Anyone who can refurbish a Conrac CBY17? - Videokarma.org TV - Video

vintage.digi · #1 03-31-2021, 04:43 PM

Is there anyone within around 6 hours of Louisville, KY who could refurbish a Conrac CBY17? Condition looks really nice but everything, including the tube, is untested. I have a tube tester so I could potentially test the tube before driving the monitor out, but I'd likely need a little help with that.

Thank you!

Electronic M · #2 03-31-2021, 06:42 PM

If it's a CYB17 then it's probably the rectangular version of my roundy Hybrid CYB21. I'm 6.5 hours away and would consider working on it if you can't find someone else.

vintage.digi · #3 03-31-2021, 09:40 PM

That's a pretty accurate description. It looks a lot like the CYA/CYB but is rectangular.

How far are you from Chicago?

Electronic M · #4 04-01-2021, 07:27 PM

You Know where Milwaukee Wi is?... I'm about half an hour west of Milwaukee along I-94.
I think I'm around 2 hours north of Chicago, but I haven't been down there since the 2019 ARCI Radiofest swapmeet.

vintage.digi · #5 04-04-2021, 05:13 PM

Do you have a number that I could reach you to discuss options with the Conrac monitor? I am planning on picking it up next week in Chicago. Right now I'm aiming for Tuesday. Taking it to you in the same trip would be the most efficient since I will be driving 6 hours already to pick it up.

Curious to hear your thoughts.

I wanted to message you my cell number, but your PMs are full.

Thank you!

Electronic M · #6 04-05-2021, 12:57 AM

I sent you my phone number by email. The subject should contain "conrac monitor repair contact".
If you didn't receive it let me know and I'll briefly publicly post my number here.

Videokarma has a feature for members that are logged in where they can click user names and send an email to said users through videokarma to whatever email the site VK uses to send said member it's notifications. (Though some members opt out of this feature) It is also possible to email me through the videokarma send email feature, but I don't check that email often.

vintage.digi · #7 04-14-2021, 08:32 AM

Please feel free to post some photos of the process if you feel like it. I'd love to see any of the details as it comes along.

I remember we saw the Conrac sticker on the tube but did you check the manufacturer? I was reading an older thread on the topic that says the rectangular tubes were made by Hitachi. http://www.videokarma.org/showthread.php?t=257965

The thread also mentions the "Mod G" version with the DC filament PSU which is what the Zenith unit is. That thread seems to me to suggest that these tubes used controlled phosphors, although the SMPTE-C standard is said not to have been published until 1968, which would make this monitor too early for it. Perhaps Conrac was doing this on their own for a while before it was externally standardized as SMPTE-C. That would explain the Conrac part number. Also the Mod-G designation would likely make this one of the latest CYBs. (seller made a typo in the listing which I carried over to this thread title)

Something else that I realized I might have wanted to bring along would have been a Conrac demodulator. It's a beast of a demodulator in a 4u rackmount chassis with deliciously chunky knobs. I actually have two if you would want one for your unit. Apparently one was used in the Apollo missions: https://www.invaluable.com/auction-l...6-c-6374754a00

Electronic M · #8 04-19-2021, 06:29 PM

Status update: I've taken the set apart, cataloged all the caps in it to change for reliability (I'm going to try to make a large capacitor restock order in the next couple of days), and changed all the caps that I can with of my current cap stock.
Right now all the cosmetic panels are off of it.

The caps I changed so far are the plastic tubular caps in the convergence, sweep, under the CRT, and the power regulator. I also changed a couple of lytics on the sweep side.
Before:After

In the last before shot the old lytics appear to be replacements from decades ago. Most of the plastic tubular caps in the horizontal section had been cut then the leads touched together and soldered (kind of a shoddy way to do it) which suggests someone was clumsily looking for a bad cap in that stage. Theres what appears to be an extra pot in the below picture, but otherwise it doesn't appear to have seen much work from previous techs.

The CRT is labeled as EIA274 which crosses to RCA. Your monitor is a CYB, but that thread is mostly about the CYA which was an older model. The CYB line likely never had the Hitatchi CRT.

After changing caps nothing had changed so on a hunch I clipped a newer used lytic in parallel with the 1500uF 50V can and the hum disappeared from the video(sync is lousy though). That can and the rest of the lytics will be on order soon. Until then this project will be on hold. It will probably be sometime next week when I get the parts I need for work to proceed.

Electronic M · #9 04-19-2021, 06:30 PM

Here you can see a size comparison from the front of the 2 CYB monitors (the 17 and 21).

With regards to your Conrac tuner offer, I'm interested, though I don't strictly need a second one. If you look at the above pic you'll see my Conrac tuner, which has illuminated channel numbers. I wouldn't mind a second one (especially since yours is slightly different), but if you think you have use for 2 I wouldn't want to inconvenience you.

Electronic M · #10 05-04-2021, 08:00 PM

So I'm going to move from the "work on it" stage to the "run it a few days to make sure nothing breaks" stage...

Repair since last post basically went, recap power supply to eliminate hum, recap sync to get sync back, then go after everything else to try and make color look right.
After each board or two I did test power-ups.

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It should be noted that all the 3 convergence lytics and the one front most lytic on the luminance board were replaced with Sprague axial lead caps that look the same as the originals (only shinier and a bit smaller). I mostly used radial lead caps to keep the cost of caps down (by more than half) but those 4 caps were values that I couldn't get anything of a close enough value for me to be comfortable with for a better price than the Spragues.

At the end of the recap it became apparent there was hardly any red in the picture. Trying to do a grayscale setup showed me that the red G2/screen control wasn't doing anything. Voltage checks confirmed the ~500VDC that should have been on the red G2 was down under 100. After a bunch of tracing I finally guessed that the red G2 kill switch was dragging the voltage down. It tested fine on my DMM so all I can figure is that it's insulation was failing at 500V. The B/W-Color Switch was an identical part and has less than 15V on it. So I swapped the 2 switches. The switch that breaks down at voltages over 100V shouldn't affect the low voltage B/W-color circuit....It should be reliable and not change the cosmetics of the control panel. Its a repair you'd probably never know about if I didn't tell you.
Since then color has been good and I have adjusted the H Lin/Efficiency coil for min H output cathode current (it dipped to 210mA which is better than my CYB21 roundy), adjusted the HV and B+ regulators, and dialed in sweep and convergence to the extent it's worth doing prior to it being moved over 6 hours drive away.
It looks excellent in person. I wish my phone could capture it better.

note: the black lines at the left of the blank raster pics above are not a problem with the monitor but rather a result of antenna placement from my use of a VCR tuned to an agile modulator transmitting a test pattern from another room (sometimes life is easier if you just transmit a signal instead of moving devices or stringing 50' of wire to get it where you want it).

One thing you may want to get is the key for the control doors...My CYB21 has it's key so on a hunch I tried it's key on your monitor and it worked...I think it's a standard cut key the way some elevator emergency keys and some fleet vehicle keys are standard cuts. You should be able to order a Chicago Lock Co. H1768 and get a key that works the locks of your Conrac.

And here's a bit of the James Bond film Dr. No. fed directly into the monitor from a JVC professional S-VHS-ET deck.

As a final aside I discovered I own a broken broadcast spec color bar generator that uses the same funky power cord connector. I'm going to try and fix that generator. If I can't fix the generator then I'll be willing to sell you the cord from it since you need a cord for this.