Picked this up yesterday, dont know when I will get to it, but at least I will have it when ready.

Nice. Its most likely a '67 model with a Looks like a 20X1C38 or possibly a 20Y1C38.

SWEET!!!! Nice save. That was a quality set for sure!

got the back off last night, all tube tv chassis, 25GP22 pic tube (will test later). The receiver was impressive. copper clad all metal chassis, all the transistors were socketed, and of course the chassis is all hand wired (don't see that with solid state very often). It had 4 IF stages on FM and 2 IF stages on AM, plus the AM had a tuned RF stage as well, Should be a great receiver. The power tranny was a good sized one, in put power rated at 85 watts.

now THIS is the way a SS receiver should be built..

got the back off last night, all tube tv chassis, 25GP22 pic tube (will test later). The receiver was impressive. copper clad all metal chassis, all the transistors were socketed, and of course the chassis is all hand wired (don't see that with solid state very often). It had 4 IF stages on FM and 2 IF stages on AM, plus the AM had a tuned RF stage as well, Should be a great receiver. The power tranny was a good sized one, in put power rated at 85 watts.



What is a "power tranny" ???

power transformer on the SS receiver is a good size one, I have some magnavox astrosonics that are a little skimppy on the PT and you notice it when volume is set to the higher levels.

Nice set.

the one thing I really like about the old consoles like this is the abilty to power the stereo amp directly off the audio source, really makes watching TV with full sound effects a lot better. I had to modify the last couple of these to take advantage of the stereo output of the DVD/converter box, but its well worth it.

now THIS is the way a SS receiver should be built..

I'm not a big fan of solid state console stereos; but, if I could find a SS Zenith console with a chassis like this, it would be a keeper.

If I ever find a Zenith combo of this quality, something else will just have to go out the door.

yep, I have never seen a SS hand wired with all the sockets, very easy to service thats forsure. It looks to have all orig transistors save for one driver. will be fun to pull them and test, just like a tube, maybe I can do some transistor "rolling" :)

What is a "power tranny" ???

It's the power transformer, but it could be something else too LOL :D



On another note:

Yay! It worked instead of wrecking the post! All those darned edit buttons everywhere! I have to be careful.

I sold those and the cabinets were solid cherry and cherry veneers. No photofinish or fake wood. If my memory is correct, all the veneers are on plywood, not particle board. The base is probably the only particle board used in that massive cabinet.

indeed, even the base on this one looks to be 3/4 ply. Def built like a tank, and in very good shape (not mint but def good). The legs looks good (not all dinged up from vacuum cleaner hits..), the speaker grill looks to have a lot of nicotine, although there is no smoke smell, maybe just the color. I have heard that oxyclean works well (foam) to clean these.

Another great score, Dave! You know, you are skating on thin ice!

Thats not the Zenith combo from TN is it? Good looking set I must say!

nope this was a south florida score. It was a bit of a drive but for 25$ I did no mind the gas money.

the one from tennessee is a flat chassis solid state.julian burke called me about it but i could never get a hold of the owner.this is a nice score.keep posting progress and we do like those pictures!

TV chassis, sorry about the glare

The red gun of the 25GP22 test a little weak, the G and B are fine. I have it cooking now to see if it comes up any.

I am a little confused on the sencore CR70 tracking instructions

I have tested each gun sep for shorts, cutoff, and emissions, then it says to set controls for R and switch to tracking, then switch to B, then G and look how much it varies, does that mean I leave the controls set for the R (2,3,4) and then just switch from R to G to B with out changing the 2,3,4?

well shoot by the time I finshed that last post I figured I would go check on it, the R gun is fine :banana: right up there with the others

My cabinet was never in a "smoking" location. The grill cloth ( fabric would be a better word for mine) is still as perfect as it was in 1970 when Zenith built the cabinet at their Springfield, MO, plant. I moved it last year to a new house and was really afraid the fabric would fall apart from bouncing around but after 40 years it is still hanging in there. I just wish i had spent the extra for the cherry doors. I added the ones on mine about 20 years ago.

indeed, even the base on this one looks to be 3/4 ply. Def built like a tank, and in very good shape (not mint but def good). The legs looks good (not all dinged up from vacuum cleaner hits..), the speaker grill looks to have a lot of nicotine, although there is no smoke smell, maybe just the color. I have heard that oxyclean works well (foam) to clean these.

I did not know the doors were an option, I would like to have some for mine as well.

The Italian Provincial was the only one available with or without the doors, except for the Oriental styling model. The one with the doors might be styled slightly different. Just moved and my brochures from back then are still packed up.

I have that exact set. Took allot to get mine going and the hv regulation is still sloppy compared to my other zeniths. If you need any service info or help I got it. The stereo works very well.
It seems this was one of the more common cabinets, I have seen several of them listed around. Glad you got it.
http://boxcarcabin.com/zenith-20x1c38.jpg

Thought I had seen that before, thanks for the offer, I will no doubt be checking with you on it.

finally hooked up the variac to the tuner, nothing, smoked fuse, hooked up, nothing, was in phono mode, finally got the AC line to show about 8 ohms, so started dialing up the variac, instant 2 amps before I got to 10volts.

I assume the primary is ok since I get the 8 ohms, so my guess is a shorted filter cap, prob what took out the fuse back when ever it was last tried. At least the fuse was not a standard auto glass type the some fool would have put a 20amp in place.

I will pull the tuner chassis later and see what the deal is.

last week a picked up a perfect tuner, the exact same model off ebay, I was thinking ahead, looks like it will pay off.

finally got the AC line to show about 8 ohms, so started dialing up the variac, instant 2 amps before I got to 10volts.

:beatnik::beatnik::beatnik::ntwrthy::ntwrthy::beat nik::beatnik::beer::beer::tongue::tongue::rockon:: rockon::drunk::drunk::smoke::smoke:

swapped the ebay stereo tuner, sounds good in the TV. Got the old one on the bench hooked up, not sure what the deal was but no short now.

couple problems, the on off switch is a SPDT with one side open, jumped past that, checked the output caps (cap coupled speakers), hooked up some test speakers. one channel is ok but has some hiss (leaky transistor) the other channel is hiss and bad garbled (guess is a coupling cap). I will get the scope out later and trace the signal which is prob the fastest way to find the issue.

...

you know andy you hit it on the head. I finally swapped the outputs since I could not figure out what was going on, bingo, both channels come back with no distortion at all. I still have a nagging hiss, its after the volume so it has to be in the finals, driver or amp. I think its the finals. I will try swapping around to see if I can isolate. I tested them for leakage and they had some, but on finals I think some leakage is ok. I tried swapping out the drivers with some good PNP germainium, no help. Maybe a leaky cap? well moving transistors around should test that theory. sure sounds like a leaky transistor.

Not a big deal since I have already swapped the tuners out, I just dont like unsolved puzzels.

well the stereo light is acting up. it comes on weakly, and the transistor that drives it get hot. gonna have to look into this a bit more. the tuner sounds great with the new coupling caps to the drivers and a couple new audio amp transistors (no more hiss at all).

a ha,

used an 1819x (glad I kept it) I replaced it with a #47

the 1819x is a 28v vs the 47 which is a 6.3v

gonna have to hit the local supplers for one.

It is the "second best" of the Zeniths. I have about 4 of the various complete chassis like that lying around, (including a 26XT20, and a 26NT20) and a complete console stereo with one. It is NOT as nice as the "big one" with the separate amp in the bottom and 15" 3 ways- (like the 6AT24 amp and 29AT24 tuner chassis--(a console set I ALSO have--and may get another one locally soon..) --but is is pretty good. Probably about 20W/CH or so, I would say. There was also ONE "horizontal version" of that chassis--laid out somewhat differently--but electrically very similar--the 26YT21--I have that chassis too. I LOVE the "look" of ALL of them--nice "eye candy" to me. I LOVE old SS stereo chassis-- and have a LOT of the Zenith ones a few RCA's and a couple GTE's.

I personally think the old Zenith SS stereos were THE BEST--MUCH better than Maggys or even RCA sets--though the Sylvania's of the time frame(1965-70) or -- were not bad--either....their TOTL and next in line anyway.

yea its a sweet chassis, its amazing to think of the hand wiring that went into that set AND the fact that it was done here in the the USA.

The only thing I dont like about it is the dumb soundess contour built into the volume pot. Kills the highs rather than pumping the lows, at least until you crank it up. I would love to just disable that tap but I respect the thing to much to start re engineering it.

I may check some of the componets in that area to see if anything has drifted making it worse that it is.

You are rigth about it in comparison to the maggie (the only other SS tuner I have), it has better sensitivity, and very low distortion at higher power settings. I seems to have a decent PS for an early SS unit.

I need to seset the opt transistors, the heat sink paste is all crumbly but at least those expensive PNP outputs are good.

there is a slight hum that is not present on the ebay find so I will need to go thru the caps. Funny how one set has bad caps and the other does not. I think it has something to do with the storage enviroment, maybe the useage as well. The Ebay find was pefect, but for a slight bend in the tuning shaft. I dont know how that could get bent and not break the tuning knob. It has a slight over center feel as you turn it, Not a big deal but just enough to bug me. The tuner that came in the TV console has a perfect tuner shaft.

new bulb fixed the MPX light, guess the #47 was messing up the bias. It now comes on like a switch and is nice and bright. Before it would always glow dim and just get a bit brighter (but still not very bright) when the MPX was detected. Not to mention the transistor was getting warm that drives it (warmer than it should be).

Only thing left is the SPDT on off. Not sure how that is going to go. my guess is a burned contact. It closes when the button is pressed, press again and its off, but will come on if the turntable is on.

progress, on off switch on stereo tuner fixed, took it apart and vigorously rubbed the contacts. seems ok now, but time will tell.

Now the decison, to I leave the replacement stereo in or put back the orig. The replacement has a slightly different face (mostly the way the channels are layed out).

Its a nothing job to replace it. But then again the switch may act up. I think I will just use the orig and test the switch.

I just got in some HV caps that I needed to finish off my 20Y1C38 zenith so I will button it up, leave the CRT for now (its the one with a weak reg gun but not too bad after it warms up), and then I will pull the chassis on this console and go over it. Its a filthy mess so I will start by a gentle cleaning, then will check the B+ for for shorts and leaky caps. If that goes well then will pull the HOT and VOT and do a slow power up to see if the filter caps are ok. after that the reg test.

the MPX light still varied somewhat with signal stength. for fun I swapped out a few and found a transistor that would act much more like a switch either on or off. For fun I tested it and the Beta was nearly 10 vs 5 of the other ones that while worked, did have some dimming on weaker stations.

The transistor checker is kinda nice since I can use it to match transistors.

Picked this up yesterday, dont know when I will get to it, but at least I will have it when ready.

That is the one I mentioned that was from Boca Raton. Glad it got saved!

while playing with the tuner I checked the phone input, seems like a lack of separation going on, seems like there is some signal leakage.

I am thinking decoupling or some other power supply problem. I will put a scope on the B+ supplies and see how much signal modulation is there if any.

my ctc17 combo lost stereo separation too. I use the tape input for the cable box.

I figured it was a burnt or failed ground somewhere but you bring up a good point.

O, btw... on both my zenith combos with the same tuner, the bass is mono and the high end is stereo.
I never questioned it because thats the way systems with subwoofers are setup. There should be little to no stereo information in the bass and it makes sense to have it monoed out.

its goofy. I put in a signal 400hz into the left channel thru the phono, then I scope the base of the left transistor and compare to the base of the right. WTF the signal is about 1/3 the Left.

there is a network of resistor that connect the two bases togehter on mine its a 56k/22k/56k. I removed the transistors from the sockets and check the resistance, total was about 160k which would make since after accounting for drift there was nothing else in the circuit but for the disc coupling caps.

I dont know why this would be the case, but I can clearly see the 400hz on the base and of course the collector of the right channel.

I wonder if there would have been any reason to tie the two channes together?

I will check the replacement tuner if it does the same thing then between us thats 3 that lack decent separation, and maybe its just the design.

If so I may be inclined to see what I can do to break that connection and see what happens. Worst case is I muck up a few transistors, but since they are in sockets, big deal....

what bugs me is to go thru all the effort in the mpx to separate the channels just to throw them back together in the amp.

