Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Dec Sun 17, 2017 3:27 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 161 posts ]  Go to page Previous  1 ... 4, 5, 6, 7, 8, 9  Next
Author Message
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 3:48 am 
Member
User avatar

Joined: Jul Wed 18, 2012 3:13 pm
Posts: 893
WeekendHacker wrote:
MrE12AX7 wrote:
No it did not look like that. It was the same shape but it had a greyish coating.


This is the problem. Of the seven resistors I showed you, five of them have a greyish coating, and 6 of them are pretty much the same shape. So either yes, it did look like that, or you really need to post pictures. 95% of the frustration here has been failure to communicate.

I did not take a picture of the old one. It was shaped like the sand ones but it had a smooth dark gray coating.
I replaced it with a vishay vitreous enamel wirewound.
I am sorry about the bad communication, Its easier for me to talk in person then online.
I also have a 300v 150uf cap for C1
Attachment:
resistors.jpg
resistors.jpg [ 77.11 KiB | Viewed 1183 times ]

_________________
Currently on the Bench - Sterling Model F


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 3:59 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 11541
Location: S. Dartmouth MA 02748-1225 USA
I am aware I am not helping...

The images on the CRT, are they of a test CRT (I thought I read that one was in use on this set) using the yoke provided to drive it?

Every time I used a test CRT in a jig there were raster problems, all due to a miss match of the yoke and the long video leads to both the CRT and the yoke. Despite jig adapters.

Chas


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 4:07 am 
Member
User avatar

Joined: Jul Wed 18, 2012 3:13 pm
Posts: 893
I am using a test CRT with the sets yoke. No extender cables except the HV.
I guess I could try the big CRT and see if it makes a difference.

_________________
Currently on the Bench - Sterling Model F


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 12:57 pm 
Member

Joined: Jul Wed 08, 2009 12:17 am
Posts: 904
Location: Wyoming, Michigan
MrE12AX7 wrote:
How do I upload the schematic to the ETF?


I gather it's pretty informal.

After you've scanned all the pages at a good resolution send a pm to Steve McVoy (that's his literal ussrname here) and ask him to assist. He runs the ETF and is a nice guy.

I'm unaware of any more explicit instructions than that.


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 1:30 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 11541
Location: S. Dartmouth MA 02748-1225 USA
MrE12AX7 wrote:
I am using a test CRT with the sets yoke. No extender cables except the HV.
I guess I could try the big CRT and see if it makes a difference.
Some B&W sets had magnetic wings or stick on magnets to correct for any aberrations from yoke/crt/raster. Sometimes I add them, soft refrigerator style magnets stuck on with a bit tape first, then contact cement. Done with set powered stay well away from the ultor :shock:

It is essential the vertical wave form be linear or at least match the image offered in the schematic. If 60 or 120 hz gets into the vertical it will not be in sync and raise havoc with the vert.hold. Be sure no line AC or small rectified 120 hz residual fro P.S. makes its way into sync separator or vert. integrator. Cathode to filament leakage is often the culprit as are poor grounds. If the integrator has had freq. determining components replaced be sure they are of the same type so stability is not affected...


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 2:16 pm 
Member
User avatar

Joined: Jul Wed 18, 2012 3:13 pm
Posts: 893
Chas wrote:
MrE12AX7 wrote:
I am using a test CRT with the sets yoke. No extender cables except the HV.
I guess I could try the big CRT and see if it makes a difference.
Some B&W sets had magnetic wings or stick on magnets to correct for any aberrations from yoke/crt/raster. Sometimes I add them, soft refrigerator style magnets stuck on with a bit tape first, then contact cement. Done with set powered stay well away from the ultor :shock:

It is essential the vertical wave form be linear or at least match the image offered in the schematic. If 60 or 120 hz gets into the vertical it will not be in sync and raise havoc with the vert.hold. Be sure no line AC or small rectified 120 hz residual fro P.S. makes its way into sync separator or vert. integrator. Cathode to filament leakage is often the culprit as are poor grounds. If the integrator has had freq. determining components replaced be sure they are of the same type so stability is not affected...

