[KCMike]

Just to be clear on adding the .22 caps in series to the green wires out of the capacitor/coupling pack. Are you saying just cut the green wires and solder the caps to each side of the wire so that they will be connected to the caps inside the can. Or should I cut the wires and solder the caps to the wire and then solder to the #5 connection on outside of can and the other cap. from the other green wire to the solder tab on outside of can. ? Eliminating the internal caps , but leaving the inductor still in the circuit.
Then the blue wires that come out of the can I see has the .005 cap that goes to the plate of the 45 tubes. So I will cut the blue wires and just put an .005 cap btwn. them. Thanks for the help Arran,John,gregb& jerry.

[Mondial]

It all depends on if you can get access to both choke leads without having to open the filter can. If you look at the drawing on the Rider schematic, one side of the choke is accessible at the red/blue tracer wire. The other end of the choke does not have a wire connected, but there seems to be a terminal marked "solder" to which it may be accessed.

If you can get direct access to both ends of the choke, you can eliminate the original caps from the circuit and just replace with new .025 (or.022) uF caps and be done with it. If however you can't access the other end of the choke winding, then add the .22 uF caps in series with the originals via the green wires so at least the leakage of the original caps is blocked by the new replacements.

The original internal .025 uF caps will still be in the circuit, but the risk of their leakage upsetting the bias will be eliminated.

Hope this all makes sense...

[KCMike]

Thanks Mondial. Yes I can and it does make sense. The solder mark is a solder spot on the outside of the can along with the other # connections 1 thru 6. The choke winding goes to the solder spot in series with the .025 cap. then goes out the can which is the green wire. I can solder a .022 cap to cut green wire and solder spot and eliminate the .025 cap. Same with othe grn wire except it will go to number 5 solder tab. which is other .025 cap. and both will be out of circuit but choke will remain in circuit.

[KCMike]

Thought I'd do do some more testing while I was rechecking the resistors. I tested all the rf chokes they all tested within 1 to 2 ohms of whats called for.
But I might have a problem with the flat center tapped resistor. This sits just under the #45 tubes.
It says on schem. 60 ohms total. My readings are: from lft tap to center tap:14.2 ohms: from rt. tap to center tap:14.0 ohms. From end to end : .3 ohms. adding both sides is only 28ohms. this resistor is across the 2 power transformer wires that go to the filaments and heaters. with the center tap going to the large round multi tapped resistor that ohms out correcly on all taps. Its is on the lower rt.of schem. posted at start of this thread. Just wondering if I need to rewind it and if it could have caused some of the volume trouble? Thanks for any help.

[Arran]

If there is a resistor across the filament winding going to the #45 tubes that is a hum balancing resistor, if it isn't open leave it alone, the placement of that tap was set at the factory to match that specific set. I would forget about exact resistance readings on the RF coils, the main concern is continuity, no open or extremely high readings.
Anyhow I would download that PDF of the factory service folder from that site, print it off, and then study the schematic and wiring diagrams thoroughly, it will answer a lot of questions you may have.
Regards
Arran

[KCMike]

Thanks Arran. You might have missed in earlier post I have that manual and have been studying it for a few days. I can't say for sure if it just for the 45 tubes. the schematic shows it right across the filament tap on the transformer.
I will leave it alone.

[Arran]

That's curious, I didn't notice that the #45s and the other tubes shared the same filament winding, most of the late 20s early 30s sets have separate windings for the power output tubes. So yes that is what the wire wound across the winding is for, hum balancing on the #45s, which isn't needed fore the rest of the tubes since they are indirectly heated. I believe that the resistor connected between the tap on that hum balance resistor and ground is for biasing purposes, to make the filaments less negative with respect to the grids, it's at one end of the long voltage divider resistor.
It's a good thing that they chose to use a tubular style enameled wire wound for the voltage divider, it's probably why all sections of it still read good. If it were a candohm type riveted to the chassis you would be mixing and matching modern standard valued power resistors trying to make a substitute.
Regards
Arran

[KCMike]

I had my first experience with a large candohm resistor couple months ago. While restoring a GE. model A-70. Had to do just what you said and add three resistors in place of it. It was a little bit challenging for me to get that right.
I hope to get started on the mod.48 recap today. I lifted one side of the large 12000kohm resistor that connects to the volume control. It is reading 8200k ohms. I will have to order an replacement I believe a 5 watt might be in order. The one in there is 2" long and a little larger circumfrence than a pencil. Thanks

