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Old 21st Apr 2020, 8:03 pm   #41
staticmind
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Default Re: B&O Capri 606 TV (17") restoration

Need an advice here. There's a problem, notably with the tuner and the PCC88. There's no "static/snow" as there should be, when there's no input. Gently bumping the PCC88 with a screwdriver handle seems to make static appear briefly and randomly. I tried it once again, but this time the picture disappeared, and the line oscillator stopped, since the 15 kHz tone was not audible any longer.

I turned off the TV after two seconds of observing this, and the screen showed some life, when powering off - it shows the raster collapsing as it should, but this time it collapsed into a single bright dot which remained in the screen for the next 10 seconds. That can't be good!

I have ordered a replacement PCC88. My theory is that it might have an internal short, pulling down the +180V (b) supply down through the 1M resistor. The b-supply is also used for the line oscillator circuits, and that could explain why the 15 kHz would disappear, right?

What can I do to not have the stationary "dot" shining at the screen for too long? Just discharge the EHT with my EHT probe? Or does this not matter at all as the AW43-88 is aluminized?
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Old 21st Apr 2020, 9:10 pm   #42
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Default Re: B&O Capri 606 TV (17") restoration

the dot is normal when you power off a set with no bright raster,many of my tvs do that and its not a fault.... if it has a bright raster it usually collapses into a rectangular shape that keeps getting smaller until it disapears.. the lack of snow when there is no input can be agc related or weak IF tubes or weak RF amp tube in the tuner. some of my sets also do that and i dont bother since they have a perfect picture when a signal is applied. if you dont have snow but also dont have any white noise on the speaker my bet would be AGC voltage or RF amp tube. did you try adjusting the AGC? some set have a control for that...if you turn it up too much the picture gets excessive contrast, it may overload and distort or even disappear, sometimes you get trailing on white parts such as movie subtitles if the agc setting is too high

generally on tuners the RF amp tube is the one next to where the antenna connection wires enter the tuner unit
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Old 21st Apr 2020, 9:26 pm   #43
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Default Re: B&O Capri 606 TV (17") restoration

Quote:
Originally Posted by staticmind View Post
It turns out all the white Wicon film caps, while looking decent and unharmed are no good at all. They all measure about 10 times their value at DC (using Fluke 175) and slowly decreases by some nF until they settle. I had a feeling this might happen, so I ordered a whole bunch of replacement film caps, and decided just to replace all the Wicons.

Next thing will be hooking up my pattern generator. Maybe sometime next week.
This AW43-88 is surprisingly bright.

Is there anything I would need to worry about regarding the LOPTx now that I know it is working? I did not heat up the overwind prior to this, but the TV has sat in a very dry environment for the past 6 months, and I did heat it up with a hair dryer. Maybe I should monitor the temperatures using an infrared thermometer...
Many people advise running some dc through the lopt to bake it from inside out...but i also see many people restoring sets that previously worked and after messing and fussing with the lopt it just gives up....

so my method is buy a set, inspect it, change ONLY obviously faulty and very problematic parts like boost filter cap and coupling caps if they are from unreliable brands,then if its a series string set i just aplly direct power to get a baseline on it..make the needed repairs...power it up and watch some movies...i start by watching 15 minutes then letting the set cool, then 30 minutes etc..some issues will appear and i repair them, after i am able to watch a full movie without issues i dismatle the thing, clean it,replace all fil caps, restuff the lytics etc etc then a final adjustment...if i see some areas on the lopt that look crummy i just coat them in automotive RTV gasket sealer(sensor safe type), seems silly but it works . i just like to avoid burying money on sets that will just not work right.

on the pictures you posted i see retrace lines,maybe you have the brightness on maximum? its bright!

at this point i would just apply a signal and see how the set behaves, many sets of mine behave wildly with no signal but work flawlessly with signal applied, especially the philips sets with automatic horiz and vertical. they freak out without sync pulses, sometyimes showing what seems poor linearity, lack of complete vertical deflection and weird noise from the vertical output transformer...all of that clears up when they are playing something.

