View Full Version : Capehart 325 restoration


bandersen
08-10-2014, 05:06 PM
Way back in May, 2010 I came across this "raped curbside" Capehart on ebay.

http://www.videokarma.org/showthread.php?p=2972644#post2972644

That sparked another thread where pugs5061 was thinking about getting it: http://mail.videokarma.org/showthread.php?t=247970

Well flash forward to 2014 and the chassis is sitting on my back porch awaiting restoration :D

https://farm4.staticflickr.com/3848/14861379052_3309699f7f_c.jpg (https://flic.kr/p/oDfsej)

Now here's the rest of the story. I had been contact a few months back someone was referred to me by Phil Nelson who was in my area and looking to have a vintage Admiral TV restored. Well we got to talking and he said he also had some other sets he'd like restored someday too. He sent some photos and there it was - that same Capehart.

It turns out he originally found it out on the curb (or maybe it was his wife ?) after the copper thieves neck it and made off with the yoke. He listed it on ebay several times and had some winning bidders but they never showed up to claim the TV so he kept it all this time.

I also just so happened to have scored this original Farnsworth "160-AR" picture tube last year which was one of the CRTs used in this chassis. I don't thinks that's the original yoke, but the CRT has some life left.
https://farm6.staticflickr.com/5530/11378433264_b7375949df_c.jpg (https://flic.kr/p/iktrMS)

So anyway, I agreed to make an attempt to bring it back to life.

On the plus side,

The chassis looks complete and has had very little work done to it
I have a good replacement CRT
The copper thieves left the focus coil


On the negative side

I'm not sure of the chassis revision
No yoke
Missing HV cover
Missing some knobs (I found the volume and channels knobs in my stash)
Missing control cover


I've been told I can probably use a Admiral or RCA yoke of the proper deflection angle as it shares a common circuit design. THat's good becuase I have some spares I can try.

The HV cover looks very easy to fabricate.

That leaves knobs and the control panel. Here's a photo of the control area. If anyone has some spare parts, please chime in :yes:

I believe "balance" is brightness and "shading" is fine-tuning.
https://farm6.staticflickr.com/5557/14880420485_c816ce5d14_c.jpg (https://flic.kr/p/oEW3zT)

bandersen
08-10-2014, 05:13 PM
Here are some more photos of the TV.
https://farm4.staticflickr.com/3882/14859254454_ed4f3f61ee_c.jpg (https://flic.kr/p/oD4yEj)

https://farm6.staticflickr.com/5560/14675035090_087d4dd92b_c.jpg (https://flic.kr/p/omMoEo)

https://farm6.staticflickr.com/5565/14861378402_e1127903c3_c.jpg (https://flic.kr/p/oDfs37)

They took the yoke but left the focus coil behind.
https://farm6.staticflickr.com/5581/14859258534_9a623e01c2_c.jpg (https://flic.kr/p/oD4zSE)

I sure hope the flyback is good.
https://farm6.staticflickr.com/5580/14859257284_563d076451_c.jpg (https://flic.kr/p/oD4zv7)

It uses a common turret type tuner. THe power supply is similar the early RCA designs where there is a B- and B+ with a huge tapped voltage divider power resistor.

I see very little evidence of repairs.
https://farm4.staticflickr.com/3878/14675089179_ff3cf4c985_c.jpg (https://flic.kr/p/omMEJX)

Down Under
08-10-2014, 08:13 PM
Looking forward to your remaining videos on this one!

Kevin Kuehn
08-11-2014, 10:10 AM
750155A-G1 Crosses to Thordarson Y13

750163A-1 Crosses to Thordarson Fly2

bandersen
08-11-2014, 12:52 PM
Thanks. Where dd you get those part #s from ?

Kevin Kuehn
08-11-2014, 03:33 PM
The Capehart numbers are from Sams 112. Then I looked those up in my Thordarson catalog.

bandersen
08-17-2014, 02:59 PM
I got a copy of that Sams and dug up a yoke from an RCA KCS-47 chassis using a 16GP4. That has a 70 degree deflection angle just like the 16" CRT in this Capehart.

Even better, it has a 56 and 270pF cap inside just as shown on the schematic.
https://farm6.staticflickr.com/5576/14763652988_1e6cfbe7be_z.jpg (https://flic.kr/p/ouBzFb) https://farm6.staticflickr.com/5567/14949920262_216cd556fc_z.jpg (https://flic.kr/p/oM5frU)

Best of all it fits. Here's a dry run with a 16KP4. I think I'll use a little 8XP4 bench CRT during the restoration.
https://farm4.staticflickr.com/3918/14763581659_24089cf5f9_z.jpg (https://flic.kr/p/ouBdtn) https://farm6.staticflickr.com/5571/14763597100_cf0e015d18_z.jpg (https://flic.kr/p/ouBi4A) https://farm6.staticflickr.com/5569/14763655868_298e0fb456_z.jpg (https://flic.kr/p/ouBAwQ)

I then proceeded to test the flyback, focus coil, vertical output transformer, etc. It all checks out - even the huge candohm resistors

Finally, I pulled the 5U4 and fired it up. All the tubes lit and I have about 5 volts on the 5U4 filament and ~700 on the plates.

