Dampfradioforum

hi
i am 30years old and i am from Portugal
i recently got into the hobby of restoring tube televisions and radios
sorry for posting in English but i cannot speak or write German
if you are bothered with this please let me know and i will not post anymore


I just finished (i hope) repairing this philips tv
it has a rebuilt crt by GE Portugal and it was rebuilt in 1980
it came almost untouched when it comes to components
it is fully packed with mullard mustard capacitors wich all test good even after all these years
the carbon resistors are amazingly within spec
it came with a melted capacitor inside the high voltage cage and i replaced the mains filters for good measure. it came with 2 cans each containing 4 capacitors!!!!
it now displays a nice watchable picture and it seems stable to watch a movie without issues
this set has 8 diodes and 22 valves..fairly complicated like most german stuff
it has automatic image stabilization so no hold controls acessible from the outside.it also seems to regulate brightness and contrast to compensate for line voltage fluctuations



only issue so far is the flyback seems to get a bit warm to the touch and after some hours of use i found a drip of wax on the chassis
the ambient temperature on that day was very high with almost 40ºC inside the house though
there seems to be no arcing and no funny smells, i watched a few episodes of miami vice with a dvd player and was very pleasant to watch



this is the audio ouput stage and i posted here the schematic because it is so wierd that i dont fully understand it yet
i was hoping someone could shed me some light on its workings
althougt it is working fine i am curious
the speaker is 800ohms impedance, it does not use an output transformer, the speaker magnet is tiny and its on the side of the speker basket (YES) and the cone is held in mid air only by the suspension foam (no spider, no magnet inside the voice coil), almost looks like a giant electrostatic tweeter
also b+ goes through the speaker to the grid of the output tube and audio comes out of the grid of the output tube instead of the usual that is feeding audio signal through the grid and audio exits anyway it actually sounds very good for a tv.

Hello Nameless,

you got a fine TV set. It was made by German Philips in Krefeld in 1960.

The line output transformer is the most vulnerable part in the set. It is normal that it reaches a certain temperature. The core should be hardly touchable after an hour of operation, not much more. Maybe you shouldn't use it with this hot summer weather. Important: the booster voltage must be adjusted to the right value, better about 5 percent less. See diagram. The capacitor between anode of horiz oscillator and g1 of PL 500 must be in perfect condition, please use a good modern one!

The audio output stage was a Philips specialty of these days, also used in many Philips radios. It is a SRPP circuit (Shunt-regulated push-pull). It is used in some of today's tube amplifiers as preamp stages.
In this circuit, the output tubes are in parallel for ac (audio) and in line for dc (rail voltage).

the strange speaker was also a Philips specialty, only used in TV sets and portable record players with the speaker mounted in the cover (because of its small depth)

Btw. The mustard-colored caps are not from Mullard, but made by Philips-Valvo in Hamburg-Langenhorn, Germany.

Regards
Stefan

Thank you for you input Stefan
i forgot to say , my name is Hugo

so you mentioned some important things
the core of the transformer i did not touch but the high voltage winding was only warm..maybe 50ºc / 55ºc not more...i just got a bit scared by the drip of wax

the capacitor you talked about i highlighted it i red on the schematic below, i have not changed it because it is ceramic...it is a 500v rated part . can i place a 630v tubular capacitor or does it have to be high pulse resistant?like the philips orange 1700v mkp series for example?

i have not checked the boost voltage, the schematic calls for 960v
when the set arrived it had a rolling picture both horizontal and vertically and i had to tweak the oscillator coil a bit for the picture to stabilize , i highlighted the coil in green on the schematic below
tweaking this coil affects the boost voltage i know that because it changes the horizontal oscillator frequency, anyway i just twaeked it a little bit maybe one turn and a half or something.
i will check the boost voltage tomorrow and report it to you
are there serious consequences if it is a bit off? the set sems to work reasonably well. i note some random contrast variations between scenes on movies but nothing too big deal, maybe some auto regulation feature, i have studied and understood most of the schematic but there are still some obscure parts and features on this tv., atleast for the less experienced...

Hello Hugo,

yes, a 630Volt type will do it. Set the booster voltage to about 930 volts, that's okay. The missing 30 v will not really decrease brightness and high tension, but helps the line output transformer to spare a few degrees to live a little longer.