[KCMike]

More clarafication needed on the .025 cap replacements. The 2 green wires that come out of the cap can internally connect to '# 5 tab and the solder spot on the can. These grn. wires go to the resistor board one to each of the 430,000k resistors, then on up to each grid of the 45 tubes.
My question is I don't know which green wire is on which side of the choke inside the can. Does it make a difference if they get reversed? Example the cap going to top of choke which goes to #5 solder tab gets connected to bottom of choke which would be the solder spot on cap. can
I wasn't sure if that might change the phase of the tubes or not matter. I hope I made this understandable. Thanks

[Mondial]

As to the reversal of the green wires, it makes no difference. Although reversing them will invert the absolute phase 180 degrees, the phase relationship between the push pull grids will remain unchanged.

Did you check the RF tube screen voltage as you vary the volume control?

Can you get a full 90 V there with the volume control at max? If you can get at least 90 V at the screens, then all the associated resistors in the volume control circuit are ok. Their exact value is less important than their voltage division ratio, which should provide the proper 90 volts or so to the screens at full volume.

I first thought that the 12K resistor only fed the screen of the detector tube, but after magnifying the schematic it looks like it is in parallel with the volume pot. If this resistor has reduced in value to 8.2K, it will compress the control range of the volume pot, so this may be part of the problem. Add a 3.9 K resistor in series with one end of the existing 12K and see if the volume action is improved.

Changing the .025 uF coupling caps may help the volume problem because if they are leaking and causing excessive current draw of the output tubes, it will load the supply and alter the bias conditions of all the tubes. I would change these first before considering any other possible.causes

[KCMike]

Thanks Mondial, I went ahead and added two .22 caps in series with the internal caps instead of trying to solder .022 to the tabs. I also added two .01 caps in inseries the (blue wires) and eliminated the .005 cap that is in the can. I have ordered some 3 watt resistors. in the mean time I will hook up a 3.9 to the 8.2 reading resistor. This will allow me to power it up and then I will check the RF screen voltages.

I will have to find the correct places to check these readings as you cannot get to the tube pins with the way it is assembled and I don't have a tube socket test adaptor.

[KCMike]

I powered up and tried to get screen grid voltage reading.
The only way I see to do this was to connect to # 2 wire on terminal strip. which goes to all 3 screens.
Using an dvm. With the volume all way down it reads 14.2 vdc when turning it up I get a steady climb in volts til it gets to about 45v that is about 80% up. Then I lose the signal completly or it drops in volume to just barely audible.
Then I have to turn it down to about halfway and tweek the tuning cap to regain audio signal. I did add resistor to bring up to the 12000k range.
Any help is greatly appreciated on what to check next. Thanks

[Mondial]

It sounds as if one of the RF stages may be going into oscillation at the point where you lose the signal. Do you hear any squeals or whistles as you tune stations with the volume control advanced?

You might try adding some .1 uf caps across the existing bypass cap cans and see if this has any effect.

[KCMike]

No squeals or whistles when changing stations. When I have it tuned to a strong station touching the 1st rf tube grid cap increases the audio. I did try jumping the by pass cap can with the .25 and .75 in it. I used a 1.0 for the .75 and .22 for .25 I did not notice any change. Tomorrow I will use jumper wires and connect to all of the by pass caps at once and see what that does.

I have the tube shield cans on but the very top lids off. with lids on the tubes are completly covered.
also I have the antenna wire( BLK) hook to copper cold water pipe.
Thanks for staying with me on this problem.

[KCMike]

I went ahead and changed 2 more resistors. The 16,000k on the resistor mounting board it was reading 19,800k and the 200,000 k btwn the by-pass caps. It was reading 300,000k. There was still no change in performance. Tried the .1 caps to the by-pass cap cans. No change.
While looking at the schematic I realized that the volume control has two sides with 50,000k ohms.
When I checked it I only took reading from the antenna side. which was ok.
I took a reading from the other side today and it was 1740 ohms with no change when rotating volume control.
Powered up and started tapping vol. control with wood dowel. It caused audio volume to go up and down.
Can that volume control be taken apart? I'm afraid with 2 control sides in it, might be trouble if I do try to disassenble. Thanks