So it's full steam ahead on this project :thmbsp:
https://farm6.staticflickr.com/5564/14763597780_777fb5fe15_z.jpg (https://flic.kr/p/ouBigj)

bandersen
08-18-2014, 03:21 PM
I cleaned out the HV cage last night and replaced the missing 1B3 rectifier. The transformer inside the cage is just for the 6W4 damper tube filament.
https://farm4.staticflickr.com/3841/14961795162_3dff57794a_z.jpg (https://flic.kr/p/oN87ry) https://farm4.staticflickr.com/3889/14962150105_d43462c74d_z.jpg (https://flic.kr/p/oN9VXg)

Then, I took a closer look underneath. The are a few deviations from the Sams but overall it matches well.

One thing that struck me though is the crazy assortment of resistor types. Lots of 30s style dogbones, some from West Germany, some odd body styles. Also some series and parallel combinations to get the right value.

This set is from around 1951 so I'm guessing it's a result of parts shortages from the Korean war and spike in TV demand.
https://farm4.staticflickr.com/3918/14775676138_6303d242d8_z.jpg (https://flic.kr/p/ovFcJS)067 (https://flic.kr/p/ovFcJS) https://farm4.staticflickr.com/3914/14775564550_583db69fb2_z.jpg (https://flic.kr/p/ovECyW)

Tubejunke
08-19-2014, 06:29 PM
I may have a Y-13 in my remaining stock. Possibly the other too. Let me know if you need me to look. There is a post of what I have in the classifieds a ways back. I used to post it once a year just so people would know the stuff exists, but I haven't updated in quite a while.

bandersen
08-20-2014, 12:12 PM
Thanks for the offer. I'll let you know if this yoke doesn't work out. I've been comparing this chassis the various service info sources and it's actually closer to the later Sams 160-2 than 112-3.

I'm also glad I reviewed the Riders info where I found this warning:
https://farm4.staticflickr.com/3922/14794883420_60100a51c5_o.jpg (https://flic.kr/p/oxnDoU)

Of course, I had mine dressed the wrong way and corrected it :)
https://farm6.staticflickr.com/5580/14981150512_6d70fcc980_z.jpg (https://flic.kr/p/oPQj7u)

Kevin Kuehn
08-20-2014, 02:33 PM
Those sure seem like tiny wires going to the plate caps.

bandersen
08-20-2014, 03:17 PM
For sure and I've been very careful around them. When this set was found, the 1B3 tube was missing and I'm amazed the cap lead hadn't broken off.

Assuming I can get this thing running again, I'll fabricate a new HV cage cover for protection.

bandersen
08-22-2014, 12:00 AM
I found this PENN TUBE branded 6AL5 in the set. Is that a clown face ?
https://farm6.staticflickr.com/5595/14996035495_792407a58f_z.jpg (https://flic.kr/p/oR9AU8) https://farm6.staticflickr.com/5564/14809509797_3a2eb7eedf_z.jpg (https://flic.kr/p/oyEBiP)

Eric H
08-22-2014, 12:19 AM
It's always reassuring to have a Clown printed on your tubes, it suggests premium quality. :D

N2IXK
08-22-2014, 09:51 AM
It's always reassuring to have a Clown printed on your tubes, it suggests premium quality. :D

http://hipsterjew.com/wp-content/uploads/2013/03/Krusty_Brand_Seal_of_Approval-150x150.gif

bigaudioal
08-22-2014, 10:01 AM
I hate clowns!!! That tube would have freaked me the hell out - making me sell the set immediately! LOL!

leadlike
08-22-2014, 05:02 PM
Hard to tell if it is a clown. It looks a little like the Quaker Oats guy, which would fit in with the (William?) Penn tube brand.

NoPegs
08-22-2014, 05:25 PM
Hard to tell if it is a clown. It looks a little like the Quaker Oats guy, which would fit in with the (William?) Penn tube brand.

We have a winner!

bandersen
08-23-2014, 05:43 PM
OK, I'll take that answer :)

Encountered my first open power resistor so far and replaced it. Also finished up the sync separator, vertical oscillator and output in this corner.

This set is proving to be quite a challenge. I now have threes versions of the schematic and none quite match. They also really packed the components in.
https://farm6.staticflickr.com/5558/15013120205_09f8b82584_z.jpg (https://flic.kr/p/oSEaA6) https://farm6.staticflickr.com/5590/14990126446_6be77ff19d_z.jpg (https://flic.kr/p/oQCjkY)

Done with the sound IF, ratio detector and output amp too.
https://farm6.staticflickr.com/5566/14995714372_ac0d15816e_z.jpg (https://flic.kr/p/oR7Xrw)

NoPegs
08-23-2014, 09:52 PM
Done with the sound IF, ratio detector and output amp too.


Done with the vintage table refinishing yet? :D

Tubejunke
08-23-2014, 10:59 PM
Did you replace the grille cloth? Just noticing that the closeup picture shows the set with what looks like a gaping hole in the speaker area. Then the full view of the set there is no hole, but the cloth looks original.

bandersen
08-24-2014, 02:01 AM
Did you replace the grille cloth? Just noticing that the closeup picture shows the set with what looks like a gaping hole in the speaker area. Then the full view of the set there is no hole, but the cloth looks original.

