My CTC-16XL Project.

[Yamamaya42]

I don't believe it.
I have started to try and check resistors in my set. (it sucks that most cant be tested in-circuit)
started checking and ran into trouble right at the start.
AGC line r36, 2.2 meg could not measure it with this cheap RS meter I have.. Off-scale high/ almost reads 20m on the 20m setting (no other higher) it cant be THAT far off

So it's
A: the cheap meter is lying to me and cant be trusted, or B: it really IS over 10x too high..
taking this resistor to work to check with a $400 fluke I have there.
Also getting another cheap autorange meter that goes up to 200m.

[Yamamaya42]

https://imgur.com/KHo8VmG

mine

[Electronic M]

Resistors tend to drift high (sometimes even open) and ones that start high tend to be worse so I tend to believe the meter...

Be GALD your set did not spend it's life outside getting rained on/in...I found a 1972 Sylvania in a ditch once with the amount of rust in its metal table model cabinet, rot in the back and lawn debris inside it I was sure the only good part would be the CRT...But then I washed the crap out and decided to 'play' with it. Somehow with little effort, it made a raster...Getting anything else out of it meant replacing 95% of the resistors in each stage (most were wildly out of tolerance). Somehow it made a damn good pic and decent sound for a while after re-resistoring it.

[Yamamaya42]

I just ordered an assortment of ½ watt metal film resistors (not carbon film, too high rfi ) Which should have most of what I find bad, I hope.
The resistor I tried to check last night checks at 31m , out of range of the cheap meter I had.
the new cheap meter coming goes up to 200m.
Someplace, somewhere, in my home is hiding a Fluke 73 III...
And I suspect that when I LEAST need it, is when it will crawl out of it's hiding place in the 6th dimension, where it has been the last 6 or more months and reappear.

[Rocket]

Originally Posted by Yamamaya42

https://imgur.com/KHo8VmG

mine

Nice looking chassis! looks to be in decent shape and not much rust or anything : D

[Rocket]

Originally Posted by Yamamaya42

I don't believe it.
I have started to try and check resistors in my set. (it sucks that most cant be tested in-circuit)
started checking and ran into trouble right at the start.
AGC line r36, 2.2 meg could not measure it with this cheap RS meter I have.. Off-scale high/ almost reads 20m on the 20m setting (no other higher) it cant be THAT far off

So it's
A: the cheap meter is lying to me and cant be trusted, or B: it really IS over 10x too high..
taking this resistor to work to check with a $400 fluke I have there.
Also getting another cheap autorange meter that goes up to 200m.

I have also ran into this myself a few time. I have had some resistors in a few of my old zenith radio sets that were meg omhs instead of low k's

also a while back I got this Klein meter, it isn't as nice as a 400 buck fluke, but its close. I love it a lot more than my old 20 dollar digital I had and it can test up to 1000vdc/vac and I have found that handy working on some of my old radios.

check it out, its just under 100 bucks

https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

[Yamamaya42]

https://imgur.com/sob7yID
this is where my CTC spent the last 13 years or so,
and before that it was rented storage spaces, so it was always kept covered.

[Rocket]

Originally Posted by Yamamaya42

https://imgur.com/sob7yID
this is where my CTC spent the last 13 years or so,
and before that it was rented storage spaces, so it was always kept covered.

Nice! glad it was kept out of the weather

im looking forward to seeing pictures of your set when you have it running

[Yamamaya42]

SAMS makes it really hard to find R34,35,36 mounted on tuner :/
All they give is an overhead shot of the chassis / tuner ( page 17) with arrows pointing to a dark fuzzy low res area of where they are, no zoom of the area with the resistors marked :/

[Yamamaya42]

Have started on the sweep PCB. around the AGC/ sinc sep circuit.( takes a LONG time :O )
https://imgur.com/vKACCKZ

seems that 15% of the resistors are out of tol so far.

[Bill R]

Keep this in mind when checking resistors. There is nothing that will make a resistor read high, other than a bad resistor. Any other parts of the circuit, ie: parallel paths, will cause a lower reading. I always check in circuit and if it is low then I remove it to check it. If it reads high, I just replace it. Since most resistors drift up in value, there is usually no need to take a resistor out of circuit for an initial test.

[old_coot88]

Originally Posted by Bill R

...Since most resistors drift up in value, there is usually no need to take a resistor out of circuit for an initial test.

There are occasions where a resistor will drift down if it's the older phenolic-encased type. If the resistor's been running hot for a long time, the phenolic case will gradually char from the inside and create a conductive path around the resistance element. Most often seen in one and two watt units.

[Yamamaya42]

i just wonder how critical i should be, i am seeing some WELL within the 20% range, and others just over /under and some WAY over. I tend to want to replace the ones not "well within range...

[old_tv_nut]

If you are looking at carbon composition resistors, you should know that the 5% ones and 10% ones often were picked out at the end of the production line, leaving the 20% ones always worse than +10% or -10% (a "bimodal" distribution).

[Electronic M]

Also if the 4th tolerance band exists; base the acceptable tolerance on that. Usually on 60's color sets the majority of resistors will be 10% silver bands with some 5% gold for critical apps and some 20% no-4th-band resistors thrown in non-critical areas for cost savings.

If a gold band checks within 10-20% but not in it's designed 5% and you leave it, then you just missed a failed component...