The vertical is unaffected. it must filter it out.
I am going to be replacing C1 with a 300v version to better handle the voltage. I also have some foil/film capacitors I can try in the sync seperator. I think Notimetolooz may have figured it out. It very well could be that resistor.

_________________
Currently on the Bench - Sterling Model F


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 3:10 pm 
Member

Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
Sorry again for being a little out of sorts. It's tax time.
I think I was a bit younger than you when an uncle gave me an old TV. I took the back off and found that the flyback looked overheated. This was way before the internet, most of my info was from electronics magazines and maybe a book or two from the library. I selected several tubes, probably the horizontal output, horizontal oscillator, damper and maybe another and my dad drove me to a local TV repair shop. Back in those days the shops would test tubes for you. I told the repair man about the flyback and he tested the tubes, the output tube flashed and sparked inside, it was shorted. The repairman was dumbfounded this kid had localized the problem. He gave me a 'cheater' cord, a interlock power cord so I could operate the TV with the back off. The flyback was OK and the set worked. Years later it occurred to me he might have been trying to kill off the competition. :shock:
About that resistor, it occurred to me that the cheapest shipping by Mouser is about $ 5. Another combination would use 2W carbon composition resistors which are easier to find, 1.2K + 1.2K + 1.5K = 3.9K. 6W. Check Antique Electronic Supply. You have to buy groups of five resistors.

_________________
Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 3:17 pm 
Member
User avatar

Joined: Nov Thu 11, 2010 6:03 pm
Posts: 652
Location: Pewaukee, WI
MrE12AX7 wrote:
I did not take a picture of the old one. It was shaped like the sand ones but it had a smooth dark gray coating.


Situations like this are why on restos I keep every part I remove from the chassis (in a pile, a cup or a bag depending where I'm working) until I've got the set working properly...If I miss-identify some part or someone needs to see it, having it on hand to photograph can be invaluable.


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 4:02 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 3775
Location: WI 54812
Is there any reason a metal oxide resistor would not perform satisfactory in this location?

http://www.mouser.com/ProductDetail/Pan ... t7Wj9JU%3d


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 5:20 pm 
Member
User avatar

Joined: Jul Wed 18, 2012 3:13 pm
Posts: 893
I am trying to find a metal oxide resistor. I put a wirewound in and that cannot be used. It adds inductance.
I am going to see if I can get to the parts store today and get something to try.

_________________
Currently on the Bench - Sterling Model F


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 8:22 pm 
Member

Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
Kevin Kuehn wrote:
Is there any reason a metal oxide resistor would not perform satisfactory in this location?

http://www.mouser.com/ProductDetail/Pan ... t7Wj9JU%3d


Sure that would work. I thought I had gone to Mouser with that other link, now I see it was Digikey.
I think I searched Mouser first and didn't find anything and then tried Digikey. Guess sometimes the search function is picky. I'm not sure how the various shipping charges would effect the choice on such small orders. I usually wait until I have a big enough order to make the shipping a minor part of the cost.

_________________
Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 9:12 pm 
Member
User avatar

Joined: Jul Wed 18, 2012 3:13 pm
Posts: 893
Well I got some resistors from the local parts shop. 4 1Ks in series. They are 1W each.
So I put it back on the bench and guess what. HV arcing sound and no picture. I am guessing it is coming from the yoke.
Can I try the yoke that came with my test CRT to see if its arcing. If it is indeed arcing can I put sealer on the windings? (the windings check fine on ohms) The yoke is made of that plastic that falls apart and it is visibly degraded. I know where I can get another yoke if needed.