The closeup is from a different set I grabbed off eBay to show what the missing knobs and control panel look like.

All I have at my place is the chassis.

Done with the vintage table refinishing yet? :D

LOL Which one ? I'm just about done giving my danish modern coffee table a fresh lacquer recoat and rubbing out my Philco charside radio. Still haven't touched my vintage kitchen table :(

bandersen
08-25-2014, 11:29 AM
Horizontal circuits done. I like how they implemented the hor. linearity control at a right angle with a wingnut.

Should be ready for a power up soon...
https://farm6.staticflickr.com/5576/15028402342_7fa7042e33_c.jpg (https://flic.kr/p/oU1urd)

bandersen
08-28-2014, 02:49 PM
This sure has been a confusing chassis to work on but I'm getting close!

All the electrolytics have been rebuilt and I'm just waiting on some power resistors to arrive tomorrow.
https://farm6.staticflickr.com/5587/15042904496_7fd722aa39_z.jpg (https://flic.kr/p/oVhPqm)

Meanwhile, I'm cleaning up the corroded chassis.
https://farm4.staticflickr.com/3843/15065625572_d80bec53fa_z.jpg (https://flic.kr/p/oXigB3) https://farm4.staticflickr.com/3863/15065626122_de6261ffec_z.jpg (https://flic.kr/p/oXigLw)

https://farm4.staticflickr.com/3866/14879340010_ec32ac63c7_c.jpg (https://flic.kr/p/oEQvp1)

I'm also reviewing all the components and finding some damage like this chipped ceramic disc.
https://farm4.staticflickr.com/3882/14879328758_8c2de05d2f_z.jpg (https://flic.kr/p/oEQs41)

Tubejunke
08-30-2014, 09:20 PM
What do you use to cut open those multi-section electrolytics so neatly without removing them. Or maybe you did remove them, but I figure if you did and then rebuilt them then you would re install them as units.

bandersen
08-31-2014, 01:24 PM
I actually did remove them which was quite easy to do.

Then heated them in the oven on the lowest setting to soften the tar holding the cardboard covers on.

Finally, used this fine toothed mini-hack to cut them open.

https://farm6.staticflickr.com/5589/14939248156_bc30a367cb.jpg (https://flic.kr/p/oL8y15) https://farm4.staticflickr.com/3917/15096478755_60dae3e603.jpg (https://flic.kr/p/p12pbt)

bandersen
08-31-2014, 08:25 PM
Here's a closer look at one of the oddball resistors in this set. It's a Rosenthal which I think is German.

https://farm4.staticflickr.com/3849/15100452355_440e0fdc4c_z.jpg (https://flic.kr/p/p1nLoP)

robert1
09-01-2014, 12:32 PM
Here's a closer look at one of the oddball resistors in this set. It's a Rosenthal which I think is German.

https://farm4.staticflickr.com/3849/15100452355_440e0fdc4c_z.jpg (https://flic.kr/p/p1nLoP)

I have Seen these in a couple of 1950 Admirals that i have worked on

Kevin Kuehn
09-01-2014, 12:33 PM
I noticed the yoke in your video has Y17 printed on it, so it's probably a Thordarson replacement. Far as I can tell a Y13 and Y17 are very close(both 70 degree) with the exception that the 17 has the octal plug attached.

truetone36
09-01-2014, 02:17 PM
I've got the knobs and the control panel/nameplate you need. PM sent.:thmbsp:

NoPegs
09-02-2014, 09:16 AM
Here's a closer look at one of the oddball resistors in this set. It's a Rosenthal which I think is German.

https://farm4.staticflickr.com/3849/15100452355_440e0fdc4c_z.jpg (https://flic.kr/p/p1nLoP)

Rosenthal, "Ja, Deutschland!"


They're now part of the glorious Vishay empire.

http://www.vishay.com/landingpage/50year/draloric.html

bandersen
09-03-2014, 02:33 PM
I found a couple fried dogbones in parallel. Enough paint remained for me to identify them as 47K which matches one version of the schematic. Together they should measure 23.5K but I got about 5K.
https://farm4.staticflickr.com/3872/14943938728_30d5275874_z.jpg (https://flic.kr/p/oLxAm1) https://farm4.staticflickr.com/3919/15127523341_5dec238a6a_z.jpg (https://flic.kr/p/p3LvDX)

Underneath them was an even crispier resistor which I can't make out. Again, the schematics for this circuit vary widely, but I'm fairly certain it should be 33K - not 7K.

I wonder hat caused the failures ? I'll replace them and keep my fingers crossed.
https://farm4.staticflickr.com/3859/15130510215_48f6386ea9_z.jpg (https://flic.kr/p/p42PxM)

mpatoray
09-05-2014, 09:10 AM
That sure is an interesting(strange) set. It's neat watching it slowly come back to life. Outside of the Farnsworth in the ETF museum I have only ever seen one other Capeheart-Farnsworth product and that was at an antique store years ago and they wanted $500 for it!

