02-16-2019, 06:25 PM
Hi Bruce and welcome,
1) The schematic shows the shadow box has a 1K (R14) resistor attached at one end to the shadow box and the other end to the screen grids of the 42 output tubes. I cannot not find any trace of R14.
I would check to see if there is hv @ the plate of the rf amp. It's not uncommon the coil in the shadowmeter to go open. Some later sets there was a resistor in parallel w/the coil so if the coil was bad the set would sill play. I see that R-14 is in series. You could check the total resistance from the sg of the 42 over to the plate of the 44 rf amp. The coil is going to be abt 1K (have seem them from 1.2K down to 800 ohms depending what version it is)
2) The schematic also show C27 connected to one end R14 and then to ground. There is no trace of this capacitor. I have two model 91 schematics that show theses parts, so I am looking for a confirmation on this.
I looked at the Rider's it has the under chassis view. It show C-27 is a bakelite block next to the 39/44 tube socket. Look closely at the small screw size holes where it would have been mounted to see if there are any threads cut into the metal.
3) I am missing the front metal piece of the shadow box Anyone know where I can get one.
If it's the part I'm thinking of it's a small piece of celluloid. For testing purposes tape a piece of paper w/clear tape. This will give you the proper reflection of the vane inside the meter. If you have an old broken dial you can fashion a piece of it to replace the missing front cover.
Here just some general notes. On the meter it's important that the set is working well and is properly aligned for the meter to work well. Lamp alignment is important to get a good image on the window in the front. Some of the meters have an adjustment screw on the back. It sets the tension on the vane, too loose vane swings a lot too tight narrow shadow and not much movement.
Not too uncommon for the osc coil to have an open feedback winding and or the ant coil to have an open primary. Both pretty simple to rewind.
Happy troubleshooting!
de N3GTE
1) The schematic shows the shadow box has a 1K (R14) resistor attached at one end to the shadow box and the other end to the screen grids of the 42 output tubes. I cannot not find any trace of R14.
I would check to see if there is hv @ the plate of the rf amp. It's not uncommon the coil in the shadowmeter to go open. Some later sets there was a resistor in parallel w/the coil so if the coil was bad the set would sill play. I see that R-14 is in series. You could check the total resistance from the sg of the 42 over to the plate of the 44 rf amp. The coil is going to be abt 1K (have seem them from 1.2K down to 800 ohms depending what version it is)
2) The schematic also show C27 connected to one end R14 and then to ground. There is no trace of this capacitor. I have two model 91 schematics that show theses parts, so I am looking for a confirmation on this.
I looked at the Rider's it has the under chassis view. It show C-27 is a bakelite block next to the 39/44 tube socket. Look closely at the small screw size holes where it would have been mounted to see if there are any threads cut into the metal.
3) I am missing the front metal piece of the shadow box Anyone know where I can get one.
If it's the part I'm thinking of it's a small piece of celluloid. For testing purposes tape a piece of paper w/clear tape. This will give you the proper reflection of the vane inside the meter. If you have an old broken dial you can fashion a piece of it to replace the missing front cover.
Here just some general notes. On the meter it's important that the set is working well and is properly aligned for the meter to work well. Lamp alignment is important to get a good image on the window in the front. Some of the meters have an adjustment screw on the back. It sets the tension on the vane, too loose vane swings a lot too tight narrow shadow and not much movement.
Not too uncommon for the osc coil to have an open feedback winding and or the ant coil to have an open primary. Both pretty simple to rewind.
Happy troubleshooting!
de N3GTE
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Terry
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