CTC-10 remote update - Videokarma.org TV - Video

frenchy · #1 10-05-2005, 09:07 AM

Since it was suggested I make a new thread for this...

I constructed a replacement for the 4.2V remote control battery. Actually I noticed the paper peeling off the old one and found out it was actually just 3 smaller cells stacked on top of each other. So when I got to the store, bingo, found a 1.5 cells that looked exactly like those (except, like watch batteries, the + is on the 'base' side of the battery). Just stacked 3 up and wrapped in tape and made my own battery, works great plus .3 volts to spare.
Remote unit is SORT of working. One minute the tint down doesn't work, next the color up doesn't, then they do, etc. But still have some filter caps to replace so see what improves after that. Its a pain to test cuz the microphone thingee in the set can't be pulled out of the set unless I take the damn pic tube out, no room... so have to lug chassis to back of set for every test. Oh well, it's progressing better than I thought.
Got some 3.58 crystals and a few tubes so will try thos out this week too.

andy · #2 10-05-2005, 11:41 AM

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frenchy · #3 10-05-2005, 02:26 PM

Yeah I think I will rig one up, thanks.

frenchy · #4 10-06-2005, 04:46 AM

Here's a pic of the set after I did a quickie convergence on it and changed some more filter caps. Color is now working great with a new crystal and a new tuner tube.
This is one bright pic tube, I'm gonna throw the brightener they had on it in my parts box, after my fixes to things like the crapping-out surge resistor killing juice to the set, it is totally not needed. I guess one could expect that on one of these old monsters sometimes, after about 10 years it starts to break down for the 48th time and owners won't spring for any more repairs BUT repairman says oh well we can put a brightener on it for only 5 bucks, what the heck, you're going to junk it anyway, right? In goes the brightener. I mean yeah most of the time brighteners were put on after the tube and set were tested but I bet other times they were just slapped on as a last low-expense gasp to keep the thing alive before it was hauled to the dump because they didn't want to put any more $ in it.

veg-o-matic · #5 10-06-2005, 08:19 AM

Tasty!

veg

frenchy · #6 10-06-2005, 01:33 PM

It looks a lot better than that picture which I took with some lights off in the room so the picture wouldn't get washed out... and it's on lousy little rabbit ears right now where only 1 channel is picking up good enough to even take a pic. And I don't even have it degaussed or precisely converged yet (one pot on the conv board is flakey but I think it just needs to be resoldered.) I'll hook it up thru my heavy-duty roof antenna system later. I'm not kidding about the unneeded brightener... I don't know what new 21FJP22's looked like back then but if they were brighter than this rebuilt one is (says "grade A" on the sticker), whew.
Probably the brightest of my four 21-inchers.

frenchy · #7 10-07-2005, 07:59 PM

I went thru the remote chassis and still have some questionable voltages. This is just on the bench with 120 ac going to it, no input, as directed in the schematics. I shielded the first 12ax7 as it has a ground spring on it, plus without it some of the functions just lock on with no input so I think it's supposed to be there. The rev. motor relay pulls in at power on, probably normal as the reverse motor keyer is called 'rev off' so I think that keyer turns the relay off instead of on like the others.
When installed in the tv, the operation is iffy, sometimes have to have the remote very close to the mike for it to pick it up, sensitivity of the functions changes when I move the keyer tubes around like they are just on the border of working sometimes and a diff. tube will allow them to work or not work, the tubes all test good. Anybody see any suspects as to why some fo these voltages are way off, mainly that 61 volts that supposed to be 165? That doesn't look right at all.

http://mysite.verizon.net/resoctff/photoalbum/

The 40 mfd and 5 mfd filters have been changed with no real improvement. thanks!

frenchy · #8 10-08-2005, 01:26 AM

Quote:

Originally Posted by bobgary

Check capacitor C1001 .1uF (the cap between R1001 and R1002)

Since I had some .1s here I went ahead and changed that one. One of those ones crammed into that little shielded box underneath the #1 12ax7. Slight change in voltages, 61 is now 62, 130 is now 135, so still doesn't jibe with the schems of 165 and 100. I don't get it, if I measure that 175v across a 1 meg resistor, I get 88v, same as in the circuit, and when goes across the second 1 meg it drops it again to 62. How the heck is it supposed to be 165?? Is it possible that 165 is a typo and is supposed to be 65? Then again I still have 135 instead of 100 at the 12ax7 soooo - I dunno.

frenchy · #9 10-08-2005, 03:05 PM

Quote:

Originally Posted by bobgary

When you measured the voltage where you should see 165V, was the microphone plugged into J1001? Try measuring with the mic unplugged. The plate voltages come from a different line. High plate voltages usually indicate that the tubes are very cutoff, which also makes sense with a more negative bias on the grids. Anyway, this all may not be helpful in the least. It could be that when you replaced some of the caps in the remote, you detuned it.

