've got it's predecessor (Capri 606 17") in working order. But yes, all the Wicons had to go - also their film type caps. The filter cans were fine, though.

I replaced ALL of the trim-pots, simply because they were widely out of tolerance, decreasing to 50% of their value. Maybe moisture affects the carbon composition over time. Maybe this is your issue?

What is the width control pot set to? If you increase the width, you also increase the EHT, thereby affecting the height as well. I have no reference to compare it to, but in my opinion it does have quite a bit of overscan - maybe more than it should have.

Kind regards,
Troels
staticmind is offline   Reply With Quote
Old 1st Aug 2022, 7:08 am   #3
peter_sol
Octode
 
Join Date: Aug 2003
Location: Welwyn Garden City, Herts. UK.
Posts: 1,786
Default Re: 1961 B&O Capri 17" height problems

I would just put a trim pot instead of the bottom 1meg resistor.
yes vdr is for stability with rise in heat. the scan coils may have slightly different characteristics.
peter_sol is online now   Reply With Quote
Old 1st Aug 2022, 8:06 am   #4
Jan Zodiac
Pentode
 
Join Date: Sep 2021
Location: Aabenraa, South Jutland, Denmark.
Posts: 117
Default Re: 1961 B&O Capri 17" height problems

Hi,

Troels, yes, except for one filter can that had gone low in value, the rest were ok. And yes, all the Wicon paper + film caps are replaced. I replaced the ceramic caps in the HV cage as well.
One of the attached pics show the trimmers before I attempted to adjust anything. The width control was adjusted to one end, making the actual picture too wide. I did notice the width control affects the height as well. I believe this is why it was turned all the way to one side.
I adjusted it to correct width and noticed the HT was 12kV which is a bit on the low side. All supply voltages match.
I didn't suspect the trim pots though, as the only thing actually, but will check and replace if needed. I believe the picture should be correct with the trimmers set to around mid position. That is at least what I have been used to so far. Maybe except for linearity, which often is most correct at one end of the control. A little bit odd that your set also tend to over scan. I believe your set still has the original scan coils? This set is in a great condition, and most of the original valves test excellent. I don't think it had a lot of hours on it.

Peter, that's a good idea with the trim pot instead of the 1meg resistor. I also tend to suspect the scan coils being a bit different, since both height and width were adjusted to their outer posistion to make a decent, but still over scanned picture.

Kind regards,

Jan
Attached Thumbnails
Click image for larger version

Name:	50.jpg
Views:	123
Size:	114.6 KB
ID:	261933   Click image for larger version

Name:	51.jpg
Views:	104
Size:	91.5 KB
ID:	261934  
Jan Zodiac is offline   Reply With Quote
Old 1st Aug 2022, 10:44 am   #5
staticmind
Tetrode
 
Join Date: Sep 2019
Location: Aalborg, Denmark
Posts: 94
Default Re: 1961 B&O Capri 17" height problems

It certainly looks like a low-hour set. That is a nice find, and great that it ended up in caring hands. Planning to install legs on it? Oh, and is that a UHF tuner that has been fitted?

The original setting of the width and linearity pots are as shown in the attached picture. Seems to be much like yours.

When I adjusted mine to what appeared to be correct width, I think the height pot was just at it's extreme end to get the right geometry (with old pots at least). That was about 13 kV of EHT, so it was definitely low as well. In the mid section of the width pot, I have around 15 kV EHT, which allows to center the height pot more. Yes, these are the original scan coils (AT1008).
Attached Thumbnails
Click image for larger version

Name:	initial_height_lin.jpg
Views:	98
Size:	80.5 KB
ID:	261941   Click image for larger version

Name:	scan_coils.jpg
Views:	83
Size:	118.7 KB
ID:	261942  
staticmind is offline   Reply With Quote
Old 2nd Aug 2022, 12:19 am   #6
Jan Zodiac
Pentode
 
Join Date: Sep 2021
Location: Aabenraa, South Jutland, Denmark.
Posts: 117
Default Re: 1961 B&O Capri 17" height problems

Hi Troels,

Yes the set is really in an excellent condition both on the inside and outside.
I got it from the local radiomuseum, because they don't collect tv's. I was given this Capri and then an older Derby tv also.
The Capri came from a Bang & Olufsen dealer in Sĝnderborg. It was in their storage for many years I was told. Maybe it was sold there from new, and then given in return on a new set later on. They never threw it out, probably because it looks almost like when new.
I don't really collect these 60's tv's myself. I'm more interested in older ones.
A friend of mine here in town really loves this set though, so I am restoring it for him. I agree that it is a well made and great looking little tv.
Apart from the height problem, it really produces a sharp and bright picture.

