Another local Hoffman! COLOR! - Page 10 - Videokarma.org TV - Video

Yamamaya42 · #**136** 10-15-2022, 05:45 PM

I did try to put in a NOS 6BK4C, but it FAILED fantastically, throwing sparks as soon as I powered it up, the grid exploded and fried a resistor.

so I'm back on the old smoky glass tube.

http://suzaku.live-evil.org/1015220040.jpg

Yamamaya42 · #**137** 11-18-2022, 10:23 AM

Here is a reminder as why one should never trust weird no-named electrolytic capacitors.
This is out of a dead 6 year old LCD monitor. A ( TAICON) branded part.

http://suzaku.live-evil.org/1117222242.jpg

they don't make em like the used to!

kvflyer · #**138** 11-22-2022, 09:52 AM

Preaching to the choir here of course, but all the more reason to test components before using them. This is a note to myself as well. I have the equipment; I need to use it.

Thanks.

Electronic M · #**139** 11-22-2022, 01:31 PM

Quote:

Originally Posted by kvflyer

Preaching to the choir here of course, but all the more reason to test components before using them. This is a note to myself as well. I have the equipment; I need to use it.

Thanks.

My rule is if it's a used part check it...I typically only use used on stuff I don't care about. New never installed parts if I'm familiar with the brand I typically don't check.

Yamamaya42 · #**140** 11-22-2022, 03:13 PM

it WAS a new part at one time, but hardly lasted 2 years b4 it went to crap, point is, there are STILL fake parts out there :O

Yamamaya42 · #**141** 03-03-2023, 02:34 PM

The set is starting to act up a bit already, not sure why, not sure if its cause the CRT is on it's last legs, or perhaps that bad 6BK4C damaged something, I swear I saw some smoke, but could not find the source.

But right now, brightness is inconstant, tends to change a lot, but the blue gun is the weakest, AND pin 11 was broken off, and is hanging on by a thread.

So before I do something crazy like try and find a new tube and pay insane shipping charges, OR , work some kind of bodgetastic miracle and fit the 25Vxx22 in this TV from the RCA CTC-90 that I hate! ( only 1.681 inches wider, super glue fixes everything! )

Gonna replace a few more stuff.
http://suzaku.live-evil.org/hoff-hv111.jpg

X5 with a pair of https://www.mouser.com/ProductDetail/78-BY228-15-TAP in series.
I don't like the look of the selenium rectifier in there now, and it's kinda smelly, so boost may be low or unstable, causing me to turn crt bias up, that will be the first thing replaced.
also, R139,,140,141,142. with new 10kv w1 rated parts.

Not sure if this will help anything at all, as the picture tube is clearly a weak point, and every time it's touched is a risk, but not much I can do, as replacements are so far away,

Electronic M · #**142** 03-03-2023, 03:36 PM

If a selenium is making smell it's gone bad.

Keep an eye out for junk 70s SS sets with delta gun 23VxxxP22 CRTs. They show up a lot out here (I'd bet there's still tons in Texas it you keep your eyes open) and the tubes are typically drop in bolt in replacements with the advantage of black matrix technology.

Yamamaya42 · #**143** 03-03-2023, 11:43 PM

http://suzaku.live-evil.org/0303232312.jpg
this is what I mean by I don't like the look of the boost selenium rectifier, it seems rater cooked!

that 100k resistor looks rather toasted as well.

http://suzaku.live-evil.org/0303232315.jpg

I am 1/2 serious however, there IS room to fit a 25v in there

it would take some serious mods, and it would lose some on the sides, but it COULD fit.

it just depends on how much trouble this gives me, and if another tube ever shows up in the area here.

Yamamaya42 · #**144** 03-04-2023, 08:25 PM

Update worked!

https://www.youtube.com/watch?v=Dt13mz-tRCQ

I was able to turn CRT bias way down after replacing that ugly diode, and screens came up by quite a bit, but of course, this DID change the vertical linearity a bit, which in turn upset the convergence, this was not unexpected, but over all, things seem better, I will re-do the convergence for the 1000th time at a later date

Electronic M · #**145** 03-04-2023, 09:57 PM

Congratulations. This reminds me of the first roundy I got in college....That Silvertone RCA clone fought me... First power up had raster, but after recap it was dead. Damper had shorted, but it tested good before it shorted and I gave up on it for a few months before another set with the same tube had intermittent shorting, I borrowed the presumed good Silvertone tube and it killed the other set..
After that I got HV back but had no raster, and only got light for a split second on power off. After a bunch of tracing I found the selenium boost diode dead and that got me raster.... Somewhere in there I learned that set would eat dampers like candy if the horizontal osc was far enough out of adjustment, and had other problems along the way....It's the fighters that teach you the most.

old_coot88 · #**146** 03-04-2023, 10:53 PM

Quote:

Originally Posted by Electronic M

...It's the fighters that teach you the most.

Yeah. I had a fighter that was kicking my butt royally. Maggie 25", hybrid chassis with transistor IF strip. No luma signal whatsoever, but chroma was unattenuated. Gotta be H-K short in the CRT or dirty service switch, easy peasy. But it wasn't. Chroma subcarrier was coming out of the video detector OK, but no luma. Replaced the diode but no diff. Can't be IF related or the chroma would be gone too, right? Wrong. Finally found the 2nd IF transistor was open. Replaced it, and prollem fixed.

Yamamaya42 · #**147** 03-04-2023, 10:54 PM

http://suzaku.live-evil.org/0304232245.jpg

it was certainly in a Princess Bride state, as in being " Mostly dead", it was not completely shorted, but WAY below the level it should have been working at. :O

Yamamaya42 · #**148** 03-11-2023, 11:57 AM

http://suzaku.live-evil.org/0310232247.jpg

after touching up the convergence last night, the picture looked a bit, gamey!