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 Post subject: Re: Packard Bell 48 just has static
PostPosted: Jun Sun 16, 2019 2:11 pm 
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Joined: Jul Mon 26, 2010 8:30 pm
Posts: 26607
Location: Annapolis, MD
Yes---wire according to the schematic....

Tip: When you find something like this, describe ALL of the relevant wiring---the best way to communicate it is to take a snip out of the schematic and mark in red anything where the actual wiring does not match.

Tip #2: Whenever you find evidence of past rework---check everything against the schematic.

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-Mark
"Measure voltage, but THINK current." --anon.


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 Post subject: Re: Packard Bell 48 just has static
PostPosted: Jun Sun 16, 2019 5:43 pm 
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Joined: Jan Tue 16, 2007 7:02 am
Posts: 3142
Location: Lexington, KY USA
I'm looking at this Rider schematic:

http://www.nostalgiaair.org/Resources/download.asp?FN=\M0012886.pdf

See the 25k resistor connected to pin 8 of the 6A8 and the other end of that resistor goes directly to a 4200 mica on my radio but the schematic shows it going through a coil first. Is that just a mistake on the drawing or is my radio wired wrong?

The 25k resistor is the oscillator grid resistor for band 3. It provides a DC path for the grid current.

The oscillator will probably run with the resistor connected to any of the three terminals on this coil. The tap is probably the lowest impedance point, so that would actually be the best place to connect the resistor. It is possible that radios left the factory with the resistor connected to either point.

The Rider schematic appears to have other errors. The resistor connection could be a typo, or there could have been a change during production.

The two different grid resistor values do give an easy way to locate the bandswitch positions. If you measure between the cathode and the oscillator grid of the 6A8, you should see 50k ohms for bands 1 and 2, and 25k ohms for band 3.

Doing this will check the coil continuity and the resistor values, as well as the bandswitch.

As already suggested, it is probably a good idea to go over the whole chassis versus the schematic. A good way to do this is to print a large paper copy of the schematic, then go over each connection and component with a red pencil, as you verify it in the chassis.

You can bring up differences here, and forum members will try to determine what to do in each case.

Ted


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 Post subject: Re: Packard Bell 48 just has static
PostPosted: Jun Mon 17, 2019 12:43 pm 
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Joined: Nov Thu 20, 2014 4:52 pm
Posts: 128
It's running now. Just something very simple wrong that I overlooked. Someone put all metal tubes in this set and of course you could not see any of the filaments light. The 6A8 had a bad filament connection and was not lighting. Fixed that and set works perfect. When I got this radio the cabinet was in horrible condition. Lots of dents and deep scratches. I repaired and restored the cabinet myself and looks real good now. I need better matching knobs. All I had for now. Picture follows.


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