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My 47-1230 Restoration - Printable Version

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RE: My 47-1230 Restoration - criageek - 01-10-2019

I'm pretty well convinced that my radio is wired correctly.  I've checked every single connection...every tube socket, every terminal strip, every function switch terminal.  Everything checks out, so I'm hunting for a bad component.  I've replaced every paper and electrolytic cap, and I've replaced nearly every resistor on the main chassis.  Since the tuner sub-chassis is difficult to get I didn't previously check the resistors or mica caps on it.  But now I have checked the resistors and found 3 to be way out of tolerance and replaced them.  So now I am down to tubes, coils, and mica caps on the tuner sub-chassis.  I have all new tubes on order for the everything before the audio stage.  I've also identified all of the caps in the front end that I think could cause an FM problem if they were leaky, open, or otherwise bad.  Most of these would be really difficult to replace but if it's my last hope I'll go for it.  Since AM is working, I'm thinking maybe one of these caps is ok at the lower AM frequencies but fails at the higher FM frequencies.

C64 - 250pF
C62 - 750pF
C60 - 100pF
C63 - 250pF
C70 - 33pF
C71 - 1500pF
C75 - 100pF
C73 - 1500pF
C72 - 1500pF

C70 is actually a Micamold cap.  I've read before that Micamolds are actually paper caps...is that true?  If so I'll replace it for sure.

What are your thoughts on this plan?  I'm running out of ideas so I hope someone can give me some guidance.

Thanks,
Rich

RE: My 47-1230 Restoration - criageek - 01-12-2019

How cool is this?!!??

https://drive.google.com/file/d/1X14n3gjQ5oyuUFA0HxM4Uaa6f384xHBR/view?usp=sharing

That's with a new needle in the original dynamic cartridge.  Once I connected a wire from the shield on the tone arm wire to the radio chassis most of the hum was eliminated and it sounds great!

Now, other than a couple of niggly little things, I am truly down to making the FM work and this thing will be done.  I received my SDR radio and I'm trying to get acquainted with it so I can poke around to see if the FM local oscillator is running.

Rich

RE: My 47-1230 Restoration - Greggshere - 01-12-2019

That is very cool Rich! My 47-1230 has been on a back burner until I gain enough experience to jump into it again. My phonograph portion is completely restored and just waiting for a decent radio to go with it. Maybe some day I'll get to hear mine play like that.?

RE: My 47-1230 Restoration - criageek - 01-15-2019

You'll get there Gregg!

Here's another new creation from the 3d printer.  The connector for the tonearm wires to plug into the impedance matching transformer was gone, so I designed and printed one.  I stole the contacts from an old computer power supply connector.

Rich

D10A Record Changer Questions - criageek - 01-15-2019

I have a couple of questions about the D10A record changer in my 47-1230.

1)  Motor mounts.  I've seen several different YouTube videos of people working on the D10 or D10A record changer and their motor mounts are exactly the same as mine.  I am certain that I have the original grommets, and they are the same as those in the videos.  In each case, the sleeve inside the grommet is taller than the grommet.  And in each video I've seen they have inserted grommets or washers to take up the extra space.  Initially I did the same...I printed some thick washers on my 3d printer using some flexible filament:

   

But after much thought I decided that the correct setup is to leave this space, so the motor is allowed to 'float'.  The result looks like this:

   

If you have worked on one of these this should be familiar to you.  I really believe this is the correct setup and intend to leave it this way.  But if someone can convince me that the first way is correct it's easy enough to change.

2)  I installed a dropping resistor in my radio which results in an AC input voltage of about 114v.  The result is that the record player runs a little slow...I think it's about 75 rpm.  I assume there is only one way to change this (other than removing the dropping resistor, which I will not do)...a smaller idler.  I'm experimenting with printing one to see if I can make it work reliably, but if that doesn't work, will I notice the difference between 78rpm and 75rpm?

3)  Record changer mounting springs.  How tight should the springs be when the record changer is mounted in the cabinet?  I'm thinking I'll tighten them enough to take up the slack, then give them another turn or two.  Sound about right?

   

I debated with myself about the correct way to post these questions...in one thread as I did, or in 3 separate threads.  What's the 'approved' way of doing this?

Thanks!

Rich

RE: My 47-1230 Restoration - Ron Ramirez - 01-15-2019

(01-15-2019, 08:47 PM)criageek Wrote:  I debated with myself about the correct way to post these questions...in one thread as I did, or in 3 separate threads.  What's the 'approved' way of doing this?

The proper and "approved" way is to keep it all in a single thread. It is specified as such in the Phorum Rules.

http://philcoradio.com/phorum/showthread.php?tid=4586

The pertinent section of the Rules:

Quote:II. Multiple threads on the same subject not allowed.

When you start a thread, please keep the discussion within the same thread.

Example: "Philco 90 broken"

After you've started that thread, please do not start another thread on "Philco 90 bad resistor" if it is the same Philco 90 being discussed in the original thread. Give others a chance to respond to your questions rather than asking them again in a new thread - please be patient.

These sort of threads will be immediately deleted, to keep clutter to a minimum.

Please cooperate with me in keeping one thread in the same place rather than scattering it around.