As for all the differences, maybe undocumented production runs but also far be it for Sams to be flat out wrong!

Matt

azbigsam
09-08-2014, 03:01 PM
Bob, I found a similar set on craigslist. Too bad it is in Texas.
http://dallas.craigslist.org/mdf/atq/4628868624.html

bandersen
09-08-2014, 03:20 PM
I stayed up late list night I finally tried to power it up :) The 8XP4 test CRT is at add odd angle because of the stiff spring around the HV lead.

As soon as I tuned in channel 6, I god strong clear sound :music: No picture though and no HV.
https://farm4.staticflickr.com/3900/15173409561_8c52807823_z.jpg (https://flic.kr/p/p7PG2F)

I discovered the 1/4 amp flyback fuse was open and tacked a new one across it.
https://farm6.staticflickr.com/5559/15173409991_8c83c80ce6_z.jpg (https://flic.kr/p/p7PGa6)013 (https://flic.kr/p/p7PGa6)

Yay! A blurry raster :thmbsp:
https://farm4.staticflickr.com/3867/14989678759_6f92ff1831_z.jpg (https://flic.kr/p/oQA2ge)

After some more control twiddling, I got a blurry but stable image.
https://farm6.staticflickr.com/5591/14989859757_107f0a264c_z.jpg (https://flic.kr/p/oQAX4T)

I figured the image was blurry because of the focus coil messing up the auto focus CRT. It's part of the power supply so can't be disconnected but I was able to unmount it.
https://farm6.staticflickr.com/5577/14995294369_e39048cdb6_z.jpg (https://flic.kr/p/oR5NA6)

Ah, much better :yes:
https://farm6.staticflickr.com/5565/15182061285_dd9103e920_z.jpg (https://flic.kr/p/p8A2Tk)

Next up, I'll test all the tubes and do some more tweaking.

bandersen
09-08-2014, 09:38 PM
Well I found and replaced some weak tubes and the set was playing better. Then while making some control adjustments I hear a faint pop and saw a brief spark near the HV rectifier and the picture went dim :(

I sure hope it's something simple like the HV rectifier died or fuse blew.

bandersen
09-08-2014, 09:43 PM
Yep, fuse blew. Now to determine why...

robert1
09-08-2014, 10:33 PM
Yep, fuse blew. Now to determine why...
sounds like the 6W4 damper tube failed with a fil to cathode short. the best thing to do is just replace the 6W4 with a 6AX4. also chect to see if that disk capacitor underneath the damper tube shorted out. i have seen these short out before.

bandersen
09-09-2014, 12:11 AM
The 6W4 tested OK but I replaced with a NOS 6AX4 anyway. Replaced the fuse too. That got HV back until I tweak the drive control when I got a flash and the fuse blew again. Still not sure exactly where the flash came from. Might have been the fuse itself.

Before it died I managed to test the HV and it was only 6.5 kV - should be closer to 11 kV. Something sure isn't right in that circuit.

robert1
09-09-2014, 08:15 PM
The 6W4 tested OK but I replaced with a NOS 6AX4 anyway. Replaced the fuse too. That got HV back until I tweak the drive control when I got a flash and the fuse blew again. Still not sure exactly where the flash came from. Might have been the fuse itself.

Before it died I managed to test the HV and it was only 6.5 kV - should be closer to 11 kV. Something sure isn't right in that circuit.

since i don't have a diagram to look at for that chassis, i could only ask a couple of things. is the horizontal drive control a adjustable coil?, or a variable capacitor? or a pot? if it is a coil type, usually, those have a capacitor across it. it might be leaky. the coil itself, may have shorted windings.

have you checked the current on the cathode of the 6BG6?

i still suspect that red disk capacitor underneath the damper tube socket.
it appears to me that something is drawing too much current in the output stage. it might be that the flyback xfmr may a a few shorted turns or any of the above mentioned things, it also could be caused by a problem in a different circuit protected by that fuse.

truetone36
09-09-2014, 09:54 PM
Nice to see you making progress, even though there's been a couple of bumps along the way. When you get the bugs worked out, shoot me a PM and I'll get those knobs and the nameplate/control cover out to you.

HighHopes
09-09-2014, 10:24 PM
Hi Bob,

I have a question about the small test CRT tubes you use. After you get a set to work with a test tube, do you need to readjust the set again when the full sized tube is installed?

Also, I am thinking these tubes do not use an ion trap, true?

Is the focus coil a problem?

Steve

bandersen
09-10-2014, 10:56 AM
since i don't have a diagram to look at for that chassis, i could only ask a couple of things. is the horizontal drive control a adjustable coil?, or a variable capacitor? or a pot? if it is a coil type, usually, those have a capacitor across it. it might be leaky. the coil itself, may have shorted windings.

have you checked the current on the cathode of the 6BG6?

i still suspect that red disk capacitor underneath the damper tube socket.
it appears to me that something is drawing too much current in the output stage. it might be that the flyback xfmr may a a few shorted turns or any of the above mentioned things, it also could be caused by a problem in a different circuit protected by that fuse.

