|
|
|
|
|
#1
02-08-2013, 09:23 AM
|
|||
|
|||
|
I see the part location diagram shows two different chassis. I remember that 25DC57 was a real dog! It had that troublesome voltage regulator. I don't remember seeing many of that model around. The 25DC56 seemed to be more common and a lot less grief.
|
|
#2
02-11-2013, 11:46 AM
|
|||
|
|||
|
You live and learn. Won't do that again. I have looked around the chassis in various places and cannot seem to find the chassis number stamped anywhere. Was that ever done and, if not, how can I find out which of the 2 chassis I'm dealing with? The only number I did find stamped onthe back of the chassis was 6003419 but I'm guessing it doesn't mean anything. And then, if it's the 56 chassis how will I tell if it's early or late production as bgadow alluded to. Thanks guys.
|
|
#3
02-12-2013, 10:35 AM
|
|||
|
|||
|
Quote:
The "D" models are 1973 model year. That's possibly a later probuction set.
|
|
#4
02-12-2013, 11:44 AM
|
|||
|
|||
|
Quote:
"early production chassis 25DC56 is in folder 1312-3, late production 25DC56 is 1375-3" if these would be the only possibilities. Thank you.
|
|
#5
11-09-2019, 10:55 AM
|
|||
|
|||
|
Here's a link to the classified listing of it if anyone's interested:
http://www.videokarma.org/showthread.php?t=272222
|
| Audiokarma |
|
#6
02-08-2013, 09:58 AM
|
||||
|
||||
|
Forget that negative "TV guy" assessment...this IS the best TV made.
Does this set have the black slate on top? I intercepted a trade-in like yours in 1985 and my parents used it as a daily set until 2003 or so, wanting a remote, they got a Sony 27" CRT Wega. It lived in my garage for a while but I parted it out due to the worn-out CRT (only after I rejuvenated it in '85!) and a pile-on of other issues. Had I been on VK then, I'd have kept it but I have the cabinet top yet  The low voltage regulator issue in ours was a zener diode but it took me a while to figure that out because it looked like a hum-bad capacitor. The undiagnosed intermittent vertical shrink was probably the service switch  but I was young then and kept cleaning the module pins and size/lin pots.If you have a shorted HO Transistor, its easy to tell. Just set your multimeter on "diode test", put black probe on chassis and red on the (121-831) HOT case (the collector), it should read open but if you get the beep, its probably shorted. reversing the leads will read the damper diode, usually OK. Never saw a fly go on these, but the "22-5001? white critical cap fails - HOT shorts" always the issues I saw. just my 2c We'll help you fix and keep it. Minor, inexpensive repairs will keep yours alive indefinetly! Like Bryan said, we has parts. just find which one is bad.
|
|
#7
02-09-2013, 12:12 AM
|
|||
|
|||
|
You guys are unbelievable. Thank you for the many words of encouragement and offers of assistance. I mentioned it to Mom and she was quite impressed as well and feel she may be on board to give it a shot. She is definitely not wishing to go for a "smart" tv that's for sure. It's not her main tv so she doesn't mind if it takes a while as I know it will due to the learning curve involved for me.
I guess the first things would be to ask if anyone has any idea where to find a schematic, how to check which of the 2 chassis I'd be working with, and what diagnostic equipment I'd need exactly to perform the tests. I may have 1 or two and may be able to obtain the rest, maybe. Thanks for being patient with me on this, guys, and for the continued guidance and assistance. DavGoodline: Yes, it has the black slate on top!
|
|
#8
02-09-2013, 07:56 AM
|
||||
|
||||
|
The guy who looked at your set obviously didn't want to work on it. It would have been nice if he would have just been honest with you and said that, instead of putting on the show he did. I've never learned the fine art of diagnosing electrical problems (other than intermittents) by tapping the circuit with the back end of a screwdriver
 I agree with the other posters. If the set had a good picture the last time it was turned on, the likelihood that your CRT has gone bad is pretty low, and you should be able to fix the set. These were great sets, and should last a long time once you fix it. I vote that you give it a shot.
|
|
#9
02-10-2013, 12:02 PM
|
|||
|
|||
|
Quote:
You are so right, as others have been earlier in the thread, in that he did not want to fix the tv. Looking back it's so easy for me to see that his intent was to come by, give me some mumbo jumbo while waving his "magic" screwdriver wand, and then tell me it needed a flyback tranny, output transister, and the tripler is a part of all this, collect his check for $39.95 for coming out and bidding us a fond thanks for the check, see ya later, bye. He first said he wanted to come out 'cause it's an old Zenith and he wanted to see it. To see if it was possibly something simple but turned out not to be. I should've had my first clue when he arrived and was just opening his repair kit while saying "I must be out of my mind for doing this", therefore setting himself up for the "it'll cost to much to fix" exit. And so here I am in the forum looking to move forward to, hopefully, a happy ending. Thanks again for the assistance and encouragement as next I will attempt to find the chassis model for the proper schematic.
