1948 Westinghouse Model 1821 (182) audio problems - Printable Version
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+--- Thread: 1948 Westinghouse Model 1821 (182) audio problems (/showthread.php?tid=21181)
RE: 1948 Westinghouse Model 1821 (182) audio problems - captainclock1988 - 09-16-2020
Would any of these output transformers work?
Output Transformer
Output Transformer 2
Output Transformer 3
RE: 1948 Westinghouse Model 1821 (182) audio problems - morzh - 09-16-2020
First two will work fine. The third one does not say (or I did not see it) what impedances there are.
The 1st one seems to be what you want.
It says "55 mADC" which I think is the primary current rated. The tube you use uses 40mA so you should be OK.
From what John propose,, the second one is OK, a 45mA one.
The first one is 25mA one, it is underrated.
RE: 1948 Westinghouse Model 1821 (182) audio problems - RodB - 09-16-2020
Those will probably work but as stated before they are overkill. You want to stay in the 2-3 watt range. The higher the wattage the bigger in physical size. I have used one of these with good success:
https://www.parts-express.com/dukane-710-3092-09-4-watt-25v---70v-speaker-line-matching-transformer--249-410
RE: 1948 Westinghouse Model 1821 (182) audio problems - John Bartley - 09-18-2020
Just to muddy the waters a bit more .... here's a snippet of a Bulova schematic for the model 100-110-120 clock radios .... they use two 50UF after a 35W4
RE: 1948 Westinghouse Model 1821 (182) audio problems - captainclock1988 - 09-22-2020
I just ordered the output transformer for this radio, the Halldorson 24S50 Output Transformer that had the 2,000 Ohm Primary and the 3.5 or 8 Ohm Secondary windings.
Hopefully it will work!
Now you guys mentioned that since this replacement output transformer doesn't have the third tap like the original did, what do I do with that connection in the radio?
RE: 1948 Westinghouse Model 1821 (182) audio problems - morzh - 09-22-2020
I don't think you connect it anywhere.
I forgot what we decided it does, looks like it might counter the DC magnetic bias, but if your transformer is large enough, it should not matter much.
RE: 1948 Westinghouse Model 1821 (182) audio problems - captainclock1988 - 09-22-2020
What do you mean "if its big enough"? Do you mean primary Impedance or wattage size?
Here's a screenshot of the audio stage of this radio, showing the output transformer and its extra tap on its primary side.
RE: 1948 Westinghouse Model 1821 (182) audio problems - John Bartley - 09-23-2020
That tap connection is the B+ feed to the entire set. Just move that B+ feed down to the top of R6 (bottom winding on the transformer) and eliminate the tap completely.
RE: 1948 Westinghouse Model 1821 (182) audio problems - captainclock1988 - 09-23-2020
Ok, because the replacement transformer has only two connections, the B+ connection and the Plate connection, so I'm assuming that the B+ connection will connect to the bottom of the 1k Ohm resistor and the plate connection will connect to pin 5 of the 35B5 tube, and nothing to C2/Pin 7 of the 35W4 tube?
RE: 1948 Westinghouse Model 1821 (182) audio problems - David - 09-23-2020
Something like this just note 50C5 vs 50B5 on the pin outs. David
RE: 1948 Westinghouse Model 1821 (182) audio problems - John Bartley - 09-23-2020
The plate connection from the transformer goes to the plate of the output tube (35B5). The B+ connection from the transformer goes to the top of the 1K resistor and to the cathode of the rectifier tube (35W4) and to the positive of the first filter cap. The bottom of the 1K resistor stays where it is, at the positive end of the second filter cap.
RE: 1948 Westinghouse Model 1821 (182) audio problems - captainclock1988 - 09-25-2020
Well I got the new output transformer today and I installed in the radio as per your instructions, and I'm still not getting any audio, so I don't know what's going on with this thing!
RE: 1948 Westinghouse Model 1821 (182) audio problems - John Bartley - 09-26-2020
Pardon my scribbling. This is how I would wire it :
RE: 1948 Westinghouse Model 1821 (182) audio problems - captainclock1988 - 10-22-2020
Well I'm kind of wondering now if the speaker isn't what's bad, because even with a new output transformer, there still isn't any audio and the last time I measured the voice coil on that speaker it measured .3 ohms or something like that, it didn't measure 3.2 ohms like it should of.
I'm wondering if whatever it was that took out the original output transformer maybe didn't also take out the speaker.
What would I use as a replacement speaker for this radio? I currently don't have any junk chassis around that have a similar sized speaker that I could use on this radio.
What do you guys think?
RE: 1948 Westinghouse Model 1821 (182) audio problems - morzh - 10-22-2020
It is a perm magnet speaker, easy (very easy) to check.
Simple stupid way - disconnect the output transformer, connect a battery (1.5V) briefly to the speaker's ends, hear scratchy sound.
A bit more refined - connect to any sound source - audio generator, a radio output.