You can download a copy of the Sams here: http://www.earlytelevision.org/pdf/Capehart_CT-27-38-45_Sams_160-2.pdf

The drive control is a pot. I'll try replacing the cap and measure all the voltages and waveforms in the horizontal circuits..


Nice to see you making progress, even though there's been a couple of bumps along the way. When you get the bugs worked out, shoot me a PM and I'll get those knobs and the nameplate/control cover out to you.

Thanks, I sure will!

Hi Bob,

I have a question about the small test CRT tubes you use. After you get a set to work with a test tube, do you need to readjust the set again when the full sized tube is installed?

Also, I am thinking these tubes do not use an ion trap, true?

Is the focus coil a problem?

Steve

Yes, you need to readjust, the height, width, linearity etc. They do not use an ion trap and are self focusing.

Leaving the focus coil in place does produce a blurry image. That's why when I unmounted it in the photos above the picture improved.

robert1
09-10-2014, 01:20 PM
You can download a copy of the Sams here: http://www.earlytelevision.org/pdf/Capehart_CT-27-38-45_Sams_160-2.pdf


Thanks!, Bob


The drive control is a pot. I'll try replacing the cap and measure all the voltages and waveforms in the horizontal circuits..

Acording to the diagram, that .25 amp fuse protects the screen grid on the 6BG6. it also supplies voltage to the horizontal drive control as well as the damper circuit. the first thing i would do is place a milliameter between the cathode of the 6BG6 & the -100 volt source that is currently connected to the cathode of the H.O.tube. power the set up & monitor the meter reading. if it is rising & starting to go over 250Ma, it is possible that the 6BG6, itself, has developed grid leakage that does not appear when it is cold. you can also sub another 6BG6 to see if it does the same thing.

about anything could be causing the fuse to blow, however the most obvious things would be the H.O.tube, the horizontal drive pot that has "whiskers" in it, the Screen resistor (r88 22k) that has lowererd it's resistance.
i would check these things first.

Eric H
09-11-2014, 12:54 AM
A bit off topic but perhaps one of these is your set.
In any case there's a fair chance it passed through that guys hands at some point.

Capehart assembly line circa 1951.

http://videokarma.org/attachment.php?attachmentid=184268&stc=1&d=1410414807

bandersen
09-11-2014, 11:59 AM
I could use his help right about now :yes:

Replacing the drive control has stopped the fuse from popping. It appears to be tin plated but I couldn't really see any whiskers.
https://farm4.staticflickr.com/3914/15022473617_a57effac66_z.jpg (https://flic.kr/p/oTu72P)

All the resistors and capacitors on the HOT have been replaced and DC voltages seem reasonable. The cathode waveform matches whats shown in the service info.
https://farm4.staticflickr.com/3881/15022370520_e70fccd539_z.jpg (https://flic.kr/p/oTtzoh)

I've also tried swapping out each of the the three tubes inside the HV cage, but the low HV issue remains. Only about 6.5 kV under load. Just for the heck of it I installed a full size CRT, and you can see how dim and unfocused it is.
https://farm6.staticflickr.com/5561/15209056875_31cc23d55f_z.jpg (https://flic.kr/p/paYoJx)

So it seems to me that leaves the two high voltage ceramic caps inside the cage, the yoke and the flyback as culprits :scratch2:

Doug66
09-11-2014, 03:48 PM
While looking on ebay, I noticed a similar one located one state up from me. Viewing the listing showed it had been robbed of some parts: tubes and looks like 12" speaker. What actually concerned me was the power transformer laying in the bottom of the cabinet with frayed wires while a power transformer was still mounted in the chassis. All that, the $100 opening bid, and the condition of the cabinet was enough to turn me off of it.


http://www.ebay.com/itm/Original-1953-The-CapeHart-Antique-TV-Sat-in-Attic-/221545305858?pt=LH_DefaultDomain_0&hash=item3395211702

bandersen
09-11-2014, 06:10 PM
At least I got a photo of the missing HV cover now :)

robert1
09-11-2014, 06:55 PM
All the resistors and capacitors on the HOT have been replaced and DC voltages seem reasonable. The cathode waveform matches whats shown in the service info.


how about the voltage on the cathode of the damper tube? it should be around 550 V. if not, the low end of the winding on the flyback most likely has shorted turns.



I've also tried swapping out each of the the three tubes inside the HV cage, but the low HV issue remains. Only about 6.5 kV under load. Just for the heck of it I installed a full size CRT, and you can see how dim and unfocused it is.
So it seems to me that leaves the two high voltage ceramic caps inside the cage, the yoke and the flyback as culprits :scratch2:

i would say that the flyback has a few shorted turns. have you done a "ring" test on the flyback transformer yet?. that can be more revealing than a ohmeter can be.

bandersen
09-11-2014, 07:55 PM
how about the voltage on the cathode of the damper tube? it should be around 550 V. if not, the low end of the winding on the flyback most likely has shorted turns.


I have 355 VDC. Capehart service info just says HV for that voltage. Sams says 250 VDC.

i would say that the flyback has a few shorted turns. have you done a "ring" test on the flyback transformer yet?. that can be more revealing than a ohmeter can be.

