[Mondial]

Warren, it seems that what you are trying to say is that the tone modulation of the signal is low.

If you can read the signal frequency of the carrier with your counter then you have plenty of RF output. What may be the problem is that the audio tone modulation is low, which is why you are hearing only a very low level tone from the radio.

If you had an oscilloscope, you could check very easily. Do you have the audio output or modulation level turned all the way up when checking?

[morzh]

If your gen has a separate audio output you can measure right from it. It should be in units of volts, or whatever the manual says.

Or as Mondial suggested use a scope to see the unmodulated frequency and then turn the modulation all the way up and see whether and how much it has changed.

[Warren]

I do have an oscilloscope, a techtronics dual trace 200 mhz. If I remember right I didnt see a difference, but since I do hear a tone when the SG is hooked straight to the radio ant input without the radio antenna hooked up the SG must be putting something out. I will give it a try again. I will check the voltage and try the oscilloscope to see if there is a difference with and with out modulation. It all sounds simple but so far I haven't been able to tell what is going on for sure.. I am going to try this weekend I will let you all know what happens for me. I really appreciate everyones help.

[morzh]

To be honest if you own one of those cheap entry level oscillators (like I do) the RF wave shape is so dismal it is hard to see the difference the modulation makes. You will see some difference though. But not necessarily your classic "bean pod" shape.

[Warren]

Hi Everyone, I checked the voltage from the Audio output of my SG, it was 1.5v AC. sounds like should be sufficient. Like you said Morzh, the scope didn't show much but I found if I hook up the ground on the other end of my loop antenna from the SG, BAM.... I get a tone. I heard you didn't need to do that but I guess with this one you do. So looks like I am making some progress.

[Warren]

Looks like I also had a bad output transformer, causing the static. One side had about 155 ohms ,the other was about 5 ohms... I had another so I changed it and now it has ALOT less static. Maybe it will also let me hear the tone better now and I can align it easier. The only thing, the other one was apprx. 150 ohm on each side but the schematic says 310 on one side and 280 on the other. Should I try to find another or is this good? Would this be a reason I don't seem to get all the stations I should? I still seem to get a little hum.. don't know if its from not pulling in the station good (antenna?). I do receive a some stations well with no hum or static now.

[morzh]

Not sure how bad output transformer causes static, but it is good you found it. It probably has one half that is baked and so it is 1) might be bringing down the power supply voltage, 2) killing its tube in the process.
Make sure your output PP transformer is close to the one you had before, otherwise though it will probably work without damaging anything you will not get the proper sound/power/quality levels.

[Warren]

Thanks Morzh, actually it is the same exact transformer. I have another chassis I took it from. Only thing I wonder about is it's resistance isnt what the schematic calls for either, it is a little low. Somewhere in the 150 to 170 ohm range when the schematic says it will be 310 and 280 ohms. Do you think that will be a problem? The reason it became suspect is I noticed when I moved one wire on it i would get more/less static depending on how I moved it, then I found its resistance was way low on one side. also, i do still get some hum even when a staion is tuned in, Have any idea's why this might be? Thanks for any help.

[morzh]

Warren

It's anyone'os guess why moving that wire did this. As for the other transformer, it is possible there was another mod that used a different part number, or if it was installed on a speaker - it used another one.

DC resistance is not that important and in this case (difference in a hunder Ohm) is not important at all.
What is important at this point is the turns ratio which, if this is the same chassis working with the same voice coil (provided the transformer is original)- it has to be the same or close.
And the core size - has to be such that it provides for the same power (in this case it is the same magnetic flux) without saturation.

[Warren]

The chasis and speaker from the other one is the same, I can use either speaker, they both work. I bought another 47-1230 a long time ago to use for parts in this radio if needed, it is exactly the same as the one i am rebuilding. I was lucky to find the same one, the circuit is the same, uses the same speaker, same phonograph, wired the same... the only difference I have seen is they used some bakelite blocks to house a couple capacitors that mine just used caps connected to lugs. The transformer is the same so if the ohm's difference isnt an issue than i should be all set. Thanks.... any idea's about getting rid of the hum when tuning in stations? is that usually a cap, or coil or....? I also still dont seem to be able to pull in all the stations I should be able to.

[morzh]

Warren

(BTW the transforme might simply use a thicker gauge wire for the primary, hence the difference. It does not affect the operation and if anything will add robustness as the primary is usually the one to go).

Tuned hum...we discussed it many times here.
It depends on what kind it is but often times it is a pick up from your home electrical wiring.
I do have it too, and it is the same in all radios and it goes away when a lighting fixture in the lobby is turned on.

You could try topo see if any breakers turned off or loads turned on affect it.
If you have the same hum in other radios of course; if it is unique, this might be different.

[Warren]

Well, My other radios do not have a hum in them. I get this hum whether I am tuning in a station or not, on a real strong stations it doesn't seem to be as bad.... it also seems to be only on AM not FM. Don't know if this has anything to do with it or not but I don't seem to be able to pull in any stations on SW either. I was hoping to get some ideas about where to look, what might cause it, etc. I guess right now I will check any resistors I did not replace, I actually replaced most of them but there are a few that seemed good that I did not replace, I will check them again. I spose I should check the SW coil again also in case I missed it to make sure it isnt why I dont get anything there. Thanks again for all the help I have received, and im sure will receive in the future.