i dont have an eht probe, what i do is: if the set is working right, then setting the width control to just fill up the screen will have to provide the Boost voltage that comes written on the schematic. if that happens then you lopt is working at the optimal point and eht should(has to) be the specified one, unless maybe a faulty eht rectifier. if the boost voltage creeps up or down too much as the set warms up there are problems. boost voltage is easy to measure with any 1000v rated dmm, unlike eht and is a good indicator

Last edited by PortugalTV; 21st Apr 2020 at 9:35 pm.
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Old 21st Apr 2020, 9:47 pm   #44
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Default Re: B&O Capri 606 TV (17") restoration

Thanks a lot, it is very helpful! I don't have any sound at all. That would have been my next task to look into. Guess I might as well buy a spare of the other valves as well. I didn't get to adjust the AGC - this would require that I have a signal on that it would sync to, right?

The LOPT has also been a fear of mine, but it seems to run cool - using an infrared thermometer to measure it, so I didn't give it much more thought. My method is otherwise also just try running it in shorter time intervals and let it cool off. The LOPT (AT2023/21) looks very close to unused. Replaced the booster cap (56n) with a new one, just to be sure.

On the pictures, the brightness control is only at about 75% of max, but need to make some more measurements to know that the pot is ok. The problem with this TV is that the side panel with adjustments rotates inwards just behind the CRT, and don't want to fumble around too much in that area when the set is on.
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Old 22nd Apr 2020, 7:29 pm   #45
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Default Re: B&O Capri 606 TV (17") restoration

Its strange to see retrace lines with the brightness "only" at 75%. i would recheck voltages at the crt base. especially g1 and cathode
if those lines dont go away even with a good picture there can be an open component on the retrace supression circuit. usually its a winding on the lopt connected to some components wich connect also the the vertical output transformer and to CRT G1 (brightness pin). there may be a diode stuffed in there and they often fail. the purpose of the retrace suppresor is to kill the beam on the retace period ( when moving from line to line)

yes i think adjusting the agc without a signal is pointless, but without a signal i think you should not have any AGC voltage or atleast very low.

remember i havent looked at your schematic yet but usually the agc is generated by a circuit with a tube adjacent to the video amp, the idea is the more stronger the signal, the less agc voltage is produced. agc voltage is negative with respect to chassis and it will bias down the tuner rf amp, and the IF stages, sometimes it also acts on the video amp itself on some sets. usually you can artificially apply agc with AA batteries, connecting positive to chassis and negative to the point you wish to apply it.

the boost cap, from my point of view is the most urgent part to replace on a set, it may take the lopt down if it shorts. choose a good ac pulse rated cap like the philips mkp series. a regular cap may not last very long because they are rated in DC volts and that means nothing in that section, they are subject to high amplitude pulses... if you dont have the correct value on your local store you can parallel a couple of caps.
at this point i would just replace that cap and apply a signal and go from there, maybe you dont have any problem with the set

PS sorry for the bad English

Last edited by PortugalTV; 22nd Apr 2020 at 7:38 pm.
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Old 22nd Apr 2020, 8:01 pm   #46
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Default Re: B&O Capri 606 TV (17") restoration

touching the antenna input should give you intereference on the speaker. if you wish you can inject direct composite video from a dvd into the grid of the video amp tube. just inject the signal directly and the composite ground you connect it to the chassis, just be carefull with electric shock on the dvd player's metal case. you can also inject direct audio on the volume control , the procedure is the same. you should have perfect audio and video and you can check and adjust everything beafore you start tackling the possible IF and tuner issues.

i have made myself some tube socket test adaptors with leads sticking out and the pin numbers marked on them... they are very usefull for testing, maybe you can considering doing the same if you plan on working on that set or other sets often
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Old 23rd Apr 2020, 8:06 pm   #47
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Default Re: B&O Capri 606 TV (17") restoration

Thanks! I'll have a closer look at this as soon as I receive a new PCC88.

Measuring G1 voltages should be when the CRT is set to maximum brightness (?) and with respect to chassis ground? In the diagram they state 8.5V at G1, but it should be negative, so not quite sure what they were thinking there.

