Dial Lamp Holder Repair.

Go down

Dial Lamp Holder Repair.

Post by NashvilleRad on Tue Feb 12, 2013 10:23 am

This picture is of the 'venerable No. 47' dial lamp and holder from a Sonora RCU-208. Before I started troubleshooting the radio, I removed it since both leads were in visible contact with the chassis where the wires are frayed.

I suspect this condition has damaged the 35Z5GT heater supply, since the lamp is in parallel with the heater and heater tap (Pins 2 & 3, respectively) and the heater string is not getting any voltage.

I was able to test the bulb - it works ... but I don't have a spare 35Z5GT to test this out, but regardless, I know the leads cannot remain in this condition.

Does anyone have a method or 'trick' remove the metal holder from inside the plastic housing from these types of dial lamp holders - so I can replace the wires?



The picture below is a little small. The voltage chart is as follows:

Pin 1: Read 0 V ..............Required 0 V
Pin 2: Read 120 VAC........Required 117 VAC
Pin 3: Read 120 VAC........Required 113 VAC
Pin 4: Read 120 VAC........Required 83 VAC
Pin 5: Read 120 VAC........Required 113 VAC
Pin 6: Read 0 V...............Required 115 VDC
Pin 7: Read 120 VAC........Required 87 VAC
Pin 8: Read 0 V...............Required 117 VAC


NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by mr_ed01 on Tue Feb 12, 2013 1:23 pm

if pins 2, 3, and 7 of the 35Z5 all read 120V, look for an open filament on one of the remaining tubes or open R8

You can replace the 35L6 with a 50L6 and eliminate R8

mr_ed01
Member
Member

Number of posts : 98
Age : 74
Registration date : 2012-03-16

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Tue Feb 12, 2013 4:40 pm

Thanks for the reply mr_ed01. I expanded the picture for clarity

The R8 you mention (As the Rider's manual denotes) which is the circle-40 (33 ohm) just before the string is good. Actually, both of the 33 ohm resistors, and amazingly the circle-9 (.05 uF) is good ... but not surprisingly, the 40 uF electrolytics read very low (around 10uF) - all of the electrolytics out of spec (of course).

I have not had a chance to check the rest of the filament string, as I wanted to address the dial light issue, which as I understand it, has a history of quickly degrading/blowing the rectifier tubes if they're failing/failed ... and I haven't been able to find a spare 35Z5GT laying around.

In any event, I have not seen a little bayonet or other clasp that holds the metal insert sleeve in that plastic dial lamp holder - and if there's someone that can break that plastic part without even trying - that's me.

Anyway, I may have some time to troubleshoot later - I will definitely have to get the power sorted out since it's a paper weight at the moment. Thanks for the help.


NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Tue Feb 12, 2013 7:33 pm

Finally had a chance to test the rest of the filament string - the 120 stopped at the other side of the 12SA7.

Now I just need another 12SA7 to continue on (hopefully) - plus rebuilding the dial lamp wiring.

NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Sun Feb 17, 2013 5:20 pm

Indeed mr_ed01, testing down the filament line to the 12SA7 did the trick -- the new one from Tube Depot restored power ... albeit, I'll have to start going through the caps for sure to get the radio back in order.

And sorry everyone for what may be posting too much information - most people, including myself, seem to always first ask for pictures and readings, so I aim to please - makes visualizing the setup so much easier.

NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by jtauser on Fri Feb 22, 2013 3:11 am

I just had this problem with a Silvertone that had an isolated lamp holder like this. The insulation failed like yours and it took out the filament on the 35Z5 when it shorted to the chassis.

You can't get it apart - I tried. My solution was to strip all the insulation off both sides and replace it with a long length of 1/16" heatshrink tubing jammed all the way into the holder (don't forget to shrink it!). There is enough room inside the base of the holder to allow the tubing to provide adequate insulation.

BTW - that's the wrong bulb. A #47 is tubular, not spherical.

Joe T.
avatar
jtauser
Member
Member

Number of posts : 19
Registration date : 2013-02-04

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Tue Feb 26, 2013 3:30 pm

Joe T., That is the incorrect bulb. From what I've read, this particular wiring arrangement was problematic, and likely added to the problems on this set.

I started down the heat-shrink route, but figured that somebody had to put that bulb holder in, so surely it can come out.

So on this particular lamp assembly, I was able to slide the metal shield/bulb socket out of the top of the lamp assembly to expose the spring and contact for the + and -

Then soldered new wires on -- and put it back into the housing without breaking it.

This is the one time I didn't even think to take pictures. I have a Silvertone I'm getting ready to work on, so I'll keep you updated.

NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Tue Feb 26, 2013 9:50 pm

Check this link out:

Notes on Dial Lamps: http://www.kevinchant.com/uploads/7/1/0/8/7108231/chrsdiallamps.pdf

Here's a picture of the metal shield/sleeve:



Here's the finished product (I'm not taking it back apart!):



Here's the bulb - a 'TS51' ... a '51' is covered in those notes at the first link:



Last edited by NashvilleRad on Wed Feb 27, 2013 8:56 pm; edited 1 time in total

NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by jtauser on Wed Feb 27, 2013 12:22 am

Glad you were able to repair it properly. Nice pictures - they always add to the quality of the post.

My Silvertone was not a socket inserted into plastic housing like that. It was metal housing with a with a crimp holding the flat phonelic tube base in place. When I tried prying the base out I got the very strong impression that I would destroy the phonelic getting it apart.