_________________
Currently on the Bench - Sterling Model F


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 9:46 pm 
Member

Joined: Jul Wed 08, 2009 12:17 am
Posts: 904
Location: Wyoming, Michigan
Attachment:
phpVX5YQLPM.jpg
phpVX5YQLPM.jpg [ 43.9 KiB | Viewed 1112 times ]


Does this resistor look like the one you took out? It looks like the one circled and labeled R49 on your uploaded clip of the Sams photo. If so, this is a wirewound resistor. Rather than coiled wire dipped in sand mix, it's coiled wire wrapped around a ceramic tube. But coiled wire nonetheless. Your original replacement of R49 was probably just fine.

You are being told what to do and accepting all advice without really understanding why. Blindly following has gotten you in deep. Sorry to hear you may have damaged the yoke now.

I think your initiative at age 16 is admirable, and hopefully your desire to tinker with this stuff will lead you to a fulfilling and lucrative career later. Sounds like you've done ok with radios and phonographs so far.

At this point you should maybe look for a local mentor who can work with you hands-on. There's a discipline to old-time TV repair that would avoid all this frustration, and it would apply and translate to modern engineering as well, if that's something that interests you. Someone who is versed in logical troubleshooting would be a valuable person to know, in person, at this point. The people here who are advising you are making fairly wild guesses based on very poor commo on both ends, based on this difficult means of getting a point across. It isn't working out well.

My original post on this thread was intended to get you to think through the problem and arrive at the solution on your own. Shame you didn't follow it. It's a much more rewarding way to get there than just following orders and hoping it works.

If you do get your raster back, go back and think about what I was driving at.

This does need to be fun. Right now you might just want to walk away for a week or two and think about girls and cars and spring break at a beach somewhere.


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 10:28 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 5152
Location: Woodinville, WA USA
WeekendHacker wrote:
look for a local mentor who can work with you hands-on.
You could contact a radio/TV collector club in your area and see whether anyone is willing to do some coaching. Here's a list of US clubs:

http://antiqueradio.com/clublist.html

Phil Nelson


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 10:29 pm 
Member

Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
So close to answering the question.
You do have to be commended for all soldering involved in replacing the parts.
The yoke characteristics are part of the sweep circuits operation so they are important. Using a different yoke could add another problem on top of what you had. Just where is the arcing? Picture? Yep, old stuff gets brittle. If the actual turns are arcing I think you will have to replace the yoke. The insulation would be zapped and the turns would be touching, can't get varnish or anything in between. Maybe it is just the terminals. There is a capacitor in the yoke.

_________________
Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 10:39 pm 
Member
User avatar

Joined: Nov Thu 11, 2010 6:03 pm
Posts: 652
Location: Pewaukee, WI
Most generic test jig yokes I've seen do okay on different chassis. It will not hurt to try it....Just make sure you check your connections carefully. If you connect the wrong winding to the wrong trans, or short H and V things could get hairy.


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Tue 04, 2017 11:44 pm 
Member
User avatar

Joined: Jul Wed 18, 2012 3:13 pm
Posts: 893
Nope It did not look like that. it was different. Looked like a rectangular black blob with two leads coming out.
I believe I got the arcing to go away. I re soldered the spring clip to the HV extender and I have not heard the arcing since.
To make sure we are all on the same page here is the current state of the set.
Sound works.
Picture is shrunken both horizontally and vertically, with lots of vertical foldover on the bottom of the screen.
I hear the horiz osc tone for about a second then it changes pitch and I shut it off.
I have not ran it in this state beyond maybe 3 seconds or so after the HV spools up.
What has been done since the last time the set worked.
C1 replaced with a 350v unit
R49 substituted with 4 1K resistors.
CRT, yoke chassis unplugged and moved off and on the bench.

I do want to fix it myself. I have a really great mentor at the local parts store that has helped me with various projects but he does not really have any TV experience (got into those after tube stuff was gone). he has someone that works with him that does though. I am going to try and contact him tomorrow. I may actually want to get a replacement yoke anyway, the plastic is degraded to the point where there are holes in some parts of the plastic.