|
|
#10
02-10-2013, 12:19 PM
|
|||
|
|||
|
Quote:
I attempting to study and understand your and others directions for testing as I learn more about the language, numbers, circuit, etc. Still a bit over my head at this point but I'm trying.
|
| Audiokarma |
|
#11
02-09-2013, 09:39 PM
|
||||
|
||||
|
You need to pinpoint the exact model or chassis number. According to the Sams Photofact index, early production chassis 25DC56 is in folder 1312-3, late production 25DC56 is 1375-3 and 25DC57 is 1315-3. I don't have spare copies of any of them but I'm positive somebody on here does. If there is a model number on the back cover that should let us figure out which version you have, if not otherwise marked. It's possible I have a factory service manual for this but that would take some digging.
__________________
Bryan
|
|
#12
02-10-2013, 07:38 PM
|
||||
|
||||
|
I think there's one guy left in the area who claims to make house calls; but, he pretty much does what this guy did. He comes to your house, he plays with the TV for 5-10 minutes, then he tells the customer that the repair will be too extensive to perform in the home and the set must be taken back to the shop for repair. Then, he adds on an additional $50 for the house call.
__________________
http://www.youtube.com/user/radiotvphononut
|
|
#13
02-10-2013, 08:07 PM
|
||||
|
||||
|
if this guy was really a repair man with many years experience,he would have told you that this is a fine set.another of the "it isnt worth my valuable services"guys.arrogant and snobbish types.we have a few here in central ohio.have no clue about an older set but will work like mad on a plasma or lcd.all crts are"round tube",never heard of a "hybrid"set,etc.they all say the same thing when you inquire about a roundie or tube set:"why are you wasting your time with that s--t?"because its fun and that was when america built something great.
|
|
#14
02-10-2013, 08:42 PM
|
||||
|
||||
|
I have the exact same set. Mine was used just a few years back for 12 hours a day, over several weeks as part of a vintage Christmas display/prop.
(I'd be glad to trade out of it, perhaps for some repair work on other sets) Either way, they are good sets and your so-called repairman sounds like a tool.
__________________
From Captain Video, 1/4/2007 "It seems that Italian people are very prone to preserve antique stuff."
|
|
#15
02-13-2013, 11:31 AM
|
||||
|
||||
|
To add to the opinions above, you have the best TV ever built. The Zenith 25DC56/57 was one of the last 100% Chicago-built Zeniths, and also one of the last hand-wired by the hands of the women of the Rosie-the-Riveter era.
The FIRST thing that comes to mind, (although this would have to assume that you do indeed have high voltage and you believe you don't), is the Chromatic switch. It's a nightmare when it's dirty, and causes blacked out screen, flickering, color problems, etc. Just to rule that out, maybe turn the set on, and fiddle with the Chromatic button and see if you get anything. If not, then your first thought is probably right; no HV. If you lost high voltage, it's very easy to troubleshoot, and most everything is available for that set (either new or from other AKers). If that one has a circuit breaker, and it's tripped, you likely have either a bad tripler, or possibly a shorted horizontal output (or both). Remove the 2 screws from the horizontal output (thus disconnecting the collector), and reset the breaker (or change the chemical fuse), and then see if the 130 volt line is live. I think you can find the 130v on the case of the regulator transistor mounted next to the flyback (see the diagram in the cabinet). If the 130 volts is back, then remove the horizontal output and measure it from collector to base and collector to emitter, and see if any direction is short. If so, you likely just have a failed transistor 121-831 (or NTE 165). If the transistor isn't shorted, put it back, and on the tripler, carefully peel off the rubber glob and unsolder the wire coming from the flyback and place the wire safely away from ground, and see if the set turns on, and you should hear a corona hiss from that loose wire. If yes, you have a bad tripler. At that point, I'd update the tripler to an NTE526A, which eliminates the focus divider and double anode wire. Charles
__________________
Collecting & restoring TVs in Los Angeles since age 10 Last edited by kx250rider; 02-13-2013 at 11:49 AM.
|
| Audiokarma |
 |
|
|
Hybrid Mode