Yes and it passes.

robert1
09-11-2014, 11:37 PM
I have 355 VDC. Capehart service info just says HV for that voltage. Sams says 250 VDC.
Yes and it passes.

Sams Says 550 v on the cathode of the 6W4 & 280 v on the plate of the 6W4. When measuring the cathode, is that where you got the 355 volt reading? the voltage on the plate of the 6W4 is supposed to be 280 v & is 20 volts low.
if the cathode of the 6W4 is reading 355, it is too low & is a possible indication that something in that immediate circuit is drawing too much current. after all, that is the B-Boost circuit. that also could be the cause of the low B+ voltage (250v)

bandersen
09-12-2014, 12:20 AM
Yes, I got 355V on the cathode. I was referring to Sams 112-3 which more closely matches my chassis and states 250 VDC for the 6W4 cathode. For example I have a 6AL5 video detector rather than a 1N34 diode as shown in Sams 160-2.

Penthode
09-12-2014, 09:49 AM
Try pulling the HV caps. I have known them to short. In my RCA 8TC271, one got so hot that it cracked.

bandersen
09-12-2014, 11:49 AM
There's one 500pF 20kV doorknob cap under the 1B3 rectifier socket. Very difficult to get at. I'm going to try a different yoke first.

bandersen
09-13-2014, 02:04 PM
I dug up another RCA yoke plus a Y-10 and Y-11 to try. All are 70 degree yokes.

https://farm6.staticflickr.com/5595/15041039667_9d77873ba6_z.jpg (https://flic.kr/p/oV8g58)

bandersen
09-13-2014, 02:11 PM
The owner also sent me a photo of the tube chart showing it used a Farnsworth 160-AR CRT.

https://farm4.staticflickr.com/3843/15040859499_6f18a75f01_o.jpg (https://flic.kr/p/oV7kvM)

bandersen
09-13-2014, 03:22 PM
Got a little more HV (~9kV) with the second RCA yoke also marked Y-17.

Kevin Kuehn
09-13-2014, 08:50 PM
Could there be a shortage of HV filtering when using that test CRT?

bandersen
09-14-2014, 01:45 PM
Well there's a 500pF HV filter cap and when I tried a 16KP4 with aquadag coating, it didn't help. My Farnsworth 160-AR picture tube has no coating at all. Not sure if it originally did or not.

NoPegs
10-12-2014, 02:16 AM
What's this? :scratch2:
An active restoration project thread that has gone nearly a month without a post? Heresy!

I'm scratching my head along with you on the HV issue but I can at least provide one facepalm-worthy suggestion to another annoyance you're having... Put the test CRT in "upside down" so the anode connection is on the other side and the HV lead runs across the top. The test CRT is small enough to probably allow the HV lead to still reach, and then the weird spring on the HV lead won't put up so much of a fight. There appears to be enough slack on the socket wiring to rotate 180 degrees without issue.


Continuing this thought-process, consider the possibility that the damned spring is sapping the HV through cracks in the very much vintage rubber HV lead insulation? That would explain the low HV measurement even with the tube disconnected. I'd bypass the whole HV lead assembly with a modern replacement and see if anything improves. There's no hidden resistor in series up under the suction-cup either, right? You've checked the filament current limiting resistors up under the HV rectifier, too? Swap the rectifier out for a string of microwave oven rectifier diodes? Aside from the flyback and doorknob cap, the HV lead is one of a rapidly dwindling list of things you haven't yet substituted for known or presumed working parts...


:para:

Going further down the grasping-at-straws path, pop an analog milliamp-meter in series with the HV supply directly after the rectifier and see if there's more current than expected being drawn. Obviously only a floating analog meter will work here. I'm sure someone makes a digital meter capable of measuring 0-100mA up around the 15kV zone, but it probably comes with a hefty price tag, and it sure isn't something you're going to use very often anyway.




:tears:

Even further down the "Nothing makes any sense, why doesn't it just work!" path:

Is your chicken blood fresh, or are you using that freeze-dried just add water stuff they sell to the wannabe-wiccans? Perhaps the bleached skulls need more dribbly candle wax on them, or maybe they need less. Swirl your tea-leaves in the opposite direction next time... Try everything! (In moderation.) :thmbsp:

bandersen
10-13-2014, 02:41 PM
Haven't had much time to work on it. The anode lead is about 6 inches to short to make it to the other side of the CRT.

As near as I can tell, there's no resistor in series with the anode lead or in parallel with the 1B3 rectifier tube filament.

When I find time, I'll try to run a new anode lead. The only way to get at that area is to take the HV box off which is not so easy since the flyback is mounted to it.

https://farm4.staticflickr.com/3952/15506300346_7876974679_c.jpg (https://flic.kr/p/pCeQRY)

bandersen
10-14-2014, 02:41 PM
Here it is stripped down.
https://farm4.staticflickr.com/3952/14909226643_11c5b9986a_c.jpg (https://flic.kr/p/oHtFDM)

I get about 0.1 ohms from the anode cap the the rectifier base, but I'll try replacing the lead anyway.