What is the separation at 100hz and what is it at say 2.5khz.

You will never notice if everything below 500hz is monoed out, its better that way. The bass will sound much fuller and fatter.

my osc is just a single hrz, I may have anoher will have to check around

BUT

I did disconnect the singe resistor that connect both the transistors bases, other than the bias voltage being a bit further off than before (it tied them together) I could hear no difference AND much better separation.

about 10 to 1 where it was about 3 to 1. clearly that resistor was the signal path between the two channels, whats left is prob un decoupled from the B+.

I am going to listen the to radio all day tomorrow and see how it does.

I may go thru my stash of transistors and see if I can match some (I have a transistor beta checker). Just to see how close I can get the bias.

I took a look and thats exactly what it looks like to me, low frequency coupling. I would leave it and listen to some music programing and see how it sounds.

4 IF stages, Nice! I never really looked at the schematic because both of mine work perfect.

still not satisfied with the lack of separation, this time over the air MPX fm, I got out my little rat shack stereo transmitter, hooked up a dual trace scope thru the tape out and applied a 400hz tone one channel at a time to the transmitter.

ugh, about 2 to 1 amplitude on the L and R.

I tweeked the 38kc coil, got to about 8 to 1 (best I could get) checked the other channel same ratio. Maybe some drift in a resistor, but only turned it less than a 1/4.

I may check all the transistors in the mpx circuit for gain, just for fun but I think is pretty darn good now for separation. for fun I may put the resistor that ties the two bases on the preamp back in just to see how much it effects the separation when using the transmitter.

ah much better. I connected that resistor back in the circuit and the scope showed BETTER separaion. I dont know whats going on, but it sounds MUCH better now with some actual over the air listening. Before you had to really listen to hear the separation, now its fine like you would expect.

There is a bit of a volume difference, this shows up on the scope as one channel being slightl higher amplitude. It can be compesated of course with the balance, but I would rather see if I can find the problem. there are a couple 5% resistors that feed the MPX detector that look like a likely suspect.

I should be interesting to see how the other tuner stacks up against this one.

ok rookie mistake #3 make sure on a dual trace that the voltage adj pot has been set. after setting up the trim pots for an equal vert on the same voltage the curves lined up perfect. this is at the tape out which is after the 1st stage of AF amp but before the volume control. I suspect my volume control is just not tracking. so next step will be to scope after the volume control and see how the curves line up.

argh just too hard to get a clean signal, too much ac hum. heck with it, if it is the loudness there is nothing I can do about it anyway. There are a couple emitter bypass caps 100uf, maybe something there, if one is weak it could cause neg feedback.

opps already did that. ok DONE...

time to get on the TV....

pic of the separation, this is with a tone on one channel of the FM stereo transmitter, scopt to the tape out.

sounds GREAT now!:banana:

come to think of it I have a fisher 400 that I have never been to keen on the separation. the tape output/dual scope/stereo xmitter/tone generator is a pretty good way to set that 38khz coil. When I get some of these TV's out of the way I may have to go back and work on that one.

I really think removing that resistor is a mistake. I checked both my combos again last night and they have great stereo separation with both channels going. With only one, yes there is some bleed over but it seems to go competently away with both signals.

The fm multiplex we use is the Zenith system and invented by Zenith. They knew how to do Stereo and I really doubt they would intentionally cripple their unit with a single resistor.

forgot to mention, I did put it back, and it did IMPROVE the stereo separation with the MPX. Not sure what the deal was but yes you are correct, leave it as designed. that last scope pic was with the resistor back in.

It appears they have some fancy phasing going on there where it blends the channels if one is missing and increases separation if both are there. I will study the circuit when I get time.

Stereo is one of those arts that has faded and been killed in modern music and programming. They got a 60/40% maximum separation rule they go by now. We wouldnt want all those home wired car stereo installs where all the speakers are out of phase and hooked up to the left channel to miss part of the crappy song.

I would like to implement something like this resistor deal at the dance club I am the sound tech for. That way when the djs crappy equipment drops a channel it blends and doesn't kill the party yet its still stereo when the information is there. I have gone to lengths to keep that place stereo, you really cant find a canned music venue anywhere that's true stereo. In fact most of the new equipment out of the box is default mono.

prob why the best separtion can be found on old early 70's rock. I listen to the classic rock station and get a good dose of separation (think whole lotta love by led zep).

Beetles and Doors weren't too shabby. Phil Spector cuts things up real nice too.

ok next up the phono, went to power it up on the variac, instant 3 amps at 10v, opps thats not good. pull the phono out and the motor coil is all toasted melted etc. guess that is what blew the fuse. the motor armature was seized up. pulled the motor and tried the turntable by hand, spent a couple hours finding out the issue there (it would not cycle properly) one tine little arm was out of place and the spring goofed up. after lubing and check reinstalling the spring is cycled correctly. Good thing too, there was a zenith TT on ebay with a starting bid of 1.99, the shipping was high but what the heck, well next thing you know the dumb thing is over 40$ bid and one day left. Needless to say there is no way I will pop for 70$ plus (inc shipping) for a cheezy zenith TT. So now I have to get this one fixed. I am pretty sure I can get a replacement motor (one of those induction motors with the stepped shaft that drives and idler pulley) from my local vintage guy (Dennis at radio relics) or Sky junk suplus. the issue maybe how to get that stepped driver off the shaft. It looks to be pressed on, too bad it did not use a set screw.

anyhoo I know the cart works (spun a record by hand) so I will deal with the motor next week.

I prob should have started with the TV at this rate it seems like it has to be easier that this TT (all automatic TT's were designed by the devil himself IMHO).

I would like to have know the failure sequence when this thing went bad. As badly as the motor is toasted I am suprized the fuse would not have cut it off before it melted down (it still had the orig fuse in, blown but in).

Try www.thevoiceofmusic.com. Most Zenith turntables from this era were built by VM and Gary can likely fix you up with a motor for a reasonable price. If not, any motor from a similar vintage VM record changer should work. And, I don't blame you for not plunking down $70 on a basic record changer. VM built changers were very common back then; and, you will find one much cheaper if you look.

I just looked at the pictures again and that is a VM built changer. Try that site I mentioned above and I'll be on the lookout for you a motor, as well.

well I was able to get the bearing unstuck, the plan now is to use the old front bearing with the wedding cake drive and just use the a new C frame if I can find one. I may have one in the shop.

this is really not something I want to spend a dime on since its unlikely I will be spinning any records on this thing. I think I only paid 15 or 25 cant remember for the whole console so this turnable is not going to blow the budget :)

Aint that a hoot about the TT on ebay. Some other guy over at ARC has an issue with his zenith as well. My guess is two guys have a need, and bingo, bet you will neve see a zenith TT go like that again. I do like magnavax micromatic imperials the older ones with the gold trim. they are solid and I dig the way the tone arm taps the record to size it. Plus they use two idlers, one for the platter and one for the tone arm drive. Now those are worth a few bucks, but man this zenith thing is CHEAP!!! I am tempted to get a later model magnavox micromatic (the early astrosonics came with a nice one, just a bit more modern looking than the imperials) and put it in there, but I wont since I am not into frankensteing vintage gear.

I plan to put the orig tuner back since I have it working so well. the replacement is identical but for some very minor differnence in the dial face.

Whatever you do, please don't stick one of those plastic '70's BSR's in there! I have a '58 Magnavox console hi-fi that someone did that to. I'd like to find an original Magnavox turntable to go in it; but, I'm running into the same situation as you did. I only gave $15 for the console and, by the time I factor in shipping cost, I'd have $50+ in a turntable, which is a bit much for a $15 semi-beat up console.

Those VM built Zenith branded changers were decent for what they were; but, certainly nothing special. The main thing they have going for them is the "micro touch 2G" cartridge. These are among some of the better ceramic cartridges that won't ruin your records as fast as many of the more conventional cartridges.

Zenith also used a belt drive changer in their highest end models. I've never actually seen the insides of one of these turntables; but, I did see a couple consoles that had them. One was an early solid state model in a nice cabinet with a dead right channel and a malfunctioning turntable. The seller wanted $75 and got PO'ed when I tried to get him down. The other was a tube type model in a beat to heck cabinet that didn't half work. This one was at the SA, priced at $75, and they also got PO'ed when I pointed out it's flaws and tried to get it cheaper.

Is it the motor with the single coil on one side? if its just the coil, you should be able to rewind that motor fairly easily. Its not even critical how many turns. Use the same size wire and get about the same amount on the bobbin and it will work fine.

No BSr for me :)

yes its just the single coil, if I can't find a replacement frame ai will consider rewinding it, yes it looks like it would be easy.

found an c frame doner in a fan. removed the bearings mounts and the rotor, reused the old rotor and bearings. It was a bit more involved since I had to grind out a rivut that was in the hole where the mount needed to go, press out the old rivut. then I had to sleave up the main bearing mound hole on the new c frame with some nested alum tubing. got it all together. Running slow, since I reused the old rotor it should be turning the correct RPM, so its prob a just a bad idler.

I may have goofed up the new motor, dumb me forgot to check the voltage, I was running in on the variac and it was cranked to 140v. the motor was getting hot, I figured it was just being overloaded some how by the TT, now I realize it was overvoltage. duh...

I am going to see if I can fabricate a new idler, I know I can buy one, but again it goes against my princples on this one. I tried turning down some of the old rubber, but its hard though and though. I also tried my old standby of a large rubber band, it worked fine but ran slow. I replaced the grommets so that is not the problem. what a pita

new ider done, oversized square edge rubber ring was glued to the cut down idler with super glue. Freeze it to harden up, turned a bevel on the new rubber edge to match the correct thickness. Looks good, will try tonight.

what a mega PITA this carp tt is.

got the new idler, got another phono motor, had to turn down the idler a bit, lube the replacement motor bearings all good. Then the cheap a$$ plastic switch messed up. Geez I mean cheap.

Anyway I had to perform surgery to take out the switch, monkey with it for a while (the detent overcenter spring was not seated correctly) get it all back together. It works (cycles thru and will turn it self off) about 75% of the time. the other 25% the switch will not go all the way to off and the end of the cycle, leaving the ilder engaged.

I am going to play with it some more and make sure its got good lube were ever I can find a rubbing point to max the force applied to that stupid switch.

argh.....

I so want to stuff a magnavox imicro matic in there.......

I just hope the TV goes smoothly.

lots of careful clean/degreasing/regreasing... seem to work ok now, no more miss fires. listening to it now so the cart is good as well.

just have to wire up the motor back to the plastic plug then figure a way to attach the orig plug back in place. I may just cut the orig power plug and make it a more perm attachement since I dont think I can work the zip tie and the orig plug all in one. hard to explain, but at least it seems to be working ok now.

yea, got it back in the cabinet, works fine now, but for a noisy idler (guess thats it, I am picking up some rumble sounding noise when the needle engages the record groove, but at least the speed is good and it cycles completly.

Next week I finally will get to the TV. will start with the HOT/VOT pulled and do a current metered variac slow start, checking for currrent and temps on the caps. will check for all filaments lighting up. If that goes well I will progress to a power up with tubes in and the HOT current metered and see how that goes.

I prefer to do this prior to pulling the chasis even for a general cleanup as a base line, so if it works I know that much before a general cleanup. I look at clean up as a good thing to do just because I dont like the idea of bringing into the house something that is real nasty (garage now). I will also have to start looking around for a replacement needle, I have no idea of the current condtion of the existing one, but I like to replace with a new one anyway.

has good vitals....

I replaced all the HV/sweep tubes (they all looked very very well done). Getting 25kv at about 220ma so that all looks good. got a raster but did not look full (but hard to tell since I had the CRT to the wall). Waiting for the HOT to cool down and then I will pull the tube bias adapter and re seat the HOT. after that I can pull it out and get a better look at the crt.

I did not have a video source hooked up, so that will be done also.

there was no sound at all, but this set uses the cabinet speakers, and not sure if they are hook up, I willl have to trace around and see what is going on there.

I can see its going to need a lot of tube socket cleanign etc. so the video test will be short, now that I have the HV and sweep baselined as working (mostly).

I will need to check the B+ of course to see if that is being pulled down. I did the slow power up on the caps (about 10 min total) and checked again after the raster test, not warm at all.