All three of your threads have been merged into this one.

RE: My 47-1230 Restoration - Greggshere - 01-16-2019

Rich my player  motor "floats" as shown in the second photo. The spring's  when I took mine apart were just as you mentioned, play removed and just tensioner a couple of turns. As far as being able to tell that 3 rpm difference, I probably wouldn't,  unless it was an artist and song I really knew well. I doubt the average person could tell, but just try it and see what you think.  Icon_smile

RE: My 47-1230 Restoration - mikethedruid - 01-16-2019

I believe this is an AC "synchronous" motor, no brushes. I don't think the speed it is turning is going to be affected much by a few volts low on the AC input. It is more likely to be a matter of dried grease in the bearings. See if you can disassemble to motor to be able to clean the bearings in some kerosene or mineral spirits, then lightly re-grease them with lithium grease, and re-assemble.

RE: My 47-1230 Restoration - criageek - 01-16-2019

Thanks mikethedruid!  The motor has been completely disassembled, cleaned and lubricated.  When I plug the record changer into the variac and crank it up to about 124v I can get the speed right on 78rpm.

I did some calculations and printed a new idler that I thought would get me to 78, but it only went about half way, between 76 and 77, so I'm printing another one this morning.

Rich

RE: My 47-1230 Restoration - Mutantmoose - 01-16-2019

The idler size should make no difference, as the idler is just transferring the movement of the motor to the turntable without any gearing. I'd clean the underside of the turntable again, as well as the idler wheel, and then check that the spring is holding the idler in place correctly.

RE: My 47-1230 Restoration - criageek - 01-16-2019

Thanks mutantmoose. I had a reply all written up but decided to rethink things and do some more math, and I think you are right...the size of the idler should make no difference. I was just about ready to resign myself to the fact that it was just going to have to run slow, but decided to take the motor out again and inspect it again. It turns out, if I oiled it I didn't give it very much. So I soaked the felts around the bushings really well. The bushings are allowed to 'swivel' in their housings, so I exercised those to make sure they are free to move. When I reassembled it, I left the nuts a little loose and applied power to allow the armature to sort of settle in and find a sweet spot. I then tightened everything and reinstalled it. What do you know...now it runs a little fast! Almost 79 rpm. I'm ready to call the record changer complete, so in my next post I'll be making another plea for help with the FM.

Thanks to all for the help!

Rich

RE: My 47-1230 Restoration - mikethedruid - 01-16-2019

Congratulations! Glad you got it all sorted out. I look forward to following your continuing progress.

RE: My 47-1230 Restoration - criageek - 01-16-2019

Thanks for your help mikethedruid.  I'm glad I paid attention to your advice and revisited the bushings.

Now, I'm back to the FM problem.  I received my new tubes today and they made no difference, so I'm back to troubleshooting.  There are several symptoms, but rather than list them all and possibly cloudy the situation, I want to go back to these tests:

   

And here is the associated part of the schematic (I hope it's readable...if not I can post a larger pdf on my Google Drive):

   

When I preform step 2, I receive a significantly smaller output signal than I received at step 1.  I looked at it on the scope and at step 1 I had 500mv peak-to-peak, at step 2 I had 150mv peak-to-peak.  I believe I have Z301 tweaked up properly.  I've had Z301 apart and cleaned the trimmers and replaced C301C (after the fact I figured out that this cap was only in the circuit in AM mode).  Everything in the can looks good and the dc resistance of the coils look good.  I've also replaced C308, C309, and C310.

So, can someone help me figure out why I'm losing signal through this can?

Thanks!

Rich

RE: My 47-1230 Restoration - criageek - 01-31-2019

I finally made a little progress toward solving my FM problem, but still no FM.  With some troubleshooting help from Radioroslyn (thanks Terry!) I decided I probably had a bad 2nd IF can so I posted ads here and over at antiqueradios.com looking for a replacement.  I found a very generous forum member over there that sent me all 3 cans from his spare 47-1230 chassis.  And I'm glad he did.  The replacement 2nd IF made no difference.  So I removed the 3rd IF and tacked in the replacement and then tried the FM alignment.  In the procedure they have you monitor the voltage across an electrolytic cap on one of the diodes in the 7X7 detector and keep it at around -10v.  Previously I was never able to get much over -6v, but with this replacement IF can I have to constantly adjust the output of my generator to keep it at about -10v.  So, a major step forward!  And it's one busy little transformer:

   

But, still no FM.  I'm pretty certain the oscillator is not running.  In the test procedure there is a test to determine if it's running and it fails.  So I'm looking for ideas.  Maybe someone has their 47-1230 on the bench and can show me a picture of their FM oscillator coil so I can compare to mine to see if it's spread similarly.  I hate to start compressing or expanding the coil to see if I can make it resonate but that might be what I have to do.  Here is what mine looks like:

   

Thanks for any help or suggestions!

Rich

RE: My 47-1230 Restoration - Radioroslyn - 01-31-2019

I have a sensitive frequency counter so I would make a loop around the oscillator tube and see if it registers any frequency. I'm not sure if the osc runs above or below the IF frequency but you be able to hear it in another fm set if tuned to the proper frequency.