_________________
Currently on the Bench - Sterling Model F


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Wed 05, 2017 12:30 am 
Member

Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
MrE12AX7 wrote:
Picture is shrunken both horizontally and vertically, with lots of vertical foldover on the bottom of the screen.
I hear the horiz osc tone for about a second then it changes pitch and I shut it off.
I have not ran it in this state beyond maybe 3 seconds or so after the HV spools up.
What has been done since the last time the set worked.
C1 replaced with a 350v unit
R49 substituted with 4 1K resistors.
CRT, yoke chassis unplugged and moved off and on the bench..


Is the shrunken picture size on the test CRT? It may not be that way on the normal tube.
I didn't realize there was an issue with the vertical foldover.
Why is it you are turning the set off after a short while? I thought you stopped the arcing.

_________________
Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Wed 05, 2017 12:51 am 
Member
User avatar

Joined: Jul Wed 18, 2012 3:13 pm
Posts: 893
Notimetolooz wrote:
MrE12AX7 wrote:
Picture is shrunken both horizontally and vertically, with lots of vertical foldover on the bottom of the screen.
I hear the horiz osc tone for about a second then it changes pitch and I shut it off.
I have not ran it in this state beyond maybe 3 seconds or so after the HV spools up.
What has been done since the last time the set worked.
C1 replaced with a 350v unit
R49 substituted with 4 1K resistors.
CRT, yoke chassis unplugged and moved off and on the bench..


Is the shrunken picture size on the test CRT? It may not be that way on the normal tube.
I didn't realize there was an issue with the vertical foldover.
Why is it you are turning the set off after a short while? I thought you stopped the arcing.

It was on the test CRT. The height was about a inch and a half and the width was lacking and it was very dim.
This is a horizontal osc/output/HV issue.
When the set was working the vertical foldover went away after warmup.
I do not let it run longer because I am afraid of damaging the flyback or yoke.
I apologize for being inconsistent with my communication. I tried it again leaving it on longer and this is what happens. The oscillator spools up then the pitch of the frequency drops then the oscillator sound goes away completely. No Raster. I am going to go over all my work in the R49 area in case I bumped something or there is a bit of solder shorting something etc. I would think that I caused this problem because it worked before I played with the resistor.

_________________
Currently on the Bench - Sterling Model F


Top
 Profile  
 
 Post subject: Re: Motorola 17T21 Video noise on sync signal LARGE IMAGES
PostPosted: Apr Wed 05, 2017 1:02 am 
Member

Joined: Jul Wed 08, 2009 12:17 am
Posts: 904
Location: Wyoming, Michigan
MrE12AX7 wrote:
Nope It did not look like that. it was different. Looked like a rectangular black blob with two leads coming out.


In my entire (long) life I've never seen a rectangular blob.

What you circled on the Sams was a wirewound resistor. We have to go on faith that it's really R49 until or unless the full Sams becomes available. ETF or otherwise. If you identified R49 correctly then it's supposed to be wirewound in your set. If it was a black blob then I thought it had a greyish coating. Unless your answer about the black blob was about something else not R49. By context or lack thereof I guess we don't know.

If your answer was about R49 and you identified R49 on the sams correctly then the black blob was probably a service replacement sometime during the set's lifetime. No way of knowing exactly what it was.

If you do have an interest in going into a technical career someday, you will be demanded to communicate precisely and clearly. We're not just being dicks here for no good reason. It's what the field requires.

Hopefully your parts guy mentor's co-worker friend will help you out. if he asks you to pull a sync tube and seek a momentary stable picture with your hold controls, listen to him.


Top
 Profile  
 
Post New Topic Post Reply  [ 161 posts ]  Moderators: 7jp4-guy, Mr. Detrola Go to page Previous  1 ... 4, 5, 6, 7, 8, 9  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 7 guests



Search for:
Jump to:  


















Privacy Policy :: Powered by phpBB