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 Post subject: Channel master 6500 schematic?
PostPosted: Feb Sun 11, 2018 6:18 pm 
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Joined: Feb Fri 09, 2018 6:44 pm
Posts: 25
Hi all
I have a channel master 6500 that came in a box of junk. It almost looks like a car was dropped on it lol.
The internals are more or less complete but not working, looks like someone had tried to repair the ferrite rod antenna. I’m looking for a schematic for this if someone can help me out.
I recapped it, originally it had the caps with the greenish molded plastic case. After recapping out of curiosity I tested all the old caps some had failed open others were still good. Surprisingly a 120uf, 6v measured 228uf with an ESR of 2.1 ohm. A 100uf, 6v measured 181uf with and ESR of 1.0 ohm. Is there something strange going on with these caps or was the tolerance that bad that they could be almost double the rated capacitance?


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Sun 11, 2018 6:42 pm 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 5052
Location: Mountains of Mourne. Ireland.
Your capacitors are 54+ years old!
Image
Schematic here...
http://www.antiqueradios.com/forums/vie ... 0#p1993080

If you need more, let me know and I will scan the 1963 service manual (tomorrow... Lol) for you.

:) Greg.
Image


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Sun 11, 2018 7:03 pm 
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Joined: Feb Fri 09, 2018 6:44 pm
Posts: 25
Thanks for the info and schematic.

My question on caps was not that they go bad but why some are testing such a high value?


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Sun 11, 2018 7:08 pm 
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Joined: Feb Fri 09, 2018 6:44 pm
Posts: 25
[2] Criteria for Defining Failures in
Aluminum Dielectric Capacitors
The criteria for defining failures are established fo
r each individual product series. In general, the
standards for establishing the guaranteed life span are as follows:
Sounds like as in point #2 this increase in value is normal part of the life cycle of caps.
1.
Changes in capacitance: A failure is defined
as a change in capacitance from the initial
capacitance level beyond the spec
ified range. The change is
generally ±20% to ±30%.
2.
Changes in the tangent of the loss angle: A fa
ilure is defined as the component exceeding
the specified range. Usually,
this range is 1.5 to 3.0 tim
es the initial value.
3.
Change in leakage current: The definition of fa
ilure occurs when there is an excess of the
specification values.


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Sun 11, 2018 7:51 pm 
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Joined: Feb Fri 09, 2018 6:44 pm
Posts: 25
Thanks again for the schematic it helped, turns out the ferrite rod antenna has an open winding, the red and white one that connects to the tuning cap.
I'm not sure if it can be repaired and rewinding would not be by favorite option.

Have to give this some thought.


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Sun 11, 2018 9:57 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 28677
Location: SoCal, 91387
Well there are two options.

The break could be at one end or the other, where the connecting leads are. Use a razor to gently scrape the insulation at each end of the winding and see if you get a low resistance reading. If so, determine which end has the break, by measuring between one end's scrape and the other's lead connection to the tuner, then reverse. Then simply tin the scrapped area and solder a lead between it and the tuner.

The other method would be to get another Ferrite core antenna/osc coil and sub it. It doesn't have to be the length of the original, and may not perform as well, but at least you'd have the set functioning.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins//////////////////


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 13, 2018 4:49 am 
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Joined: Feb Fri 09, 2018 6:44 pm
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There is always a way to fix almost anything. The coil that is connected across the tuning capacitor was open. In this radio the coil is (see Photo) wound partly on the right side and then skips over to the left side for the final 10 or so turns. The green coil on the far right is for an external antenna hookup and kind of hides the secondary coil that feeds the signal to the radio. Luckily the open was in the 10 turns on the left so I unwound them tinned and soldered the litz wire back together then rewound the coil and secured it with melted bees wax. I had to add the short (green) wire as the litz wire would not reach the tuner. Someone had attempted a botched repair on this once before so I’m not 100% sure how this wire was originally connected.
The final result is a working radio.


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 13, 2018 7:44 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: SoCal, 91387
Well done, congrats!

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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 13, 2018 6:38 pm 
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Joined: Aug Wed 26, 2009 1:50 am
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Location: Mount Pleasant UT 84647 (from Coventry, UK)
Well done!


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Wed 14, 2018 12:00 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Glad you have it working !

Is the cabinet beyond repair or use ?

John


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Wed 14, 2018 1:41 am 
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Joined: Feb Fri 09, 2018 6:44 pm
Posts: 25
Just starting to tackle the case it was covered in back greasy residue like an old garage radio. I striped all the nameplates off and scrubbed it with warm water and dish soap. Then glued all the cracks and let it setup. My current plan is to use epoxy putty to repair the bottom leg on the case and then paint the case with a Krylon ivory. The only missing parts are the back cover and the positive battery terminal that attached where the bottom case is broken. If anyone has a better plan to repair the case please let my know.


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Wed 14, 2018 2:14 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Looks like you have the project well in hand---can't wait to see it completed !

John


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 20, 2018 1:38 am 
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Joined: Feb Fri 09, 2018 6:44 pm
Posts: 25
Well this is interesting, found some Krylon ivory and started spraying the first coat. Does this look like Ivory to you??? Someone at Krylon is color blind.

I now have another can of Krylon ivory so will call the first coat a primer coat lol.


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 20, 2018 2:03 am 
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Location: Mount Pleasant UT 84647 (from Coventry, UK)
Never had that happen before.


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 20, 2018 3:23 am 
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Joined: Nov Wed 14, 2007 11:37 pm
Posts: 1475
That blue looks pretty good!


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 20, 2018 4:11 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
I've never seen that before either !

But even though I don't usually like blue, that shade sure fits the era in which the radio was made... Would probably bring some bucks on Ebay !

John


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 20, 2018 4:14 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 28677
Location: SoCal, 91387
I'd certainly leave it that color; looks great!

_________________
\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins//////////////////


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 20, 2018 6:29 am 
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Joined: Feb Fri 09, 2018 6:44 pm
Posts: 25
Ya, I kind of liked the blue too but I like to keep things close to original if I can.

Now this is a close shade of ivory.


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 20, 2018 9:58 pm 
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Joined: Feb Fri 09, 2018 6:44 pm
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I think I'm done with this one.


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 Post subject: Re: Channel master 6500 schematic?
PostPosted: Feb Tue 20, 2018 10:00 pm 
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Joined: Aug Wed 26, 2009 1:50 am
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Location: Mount Pleasant UT 84647 (from Coventry, UK)
Nice job there!


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