Thomas
thank you for your input Thomas and a very merry christmas to ya,yeah this rig does have an ac ps in it i will check some of the sites you mentioned,so thanks again.....
Thomas
::Is this an AC radio or a battery radio? If noone on here can come up with a schematic for you, you can try your local library for a Sam's print-out. Also, www.tubesandmore.com may have your schematic. Furthermore, www.samsphotofact.com may have it. If you absolutely cannot come up with any information on this radio, you can still get it working fairly easily. If you are fairly familiar with radio, you can come up with tube numbers that satisfy what you need, especially if it is a battery radio. If you cannot find info on this radio, and it is a battery radio, I will give you some tube numbers to try on the radio, depending on how it's wired.
::
::Thomas
:
:thank you for your input Thomas and a very merry christmas to ya,yeah this rig does have an ac ps in it i will check some of the sites you mentioned,so thanks again.....
Rogers made a 741 in 1930-31 using four 24A's, two 45's and one 80. This may be your radio. I say may as Rogers model numbering and indexing was inconsistent.
Being a Canadian radio it may not be found in USA schematic sources although it may be on this site in the Canadian data I provided to Richard.
I will email a schematic to you, use the one on the top of the page. It does not say 741 but the indexes say to use the schematic for 630/640/650 etc. The schematic is very primitive, Rogers did not show the tube envelopes on their early schematics.
Ed.
Thanks for the great info guys,i will look at the schem and see if it jives with said radio,where is a good place to find these kind of tubes,
i think i am lookin for r245 and 25a??i looked in tubesandmore catalogue and they were not listed there.
any ideas folks?
thanks and merry christmas!!!
The two #45 tubes you need will be costly as the Audiophiles have taken a liking to them and pushed the price way up. The 24's or 24A's should be reasonable. I usually look for tubes on eBay. You take a chance there on quality but often they are cheaper. Sometimes posting one of the radio forums will find someone willing to part with them. Last choice would be one of the tubes/parts sellers as they usually want top dollar.
Some have used 1619's in place of 45's with an adapter. I have not tried that but hear good reports.
I would not order them until I was sure that you have the right schematic.
Happy New Year,
Ed.
24A is under the 13CW4-25Z6GT category on page 12.
45 and 80 are under the 26-95A1 category on pages 9 and 13 respectively. The 45 as new from tubesandmore is quite expensive. You might be better off getting them from eBay or some other source. Currently there are several auctions for the 45 tube at reasonable prices. The globe 45 tubes will be incredibly expensive as compared to the "ST" style. You are best off searching under "45 tube," or "45 tubes," or some other word after 45, because if you just type in the number 45, you will get a huge list of items with the number 45 in them.
Thomas
Thanks a bunch guys,you are being very helpfull,i have checked the tubesandmore site and they do have what i need for tubes,i was able to cross them to other# so i could obtain data sheets on the tubes in question.
the www is a waterfall of information eh!!
so yeah i am still digging for a schematic,i went through all at nostalgia air and was unable to find one that even resembeld this radio in any way.
i am thinking perhaps it was a custom built rig for sears or eatons of the time.the radio is housed in a very impressive oak or applewood cabinet that stands about 3 feet tall with sliding doors on the front, a round tuner dial that is incremented in reverse and two other knobs,one is a wire wound reohstat,volume i presume,one is a tuner dial,and the other is a pull for ac switch and a turn switch, hence ac power and ???
maybee band, not sure.
this unit has a serial plate stating that it was made by rogers majestic and it is a type 741.chassis
it has 4 24a rf tubes,,1 rectifier tube 280 or 5z3 was a sub i found the power end has a 245 single ended i think there is only one output power tube,hmmmmmmm not a marshall thats for sure lol..
at this stage i am in dire need of a valid schematic,anyone having one would be my biggest hero...
thanks for all the replys guys and have a very happy new year to all !!!!!! tom
The schematic for your radio is out there and you will find it. There are lots of schematic sellers on the web. A prime source would be www.samsphotofact.com. www.tubesandmore.com also carries a huge inventory of schematics. They will charge you a small fee, say $5 to $10, and mail a paper copy to you. I might add that their paper copy will not be a digitized print-out like that you find here, but will be a very clear photocopy. Nostalgia Air, though, is one of the only places you will ever find free schematics in such a huge variety, dispite the sometimes blurry digital print-outs.
Another place you can try looking for FREE!! is your local public library. They have Sam's and Rider's stuff in their reference section. Ask the librarian. You'll be surprised at what you find. Furthermore, I encourage you to go there as often as you can. The less people look at these old diagrams and stuff, the more the libraries will think about discontinuing them. Sadly, my favorite books from when I was younger, The Boy's First, Second, Third, and Fourth Book of Radio and Electronics by Alfred Morgan, have all been pulled from the shelves of most libraries. Of course, when I was younger the books were already about 40 to 45 years old.