Also in the diagram, the only diode connecting to the vertical deflection transformer is the "GSD 6/6", component number 177. Could this be it? I can't find anything on this diode, and what a suitable replacement would be, but I'll wait until I have a picture again with further debugging on this. Hopefully some silicon device may be suitable.

The VDR E299DD/P354 has got a crack in the side, which someone attempted to solve using some silvery looking touch-up paint. It's in the vertical deflection section, and may affect the height control. Should probably try to look for a new one somewhere.

I also finally found the AGC part of the schematic as well, it is called ASK in Danish apparently (at that point in time). There's a 2M pot to control the level of feedback.

I replaced the original Wicon 56 nF (1000VDC rated) with a - now discontinued - Wima FKP1 with the same ratings (and 400VAC) - even before the set was started up. It was actually quite hard to find a 56 nF, but it is stated as recommended for "Deflection systems in monitors and TV-sets".

Another cap that was replaced in the same section was a Jensen (audiophile grade) 0.1 uF 630 VDC electrolytic. Definitely a weird choice . It was replaced by a MKP18HQ (Vishay) which is also rated for high current and pulse operations.

P.S. No worries, your English is absolutely fine!
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Old 23rd Apr 2020, 9:40 pm   #48
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Default Re: B&O Capri 606 TV (17") restoration

On a typical german or holland tv set wich is what i usually work on i would expect around +30 to +100v from g1 to chassis depending on the brightness setting and maybe 30 to 40v higher on the cathode...the cathode voltage is fixed while g1 varies with the brightnes pot...schematics usually specify min and max voltage but if not, they specify were the controls should be positioned for testing, if not you can just check if you can reach the schematic's voltage by adjusting the brightness control. remember that on the tvs i usually work on, the video modulation is fed into the cathode of the tube, but i think there are sets were video is fed onto the grid of the tube and i am not sure if my advice is valid for those since i never worked on any.

about the diode, if you can you can send me a link to the schematic of your set and i can take a look. on my usual sets they use germanium diodes all around ,oa81 or something similar and sometimes selenium...the selenium small diodes are particularly crappy because they are made of "biscuits" of different materials and they develop internal poor contact.... i usually stock germanium diodes from parts sets. on some areas silicon diodes dont work because of the different voltage drop across them. but for example on the horizontal you should have 2 diodes for the sync phase detector and those if bad cause poor or no picture sync, you can replace them by ANY silicon diode as long as it is fast recovery. i usually have welding machine diodes for that or those 3 leg double diodes used in SMPS's. i dont buy them new,i scavenge them from broke equipment, i know they are massive overkill but i like to use them. For the retrace circuit i guess a silicon should work as long as its fast enough for the 15khz. Would have to look at the schematic though.

about the boost cap, the fkp series is, like you say, also good for ac pulses, like the mkp series too. they are quality parts and good for that application
the audio cap was probably what a tech in the 70's had at hand maybe?? another cap that should be replaced urgently if its not already done is the one that couples the oscillatior tube's plate to the output tube's grid on the horizontal. on normal operation you should have something from -20 to -50vdc on the grid of the output tube...but if you chaged the cap and the set is working no need to bother to check that

USUALLY VDR's on the vertical are used to stabilize picture height when you adjust other controls and the voltage fluctuates etc so dont bother with it for now. dont waste time trying to find a replacement if the set works without it wich it often does. finding a replacement vdr is impossible and there are no modern equivalent components. modern vdr's work on a totally different principle. old ones are a rudimentary shunt regulator while modern ones are for voltage spike suppression. modern ones either have high resistance or very low when they reach a threshold, but the old ones have a "smoother" resistance curve when voltage varies. hope i made sense

Last edited by PortugalTV; 23rd Apr 2020 at 10:06 pm.
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Old 24th Apr 2020, 12:46 am   #49
Maarten
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Default Re: B&O Capri 606 TV (17") restoration

Quote:
Originally Posted by staticmind View Post
Another cap that was replaced in the same section was a Jensen (audiophile grade) 0.1 uF 630 VDC electrolytic. Definitely a weird choice .
Not really a weird choice. It's a reasonable quality paper capacitor so suitable for impulse applications. Those were somewhat better than the competition but by now should probably all be replaced anyway.
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Old 24th Apr 2020, 8:58 pm   #50
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Default Re: B&O Capri 606 TV (17") restoration

You may be right on that Marteen. Back then there might not have been a lot of choices locally.