I finally got up the nerve to tug on the HV cage hard enough to pull it back so I could get to the reg tube. That one looked REAL bad.

anyway off to a good start :D

I also see there is a jumper that allows for horz adj if needed, not sure how it was set.

Whatever you do, please don't stick one of those plastic '70's BSR's in there!

What is it about BSR record changers that's so terrible? :scratch2: I had a Zenith 4-mode integrated stereo system in the early '80s (was probably manufactured in the late '70s) that had a BSR changer. I did not have one bit of trouble with it, and I used it a lot in the 17 years I owned the system.

When I graduated from Claricon to Dynaco in 1970, I found out. Rumble.

They were good for what they were; and, that is their use in cheap "all in one" systems of the '70's and early '80's and they usually did their job until whatever sort of grease that they used turned to cement. Since these are so cheaply made, one has to be very careful when freeing one of these up as the parts bend very easily. BSR did make some changers that used a metal platter, a four pole motor, and a magnetic cartridge; but, the mechanism was basically the same as what was used in the lower end plastic platter models. When I was about 14, I bought a used Electrophonic 8-track/radio/BSR 3 speed record changer combo along with it's matching speakers for $2 at a church rummage sale because they thought something was wrong with it. It turned out that what was wrong with it was that they were plugging the speakers into the AUX input jack. That stereo was quite a step up from the late '60's el cheapo Westinghouse portable with seperate L and R volume controls that I'd been using; but, it didn't take long for me to find a '70's era component stereo system and once that happened, the Electrophonic with it's BSR changer found a new home. And, I have a '58 Magnavox console that someone pulled the original micromatic changer from and replaced it with a cheap BSR (which is frozen solid by now). One day, I plan to correct that. I don't mind sticking a BSR in a cheap '70's "all in one"; but, I tend to frown on doing it to an older instrument.

made some progress

hooked up a signal, Lots of snow but it would sync lock and audio was fine.

I sub in new IF tubes, no change, subbed in tuner tubes, no change.

B&k analyst, IF and its fine, (well lin/vert all off but that was with the snow as well).

This was the 1st time I used the B&k as an IF source, so I dont know if I still have an IF problem (and the B&K was just putting out enough signal to blast thru) so I will leave the settings and try on another zenith.

Maybe just a real real real dirty tuner.

another problem, the CRT was blooming so I checked the HV, with brighness turned all the way down its about 24kv, but with brightness up enough to get a decent pic its only about 14kv.

I checked the CRT and it was fine back when I 1st got the set.

I replaced the regulator tube. I have not checked the B+ to see how its holding up. I replaced the HV rectifier (3A3).

I will prob start by checking around there.

not so fast big boy...

I was over my metered variac, so I got my big boy variac out, adj line voltage to 117 and HV returned to normal, well regulated etc...

even got good color bars from the B&K and I did confirm the output settings by checking against a good set.

So... it seems like its just the tuner. I will sub tubes on last time from a known working tuner, my tube testers can't check them (HK 533 and Bk600) so I cant be 100% sure I have good tubes in there. My guess is the osc must be ok since it was working, but I will sub them both anyway.

I have heard of lightning strikes messing up tuners, not sure what gets fried but I will check. I am hoping its just dirty contacts.

I must admit I am tempted to just run a composite signal to the test point just after the video detector.

think I will check the tuner AGC voltage before I go too far

tried a new 6BA11 (agc keying/syc sep/noise cancel), no joy, need to find the tuner AFC source lug and see what its reading. Or just try adj the agc pot. Getting late tomorrow morn looks good to continue.

agc voltage with no signal is 4.7v (sams say 4v) with signal its about .150-.300.

I get a better pic with my BK1076 on a modulated output, perhaps I am just putting out more than the DVD or converter box is able to.

I am getting a wierd interference lines in the pic, more that than snow, but not with the B&K.

I may just hook up a pair of rabbit ears to it and broadcast a short distance with my agile Modulator, just to make sure its not some oddness due to the connections.

The BK test pattern looked good as did the color bars.

well did not do any of the above yet, but did connect the IF out from the video modulator to the IF in of the set, perfect pic, so it has to be the tuner.

the modulator was broadcasting fine to another set so I know the RF out is good.

I did notice that on this set the antenna did not help the reception at all, its like it was not even connected. This is when I had the modulator broadcasting the RF. So I assume there is some kind of issue with the connection from the antenna term board to the tuner.

Guess I am going to have to pull that tuner after all.

getting better now, see the thread on the tuner.

next up I need to fix up the channel indicator (cracked) super glue and nylon tread should fix the cracked shafte housing.

the CRT brightness changes from top to bottom, dark at top brighter at bottom. I notice it the most in letter box format.

its as if the video signal is losing contrast as it nears the end of the vert sweep.

I have not checked any tube other than the IF and RF, and this happens regardless of the video source from the tuner or the direct IF feed.

Its like the vert blanking resets the tube.

Since I have a very another tube chassis zenith (20yc130) which is nearly the same, I decided to scope the video signal at the video amp transistor collector and the grid of the video output tube. Just to see how it should look when there is a signal. I prob should have check the videok cathode follower (6KT8) but its getting late so need ot knock off and resume tomorrow.

I also checked the agc on the working zenith so see how much hash is ok on the AGC line. Should be very little and it was. This set (the 20x, not the 20y) is VERY sensitive on the AGC setting from blank to loss of sync in only a few degrees of rotaion of the pot. I have a feeling the AGC is still not right. I dont think it should be that critical.

there are a couple 6KT8's so I wil be checking subing etc... the other is for the syn amp.

so anybody run into the screen that loses contrast toward the bottom of the screen (a progressive loss from top to bottom).

just hoping to get some pointers..

went out to hook up the scope and start trouble shooting the pic issue, power up, PERFECT pic.

the only thing I did was attach a lead to pin two of the video amp.

So I will clean up the garage, button up the back and get a pic.

Not sure why but I aint complaining.

the vert is a tiny bit jumpy, not as bad as my other zenith 20y chassis.

So now I will need to decide if I should pull the chassis or not.

the only issue I have is I know about those old paper caps HV hard shell tube caps. I am tempted to leave well enough alone as I know there is always a risk when disconnecting old plugs etc.. that something could break.

So I will button it up, get some pics, see if the picture contrast at the bottom of the tube returns and see if the vert jump settles down.

The picture color and focus is excellant. Needs a slight dynamic convergence adj. I may replace the diode pack on the board just because its old and I assume the Se's are getting leaky.

one of the reasons I want to pull the chassis is its just so damn dirty, WAF comes into play (if she happens to catch me with the back off, and its in the house).

disconnect lead get ready for pics, turn on set, contrast problem has returned.

turns out the video amp tube must have a dirty socket issue, wiggle that vert amp tube and all good again. I guess I was on the right track to check there 1st :yes:

Just another reason to pull the chassis and do a though cleaning, including the sockets.

the AGC seems to have a bit too much AC ripple in it, no hash but ripple.

Not sure if that could account for the overly sensitive AGC adj. Anyway I will end up pulling the chassis and checking all the filter caps. No audio hum and no hum bars in the pic. I should check the B+ for ripple before I pull it out, IIRC there is a big power resistor that sits on top of the chassis, one side of which connects to the choke and is where they sams show the ripple (2v).

some pics, the last two show the need for a lin adj and the pie crust effect that happens when the yoke is squealing, only last for a few seconds. I need to check purity so when I do that I will make sure the screws on tight that holds the yoke in place.

the pie crust is on the last shot of the womens face

micro panic time...

I am cleaning up the contacts, including the CRT cathode plug in connections.

Of course I put the red gun to the wrong post. After futzing with if for 30 min I realize my error, put it back all fine now, except for my messing up all the screen drives and controls trying to get the red to work.

I checked the CRT no damage, excellent tracking and good emissons, so at least I did not hurt anything but my wits.

Oh well it needed a good setup anyway, now I have a reason to do from scratch.

still has that annoying high pitched un even noise at start up, I cant be sure where its coming from. I tried touching the fly and the yoke with a wood stick to see if I could affect it, but no joy. I wonder if it could be coming from the pin cushion? the thing is its also gets some noise into the pic (the streaks). I will keep running it and see if it improves. Its not a big deal since it always stops and does not come back after the inital warm up.

boy this thing is kicking my butt. The new HOT tube fixed the squeal, but then I lost HV regulation (would bloom too easy, and the HV adj did nothing. Wide open with no beam current would be about 24k, but would drop to below 20k and be moving all over the place with the beam current. I also lost width. So I tried ANOTHER 6JS6 HOT, plenty of HV now, in fact all the way down and even with a bright screen its 25-27kv, too much really. Not sure I will try a couple more HOT's if I can find (I have a few pulls to try) but I may end up having to buy one. Oh and the width problem went away. Still now squeal so that is good. I may but that squeal tube back in and see how it goes.

I tried the purity setup, the yoke did not seem to go back far enough to get the red blob in the middle, so I just fiddled with the purity tabs to get the red centered as best as I could (most of the screen was red) then pushed forward to get it to cover the whole screen in red. Color purity looks good now. still some dynamic convergence to work on.

Still have not pulled the chassis to replace those few HV film caps.

progress, working on HV regulation with help from CTC17 (dan).

seems I can dial in the HOT current and HV with different HOT
s but the regualation is just not happening. will be checking the reg tube voltages tomorrow. the Plan is to replace the focus resistor (at the edge of adjustment now) and hope that effects how the regulator is working.

I had noticed the color was a bit weak, found a chroma amp screen grid resistor that had driffted up about 400% so that will get replace as well. while I have it out I will check the disk decoupler cap, just in case it was leaking, thereby stressing out the screen resistor. its just a little 82k 1/4 watt.

stopped by my tube guy, checked all the tubes on a 539 hickok, turned out the HV regulator tube was very weak (and yet looked brand new). I hope that helps resolved the regulation problem.

Today I replaced 3 resistors on that chroma amp tube, while checking the other tubes he thru in the syn/noise/agc tube, two color demodulators, a new audio tube (6z10), a 2 IF tubes (one shorted, the other very weak), and an RF amp tube (again very weak).

I also replaced the focus rectifier stick.

Cleaned the chassis top, inspected the ground stakes (two were cracked) and resolded.

Cleaned all the gunk around all the term strips/tube sockets, cleaned the tube socket pins (small nylon spiral brush and cleaning juice). cleaned all the tube pins (brass brush). Cleaned all the plug in sockets (hue/color, convergence, yoke) cleaned the CRT socket (sprial brush). Wiped off all the sticky goo from the wires (yoke, CRT, speaker).

inspected the bottom for any componets that may have been moved after working on the resistors, and transporting the chassis.

Cleaned up the fly back plate (dust, general nastyness) careful not to work behind it where you cant see the fine wires.

Still need to give the pots a quick shot of cleaner/lube, that is all the pots on the chassis front, and the volume pot.

the Thermistor is busted, every set I have seen has a busted thermistor. I have a CL90 but not sure if the rating is correct. Will do some checking and see.

looks like the CL-90 specs out at least to the cold resistance (120@25c) and since its in the B+ it should be fine current wise. I have used them on other things, but that was on the primary side of the power tranny to soften the blow to the power switch (fisher 400).

so the thermistor is in, but its getting late so I will have to wait till prob Sat to reinstall the chassis and see how it goes. wish me luck...

Sounds like you're almost done. So close I can taste it...:yes:

The adjustment on the front labeled brightness limiter should really be 'bloom limiter'

whew.. lots to report

voltage regulation was not happening, I check the voltage at the grid and the cathode, should be 350/360 (-10v bias) was more like 375/300 or -75, so the shunt tube was completely cut off, not loading the fly at all, so no regulation. I checked everything there was to check but the VDR, no joy.

since there is no specs on the VDR I decide to just replace it. I found on that was suppose to be a cross, put it in, bingo regulation. I was able to get the grid voltage up to about 340 so a little low there, and I need to keep the HV set as low as it will go, that gets me to about 25kv.

I am going to check a couple more resistors and the boost voltage (yes replaced the focus diode that supplies the 900v boost that drives the regulation). I thought I checked them but will check again. I have another zenith set to compare to. there is a voltage divider in the fly cage that gets the focus voltage down from 5kv to the 900v so I will look there again. but at least its in the ball park now.


after I got it installed another problem popped up, color hum bars. Now it was fine before I pulled the chassis so I really doubt anything went bad.

after a few careful looks I found a rather large disc cap that seemed pushed down and possibly having a lead touch where it should not.

this is the only thing I really dont like about point to point wiring, esp with open bottom chassis. you have to be REAL careful about how you handle and transport the chassis.

anyway I moved the cap and the color hum bars are got, thank goodness.

I really like what zenith did on some of there 50's era tube sets, where there was a metal bottom plate. this not only shielded from EM radiaition, but prevented just this kind of problem, AND the chassi was much stiffer so less flexing and possible damage from that as well.

getting late so I will reinstall later in the week, but getting real close now.

Oh I also replaced some resistors that had gone out of spec on the chroma amp tube, that helped with the weak color (had to have the color turned all the way up).

Not too far to go :)

...after I got it installed another problem popped up, color hum bars. Now it was fine before I pulled the chassis so I really doubt anything went bad.... anyway I moved the cap and the color hum bars are got, thank goodness.
Colored hum bars can be caused by residual ripple in the degauss coil. It could be an intermittent in the auto-degauss circuit. Might try wiggling stuff in that area if the problem shows up again. Bill(oc)

it's ok now OC, I found a cap (large disc) that had gotten moved and looks like one of the wires had come into contact with some it should not have. I repositioned the cap and the color hum bar is gone :)

I just hate when I create a problem. Needless to say I will just be that more careful when handling the chassis. I think the prob happened when I was transporting the chassis in the back of the SUV. I had a soft blanket to set it on thinking it would cushion it, but I think what happened is the chassis just settled down and the blanket pushed the caps up into the chassis.

next time I will set the chassis on a hard surface and then put that on a cushioned surface so I don't bounce it around.

I figure this was a rookie mistake, I will not repeat it.

Thanks for the heads up I will keep that in mind if it happens again (looking around the degausse).

I did find several changes made in the zenith color service manual talking about revisions to the HV regulation. Some had a 6.8meg resistor across the varisistor, and a change in a 1 meg to 2.0-2.4 meg resistor off the HV pot, part of which sets the voltage divider range.

The easy thing would be to 6.8meg across the VDR, esp since I could do it from the top fo the chassis on the exposed term strip.

the regulation is working but its range is very narrow (all most all CCW) again this may be due to the use of a non factory orig VDR (the only one I could find that the supplier said was a correct cross).

bridged the varistor with a 3.9meg resistor, get a bit closer to the correct bias. Found a weaker HOT, was able to get the cathode currrent down to about 230 vs 260 with a stronger one.

I wonder how a 6KD6 would work? I am out of 6JS6's to try, one was very weak 180ma but the width would not fill out.

Just for fun I am going to try a few different horz osc tubes to see if I can get it any lower. pic looks good.

ok button up time I need to go thru my stash of volume control knobs (did not have one when I got it), pretty sure I have one that will work.

Gonna put the orig stereo tuner back in since it has the correct wire harness and works at least as well as the backup I got off ebay.

wiped the insides clean of dust (WAF). I think I will make up a DPDT switch to swich out the speakers between the normal TV output and the stereo output so I can use the stereo amp drive thru the tape input and the decoder box audio out for true stereo. There is plenty of access holes not used on the back.

I managed to crack the back today ((&(*( it) then I tripped and my foot caught it. I will get some 1/8" ply (used in model building) to reinforce the crack, I hate when that happens. Slow setting epoxy should work well with the masonite. It really bugs me when I manage to break something that has gone undamaged for so long.... argh....

The pictrue is looking very nice, I did the grey scale setup per the sams.

It still needs convergence but I would rather do that once I have it inside and where it will be setup to watch.

Just need to make a place for it now :)

found the perfect volume knob, only thing is its so new looking that now the rest of the set looks shabby... :)

argh, green static magnet does nothing, turns ok must be broken inside, no movement at all.


dynamic weak, time to replace the diodes on the convergence board. the left side is not too bad, the right does not seem to work at all.

replaced the 4 diodes, put all back together, started the setup, some smoke, pull the board. The pot that was getting hot was the left blue horz. someone had jumpered a 47 ohm 2 watt resistor. I noticed it but decided to leave it be and try as is after the diode swap. Removed the wire jumper (was very sloppy), and replaced with a 50ohm WW resistor (all I had on hand). the resistor that was in there that had been jumped over just fell apart so my guess is it was high or open and the jumper was just being cheap, prob ok as long as the pot was not turned to far.

Convergence is MUCH better now, only issue I have is one of the right side coil forms is stripped (the slug just pushes thru.

I may pull the board again and see if I can find a inner threaded section to fit into the existing bore. Or I could just glue a non metalic extention to the ferrit slug, and wrap it with some wax paper or some other friction fit. Or just try and get it set and then tack glue a drop of white glue (just enough to hold it, so if it needs to be reset it would break free.

could use some idea from other that have had to deal with this...


Had some sync buzz, adj the quadrature coil got rid of that. The speaker cut out switch on the on off (disables the speaker from the stereo) is a bit dirty, so one speaker comes and goes, tweek the on of just a hair and it comes back.

I am going to try a direct video feed to compare the pic to that of the tuner RF pic. I tried this on the other zenith connecting the decoder box composite video signal to the test point C1 (output of video detector) but for some reason it did not work on that set so will be interesting to see if this chassis has the same problem. there was a +5vdc on that test point so I used a large cap to block the DC.

replaced the 4 diodes, put all back together, started the setup, some smoke, pull the board. The pot that was getting hot was the left blue horz. someone had jumpered a 47 ohm 2 watt resistor. I noticed it but decided to leave it be and try as is after the diode swap. Removed the wire jumper (was very sloppy), and replaced with a 50ohm WW resistor (all I had on hand). the resistor that was in there that had been jumped over just fell apart so my guess is it was high or open and the jumper was just being cheap, prob ok as long as the pot was not turned to far.

Convergence is MUCH better now, only issue I have is one of the right side coil forms is stripped (the slug just pushes thru.