Flyback close up. The shiny goo around the HV lead is some RTV133 I applied to reduce the odds of it snapping off.
https://farm4.staticflickr.com/3940/15343430019_554872bc6d_c.jpg (https://flic.kr/p/pnR6bT)

HV rectifier area looks clean. I'll try using a solid state rectifier as suggested.
https://farm6.staticflickr.com/5615/15343620520_26f11ba314_c.jpg (https://flic.kr/p/pnS4Po)

bandersen
11-14-2014, 04:54 PM
I recently won a little assortment of vintage TV parts on ebay and it including this air core flyback. The part # is different but it sure looks like the one in the Capehart and it ohms out very close as well. Might as well give it a try.

https://farm8.staticflickr.com/7549/15788257081_d6fd9f62fe_z.jpg (https://flic.kr/p/q49WLZ)

kvflyer
11-15-2014, 08:56 AM
[QUOTE=bandersen;3119451]I recently won a little assortment of vintage TV parts on ebay and it including this air core flyback. The part # is different but it sure looks like the one in the Capehart and it ohms out very close as well. Might as well give it a try.

Bob, you certainly have nothing to loose and a lot to gain! Good on 'ya, Mate!

Kevin Kuehn
11-15-2014, 02:25 PM
I think I'd have me a peek under that electrical tape before applying power.

StellarTV
11-15-2014, 10:45 PM
Nothing wrong with using a temporary alligator clip jumper lead to lengthen that second anode wire. I've never had the HV arc through the insulation to the dag, chassis, or wherever else it may be contacting or draped, even with cheapies.

NoPegs
11-16-2014, 01:47 AM
I think I'd have me a peek under that electrical tape before applying power.

I'd be more scared to risk removing it absent any other justifiable reasons for investigating underneath. Obviously I'd spend a good few minutes going over the whole thing with all the bright bench lights on and with my mag-visor for signs of trouble.

Reece
11-16-2014, 09:45 AM
I don't like those wafer-type sockets, especially on high voltage. They can have secret interwafer problems. It would be a valuable adventure to change them to good new molded ones, even ceramic ones if you're paranoid like me.

bandersen
02-15-2015, 05:11 PM
I finally got back to working on this chassis :)

The ceramic HV cap on the damper tube has been replaced and a new HV anode lead installed.

https://farm8.staticflickr.com/7353/16357032077_c6b728d400_z.jpg (https://flic.kr/p/qVq4Lr)

https://farm8.staticflickr.com/7424/16523174162_b8dc8584b8_z.jpg (https://flic.kr/p/rb6A29)

I also installed a genuine Farnsworth 160AR CRT I stumbled across on craigslist.

It had no trace of any external coating but I did fine a ground spring on the chassis so it probably should have one. I went with a temporary one made from aluminum foil and tape :)
If I get it working, I'll coat it with some Slip Plate.
https://farm8.staticflickr.com/7446/15872228194_4b8c499118_c.jpg (https://flic.kr/p/qbzjsN)

https://farm9.staticflickr.com/8563/16494782465_f5967bb96c_z.jpg (https://flic.kr/p/r8A5a8)

https://farm8.staticflickr.com/7383/16307052678_3c3b0393a0_z.jpg (https://flic.kr/p/qQZUCE)

The old hardened tape was replaced wit some cloth tape.
https://farm8.staticflickr.com/7454/16327858488_3ef88ef048_z.jpg (https://flic.kr/p/qSQxtw)

While I had the brackets off, I finally found the chassis revision number - C-281.
https://farm9.staticflickr.com/8657/16329680707_33590f7a1b_z.jpg (https://flic.kr/p/qSZTa6)

TIme to fire it up again.
https://farm8.staticflickr.com/7401/16522507201_872baa6c19_c.jpg (https://flic.kr/p/rb3aKP)

bandersen
02-15-2015, 05:16 PM
HV is around 10kV. I'd rather see 11 or 12, but should be plenty to produce an image.

Sure enough after a lot of fiddling with the trap magnet, I got a raster.

I get occasional arcing. I think it's my temporary aluminum dag isn't making good ground contact.
https://farm8.staticflickr.com/7329/16338300267_1108fda29e_z.jpg (https://flic.kr/p/qTL4sc) https://farm8.staticflickr.com/7452/16522508451_bd570ee622_z.jpg (https://flic.kr/p/rb3b8n)

I'm gonna let it run a while and see if any problems crop up. If not, I'll give that CRT a proper coating :yes:
https://farm8.staticflickr.com/7407/16336751200_653f2d80c5_c.jpg (https://flic.kr/p/qTC7Y9)

NoPegs
02-15-2015, 06:14 PM
HV is around 10kV. I'd rather see 11 or 12, but should be plenty to produce an image.

