[willydcamaro]

Hi Rich, Very nice collection ! The 47 1230 is not for the weak of heart. What a S.O.B. to work on. Good luck with your Seeburg.. I always loved those old juke boxes.

[Marsupial]

... I have never really received a sw station on on my 47 1230 either....you can hear the usual static between stations but not a station to come in. My fm does work though.

That is also what I get on my 47-1230

I don't know it there's a sw hole where I am or if the sw circuit is off so I just stopped trying.

[Greggshere]

Guys not to sound stupid, but what is the big long brown component on the right (6th from the left), next to the 6800 ohm resistor? It appears to be some sort of huge resistor with the markings on it, but what number in the schematic references it? Mine measures open on my meter whatever it is. I'm trying to determine if it is bad and needs replaced.
   

[Radioroslyn]

Not a resistor but a capacitor. Believe it's C-402.

[Greggshere]

Thank you Terry!

[criageek]

Ok...I FINALLY decided to get back to my 47-1230.  In the past 18 months or so I've learned a lot about these old radios and re-learned quite a bit of tube knowledge that I had forgotten over the years.  There is still plenty to learn but I felt confident that I could proceed with troubleshooting the 47-1230.

Philco's documentation has a GREAT troubleshooting section.  By following it I isolated the problem area and then by doing some staring and comparing I found that I had connected a capacitor to the wrong terminal of the band switch.  Once I corrected that the AM section came to life!  I did a complete alignment on the AM section and it works well.  But...I still don't have any FM so I'm looking for help.

I followed the procedure on this page
   
and found that step 3 fails (of course steps 1 and 2 fail as well) which indicates that the FM oscillator is not running.  I get about -0.1v.  When doing this test on the AM section I get a little more than -4v.  I've tested the 7F8 tube and it's good.  L406 is just a small coil of copper wire (maybe 5 or 6 turns, about 3/8" diameter) attached to the tuning condenser and looks good.  I believe the band switch is good.  So I'm looking for advice...what should I do to proceed?  Here is the schematic of the front end - L406 is at the bottom

   

By the way, did you get your FM section working willydcamaro?

Thanks,
Rich

[willydcamaro]

No, As a matter of fact I just started working on mine again after a well needed break. I'll let you know of any progress though. Bill

[willydcamaro]

Hi Rich, might you have a good picture of the underside of the chassis. I'm starting from scratch. Thank you,Bill

[criageek]

Hi Bill - I started this radio over a year and a half ago and it was my first attempt at a restoration.  Since then I've developed a much better documentation process, but I do have quite a few pictures.  This one shows the location of the capacitors on the main chassis:
   

The designations match those on the Sams schematic.  The yellow lines point to connections for each cap (I see I missed one end of C19 and both ends of C25) and the red lines (where used) point to the body of the capacitor.  In most cases the designation is directly over the capacitor body.  I have quite a few detail pictures of the underside of the chassis...let me know if you need anything in particular.

Rich

[willydcamaro]

Dear Rich, Thank you so much. If you have pictures of the tuner section that would really help too. Again, Thank you. This will really help !!!!

[criageek]

Here you go Bill!  Again, I have many more pictures of specific areas of the tuner section from different angles so let me know if you need anything specific  ;)

Rich

[criageek]

By they way, for reference to anyone that can help me out with my FM problem, L406 is circled in blue and the tuning cap section for FM (C405) is circled (ovaled?) in red.  Just 2 plates on the stator and one on the rotor.  C405C...the trimmer for the FM tuning cap...is the small (maybe 1/4" - 3/8" diameter) circular device at the right side of the red oval.

I still haven't been able to make FM work.  I've checked the relevant bandswitch connections, and I checked R410 and R411 (the schematic shows R410 as 33k, but mine has a 27k.  The Philco documentation has a note that says it was changed to 27k at a certain point).  It's very difficult to check the tuning cap sections since they are across L406 which is less than 1 ohm and is tied to ground at one end, but visually I see no problems.  Any ideas?
 
Thanks

[Radioroslyn]

Hi Rich
To continue the troubleshoot on the FM osc section I would use a counter to read the oscillator frequency. That would give you the definitive answer.
Trying to measure the dc voltage on the control grid of the osc tube is going to be marginal at best. The voltmeter more than likely is going to cause the osc to shutdown when connected. It's a fairly critical circuit @ 100mc or so @ 1mc not so much. Wouldn't necessarily believe the tube tester as the tube might work ok at bc and sw frequencies but not fm frequencies. I usually try a few spares just to be sure it's not an anomaly w/the tube in question

If you have a 100mc scope w/a low capacitance probe you can have a look at pin 5 of the 7F8. this is where the osc signal is coupled thur C-414 to the rf side of the mixer.

Do check the dc voltages @ the plate and cathode. Should be within 5 or 10% of the list voltage. Low plate voltage more than likely is caused by a resistor in the hv leg have gone high in value or a leaky cap. Too high of a reading on the cathode would indicate an open osc coil or a switching issue, dirty contacts or miss wired.

Happy Hunting!

[willydcamaro]

Thank you very much! I just got a Sam,s for this. I'm in the process of enlarging it. I will keep in touch, Bill

[criageek]

Thanks for the input Terry - I appreciate it.  Based on this I decided to take a step back.  I recalled that when I tried to complete the FM tests on this page:

   
   
step 2 actually failed.  I've attached a different copy of the schematic so you can see the test points called out in the tests.  Test point A is the control grid of the 7R7 and test point B is the plate of the 6BA6.  I was able to get a signal through but it wasn't the same signal strength as in step 1.  In fact it was a fair amount lower.  I guess I chose to ignore it since I did get a signal through, but I think this may be where the problem is.  So I tried to do an alignment again and this time I noticed that adjusting C301A has virtually no effect.  If I go back from there and inject into Z300 I can adjust C300A, C300B and C301B and all react as you would expect...I can peak up the output.  But C301A has no affect.  I think I need to remove Z301 and check C301A...perhaps the mica has failed.  Thoughts?

By the way, I did check the plate voltage on the 7F8 and I got about 110 for AM and about 120 for FM.  The schematic says I should have 95 and 105, but I measured with a Fluke 77 so I would think that's ok.  And I don't have a 100mc scope...I have a Tektronix 2215, so just 60mc.

Thanks!

Rich