If you are familiar with electronics, though, with such a simple radio as your's (all four pin sockets), you should be able to figure out how the tubes are arranged. If you can locate the power transformer, find the low resistance (1 to 3 ohms, perhaps less than one ohm) filament winding that goes to pins 1 and 4 of only one tube socket. This filament winding does not supply any other tube. Furthermore, with the set powered up, you should get 5.0 volts AC across pins 1 and 4. Across pins 2 and 3 you should get from perhaps 400 to 800 volts. These are the high voltage leads, one to each plate of the rectifier. This is where your #80 tube goes. All of the other tubes in your radio use 2.5 volt filaments. They may all be wired in parallel, or the #45 tubes may have their own separate filament supply. Their separate filament supply, or if one supply supplies all of the tubes, will have a center tap for applying B- to the cathodes. If your radio uses #24A tubes, though, you will see 5 pin sockets for these tubes. If your radio has 4 pin sockets throughout, as you originally said, I have to think of an indirectly heated 4 pin triode. If your radio does have 4 pin sockets throughout, and the ones in the RF sections have grid leads lying near by (lead that clips to a terminal on the top of the tube, then it most likely uses a 4 pin indirectly heated triode. I looked through my tube manual, though, and found no 4 pin indirectly heated triodes. Directly heated tubes were almost never used in the RF sections of an AC radio, as this would introduce a lot of hum, but it is possible.
It is much more likely that your radio has 5 pin sockets in the RF sections (you know for sure, of course), and either uses the #24A tetrode, or the 27 triode. If there are grid wires for each 5 pin socket, the set more likely uses the 24A. If no grid wires, it more likely uses the 27. Copy the diagram for each tube onto a piece of paper and check the connections to the pins at each RF socket in the radio. The cathode, screen grid (if any), plate, and control grid connections should tell. If there is a control grid lead on top of the chassis for each tube, there will be no control grid connection under the chassis.
Finally, the two #45 tubes, if two are used, will go to the output transformer (the transformer that connects to the speaker), which will most likely have a center tapped primary of a high resistance. The two ends of the primary will go one end to each plate of each #45 (one plate in each tube), and the center tap will go to B+. If the output transformer only connects to one tube socket, then your radio may not use push-pull output (two #45 tubes), but may instead use only one #45 for single ended output.
If you are not al that familiar with radio and my instructions confuse you, wait until you have obtained a schematic or until someone very knowledgable is able to help you. If you plug the wrong tubes into the wrong sockets, you can ruin the radio, so be patient.
T.D.
Hi,
Did you not receive the schematic and the second email that I sent to the email address that you provided this forum. It contained the schematic in pdf format that RCC index calls out for a R-M 741 chassis?
Although the radio may have been made for Simpsons's or Eatons it is more likley to have been sold as a Rogers brand. They often rubber stamped a model name (different than the chassis number) inside the side or back of the wooden cabinet. Rogers also made DeForest Crosley and Majestic brands at that time using the same chassis but different model names.
I have many of these schematics and can email various ones for you to look at. It is very unlikley that any US based publishers would have printed a schematic for that radio. Another Canadian source would be Dave Cantelon at www.justradios.com .
Many of the early Rogers products had elaborate cabinets and are well worth restoring.
Ed.
::at this stage i am in dire need of a valid schematic,anyone having one would be my biggest hero...
:
:Hi,
:
:Did you not receive the schematic and the second email that I sent to the email address that you provided this forum. It contained the schematic in pdf format that RCC index calls out for a R-M 741 chassis?
:
:Although the radio may have been made for Simpsons's or Eatons it is more likley to have been sold as a Rogers brand. They often rubber stamped a model name (different than the chassis number) inside the side or back of the wooden cabinet. Rogers also made DeForest Crosley and Majestic brands at that time using the same chassis but different model names.
:
:I have many of these schematics and can email various ones for you to look at. It is very unlikley that any US based publishers would have printed a schematic for that radio. Another Canadian source would be Dave Cantelon at www.justradios.com .
:
:Many of the early Rogers products had elaborate cabinets and are well worth restoring.
:
:Ed.
Sounds like you are somewhere between Winnipeg and Edmonton. I sent 2 emails, if you cannot find them click on my name at the top of this posting, my email address will come up, let me know and I can send them to whatever email address you want.
Ed.
Ah, the west coast of BC, the place I always wished I lived.
The schematic has been resent to the Hotmail address. If the top one on the page is the right one you will need 450 volt caps, two 4 mfd and two 2mfd. The proper speaker has a field coil of 2500 ohms and you will need a replacement choke or power resistor of similar value. There appears to be a 30k resistor across the field coil also. The 2 mfd caps can be increased to reduce hum, the first 4 mfd should not as B+ will be too high. An output transformer is shown on the schematic, probably on the chassis. It appears that there may be 2 chokes on the chassis, maybe in one can and one interstage transformer.
Let me know if the schematic is too far off, we may have to look at several of their other models of the same vintage and "fudge" it.