I may pull the board again and see if I can find a inner threaded section to fit into the existing bore. Or I could just glue a non metalic extention to the ferrit slug, and wrap it with some wax paper or some other friction fit. Or just try and get it set and then tack glue a drop of white glue (just enough to hold it, so if it needs to be reset it would break free.

could use some idea from other that have had to deal with this...
First off, those coil forms that Zenith used tend to crystalize from heat and fall apart after a few years. If yours haven't fallen apart, the set is probably very low time. Also, concerning one of those blue coils (forget which one, been a lotta years), if you run the slug too far out (or if the slug is missing), it will fry one of the wirewound pots. This is probably what's happened in your case.

For that stripped slug, you could take a very thin strip of rubber from a bike inner tube (but not a gum rubberband which will rot) and lay it full length inside the form, then push the slug in. The strip will provide a friction fit and you can still adjust the slug as needed.

You might consider a small muffin fan to keep the conv. board cool, to slow deterioration of those coil forms. BTW, RCA conv. boards will also smoke a pot if one of the blue slugs is turned too far out. A little tidbit worth bookmarking. Bill(oc)

Great info OC, this is something that needs to be passed on to the current crop of TV restorers. I will go back and check that slug. I am still getting the hang of convergence, I just read up that perfect convergence on the side is just not going to happen (example blues bend down). I notice that old show that dont have a lot of text just seem to work better.

here are some pics, I have since these were taken worked a bit on the lower blue horz for some improvement.

OC, I checked that pot, it was indeed hot. I ran the slug in some seemed to help it, but of course it also goofed the horz blue convergence on the right side a lot. So I set it up so the slug was not as far out as I started and comprimized on the pot setting for best blue convergence horz left and right. Its still pretty hot.

First off, those coil forms that Zenith used tend to crystalize from heat and fall apart after a few years. If yours haven't fallen apart, the set is probably very low time. Also, concerning one of those blue coils (forget which one, been a lotta years), if you run the slug too far out (or if the slug is missing), it will fry one of the wirewound pots. This is probably what's happened in your case.

For that stripped slug, you could take a very thin strip of rubber from a bike inner tube (but not a gum rubberband which will rot) and lay it full length inside the form, then push the slug in. The strip will provide a friction fit and you can still adjust the slug as needed.

You might consider a small muffin fan to keep the conv. board cool, to slow deterioration of those coil forms. BTW, RCA conv. boards will also smoke a pot if one of the blue slugs is turned too far out. A little tidbit worth bookmarking. Bill(oc)


I ended up destroying the coil, but was able to find another coil (diff winding) which I removed all the old windings, so I just had the form. Then I removed all the old wire from the messed up coil and rewound on to the donor coil form. Put it all back in and it works great. The donor coil form plastic is in much better shape and the slug moves very smoothly.

I ended up destroying the coil, but was able to find another coil (diff winding) which I removed all the old windings, so I just had the form. Then I removed all the old wire from the messed up coil and rewound on to the donor coil form. Put it all back in and it works great. The donor coil form plastic is in much better shape and the slug moves very smoothly.
Cool! Good job :beerchug: Does the pot run cooler now, and is the convergence better?

the only thing I have left to do is to find a 4 by 6 speaker to go in the TV speaker hole. As is it has a switch that cuts out the stereo and routes the TV amp tube output to the main stereo speakers. Works ok, but I would much rather have the option of power the TV audio thru the tape input (aux) and bypass the TV tuneer completly for audio. I have done this on a maggie astrosonic tv and it sounds great. I tried it out already (to check levels on the aux input to the convert box output, all fine).

The only reason I want the small speaker is on the off chance I get a UHF channel that is OTA and need the analog tuner for sound. Also I dont like the idea of disabling the audio completely, as it would no doubt be confusing to any one that gets this thing some were down the road. I will of course leave all the wiring harness in place so it can be converted back to the orig setup.

I will check around my stash and see if I can find that 4x6. I check the mounting with a scrap speaker (cone shot to heck), it has some nubs that just barely are long enough to do the job. They are not machined, more like locating pins, but I can not see any thing to screw into. I will prob just silcone in the speaker around those nubs or see if I can find some of those star washers, the kind that push on but don't come off. Not sure if the pins are long enough for them.

well I decided to take one more stab at the HV regulation..

I have the "early" production version of the 20C1x38 chassis, my service notes showed the changes from the early to the late, one of which was HV regulation

I rewired the HV pot per the late version. the only diff was the output from the varistor was directed to the unused side of the pot, and the input for the grid bias of the 6HS5 tube was moved to the center wiper. the 1 meg resistor was left in place. This results in the pot as a true voltage divder (+ one side, ground thru the 1 meg on the other) rather than acting like a reostat with only one side and the wiper in the circuit.

I also added a second varistor piggy backed to the replacement (actually I just reused the old one I had taken out) This was done on the top of the chassis after the initial trial did not have good range.

I had tried the piggy back method before the rewire of the pot and it did not help much, some but not much. So I know the rewire was the key.

I am not able to dial in the HV to the exact amount specified and its very near the middle of the pot setting.

My guess is the varistors are not very precise, I know this since I tried a few by just putting them to a mA meter and dialing in up to 450v. They were very different readings for the several SAME rated ones I tried. These were NOS so dont know if they just age poorly or if its just the way it is.

But now I am happy, I get rock solid HV (very little movement regardless of the screen brighness) and I am able to lock it in right at 24.5kv.

I just have to work that speaker issue out and I can button it up for good.

Today I picked up some 3 conductor wire and varios spades/lugs, and made up a speaker hookup to bypass the factory wire harness that incorporates a stereo cut out built into the TV on off.

I also hooked up a nice little zenith 4X6 speaker (the front bezel has a place for it and the speaker slots are open). I just need to find some star washers to hold the speaker in place, will look tomorrow.

So now you can turn on the TV, and turn up the volume to listen thru the little front speaker OR hook up L and R audio from the DVD or converter box, drive the Tape in and listen to the audio using the built in stereo amp.

MUCH nicer this way, I figure if I am going to be watching on a 40 year old CRT I can at least max out the audio.

I was watching the new star trek movie (kid kirk driving the stringray corvette) when he had on the head banging music, it rocked...

after I get the speaker secured I will get started on my last console in the que, a CTC 17 combo.

oh yea I just left the orig harness in place so it would be very easy to put it back to factory orig setup.