Regards Stefan

ok Stefan and everyone else

before we go to the boost voltage topic ,here is a pic of the inside of the tv and a more detailed description of the work made:
you see the blue ceramic caps? when i first plug in the set, some tubes flash or light up very fast and very hard and then they go to normal filament brightness so i thought i had leaky capacitors on the filaments series string to ground(very common) so as a precautionary measure i replaced all of the ceramic caps that go to ground (1,5 nf 500v) (did not touch the ones on tuned circuits etc, only decoupling caps to ground were precision is not critical) but then i found out that the old ones were good! it was a thing of my tubes, if i put different tubes they don't do that anymore

but anyway new 2kv ceramic caps instead of the 500v old ones cannot hurt.
also as you can see i replaced the small electrolytics because they were leaking fluids to the boards...for 8uf i used 10uf and there were some 0,32uf and 0,64uf wich i replaced with 0,47. they tested fine but had signs of fluid leakage.
the mustard caps that coupled signals from plate to grid of the next tube i removed them carefully and tested them for leakage...they were perfect and i put them back on with the exception of one wich was a bit leaky.
this work was done before my first post here on the forum

i dont have a leakage tester so when i want to test 400 or 500v capacitors for leakage i have a crude method: put my meter on dc volts, plug the capacitor to the 220v socket with a diode and the meter all in series, it should show 0v on the meter..if it reads any dc voltage than the capacitor is leaky.it actually works very well.






ok now regarding your advices:

i replaced the capacitor you mentioned with a 630v tubular new one
tv is working fine of course

my boosterspannung is at 1020 volts ...a touch on the high side but if i tweak the horizontal oscillator coil the voltage goes up or down depending on the direction i turn it but i loose image sync...what should i do?

thanks for your time

Moin!
Please adjust the Booster Voltage with R125.
It is marked 'BB', which means 'Bildbreite' or 'Picture With'.
Regards, Gerrit

i am glad i found this forum

on the american foruns people dont even want to comment on german Tv topics, thats just too complicated for them, american sets seem to have have half the components

anyway lets move on

i just tweaked r125 to get the boosterspannung to 930v but i had no full horizontal deflection, i could see 1 centimeter of black bar on each side of the screen
full horizontal deflection happens exactly at 960v like the schematic calls so i left it at 960v because i like to see the screen all filled and no black bars
this tells me that the PL36 horizontal output tube must be in good shape

so thank you A LOT for the good advice
i did not know that the width control affected the boost voltage so i learned something new

Hugo,

of course the screen should be fully written without bars. If these only applies with 960volts, adjust it to that voltage (normally, this is not that critcal). But 1020 is definitely too much. The booster capacitor is a new one? It should be.
Btw, with every change in the line output stage, such as replacing the PL 36, booster voltage has to be checked and adjusted the way yehti says. He also has large experience with the tv stuff.

Of course, first horizontal sync must be adjustd to a stable picture, then fine tune the booster voltage.

With the capacitors you did a fine work. Replacing the ceramic caps in heater circuit was, I assume, not neccessary, but it cannot hurt, as you say. Lighting up brightly for a short moment after switching on is in fact normal behaviour of SOME tubes and no reason to worry!
Didn't you have any trouble with the printed circuit when soldering on it? The copper leads tend to loosen from the board when heating up, this is due to bad quality of these early philips pcbs.

There is an additional source of future trouble in your Philips. If you surely learned, there are two different types of resistors used. There are the ones with shiny dark red laquer on it - theses are excellent - and some with a brown, dull, uneven surface with broad, uneven color rings. These are carbon composite resistors of bad quality (Vitrohm-Kohlemasse-Widerstände). They tend to increase their values with age significantly. Please check them, at least those with higher values, maybe from 47k upwards.

Did you check if there is a large capacitor of about 0,1µF hidden behind the mains switch? They can be found in some Philips sets. Replace it.

Much fun with your Leonardo wishes Stefan

hi stefan
thanks for the tips

if i ever one day change the pl36 i will remind to verify that

about the board i did not have any trouble, i am used to that since i restored a Dynacord concert valve amplifier and the boards are even worse..and it had immense moisture damage..
the trick is not to pry sideways on the component you remove and when installing the new one the holes must be heated up or it will hit the solder residue and lift the trace off the board, or you can also use a good solder sucker but i didnt need to. when installing the new component i advise to leave it in contact with the board. if you leave it hanging high distant from the board then if you accidentally press down on the component, the copper trace will lift off the board...hope my english makes sense... i also found a lot of cold solder joints on the left board but all joints were good on the right board..

yes i know those nasty carbon resistors especially the ones with high values they tend to get even higher...i checked a bunch of them (not all) and they were reasonably in tolerance suprisingly

the across the line capacitor (tar capacitor) was hidden like you said but i found it and replaced it with a X Y safety capacitor, those square ones, i think i put a 0,22uf but the value is not important there

the boost capacitor was melted into a soup of black tar and i put a 1700v mkp one. i zip tied it, glued it and put a piece of cardboard between it and the chassis (photo above)

guess its time to move to other projects and watch some movies!

i also have a habit of buying the most cheap and broken radios with bakelite cabinets missing pieces and i like to repair the cabinets ( i worked on auto body shop) so if you guys think it would be interesting i can put some topics of those radios and the methods i use may be of interest to someone.
check out this nordmende tv before and after (unfortunately crt dead and Line output transformer open)

Well, that's a difference! Obviously you are a wood artist!

Stefan

thank you but i am not very good with wood, i just had a lot of patience

i used mostly automotive products to restore that tv cabinet (filler, paint , etc)

i put a topic on the valve radio cabinet restoration section on this forum showing what i normally use, check it out




Danke, aber ich bin nicht sehr gut mit Holz, ich hatte nur eine Menge Geduld

Ich verwendete hauptsächlich Automobilprodukte, um diesen Fernsehschrank (Füller, Farbe, usw.) wieder herzustellen

Ich habe ein Thema auf dem Ventil Radio Schrank Wiederherstellung Abschnitt in diesem Forum, was zeigt, was ich normalerweise verwende, überprüfen Sie es aus


viewtopic.php?f=33&t=28314

Hi to all

a few weeks ago i had a problem while watching my tv!
i heard a "bang" and saw a flash on the inside... But the tv contined working!
when i pulled off the first video IF tube, the ef184, i noticed it has something mettalic loose inside of the tube but the tv was working normally
when you shake the tube you can hear the mettalic noise inside. like a loose piece of filament or something..
so i ordered some new tubes, infact i like this tv so much that i ordered 10 new tubes for various important parts of the circuit like the vertical etc (this was not very smart i guess)
so when the tubes arrived i replaced them all

now i have a raster , but no image, only sound. i can see a tiny bit of snow but very faint
i put back all the old tubes and the problem remains

i checked the video detector diode and it read infinite on one direction and 295 on the other direction so it seems fine since it is a germanium diode

if i inject a composite video signal in the video amplifier grid , the tv displays the video fine

this tv always had a dark picture even with the contrast to the max so i started checking voltages around ro9 (pcf80)
please check my diagram

the negative voltages marked on red are not present and they go to various places including the tuner and the first video IF tube
i cannot figure out how this negative voltage is generated or where it comes from
the two capacitors marked blue have been removed from circuit and the voltage is still zero, then i replaced them with new ones and the same result.
r63 is a VDR and it reads infinite resistance so i guess it is OK
what am i missing?


Hallo an alle

Vor ein paar Wochen hatte ich ein Problem beim Fernsehen! :wütend:
Ich hörte einen "Knall" und sah einen Blitz im Inneren ... Aber der Fernseher funktionierte weiter!
als ich die erste video IF-röhre, die ef184, herauszog, bemerkte ich, dass es etwas metallisches lockeres in der tube gab, aber der tv funktionierte normal
Wenn Sie die Röhre schütteln, können Sie das metallische Geräusch hören. wie ein loses Stück Filament oder etwas ..
Also habe ich ein paar neue Röhren bestellt, eigentlich mag ich diesen Fernseher so sehr, dass ich 10 neue Röhren für verschiedene wichtige Teile der Schaltung bestellte, wie die Vertikale usw. (das war nicht sehr schlau, denke ich)
Als die Rohre ankamen, habe ich sie alle ersetzt

jetzt habe ich ein Raster, aber kein Bild, nur Ton. Ich kann ein kleines bisschen Schnee sehen, aber sehr schwach
Ich stelle alle alten Röhren wieder hin und das Problem bleibt bestehen

Ich überprüfte die Videodetektordiode und es liest unendlich auf einer Richtung und 295 auf der anderen Richtung, also scheint es in Ordnung, da es eine Germaniumdiode ist