Ed.
thanks a bunch for the schematics there ed,i think we can fudge from this,they are not quite right but a bundle of help just the same,looks to me like the detector is the same but the ps/power end are somewhat different from the 741,now i have not looked in the cabinet for the funky speaker stuff yet but i am quite sure that the 741 has an onboard output tranny such as the 630-640 but the ps is more like the 610-620 type with the 8u caps instead of the 4/2 in the 630/640 also the 741 has the adjustable ac fuse holder,let the fudging begin,whats up with that speaker output?? do we put a dummie load on the field side and then ??? voice coil 2/4/6/8/ohm load??
yikes that end is different!!
hmmmmmmmmmmm.bhhhrrrrrrrrrrr
Hi,
I have emailed a few schematics in pdf form of radios that Rogers made about the same time with similar configurations. Perhaps you may find yours there. As I said the indexing and labelling of these old radios was erratic and poor. For example the "Wellington B" I sent is indexed as using your chassis but on the schematic a different number is used. I think Rogers was changing so fast in that era that running changes were made that are not indexed.
That is why I suggested looking inside the cabinet for a rubber stamped name. "Wellington" is an example.
Since you have an output transformer on the chassis I would attach a PM speaker to it. The old one may have been closer to 4 ohms but an 8 should work for the trial.
As mentioned you would have to substitute a hefty power resistor, probably about 20 watts to replace the missing speaker field coil. The schematics give various field coil resistances if you can find the right schematic. They seem to be using ones from 1000, 1250 thru 2500 ohms.
Certainly the filter condensers will have to be replaced before a trial to protect the power transformer. Thomas had mentioned the "dim bulb" tester that can be used for safety.
Ed.
You should bring the radio in, though. Cold is not good for it or you. It is especially hard on the finish, as temperature and humidity changes expand and contract the wood severely, which can crack and separate the finish.
In my last letter, when I talked about turning the set on, I was talking about turning it on with no tubes in place (just to let you know). You can do this without much worry, unless a wire is shorted out. Without the tubes in place, most, if not all, of the components that could fry will not be connected to any power. The voltages you will be looking for will be AC voltages, which will tell you what you need to know about tubes. Ed's schematic, though, will be more helpful in many ways. If you are not familiar with radio at all, and do not know how to test for a shorted transformer, and then other things once you purchase tubes, purchase (or take out from the library) David Johnson's "Antique Radio Restoration Guide, 2nd edition." I think that's the title. I always forget. It's up in my room. The book will be a large help to you, though you may also want to purchase more specialized books dealing with TRF and early AC operated radios. All books can be found at www.tubesandmore.com
David Johnson's books will explain to you how to build a simple device used in testing the power supply of the radio for shorts. This device can also be used, once you think you have the radio in good order, to bring the power up gradually. What you do is wire an outlet and a standard light socket in series with eachother and mount them to a board. You also wire a cord to this assembly so that the power goes in the outlet, then on to the socket, and then back out the power cord. Plug the radio into this unit and install say a 60 watt bulb. The bulb should glow very dimly with no tubes in place. If it glows brighly, then you have a short. Gradually increase the wattage up to 100 watts, and then operate the supply this way for a bit and note if it gets hot or not. If not, go about making voltage checks to locate the various tube sockets.
When you operate the radio with the tubes in place, a 60 to 75 watt bulb will glow moderately. The book will explain in more detail what to look for when checking a working radio. Generally I do not use this method as anything more than a safety measure when powering up a radio that I have repaired. I feel more comfortable testing components (electrolytic condensers, etc.) with my multi-meter than by actually powering them up. Then I replace all the bad parts and try out the set. Gradually powering up the set and slowly increasing the wattage of the bulb will allow you to observe any trouble gently.
Thomas
With indirectly heated cathodes, which took over for the most part by the early to mid 1930s, a thinner filament can be used. Higher voltage/lower amperage can drive this filament (thin filament has more resistance, requiring more voltage, and less current flows through it), which will reduce the requirements of the wiring in the radio and reduce the wiring size, transformer size, etc. And so the 6.3 volt system took over in radios.
If you ever look at the headlamp wiring (or the starter wiring for that matter) of a 6 volt car verses a 12 volt car, you will notice that it is much thicker. Yet both headlamps in both cars draw the same *wattage* (generally from 45 to 60 watts depending on bulb and whether high or low beam is selected), and are quite similar in brightness (comparing the standard 6 inch round 6 and 12 volt sealed beam bulbs). Since there is less voltage (strength) in the 6 volt system, more amperage (amount) is required, which requires thicker wiring to fit that extra amperage. If we were to use 6 or 12 volt wiring in our houses to power our saws and refrigerators, the wiring would be enormous.
Anyway, that's my stab at it. I feel that I'm fairly accurate, but I'm sure that someone else knows more. At any rate, the 2.5 volt system was pretty much an AC system only, and didn't have much to do with the battery sets that preceeded it. Incidently the 6.3 volt system worked very well with the then standard 6 volt system used in automobiles (actually operated between 6 volts--engine off, to 7.4 volts--engine on). This may have helped it take over to some degree, though radios were not all that popular in cars yet.
Thomas