I believe the UHF tuner was fitted very early on. It is a valve tuner with two PC86's. It was fairly common here in the south of the country to have either a tuner built in to the set, or having a separate UHF tuner on top of the tv. This made it possible to receive the new german UHF stations.
This tv did not come with legs, but I have ordered some for it.

I attached a picture of the scan coil on this set. It is obviously a newer type. The original for the Capri 607 is an AT1009.

You are right about the trim pots. I removed all of them and to my surprise they have all decreased significantly in value. The 1meg for the height was down at 380k and the 2meg for the width was at 116k
I have never experienced that before. I didn't have the 2meg (or 2,2meg) so I ordered some. I'll have to wait until they arrive and then see what happens.

Jan
Attached Thumbnails
Click image for larger version

Name:	IMG_1600.jpg
Views:	61
Size:	71.5 KB
ID:	261981  
Jan Zodiac is offline   Reply With Quote
Old 2nd Aug 2022, 12:30 pm   #7
staticmind
Tetrode
 
Join Date: Sep 2019
Location: Aalborg, Denmark
Posts: 94
Default Re: 1961 B&O Capri 17" height problems

Hi Jan,

That's a very interesting story. Perhaps it could have been a display model for the store back then. Is it walnut or teak?
The Capri 607 (17" and 21") are quite rare, because I think most people went for the brand new square 23". The 17" would in many people's opinion be too expensive. All three feature the exact same chassis.
The Capri 17" is the only vintage TV I have (apartment...), but I do get your point on pre-1960's TVs - rarer and more work went into them.

If all else fails I think I ordered a few extra Piher PT15 series pots you can have. They look way too modern though, and need to be modified a little to fit

If he wants to use the VHF tuner without powering the TV off an isolation transformer, I'd recommend replacing the 2 1nF isolation disc capacitors as well. Mine did not withstand mains voltage, but luckily went open instead of destroying the VHF modulator.

Kind regards,
Troels

Last edited by staticmind; 2nd Aug 2022 at 12:41 pm.
staticmind is offline   Reply With Quote
Old 3rd Aug 2022, 9:02 am   #8
Jan Zodiac
Pentode
 
Join Date: Sep 2021
Location: Aabenraa, South Jutland, Denmark.
Posts: 117
Default Re: 1961 B&O Capri 17" height problems

Hi Troels,

This one is in teak. I attached a few pics, so you can see the actual condition. It really looks almost untouched. It could very well have been a display model for several years. It was used some though, and a few repairs had been made before I received it. The UHF tuner was also added at some point. Could have been done at the shop that sold it new actually. I think the german ZDF station started broadcasting in 1962, so it is possible that the tuner was added from the beginning.

I think you are right that they are rare. I don't recall having seen any of these around, except for a 23", years ago. When new it cost dkr. 1590,- which seems like a lot for a 17" back then. No wonder most went for the new 23" model. That one is actually great looking also.

Thanks for the tip on the ceramic "safety" capacitors. I usually don't trust them, and replace them with modern "Y" caps. I experienced ceramic caps that shorted, but not the 5kV types though. Still it's better to replace them for safety. And especially since the tv will be used frequently.

I will let you know about the trimmers, when the ones I ordered has arrived. They are older Piher types, and they looked as if they could fit nicely.
If you ever decide to try an older set, you are welcome to take contact. I have some unrestored ones myself, and also have a friend who has tv's that are not restored.

Kind regards,

Jan
Attached Thumbnails
Click image for larger version

Name:	IMG_1606.jpg
Views:	109
Size:	59.3 KB
ID:	262041   Click image for larger version

Name:	IMG_1608.jpg
Views:	94
Size:	61.1 KB
ID:	262042   Click image for larger version

Name:	IMG_1609.jpg
Views:	93
Size:	73.1 KB
ID:	262043   Click image for larger version

Name:	IMG_1610.jpg
Views:	98
Size:	82.0 KB
ID:	262044   Click image for larger version

Name:	IMG_1611.jpg
Views:	89
Size:	79.4 KB
ID:	262045  

Jan Zodiac is offline   Reply With Quote
Old 5th Aug 2022, 1:07 pm   #9
staticmind
Tetrode
 
Join Date: Sep 2019
Location: Aalborg, Denmark
Posts: 94
Default Re: 1961 B&O Capri 17" height problems

Hi Jan,

Beautiful condition, and very rare in teak. I have attached a picture from the B&O book of the set with legs, in case you haven't seen that. The VHF/UHF switch and channel selector looks very professionally made.

Hopefully he will have a lot of enjoyment from it, and hopefully the LOPT will last a very long time.

Just thought of something. The underside of the cabinet (of the 606 at least) has "slanted" indents for the legs, so that the legs don't just go straight down. That means the thread of the fixings should also be slanted, which the original ones also are. If the new fixings aren't and the threaded section can't bend, it might be a problem. If you must revert to the old ones, then the thread is 5/16" either UNC or BSW.