Very interesting article on bulbs. I'll save that one to my archive. I have seen a repair note in one of my Rider's describing adding a 270 ohm resistor in parallel with the bulb to carry some current in case the bulb burned out. This would, of course, make the bulb dimmer and I don't know what the final results look like with a working bulb. I'll have to try this and take a picture.


Joe T.
avatar
jtauser
Member
Member

Number of posts : 19
Registration date : 2013-02-04

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by Ben Delk on Wed Feb 27, 2013 9:27 am

Good info and nice job on the lamp holder. I just purchased a
Sonora RCU-208. I haven't had a chance to check it olt, just a quick once over but the lamp appears to have been rewired and it is working. Sadly the dial glass is broken and I have no idea where to find one. I may have to get creative.

ben


Last edited by Ben Delk on Wed Feb 27, 2013 6:30 pm; edited 1 time in total
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by jerryhawthorne on Wed Feb 27, 2013 6:16 pm

Ben, not familiar with the radio but is the glass round? If so, I go to our local antique clock shop and he scans his reference material and has always found the right size. If he does not have the right size, orders it for me. Cheap.
Jerry

jerryhawthorne
Member
Member

Number of posts : 730
Age : 73
Registration date : 2012-10-13

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by Dr. Radio on Wed Feb 27, 2013 6:35 pm

Unfortunately it looks like Ben's radio uses a rather unique, ornate, dial glass. I know there are people out there that are able to scan the original (assuming you can piece it together enough for a good rendering) and then do some custom silkscreen work.

Ben, how do you find these cool radios? Cool
avatar
Dr. Radio
Member
Member

Number of posts : 937
Age : 37
Registration date : 2012-09-17

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by Ben Delk on Wed Feb 27, 2013 6:55 pm

DR. Radio wrote:
Ben, how do you find these cool radios?

Craig's List, auctions, estate sales, ebay, dumpster diving.....just where ever I can. Last month I had someone give me a Philco 37-610 plus $10 to haul it off. I'm not sure who got the best of that deal. Most of the veneer is off, the left side of the cabinet frame has been eaten by carpenter ants. Looks like I'll have a few challenges with the frame but I have wood shop so I think I can reproduce the parts. Other than that all the elecetronics, knobs, speaker , etc. are all there. Not sure if it is worth the time and effort but at the very worst the parts are worth something to someone.
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by Ben Delk on Wed Feb 27, 2013 7:02 pm

Jerry wrote:
Ben, not familiar with the radio but is the glass round?

The dial cover is glass. The left and right sides of the glass have about a 1/4" curved edge that turn toward the cabinet. I suspect a replacement will be near impossible to find. At worst I'll send it to Palmquist and have him make me a plastic one, then use photo shop to scan the old glass pieces in and make a water slide decal to apply to the plastic.

avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Wed Feb 27, 2013 9:06 pm

Here are a few more pictures ...

Overall picture - fortunately the dial cover is intact:



All screws and small parts I press into the blue not-so-sticky-but-sticky-enough masking tape and stored in Ziploc bags:



Knobs are different than Ben's - I suspect those are replacements ... I only have two of these:



NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Thu Feb 28, 2013 12:11 pm

Ben - something else I could do is figure out a way to get a to-scale 'clean' scan of the dial cover I have and then clean it up in Paint Shop Pro or something and send you the image to use for a decal.

NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by Ben Delk on Thu Feb 28, 2013 12:21 pm

N_Rad.....that would be great if you can and don't mind. I would certainly appreciate it. You can PM or email me the dtails if you'd like.

Blessings,
Ben
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Fri Mar 01, 2013 10:46 am

Ben,

I'll be on the road for work (as usual) but will get the cover by my office as soon as I can - we have a pretty good Canon scanner there.

NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by Ben Delk on Fri Mar 01, 2013 11:29 am

N_Rad.....no rush, just when ever you get a chance.

Thanks,
Ben
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Sat Mar 02, 2013 4:56 pm

Ben, et. al.,

Here's are pictures of the recap - please note the electrolytics are temporarily wired and grounded for testing and will be placed and soldered accordingly.

The only problem(s) I have now is the volume only works when turned all the way up - and then it's at full volume only ... and there's a slight hum that's probably related.

Be aware there are 2 'mica' caps - one is the standard brown mica square with colored dots (0.0001) and the other was a wax paper (0.0005 1,000V).

I replaced the 0.0005 .... the 0.0001, that is termed the 'IF Bypass Diode' is out of range and just happens to be grounded through the ON/OFF/Volume switch.





Last edited by NashvilleRad on Sat Mar 02, 2013 5:47 pm; edited 1 time in total

NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by Ben Delk on Sat Mar 02, 2013 5:09 pm

Thanks for the update N_Rad. My RCU 208 is my next project. Need a replacement glass and some knobs but the rest should be pretty straight forward.
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by Bill Cahill on Sat Mar 02, 2013 7:37 pm

Is that a short I see between the resistor, and, the center tap??
Bill Cahill

_________________
Please also join us here;  http://videokarma.org/index.php
avatar
Bill Cahill
Admin
Admin

Number of posts : 4577
Age : 67
Registration date : 2008-03-12

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by NashvilleRad on Sat Mar 02, 2013 9:51 pm

Hi Bill,

No short ... it's hard to see, but those are the two electrolytic filter caps grounded together - the ground wire is black and hard to see, but it's there.

I didn't wire/solder everything in place until I checked it ... other problem though, as noted in the forum.

NashvilleRad
Member
Member

Number of posts : 93
Age : 52
Registration date : 2012-01-05

Back to top Go down

Re: Dial Lamp Holder Repair.

Post by Sponsored content


Sponsored content


Back to top Go down

Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum