Rare find! A Magnavox Brittany tv!

[Yamamaya42]

I assume this is the 180pf cap?
http://suzaku.live-evil.org/0624252143.jpg

I never could work out how to decode these dots on these things!

[bandersen]

Looks like 82pF

[Yamamaya42]

Meaning I got the wrong cap, as the documentation / schematic is radically different from the set.
Not sure if I should even touch the area.

This is getting very frustrating trying to work out how the sync section is wired, it seems to be the opposite configuration as shown in the schematics, where the schematic shows a positive tied plate and negative cathode, in this set it's opposite, cap (mica) and resistor values don't match documentation, there are more resistors than shown.
I'm hesitant to touch any of the mica caps in the sync area no, as I'm not sure of their value, and if I was to move them, it may make things worse.

Specifically C156, that seems not to be 180pf, but 82pf, C155, which is said to be 100pf, but is at an angle where the dots can't be seen, don't want to move it.

Another example of difference, is that R169, the link for vert sync from the clipper seems to be tied to the plate, not the cathode, and is 22k, not 12k as shown in the documentation.
I'm aware that they make design changes and such, but I have never seen a deviation of this magnitude before, especially when this chassis # was listed in the documentation.

Hopefully C169 C172 C177 in the h-osc area are not different as well.

[dtvmcdonald]

At some point of frustration it pays to replace every cap and resistor (and diode if any) in a sync circuit,and do it carefully, undoing every lead completely and
resoldering with all new solder. And at least check each coil as best you can.

I fixed a flaky horizontal sync in my CT-100 and the similar circuit in an older
RCA set by doing that. And yes, its perfectly OK, in sync circuits (not RF oscillators!) to replace mica with NP0 ceramic. Its also perfectly OK to attach leads to surface mount caps (less so resistors, as they depend on the board for heat sink) and use them.

[Yamamaya42]

Originally Posted by dtvmcdonald

At some point of frustration it pays to replace every cap and resistor (and diode if any) in a sync circuit,and do it carefully, undoing every lead completely and
resoldering with all new solder. And at least check each coil as best you can.

I fixed a flaky horizontal sync in my CT-100 and the similar circuit in an older
RCA set by doing that. And yes, its perfectly OK, in sync circuits (not RF oscillators!) to replace mica with NP0 ceramic. Its also perfectly OK to attach leads to surface mount caps (less so resistors, as they depend on the board for heat sink) and use them.

problem is, the schematic has proven to be unreliable, at least for the sync area, bandersen has IDed that cap as 82pf, i have no reason to doubt him,and if so, then 75-561R10TCCQ82 is the mouser part to use.

the 100pf will have to be unhooked to be read, as its at an angle, and the dots can't be seen yet.

And yes, the resistors are easy enough to change, I have tons of metal film ones, most of the ones in there seem OK, but I'm starting not to trust them.

And again I don't really understand how to decode the dots on the mica caps, so I will most likely post pics of them. :/

[bandersen]

I'm reading it as 82pF like this. The crazy part is there are several variations of the dot order
Grey = 8
Red = 2
Black = 0

It might also be 200pF where the first dot is the tollerence or dialectric material

[Yamamaya42]

I have tried to use this site, but don't know what way to plug in the colors or if i should be using all 6, or 3, or what?

https://www.amplifiedparts.com/tech-...2bXABKsnZNvP_a

[Yamamaya42]

This is giving me a headache.

https://antiqueradios.com/forums/viewtopic.php?t=222168

This is kinda saying 820pf if i understand it.
FSN 8 SSN 2 TSN 0 multi = 0
820
Which agrees with that calculator site above.
confusing,


So, therefore, would not 82pf be black(0), grey(8) , red(2), with a multi of black? (0)
Or am I reading it all wrong?
I guess i can remove the silly thing and test it, one thing for sure, it's NOT 180pf.

[Electronic M]

Because of the multiple color coding standards I usually just take a tester to them if I can't see colors that match the schematic value.

[bandersen]

Never, ever seen a cap with a 3rd significant digit. Read it the same as resistors.

black means number of zeros = 0. So 82pF not 820.

820 would be grey, red, brown.

[Yamamaya42]

So, that calculator site is inaccurate :/ or just confusing

[bandersen]

It's not right for your brand of capacitor. There was no industry standard.

[Yamamaya42]

just took it out, and the M-tester says 82pf :O and the LCR says 83pf
so your first read was correct!

guess i gotta put it back for now till i get the right new part.

this will be a mess working out the right parts now.

shame that there was no standard back then.

[Yamamaya42]

sorry to be asking for help with these, but the dots just don;t make sense, and there is no standard like the resistors

the schematic SAYS this should be 100pf, but it is testing as 160, so the docs are wrong, or the part is really bad!
http://suzaku.live-evil.org/0625252105.jpg

If it's bad that would explain the poor sync! do the dots say 100 pf?

[bandersen]

Yes, 100pF rated for 500 volts.

brown - black - black = 100pF

green = 500 volts