Sooooooo, are we listing the HV lead as the culprit? :scratch2: Glad to see that you climbed right back up on this horse and got rewarded with some success. :thmbsp:

Electronic M
02-15-2015, 07:57 PM
TIme to fire it up again.
https://farm8.staticflickr.com/7401/16522507201_872baa6c19_c.jpg (https://flic.kr/p/rb3aKP)

Did you connect that HV lead before the power up, or was there a brief lightning show before you noticed? :D

bandersen
02-15-2015, 10:00 PM
Sooooooo, are we listing the HV lead as the culprit? :scratch2: Glad to see that you climbed right back up on this horse and got rewarded with some success. :thmbsp:

No, unfortunately replacing the HV lead had no effect. The HV is still about 20% low and for a while it dropped down to only 5 kV. Still not sure what the problem is. Also, I just discovered the sporadic arcing is actually inside the electron gun. Maybe there's a loose bit of metal ?

Did you connect that HV lead before the power up, or was there a brief lightning show before you noticed? :D

Yes, I did remember to connect it up :D

bandersen
02-18-2015, 03:40 PM
My Sencore CR70 has the meter right at the edge of bad in the HK short position. It typically arcs once or twice on power up the settles down.

I went through the centering and linearity adjustments and it's looking pretty good.
I'll install an isolation type CRT booster if I can find one :yes:
https://farm8.staticflickr.com/7408/15943777554_9fb98fa0ef_z.jpg (https://flic.kr/p/qhU2As)

Meanwhile, I decided to go ahead and coat it with Slip Plate. I'm quite happy with the results :)
https://farm8.staticflickr.com/7449/16385442080_3ed9b050ec_z.jpg (https://flic.kr/p/qXVF55) https://farm8.staticflickr.com/7350/16573035482_2aa548ac7e_z.jpg (https://flic.kr/p/rfv945)

bandersen
02-23-2015, 12:51 PM
Installed the recoated CRT and did all the ion trap, focus coil linearity etc adjustments again. It's playing well but still get the occasional arc in the CRT on power up. Will try an isolation type booster when it arrives in a couple days.

Meanwhile, the picture isn't quite as sharp as I think it could be so I'll try a video IF alignment. It used a staggered tuner IF and it's a an easy procedure. Feed an RF signal into the mixer tube shield an peak each coil to the specified frequency frequency.
https://farm8.staticflickr.com/7362/15976578324_8ba5f6d25d_z.jpg (https://flic.kr/p/qkN97Y) https://farm9.staticflickr.com/8573/16597562321_91f2889ff5_z.jpg (https://flic.kr/p/rhER2B)

https://farm9.staticflickr.com/8612/16439243648_1233a55b1b_c.jpg (https://flic.kr/p/r3Fqpj)

bandersen
03-07-2015, 09:06 PM
I gave up on the alignment once I realized all the slugs were glue in place with something like loctite! Meanwhile I got a nice shading and balance knob for a forum member :) That just leaves the "Capehart" control name plate.

https://farm9.staticflickr.com/8632/16550277209_eb2ee6d176_z.jpg (https://flic.kr/p/rduuP4)

I also received a link to the video about gold or silver plating plastic parts. Basically you apply a special conductive paint then use conventional electroplating solutions. http://youtu.be/czTjYlsct_k

Cool technique but all the supplies are a little expensive for just plating a few knobs.


Meanwhile, the owner of this set scored a Capehart 323 off ebay for $50 :) This one is a bit earlier with a metal cone 16GP4 picture tube.
I expect I'll be restoring it for him someday too.
https://farm8.staticflickr.com/7343/16382257035_55080438b5_z.jpg (https://flic.kr/p/qXDmgv) https://farm9.staticflickr.com/8651/16196352497_270a5871ea_z.jpg (https://flic.kr/p/qFdxjR) https://farm8.staticflickr.com/7389/16382257545_e8c0c6a5b7_z.jpg (https://flic.kr/p/qXDmqi)

The missing nameplate was hiding in the bottom of the cabinet along with the owners manual :D Looks like silverfish got to it and it's falling apart but I hope it can still be scanned.
Perhaps a mold can be made from this nameplate and dups made ?
https://farm8.staticflickr.com/7405/16380500081_3d77bd42d1_z.jpg (https://flic.kr/p/qXukZc) https://farm8.staticflickr.com/7288/16380499731_706e77ea87_z.jpg (https://flic.kr/p/qXukTa)

bandersen
02-23-2018, 11:48 AM
Hey guys. I recently hear from the owner that he had the cabinet full refinished, installed new grille cloth, painted the knonbs and even scored a control cover door on ebay :)

Here are some photos. Hard to believe it's the same set.

https://farm5.staticflickr.com/4602/25571169867_652bd8d913_c.jpg (https://flic.kr/p/EXCVV6)

https://farm5.staticflickr.com/4765/25571169917_bd88d73acf_c.jpg (https://flic.kr/p/EXCVVX)

https://farm5.staticflickr.com/4705/26571393378_b27a0439dc_c.jpg (https://flic.kr/p/Gu2kw3)

https://farm5.staticflickr.com/4764/26571262378_c3e1e72bbf_c.jpg (https://flic.kr/p/Gu1Ezq)

compucat
02-23-2018, 06:50 PM
It looks like the hold controls are under that screw mounted plate. Sets of that vintage often need touching up of the sync controls. I am surprised they would design it like that unless they used very stable sync circuits. What a beautiful set. I sure miss the days of stylish TVs.