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 Post subject: Continental TR-682
PostPosted: May Tue 02, 2017 6:05 am 
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Joined: Jul Mon 23, 2012 2:10 am
Posts: 686
Location: N.Y., NY
I was poking around on this with a signal tracer tonight and I got a signal from the 1st and 2nd IFs and the areas around there, but that was about it. Can't seem to get anything out of the actual radio speaker except little bursts of static here and there. Anybody have an good insights on where to go from here? Over the last year or so my I think my skill in troubleshooting has gone up maybe a half (or whole) notch but I'm still pretty much a newbie...

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 Post subject: Re: Continental TR-682
PostPosted: May Wed 03, 2017 3:55 am 
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Location: Knoxville, Tennessee, USA
Its always hard to armchair troubleshoot, but here's my go at it:

(1) Check the power supply connections and make sure 9v is being delivered to the on/off switch.
(2) Make sure the on/off switch is clean
(3) Check for loose wires on the earphone jack and that the 'L' connection is not not bent/corroded open.
(4) Since you do hear 'little bursts of static here and there', we can have some hope that the speaker works and the audio stage works, maybe.
Do a click test (roll the dial off/on several times and listen for crackle or clicking), if no sound then do an audio signal test. If no sound, then the audio stage is the troublemaker, possibly a transformer (that's a wild guess).

If you do hear sound on either the click test or audio signal test, then the audio stage is OK. Move to oscillator and test it. Then test backwards from the antenna, through the tuner and into the IFs.

Replacing the electrolytic caps will do wonders (and may solve the entire problem).

I hope this helps.


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 Post subject: Re: Continental TR-682
PostPosted: May Wed 03, 2017 7:15 am 
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Do the second radio test, to make sure the oscillator is functioning. Before that, however, replace it's Electrolytics; S/B four of the critters.

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 Post subject: Re: Continental TR-682
PostPosted: May Wed 03, 2017 5:48 pm 
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Joined: Jul Mon 23, 2012 2:10 am
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Location: N.Y., NY
Hey guys

Thanks for all the info. I should have mentioned in my original post that when I first got the radio all I heard was a click when I turned it on. I went on to recap the electrolytics and two of the fixed caps but still no signal. Since my last post I went ahead and injected a signal at the volume and that all checked out. Oscillator checks out as well. Guess I'll poke around some more and see what turns up.

I bought this thing about two years ago because I thought it was cool looking. Prior to that had never seen a Continental radio like this. After I recapped it and didn't get it to work I just shelved it. It's been sitting there out of commission for a while now so I think it's about time this thing come back from the dead!


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 Post subject: Re: Continental TR-682
PostPosted: May Wed 03, 2017 8:38 pm 
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Location: Mountains of Mourne. Ireland.
Sams schematic with currents + voltages.
https://dropbox.com/s/u0xzuo3ji8zbtxo/C ... 2.pdf?dl=1

Have you installed the capacitors correctly? :)

Greg.


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 Post subject: Re: Continental TR-682
PostPosted: May Thu 04, 2017 1:03 am 
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egg wrote:
Sams schematic with currents + voltages.
https://dropbox.com/s/u0xzuo3ji8zbtxo/C ... 2.pdf?dl=1

Have you installed the capacitors correctly? :)

Greg.


I'm pretty sure I did, but it's always worth checking...

and thanks for the diagram, appreciate it!


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 Post subject: Re: Continental TR-682
PostPosted: May Thu 04, 2017 1:45 am 
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Location: Mountains of Mourne. Ireland.
Signal tracing transistor radios: viewtopic.php?f=4&t=278833

Signal Flow Transistor AM Radio: http://youtube.com/watch?v=qlx7KRSiPM4



Reading a Schematic.

Three drawings, one circuit.

This is from an article written by Doug DeMaw W1FB an ARRL contributing editor for QST magazine. It appeared in the February 1984 issue.
Search... arrl 8402019.pdf

Image
"Examples of an identical circuit (A and B) drawn in different ways.
The pictorial representation at C is for the circuits shown in illustrations A and B.

This shows how we can relate the drawing to the assembled circuit, which would normally be mounted on a circuit board or a metal chassis."



To save videos for later viewing, use→ http://keepvid.com/ Save at (Max 480p)
Image

Just copy + paste the youtube video URL into the top download box... avoid the advertisements (cleverly named Download) and the offer to install Video Downloader on your desktop.

Greg.


Edit: image update.


Last edited by egg on Jan Wed 24, 2018 4:38 pm, edited 1 time in total.

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 Post subject: Re: Continental TR-682
PostPosted: May Thu 04, 2017 5:47 am 
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Location: N.Y., NY
Greg, thanks so much for posting all of that information it's a big help. One question...in the Radio Electronics when they say to inject IF and RF signals how do I set that on my signal generator?


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 Post subject: Re: Continental TR-682
PostPosted: May Fri 05, 2017 12:41 am 
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Most IF's use a frequency of 455 Kc, so that's what you would set the generator at.

Most alignment instructions recommend 600 Kc for RF, and to mesh the tuner blades (540 Kc).