Wenn ich ein Composite-Videosignal in das Videoverstärkerraster einspeise, zeigt das Fernsehgerät das Video an

Dieser Fernseher hatte immer ein dunkles Bild, selbst mit dem Kontrast zum Maximum, also fing ich an, die Spannungen um ro9 zu prüfen (pcf80)
Bitte überprüfe mein Diagramm

die negativen Spannungen, die auf rot markiert sind, sind nicht vorhanden und sie gehen zu verschiedenen Stellen, einschließlich des Tuners und der ersten Video-IF-Röhre
Ich kann nicht herausfinden, wie diese negative Spannung erzeugt wird oder woher sie kommt
die zwei blau markierten Kondensatoren wurden aus dem Stromkreis entfernt und die Spannung ist immer noch Null, dann habe ich sie durch neue ersetzt und das gleiche Ergebnis.
r63 ist ein VDR und es liest unendlichen Widerstand, also denke ich, es ist in Ordnung
Was vermisse ich?

Hello Hugo,

the sampled control voltage is obtained from the line retrace pulse. This comes via C74 from a winding of the line transformer. Its amplitude is around 550 ... 600Vss. For accurate measurement, an oscilloscope is required.

This control voltage adjusts the gain of the IF stages so that the IF amplifier is not overdriven. The tuner is controlled delayed from a fairly high antenna voltage.

In your device, the IF signal is probably too low to build a control voltage. The IF amplifier is therefore fully regulated.

Maybe an anodes or G2 voltage is missing on the ZF tubes. Therefore, a measurement of these voltages is recommended.



Hallo Hugo,

die getastete Regelspannung wird aus dem Zeilenrücklaufimpuls gewonnen. Dieser kommt über C74 aus einer Wicklung des Zeilentransformators. Seine Amplitude liegt bei ca. 550...600Vss. Zur exakten Messung ist ein Oszilloskop erforderlich.

Mit dieser Regelspannung wird die Verstärkung der ZF-Stufen angepasst, damit der ZF-Verstärker nicht übersteuert wird. Der Tuner wird erst ab einer recht hohen Antennenspannung verzögert geregelt.

Bei deinem Gerät ist das ZF-Signal wahrscheinlich zu gering um eine Regelspannung aufzubauen. Der ZF-Verstärker wird daher voll aufgeregelt.

Vielleicht fehlt eine Anoden oder G2-Spannung an den ZF-Röhren. Deshalb ist eine Messung dieser Spannungen zu empfehlen.

_________________
...und glüht auch die Anode rot, ist die Röhre noch nicht tot.

Mit freundlichen Grüßen, Peter R.

hi glaubnix
c74 connects to c144 via the G wire marked on red on the schematic and it goes to what appears to be the grid of the sync separator.

Hallo Glaubnix
c74 verbindet sich mit c144 über das G-Kabel, das auf dem Schaltplan rot markiert ist, und es geht zu dem Gitter des Sync-Separators.



near that there is some coils and what seems to be two phase detector diodes
this part of the circuit should be working fine because otherwise when i inject video into the video amplifier grid it would not sync, am i right?

so my problem must be in the IF section or tuner...right?

this is the video if section:
i dont see what could go wrong here other than bad tubes....

in der Nähe gibt es einige Spulen und was scheint, zwei Phasendetektordioden zu sein
Dieser Teil der Schaltung sollte gut funktionieren, weil sonst, wenn ich Video in das Video-Verstärker-Netz injizieren würde es nicht synchronisieren würde, bin ich richtig?
Also muss mein Problem in der IF-Sektion oder Tuner sein ... oder?
Dies ist das Video wenn Abschnitt:
ich sehe nicht was hier schief gehen könnte außer schlechten Röhren ....: wut:

Hello Hugo,

first to the line pulse: this is supplied within a branch of the wiring harness. I have entered in the summary of your part diagrams.



Hallo Hugo,

zunächst zum Zeilenimpuls: Dieser wird innerhalb einer Abzweigung des Kabelbaumes zugeführt. Das habe ich in der Zusammenfassung deiner Teilschaltbilder eingetragen.

... and here the voltage measurements in the IF amplifier:

_________________
...und glüht auch die Anode rot, ist die Röhre noch nicht tot.

Mit freundlichen Grüßen, Peter R.