PortugalTV, This weekend I will work on creating a high-res schematic with translations to English where possible.

I desoldered the GSD5/6 diode today. It is open, doesn't work as a diode using diode measurement on a multimeter. Here's some more info on the manufacturer TeKaDe : http://www.wylie.org.uk/technology/s...aDe/TeKaDe.htm
According to https://nvhrbiblio.nl/biblio/boek/10...ents-guide.pdf page 47, OA95 is a suitable replacement, so that's what I'll do.

When firstly inspecting the capacitors, the 0.1uF cap connecting PL36 grid to ground looked as if it had melted, so that was actually the first one to be replaced. The only original film caps left are those of the Philips/Mullard mustard/green type (polyester film).
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Old 25th Apr 2020, 9:30 pm   #51
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Default Re: B&O Capri 606 TV (17") restoration

Installed a new PCC88, and the line whistle is back. EHT is still fine at around 14 kV. No raster at all though.

Cathode (Vk) measurement = 117V DC (using multimeter). Something is clearly amiss here.
The voltage (b) drops to 143V, but it should be 180V. The "b" voltage rail is fed through various resistors at the grid of many of the tubes to create a bias current, but am wondering what could pull it down so much.

I think the video section will be the next section to look at - replace PCL84, when I get a new tube for that. It is also fed by "b", but with no resistor/bias.

Schematic in English will be completed by tomorrow.
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Old 26th Apr 2020, 12:34 pm   #52
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Default Re: B&O Capri 606 TV (17") restoration

Ok, high-resolution (600 dpi) schematic with English translations available at:
https://drive.google.com/file/d/1DKn...2nhJQwvpg/view

Download and use your favourite PDF viewer.
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Old 28th Apr 2020, 4:09 am   #53
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Default Re: B&O Capri 606 TV (17") restoration

very nice shcematic!
according to the schematic you should have around 60vdc on the crt cathode
g1 also gets its voltage from the 180v B source through 3.3k then 220k then the brightness potentiometer then a 100k resistor. It should be lower than the cathode , the schematic doesnt specify but usually its around 30v difference but it changes as you adjust brightness
after the pot you see the point marked in red as 78 and then 175 that is the retrace suppresiion line and it connects both to the flyback and to the vertical output transformer.


oa95 is a fast recovery germanium diode so it should work, that tekade diode is probably germanium so it should measure 300mv and not the usual 600mv on the meter, but if it tests open, then replace it

the pcl 84 video amp tube's pentode section is used for video amplification and the triode section for the AGC voltage generation

the lack of video and higher voltage on the anode of the pcl84 suggests the tube is not conducting, check the cathode resistor for any altered value, they get preety hot, while there check the 1n bypass cap
there is not much to go wrong there its a very minimalistic circuit and the schematic is good, there are schematics wichare hard to read, its not the case

you have a selenium recifier oon the power supply, thats the reason the B+ drops a bit...its probably tired...40v lower should not matter much but when the set is working OK consider replacing it with a silicon diode in series with a dropping resistor, dont waste time on that right now

it was good that you left the "mustard" type capacitors alone. only seen one shorted in my lifetime. never saw them in green though

Last edited by PortugalTV; 28th Apr 2020 at 4:35 am.
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Old 2nd May 2020, 9:46 pm   #54
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Default Re: B&O Capri 606 TV (17") restoration

Thanks for all the tips and insight. The green version predates the mustard colored ones by a few years, but they should be the same quality. Some more info. https://www.vintage-radio.net/forum/...d.php?t=128169
I've also left in the original styroflex types and ceramics types.

I am still awaiting the tubes to arrive. But received the OA95 and a selection of 1.6W tube cathode resistors.

All the 47 ohms measured about 65 ohm, so these were replaced. GSD5/6 replaced with OA95.

Still no raster. Maybe my hearing is better today than last time, but when I measure the cathode voltage at the tube, the line whistle stops. When I lift the probe again, line whistle resumes. Any idea if this is normal and why this occurs?

No matter the input to the grid of PCL84, the output should fairly close to the 63V, correct? I've measured all resistors in the video section, except for the coils wrapped around resistors (point 74 and 75). So conclusion is that PCL84 must be bad?
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Old 16th May 2020, 10:21 pm   #55
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Default Re: B&O Capri 606 TV (17") restoration

All tubes arrived.

I changed PCF80 in the tuner and PCF80 in the line separator circuit, because the the video section is also an input to this part. I also replaced PCL84. All tubes are NOS.
I took apart the tuner and replaced a few resistors which were out of tolerance. The silver contacts were also carefully cleaned (using Kontakt WL, 60, 61).

The result is the same, about 120V on the CRT cathode. I'll dig into this again later - but does it sound like the correct approach to look at the Image IF circuitry next, or is there something obvious I'm missing?

I still have line whistle, and the speaker is producing white noise.
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Old 17th May 2020, 9:04 pm   #56
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Default Re: B&O Capri 606 TV (17") restoration

Ok, resoldered the PCL84 socket, changed the three EF80 in the image/visual IF stage. Also changed the grid resistors, as they looked a bit baked. But they were all within specification.

DC measurements on PCL84: g1 = 147 V, g2 = approx 4V, ap (anode voltage) is about equal to g1 voltage. Actually it starts out a bit higher as the set warms up.

Any hints on this at all?

g2 should be 15.5V according to the schematic (I have contrast maxed out), but then again the oscillogram only shows a 10Vpp signal with signal applied, so it may be right (?).

Hopefully I haven't ruined the CRT at this stage
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Old 17th May 2020, 10:27 pm   #57
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Default Re: B&O Capri 606 TV (17") restoration

Hmm, there's something I don't get at ALL about the schematic and the voltages they show at the PCL84 pins.

For example Vg2= 145V, but this SHOULD equal the b+ voltage rail, as there is no dropping resistors as with EF80 in the image IF section.
As mentioned by PortugalTV, my b+ voltage rail is low, due to the selenium rectifier (maybe).
So why do they write 145V on the schematic, when it should be 180V? I don't get it.
Also according to https://frank.pocnet.net/sheets/030/p/PCL84.pdf there is no data for Vg2 below 170V. I'm really confused now.

Is the low (out of range) Vg2 the reason why Va equals the b+ voltage?
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Old 18th May 2020, 1:55 am   #58
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Default Re: B&O Capri 606 TV (17") restoration

Higher voltage on the tube's plate indicates the tube is not conducting...bad tube or open circuit somewhere around the tube. the tube receives voltage at the plate via a 10k and a 3.3k resistor if i am not mistaken so if the tube draws current the voltage at the plate will drop to the specified 60v, if the tube doesnt draw any current then no voltage will be dropped on the resistors and you will see a higher voltage there.
this happens either with or without a signal

the circuit is very simple so only things that can go bad is the tube or the two cathode resistors in series or the bypass cap that could leak and short but that would cause excessive current draw not lack of it.

the contrast control seems to act on the grid of the tube changing its bias. it goes from b+ to a potentiometer voltage divider then through a series of coils and to the grid of the tube. making a grid more positive makes the tube conduct more. check voltage at the wiper of the contrast pot. then check if the same voltage is present at the grid of the tube, the coils should have very low dc resistance so i expect no drop or very low drop across them.

plate voltage is there and its higher than it should be so no need to check resistors there
g2 is supposed to be 145volts, it comes direcly from B supply, it needs to be there
.g1 is supposed to be 15v. and its a bias voltage it comes via the coils i mentioned, if its missing the tube will not conduct enough
if voltages are there but higher means the tube is not conducting
any missing voltage means a break in the circuit
you have not ruined the crt dont worry
forget the IF for now, the tv works without the iF if you inject the signal directly on the video amp grid via a coupling cap
if there is no signal a blank bright raster must appear so forget IF and tuner etc you can create more problems when messing with lots os stages at the same time, solve one problem first then proceed
since we are measuring DC voltages forget the oscilloscope for now, use just a multimeter. when using a scope on a tv for other reasons bare in mind that if you set the scope at a certain speed you will see some stuff (15khz) horizontal related pulses etc, and if you slow down the scope you will see 50hz stuff sometimes on the same point of measurement so you need to know what you are looking for but forget that for now.


this should be a very easy fix dont give up just take some time. dc voltages are very easy to troubleshoot. harder problems would be sync issues, if, and tuner problems, intermittent faults vertical issues etc etc...

Last edited by PortugalTV; 18th May 2020 at 2:18 am.
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Old 18th May 2020, 2:22 am   #59
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Default Re: B&O Capri 606 TV (17") restoration

Quote:
Originally Posted by staticmind View Post
Hmm, there's something I don't get at ALL about the schematic and the voltages they show at the PCL84 pins.

For example Vg2= 145V, but this SHOULD equal the b+ voltage rail, as there is no dropping resistors as with EF80 in the image IF section.
As mentioned by PortugalTV, my b+ voltage rail is low, due to the selenium rectifier (maybe).
So why do they write 145V on the schematic, when it should be 180V? I don't get it.
Also according to https://frank.pocnet.net/sheets/030/p/PCL84.pdf there is no data for Vg2 below 170V. I'm really confused now.

Is the low (out of range) Vg2 the reason why Va equals the b+ voltage?
for your first point i have no explanation....tvs and tube stuff have wayyyyy high tolerances so dont bother with that. 20% higher or lower will work perfectly.
Va equals b+ voltage beacuse the tube is not conducting so no drop occuring on the resistors from b+ to anode of the pcl84. missing bias or bad tube like i said above. dont worry you will find it out


you mentiond above some coils wrapped around resistors
they often get broken and often you can repair them or even bypass them. normally they measure very low dc resistance so if they measure high you are probably reading the resistor and have an open coil.
after reparing coat them in wax, no hot glue beacuse if they fail again then there is no more fix possible

the 1.8meg before the contrast control could be high in value. you are reading 4v instead of 15, it would explain that

Last edited by PortugalTV; 18th May 2020 at 2:33 am.
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Old 18th May 2020, 8:26 pm   #60
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Default Re: B&O Capri 606 TV (17") restoration

Hi PortugalTV,

Thanks for your replies, as always, much appreciated.

The coils wrapped around resistors: They all measure between 2-6 ohms at DC, and don't look damaged, so they should be good. I have measured components 65, 66, 74 and 75. Just noticed I missed component no 63, will test that soon.

I completely forgot about that the previous owner had paralleled the 220k resistor (component 77) with a 100k resistor, effectively making it 70k I suppose his intent was to increase brightness of the CRT? Anyway, I cut it out of circuit, so we're back at 220 kohm. The grid (g1) of PCL84 is unfortunately very close to 0V. The cathode of PCL84 measures 5.5V, and all the resistors in the video section are correct.
As I recall, the cathode voltage is a bit lower at around 110V, but still. When I power up the set the anode of PCL84 starts at what looks like 200V, until the tubes heat up.

One curious thing is that I noticed is that the output of the tuner, when measured with a multimeter at DC is close to 0 ohms, or grounded in other words. I know it probably doesn't tell anything about the cathode voltage of the CRT, but in the end this should affect the grid voltage of PCL84.

The 1.8M resistor at the contrast control measures 2.09Mohm so I would assume that to still be ok (?). The contrast pot also works from a few ohms to 51k, without any flakiness. The 4.7k is 4.9k. I will get to measure voltages at the viper soon as well.

The reason why I'm so focused at the tuner section and IF stage is that I made the raster disappear by tapping the PCC88 in the tuner section. My big mistake.
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