[victor3d]

hi....just came across your post.....Not sure if you have resolved your issues with your 47 1230 or not. If you search and read my posts on the 1230 you will see that I have been working on one for the last year with many difficulties.....after much labor I discovered that many things in my radio did not match the schematic, the parts list or the testing diagrams.....some of this was explained by previous people making changes, mistakes etc....and part I think was due errors, changes between the service manual and the radio. I found this a difficult radio to work on and most who have tackled it I think agree. I did learn a lot though.

first, your am reception....I found that I get completely different reception depending on how I connect the antenna. There are three connectors as you face the back of the chassis. The white wire should be connected to the left screw This is the same screw that you would connect your signal generator to. The black or ground wire can either be connected to the second or third screw. I found that in my area the second screw works best...(I live in nyc). I think that the second screw is for local reception and the third is for distance although there is nothing in the manual that I could find.

Second, alignment.....or I should say AM alignment. I discovered the same thing that you refer to, that I had to connect the signal gernerator directly to the first and second screws of the antenna. The loop or induction testing outlined in the alignment procedures DID NOT work for me either. Once again, I am not sure exactly why. I just kept the signal generator connected directly to the antenna and completed the last part of the test.....and the am reception was much improved. I could not get the loop induction method to work for the SW or FM either and since I did not have a scope I just relied on my ears and now get good SW and FM reception as well. Maybe someone out there who is smarter then me can tell me why we could not get the radio to receive the generator signal using induction....Hope that this helps....this radio can play incredibly well when working properly. Many including myself use the RCA jack to plug an iPod into the phono section.....I have heard of different ways to make the attachment on the board but found that the simplest was is to get an RCA female to iPod STEREO adaptor from radio shack for $3, attach this adaptor to your iPod or iPhone and then run an RCA wire with two male ends from the adaptor/iPod to the RCA jack on the radio.....sounds more complicated than it is but only requires this little adaptor and an RCA cable that you have laying around your house.....hope that some of this is helpful.

[victor3d]

just read some more of the posts and a few more comments....NONE of the measurements suggested in the manual match my radio and yet it plays perfectly.....and I have changed, checked and rechecked every wire, cap and resistor in the radio and still get different readings.....I also noticed that the voltage reading on the schematic seem to differ from those outlined in the trouble shooting for section one. So after almost loosing my mind....I have the radio working great but no explanations. I looked for service bulletins and thought that perhaps there were some modifications made by thecompany to later or earlier chassis in the production runs.... I found nothing to explain it...Once again someone out there may have an explanation. This was my first Philco and found it extremely quirky with all of the bakelite blocks, three lead capacitors (be sure to check the one in the 1230 for the FM section) and variations or differences in the service manual.

Second....I still have undesireable hum in my radio. I rerouted all of the wires as close as possible to the underside of the radio as this is a known cause for hum and am using slightly larger value filter caps. Still some hum......Here is what I think at this point.....this chassis is so crowded that it is suseptable to hum. The power cord usually attached to components where it enters the chassis is routed accross the chasis from back to the front and under the transformer......to the one bakelite block. By the way, the two .01 caps in this block must be changed out with "safety" caps as they are directly attached to the AC. Anyway, as one poster mentioned the hum may be caused by the environment and this radio is more suseptable than most to picking up AC noise from lights, building structure etc. I do notice that when I play the phono section with my iPod that there is still a bit of hum but much less..so I think that this would tell you the problem is with reception interference form the old 60 cycle hum thing.....I also would love to hear what others think about this......

[Joeztech]

Many of the terminal strips and grounding points in older radios are riveted to the chassis metal. This type junction can become corroded at numerous points in the chassis and cause hum. Sometimes you can ground a clip lead to a suitable bright chassis point and get a good ground and one by one try grounding each ground lug throughout the chassis looking for change in the hum level. You will probably want to turn power off while making the connection to avoid shorting something out. Make sure you get the clip lead onto the suspect connection securely before turning the set back on. Work your way through the set section by section this way. If you find a ground lug that when grounded by the clip lead produces better audio with less hum, that ground lug needs to be drilled out and remounted with screw, nut and star washer. You may be able to find bad grounds if you have a very sensitive ohmmeter on RX1 scale.


Also some tubes can develop leakage or a short between the heater element and the cathode. It may or may not show up on a tube tester. Having another set of tubes to try that are known to be good is a good troubleshooting tool.

I have a Heathkit SG-8 RF signal generator and using a loop to feed a signal into a set with this unit is not successful as the loop usually just acts like a short to the RF. I added some resistors at the loop so that the total resistance was about 50 ohms and managed to get that method to work for AM and SW RF input circuits. The mixer grid connection via a coupling capacitor will work too as suggested above. That gets around dealing with tricky connections on some sets for aligning the IF circuits. For alignment of the AM front end or converter stage, as someone mentioned, tune as high in frequency as you can to adjust the trimmer capacitors for best reception there, then tune to the lowest station you can find and adjust the ferrite slug of any RF input coil to get best reception. Your information on the set should at least tell you which adjustments to work on for high and low frequencies on AM or SW. You may have to make several passes at it until you get it best across each band as the adjustments do interact some.

If you find that some stations do not appear at the right point on the dial, the oscillator circuit is where you need to concentrate effort. Again there is a trimmer to handle the high end of the band and a coil with slug and/or a padder capacitor to help with the low end of the dial. Often tracking is not ideal with any radio and a compromise has to be reached.

Good luck.

Joe