Thanks so much for your kind offer - if I just had more space.

Kind regards,
Troels
Attached Thumbnails
Click image for larger version

Name:	Capri_607.jpg
Views:	70
Size:	26.0 KB
ID:	262240  
staticmind is offline   Reply With Quote
Old 6th Aug 2022, 1:58 pm   #10
Jan Zodiac
Pentode
 
Join Date: Sep 2021
Location: Aabenraa, South Jutland, Denmark.
Posts: 117
Default Re: 1961 B&O Capri 17" height problems

Hi Troels,

You are welcome, and that's a great picture of the set with legs

My set has the "slanted" holes underneath for the legs like yours. I removed the original threads because the new legs will have M8 threads. The original inserts did not seem to have slanted cut threads though. I fixated the new ones a bit loose, so the thread on the legs will grip on easily and pull them down tightly.

Yes, it does seem like the UHF tuner was fitted at a shop. At least it sounds most reasonable, unless the buyer was a technician himself. It's a Philips kit. I have seen several of those built in tuners in this area. Some original ones, and some universal kits like this Philips.

Is the LOPT giving problems on these sets? In this one all seems nice and clean inside the EHT cage, as can bee seen in the attached picture. The ones I experienced most problems with, are those with the HT winding molded in plastic. I had many of them go bad, which is one of the reasons I prefer pre 60's sets. The ones wound as a large "disc" seem to last longer. It is also easy to preserve them with HV varnish to prevent arching.

Kind regards,

Jan
Attached Thumbnails
Click image for larger version

Name:	48.jpg
Views:	83
Size:	72.5 KB
ID:	262303  
Jan Zodiac is offline   Reply With Quote
Old 7th Aug 2022, 7:40 pm   #11
staticmind
Tetrode
 
Join Date: Sep 2019
Location: Aalborg, Denmark
Posts: 94
Default Re: 1961 B&O Capri 17" height problems

Hi again,

LOPT looks great.
I have no knowledge of that, but within a few years or so, Philips went from AT2016 to AT2018 to AT2021. The AT2018 replaced the AT2016 even in Capri 606, which was revised at some point (within one year).
The good thing about these "newer" sets is that donor sets for parts pop up for sale from time to time.

Kind regards,
Troels
staticmind is offline   Reply With Quote
Old 8th Aug 2022, 9:45 am   #12
Jan Zodiac
Pentode
 
Join Date: Sep 2021
Location: Aabenraa, South Jutland, Denmark.
Posts: 117
Default Re: 1961 B&O Capri 17" height problems

Problem solved!

It turned out to be the bad bad trimmer pots, making it impossible to adjust height, width, vertical linearity and AGC properly.
They had all decreased significantly in value.

I replaced them, and now adjustments are well within the range of the trimmers.

EHT is still on the low side though, only 12kV, but the picture is bright and sharp, so I am not going to do anything about it. It is, as mentioned in one of the other posts, affected by the width setting.
It is now a nice little well working set.

I did a few modifications in the power supply. At some point the selenium rectifier had been replaced by a silicon diode.
The tech. who did that, apparantly forgot to increase the voltage dropper resistor, resulting in way to high supply voltages. I corrected this, and also mounted a 220uF across the original multi section capacitor to decrease the ripple and put less stress on the original cap.

In the filament series string, the series resistor was never corrected after the UHF tuner was built in. It is only 8V though, but with the 10V increase in mains voltage here, compared to when the set was new, I decided to fix that too. This set does not have an NTC in the filament string. So to protect especially the picture valve, I added one, and replaced the series resistor with the correct value. The current is now held at exactly 300mA, even if the mains voltage varies a little. And more important, heating of the valves starts up slowly. These supply mods can be seen in the last picture.

Kind regards,

Jan
Attached Thumbnails
Click image for larger version

Name:	IMG_1638.jpg
Views:	64
Size:	77.7 KB
ID:	262412   Click image for larger version

Name:	IMG_1640.jpg
Views:	65
Size:	66.2 KB
ID:	262413   Click image for larger version

Name:	IMG_1646.jpg
Views:	82
Size:	61.3 KB
ID:	262414   Click image for larger version

Name:	IMG_1647.jpg
Views:	76
Size:	49.6 KB
ID:	262415   Click image for larger version

Name:	IMG_1601.jpg
Views:	74
Size:	98.5 KB
ID:	262416  

Jan Zodiac is offline   Reply With Quote
Old 8th Aug 2022, 7:22 pm   #13
staticmind
Tetrode
 
Join Date: Sep 2019
Location: Aalborg, Denmark
Posts: 94
Default Re: 1961 B&O Capri 17" height problems

Excellent result, Jan.