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 Post subject: Re: Continental TR-682
PostPosted: May Fri 05, 2017 5:28 am 
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Still messing around with this radio. So far when I use the signal generator I have audio through the driver and the output transistors, not getting anything out of the IFs or the converter. When I use the signal tracer I get a signal out of both IFs.


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 Post subject: Re: Continental TR-682
PostPosted: May Fri 05, 2017 6:40 am 
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Did you ever try this?
fifties wrote:
Do the second radio test, to make sure the oscillator is functioning.

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 Post subject: Re: Continental TR-682
PostPosted: May Fri 05, 2017 4:34 pm 
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fifties wrote:
Did you ever try this?
fifties wrote:
Do the second radio test, to make sure the oscillator is functioning.


Yup, oscillator working fine.


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 Post subject: Re: Continental TR-682
PostPosted: May Mon 08, 2017 4:57 am 
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Finally managed to get some sound out of this radio. Without getting into the trial and tribulations of how I arrived there, I basically jumped around the solder side of the pcb with a 4.7mfd electrolytic cap and some life appeared when the leads hit terminal 2 and terminal 4 of A1...the 2nd IF transformer. Terminal 2 of the 2nd IF transformer is connected to a 10mmf cap that is coming off of terminal 4 of the 1st IF transformer. Terminal 4 of the 2nd IF transformer is going to the neg side of the diode. so I'm guessing the whole 2nd IF transformer needs to be replaced?


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 Post subject: Re: Continental TR-682
PostPosted: May Mon 08, 2017 7:09 am 
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Have you verified resistance readings on the 2nd IF's two coils?

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 Post subject: Re: Continental TR-682
PostPosted: May Mon 08, 2017 3:25 pm 
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fifties wrote:
Have you verified resistance readings on the 2nd IF's two coils?


No I haven't, how would I go about doing that?


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 Post subject: Re: Continental TR-682
PostPosted: May Mon 08, 2017 8:24 pm 
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nipperscousin wrote:
fifties wrote:
Have you verified resistance readings on the 2nd IF's two coils?


No I haven't, how would I go about doing that?

On the trace side of the PCB look for for their solder landings. The footprint for each would be two on one side, three on the other, and grounds on the two opposite sides.

Simply put your meter probes across the two, and then on the other side across the two outer, and then either outer and the inner.

The coil resistances are low enough that any component tied parallel shouldn't affect them. If you get an infinite reading on either, it means it's open, and the probable cause.

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 Post subject: Re: Continental TR-682
PostPosted: May Tue 09, 2017 3:36 am 
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fifties wrote:
nipperscousin wrote:
fifties wrote:
Have you verified resistance readings on the 2nd IF's two coils?


No I haven't, how would I go about doing that?

On the trace side of the PCB look for for their solder landings. The footprint for each would be two on one side, three on the other, and grounds on the two opposite sides.

Simply put your meter probes across the two, and then on the other side across the two outer, and then either outer and the inner.

The coil resistances are low enough that any component tied parallel shouldn't affect them. If you get an infinite reading on either, it means it's open, and the probable cause.


Hopefully I'm doing this right. So if I'm understanding this correctly...in the case of this particular IF can in this radio terminal 4 and 5 are the two on one side and 1,2 and 3 are on the other side. If I put the probes across 4 and 5 I get a reading of 13.2 meg ohms. On the other side I can't seem to get readings touching any of those terminals.


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 Post subject: Re: Continental TR-682
PostPosted: May Tue 09, 2017 6:25 am 
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Well, something ain't right.

I have 3 Viscount 602's and a Remington 6TP112, which I grabbed to see what the coil readings should be. The print below is for a Viscount 602. All these sets including yours are the same, circuit and PCB layout wise, with just different front cosmetics. It's a good circuit, selective and with plenty of audio.

I read 3.3 ohms between terminals 2 & 3, (black square #'s 19 & 20), 1.8 ohm from terminal 3 to terminal 5 (black square 10), and 1.7 ohm from terminal 2 to terminal 5. The resistance between terminals 1 & 4 was .8 ohm.

Try measuring again, making sure your probes are on solder landings across (left-right) from each other, as you look at the PCB from the bottom.


Attachments:
P1010001.jpg
P1010001.jpg [ 122.55 KiB | Viewed 4492 times ]

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 Post subject: Re: Continental TR-682
PostPosted: May Tue 09, 2017 1:39 pm 
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Ohming out a transformer is really basic stuff. it may look confusing, but VERY simple once you look closely at a diagram/schematic.

Fifties is giving you good advice. You'll have this narrowed down in no time,
Mitch

P.S. - You're doing good. Don't get frustrated because there's a fairly steep learning curve here.


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 Post subject: Re: Continental TR-682
PostPosted: May Thu 11, 2017 2:06 am 
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Location: N.Y., NY
So after racking my brain slightly to figure out what terminals were where on A1/L5 I realized the the layout for them was right there on the schematic!

So...here's the readings I got:
2-3 6ohms
3-5 3ohms
2-5 3ohms
1-4 45kohms.


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