I am pretty sure it has not been detuned, I only did a large paper and a metal electrolytic in the hand unit, none of the smaller ceramic caps, and in the chassis, just a few .1s and .01s here and there. It basically didn't work at all before I did the hand unit caps. Now it works pretty good except needs really strong and close remote signal.
I don't have the mike plugged in. Some dude in Brazil said I may have leakage between the 180v and the mike plug, so I am going to just snip the wire at that point and see what I read, the mike socket may just be leaking or something. Thanks...Frenchy

frenchy · #10 10-08-2005, 03:39 PM

Nah I even snipped the wire coming off the first 1 meg resistor and only measure 88 coming of it. How the hell I'm supposed to end up with 165v after the 175v goes thru only one of the resistors and already only reads 88, I'll never know (but then I wouldn't expect me to ; ) ) I think I need to understand more about voltage and resistance formulas or something.
Arghhhhh

frenchy · #11 10-10-2005, 04:17 AM

Damn I'm about to shove this set out to the curb. I decided to test the hand unit to see if could see if possibly it is cause of seemingly low power of the remote transmitting. Realize my tester has a frequency measurement on it, great, so I hook it up to ground and a terminal that leads to the transducer, sure enough I get 4 different frequencies in that 19-24 range like the schematics. And measured voltages coming out of there too which were kind of wacky on the meter (AC changing around). But now the remote refuses to do ANYTHING when pointed at the set even if I shove it right up to the tv's mike. I don't know what happened, maybe the one transistor has finally given out. There's nothing left in the thing that could break, I changed the two flaky caps that affect all frequencies, there's only 4 resistors check out, all the other caps are specific to one frequency only, I don't get it. Wonder what the transducer is, maybe something I did blew it? All I did was measure voltages and frequencies. How can I test the transducer? This set has been one big pain in the ass, one minute I think I got it and then it bites me like this.

old_tv_nut · #12 10-10-2005, 12:00 PM

It's not clear if you finished debugging the receiver. First thing is to verify that the DC voltages are more or less normal. If they are, you could verify that the receive mike is working if you have a scope and can look at a point where the signal has been amplified - jingling keys or silverware near the mike should produce some output.
If the remote transmitter uses an electrostatic emitter, it's possible it is burned out, but hard to tell if you don't have the receiver working.

Chad Hauris · #13 10-10-2005, 01:18 PM

Do you have any other ultrasonic remote transmitters? Most of the time at least one of the frequencies will do something on another set.

When there is no load on a resistor (no current being drawn through it, one end disconnected) there should be the same voltage on both sides. There is only a voltage drop when current is being drawn so if you have 175 volts being dropped to 88 through a 1 meg resistor:

using E=IR (voltage drop=current times resistance)
87 volts being dropped= I times 1,000,000
divide 87/1,000,000 equals .087 milliamps (if my math is all correct)
this leakage could be caused by a carbon path on a terminal strip or some other very slight cause.
Also, what kind of a meter are you using...electronic (VTVM or digital) or an analog VOM? Some types of analog meters draw some current and the meter may be drawing enough to cause the voltage drop on the resistor.

frenchy · #14 10-10-2005, 03:14 PM

Quote:

Originally Posted by old_tv_nut

It's not clear if you finished debugging the receiver. First thing is to verify that the DC voltages are more or less normal. If they are, you could verify that the receive mike is working if you have a scope and can look at a point where the signal has been amplified - jingling keys or silverware near the mike should produce some output.
If the remote transmitter uses an electrostatic emitter, it's possible it is burned out, but hard to tell if you don't have the receiver working.

The chassis has been working yesterday in testing and for last couple of weeks, weak response from the hand unit as usual but every function would work if you got it close enough to the set, sometimes from a good distance.
Then all I did was poke around the hand unit a little with the ohmmeter checking things and walk back to the set and - zippo, no response anymore . The chassis pulls in relays when I add capacitance to the mike plug just like it did before (like touching a piece of wire to it) and voltages all check out. And on top of it I think I may have found the actual cause of the weakness, the little round screen in front of the transducer was 99% clogged with dirt and wax so the sound was probably being almost totally muffled. And even now the hand unit ACTS like it isn't dead, I read frequencies off each function and voltages to the transducer. I'm gonna have to leave this thing alone for a few weeks, too ticked off at it right now.

frenchy · #15 10-10-2005, 03:45 PM

Hey I went back to it this morning and now it is acting like it still wants to work, yayyy, tint and color work if I get it within a foot of the mike, very finnicky, so maybe the transducer is ok (I unscrewed the screen and cleaned out that crud, but still very weak response). Maybe it's the one transistor that's dying, since the problem seems to be weakness? I could take it out I guess and test it, that's about all that's left to be broken in there that hasn't been replaced already or checked, as far as output it puts out. It's as though this thing just keeps getting weaker and weaker even if I use a power adapter and not the battery. Would testing it prove that it just isn't dead, or would it tell me if it's weak too? If not, I could just spend a buck on a replacement. Anybody offhand know a sub for a 2n406? Damn remote!
thanks