Hehe, that's funny. I also mounted the same NTC (VA1015?) in mine, was not a fan of overrunning the heaters just to save a little on power on time.

Yes, the EHT is on the low side when not over-scanning. But I am wondering if that is how TVs were designed to behave. Have you noticed on your other TVs if they require similar over-scanning to produce the desired EHT?
staticmind is offline   Reply With Quote
Old 9th Aug 2022, 8:34 am   #14
Petedox
Pentode
 
Petedox's Avatar
 
Join Date: Feb 2020
Location: Waterlooville, Hampshire, UK.
Posts: 167
Default Re: 1961 B&O Capri 17" height problems

That's a great set you've got there Jan. Well done!
__________________
Pete
Petedox is offline   Reply With Quote
Old 9th Aug 2022, 9:21 am   #15
Jan Zodiac
Pentode
 
Join Date: Sep 2021
Location: Aabenraa, South Jutland, Denmark.
Posts: 117
Default Re: 1961 B&O Capri 17" height problems

It is a beautiful little set yes. The picture is actually a lot better than shown in the attached photos. I don't really know why it is sometimes so difficult to get the camera to capture a more correct view of a tv screen.

About the NTC, I am not sure about the type. I seem to remember the part number though, but I actually just took the resistor from a spare chassis I had

I don't recall having low EHT on other sets. At least not like 3kV low, so I am not sure if this is normal. Maybe others here have more knowledge about this. I don't think the EHT was measured much. I am in the process of starting up older restorations, and will then check what the actual EHT is on them, compared to the schematic and also if it varies when fiddling with the width control. I will make another thread on all this.
I do know that on the Torotor LOPT (attached pict.) which has a width selector switch (and probably other similar LOPT's as well) the EHT does not vary when width is changed on this switch. At least not significantly. It just works by changing windings on the LOPT that goes to the horizontal scan coils, rather than affect the signal to the line output valve like in the Capri.

Kind regards,

Jan
Attached Thumbnails
Click image for larger version

Name:	68.jpg
Views:	59
Size:	65.0 KB
ID:	262497  
Jan Zodiac is offline   Reply With Quote
Old 11th Aug 2022, 5:42 am   #16
German Dalek
Hexode
 
German Dalek's Avatar
 
Join Date: Jan 2011
Location: Düsseldorf, Germany.
Posts: 291
Default Re: 1961 B&O Capri 17" height problems

Hi,
I am fighting with the same problem.
You can get rid of the 50 Hz vertical bar, but the contrast and the sharpness
is the problem.
One point is the problem, that our eyes have a different view than a camera.
The camera has a better one, we see more a flickering illusion.

In the past I used a real photographer, not a digital one.

The best pictures were, when I reduced the brightness until I couldn`t see closeby nothing on the screen!
But for my camera (mirror-reflex) ist was a bright picture with more contrast!

Another problem is the light. I wanted to show a picture with a strong contrast
and the veneer with its true colour.
Getting both under one hat is difficult!

Example:
Sunlight from the right, stand of camera is visible on the safety glass.

-- sorry, upload doesn´t work --


Regards,
German Dalek
__________________
And now something completly different:

MARC BOLAN, he was/is the real king of Pop Music!
German Dalek is offline   Reply With Quote
Old 13th Aug 2022, 2:13 pm   #17
Jan Zodiac
Pentode
 
Join Date: Sep 2021
Location: Aabenraa, South Jutland, Denmark.
Posts: 117
Default Re: 1961 B&O Capri 17" height problems

Yes I find it pretty difficult to get both a nice view of the set, and a nice picture on the screen at the same time.

Here are a few pictures with nothing on the screen. I received the legs a few days ago. They are beech, so I stained them and gave them a few coats of semi gloss varnish. They now match the color of the set very closely.

The set is now ready and will hopefully be picked up soon. I need the space

Regards,

Jan
Attached Thumbnails
Click image for larger version

Name:	phpypnITtAM.jpg
Views:	45
Size:	37.0 KB
ID:	262710   Click image for larger version

Name:	phpvfvNd1AM.jpg
Views:	50
Size:	38.7 KB
ID:	262711   Click image for larger version

Name:	phpzT4Qm1AM.jpg
Views:	44
Size:	38.1 KB
ID:	262712   Click image for larger version

Name:	IMG_1668.jpg
Views:	41
Size:	54.1 KB
ID:	262713  
Jan Zodiac is offline   Reply With Quote
Old 13th Aug 2022, 8:02 pm   #18
staticmind
Tetrode
 
Join Date: Sep 2019
Location: Aalborg, Denmark
Posts: 94
Default Re: 1961 B&O Capri 17" height problems

That's a beautiful result Jan!
Looks like a great match with the color. Even if you got the legs done in teak, you would still have to stain the linseed oil.
staticmind is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 6:37 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.