Cool $10 dollar find(s)

[jpdylon]

I answered a CL ad for a "very old but functional tv" this morning. There was no picture, but I thought what the hell.

I met a nice elderly lady who had inherited her house from a relative. He happened to be a radio and tv tech and had a garage filled with stuff. Unfortunately someone had gotten to most of the equipment before I, but there were two things that I did grab.

1. A Curtis Mathes 19" tabletop. I haven't cracked it open to see if there are any tubes or not, nor did I power it up because of its horribly dirty appearence.

2. an early Sony transistor portable thatis missing its power cord.

She told me there was more "junk" to be cleared outof the attic, but she would call me if she found anything of interest.

WooHoo! I love it when things like this happen!

[peverett]

Good luck on that Curtis Mathis. I have 4 of these with good CRTs, but have not gotten any of them to work. I believe that at least a couple of them have bad flybacks. The one that has a good flyback, has multiple other issues.

Compared to the Zeniths of the same time period, these are very poorly constructed, with many tubes close together on a PC board. Also very difficult to work on.

Be sure you have plenty of 5GH8s, it is full of them. If you need some, I will send them to you for shipping as I have quite a few.

[jpdylon]

Thanks for the offer. I have yet to check everything, but it is indeed a tube set. The lady I got it from said it worked, however for free I don't really care. Its yet another thing on my list to fix.

What caused the flys to fail? poor construction? poor cathode current regulation?

[Carmine]

I see a little "vent" next to the Curtis Mathes logo. I wonder if this set is a remote?

I think it's kinda funny how so many manufacturers promoted their sets on "quality", but were the same PC-board stuff that everybody else used. IMHO, PC boards and tubes just don't mix. When I was carrying all those sets out of the TV-house, I could tell the Zeniths without even looking... They weighed twice as much!

Since so many people consider Consumer Reports to be the last word on anything, I'd like to see an old issue, from say 1963-1970 that reviews color sets... I wonder if they were smart enough to recognize the difference between a Zenith set and whatever else they reviewed. Doubtful.

[andy]

I've got a bunch of consumer reports from the 60's and 70's. The TV reviews are more comprehensive than the recent ones. They compare specific things like DC restoration and accuracy of the color decoder. I think some even mention if they use circuit boards, or not.

[peverett]

I do not know what cause the flyback failures. The came from an old TV shop and this is the condition that I received them in. The shame is that all 4 of the CRTs show to be in excellent condtion.

Carmine comments are correct about the Zeniths, although they did make series string B&W sets. Even these are hand wired. It is probably no accident that of the TVs of this era, the Zeniths are the easiest to get running.

[jpdylon]

Typical low budget chassis. it is a remote set, the tuning motor can be easily seen along with the two control units. The previous owner was nice enough to replace most if not all the lytics with orange drops. The big filter can was replaced as well, and all but 5 original tubes.

The Number on the CRT does not match any listed on the tube chart. i wonder if this was replaced as well. The tube was made by toshiba for Curtis Mathis.

First run proved to be crap. There was sound and HV, but only a line. I killed the brightness to avoid burning the tube face. I thought the service switch may be dirty, but there was no improvement even after cleaning.

Pulling off the bottom service cover revealed all, including why pc boards and tubes do not mix. All the solder joints on the tubes sockets have worn and broken. The posted picture of the vertical socket explais my loss of V sweep.

I'll re-solder all the sockets and take care of any other problems I may find and post some screen shots.

BTW, where can I find a little cord for the back of that sony, or am I better off making one of my own?

[Eric H]

Does that Sony use 120v or is there a transformer in the line cord?
Just wondering why it has 4 prongs.

Edit:

Oh I see, from the diagram it looks like two are for AC and two are for 12v DC

[andy]

Two of the pins on the Sony are for 120v AC and the other two are for 12V DC. Sony used the same type of line cord on most of their B/W TVs from the 60's and into the 70's. I think the top pair of pins is for 120v. There is also a switch in the power socket to detect whether you're using a 12V, or 120V power cord.

[peverett]

The chassis looks identical to the ones that I have.

[Chad Hauris]

Something about that CM circuit board looks like a GE??
I would solder buss wire to each tube socket terminal and run it back to the next solder joint on the pc board trace. This will give a little more "meat" to the connection and help prevent another thermal fault.

[jpdylon]

I now have vertical sweep. However the horizontal oscillator frequency is way off (too low) and cannot be affected by the horizontal hold one bit. I cannot seem to find a oscillator trimmer pot or coil. Where should I go about troubleshooting this?

[jpdylon]

I've narrrowed down to the sync section. There doesn't seem to by any sync pulses, as vertical and horizontal are off and will not lock in. I can get the vertical hold to slow the rolling, but it will not stop.

*EDIT* I replaced the sync amplifier and I now have a strong vertical lock. However the horizontal problem still exists.

[jpdylon]

I tore into the horizontal oscillator circuits this morning and found a 56k resistor that has increased to 70k, this controlled plate voltage. I also found a 120k cathode resistor that had climbed to 142k.

The real kicker is that the Phase Detector diode is open. I've tried testing it with my dmm, but no matter what its open.

Posted is the pic of the PD. Where Can I get a replacement?

[Duane]

Jordan,

Have you tried contacting some of the older TV repair shops in the San Diego area? Tommy's TV,Poway TV.I believe there's a shop in El Cajon on 2nd.Maybe some of them have parts..