President Jackson OLD shutdown in USB mode

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[CRT]
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President Jackson OLD shutdown in USB mode

Post by [CRT] » 07 Jun 2019, 15:22

hello folks, i need a help.

I have a president jackson that works fine in AM, FM and LSB.
When i switch it on USB mode, then happens like i turn off the rig. No channel display, no smeter light. Off, completely off.

What i can check ? Wires from mode switch to board are all in place.

TIA for any hint.

Cristiano

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Re: President Jackson OLD shutdown in USB mode

Post by cb4ever104 » 08 Jun 2019, 06:39

Hi.

Has this fault just appeared, or has the radio always been like this ?

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Re: President Jackson OLD shutdown in USB mode

Post by 13EL121 » 08 Jun 2019, 07:11

Check the 8v USB line from mode switch and all wires connected at the mode switch. Maybe replace modeswitch. Sounds like a short somewhere.

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Re: President Jackson OLD shutdown in USB mode

Post by cb4ever104 » 08 Jun 2019, 08:48

13EL121 wrote:
08 Jun 2019, 07:11
Sounds like a short somewhere.
That was my train of thought too , although I'm not sure about the s meter light on the Jackson . The guy says that it's off too . I can't remember if it gets fed directly off the 12V line, or not . Cause if it does then the radio would blow a fuse I would have thought .
Last edited by cb4ever104 on 08 Jun 2019, 08:50, edited 1 time in total.
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Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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Re: President Jackson OLD shutdown in USB mode

Post by cb4ever104 » 08 Jun 2019, 08:49

Double post
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Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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Re: President Jackson OLD shutdown in USB mode

Post by astradyne » 08 Jun 2019, 12:40

Checking the back of the mode switch would be my first port of call. A visual check for any loose wires or stray strands which may be causing a short. Also check for previous mods/work.

Use a multimeter to check for correct voltages. Also check for stray voltage (DC where it shouldn't be).
Never, ever, ever....bloody anything ever!

Far too many radio's to list here. But I do own a legal one...

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Re: President Jackson OLD shutdown in USB mode

Post by 13EL121 » 08 Jun 2019, 21:16

I remember that S-Meter light is powered by 12v via power on switch. Grant is 100% this way...
So I would check if voltage at the 2SA473 voltage regulator is switched off or shorted when switching to USB mode.
Seems to be a mode switch problem.

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Re: President Jackson OLD shutdown in USB mode

Post by lbcomms » 09 Jun 2019, 01:28

We had one similar a long time ago, there was a short at or inside one of the frequency adjustment cans. Can't remember is it was a solder / wire bridge or a shorted component, it was 5 or 10 years ago. The radio was in for a failed regulator, when it was replaced we found the cause was the short on one mode only.

You didn't say what test equipment and tools you have, if any. You'll need a multimeter and probably a soldering iron. Find which wire / connection is used for USB by comparing to the other adjacent mode wires and trace the short to ground using low ohms range.

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Re: President Jackson OLD shutdown in USB mode

Post by cb4ever104 » 09 Jun 2019, 09:21

13EL121 wrote:
08 Jun 2019, 21:16
I remember that S-Meter light is powered by 12v via power on switch. Grant is 100% this way...
The later GRANT with the front panel DIM switch is not like this. The bulb isn't directly connected to 12V. There's a couple of components on the front pcb which drop the voltage when the dimmer is on.

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Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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Re: President Jackson OLD shutdown in USB mode

Post by 13EL121 » 10 Jun 2019, 16:42

Hi Paul,
The meter lamp is switched on via power switch. See here...
Screenshot_20190610_183525.jpg
Grant is the same way, dimmer works on negative side.
Screenshot_20190610_182558_com.adobe.reader.jpg
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Re: President Jackson OLD shutdown in USB mode

Post by cb4ever104 » 10 Jun 2019, 17:30

Hi Ralf.

I know the lamp is switched on when you switch the radio on . What I'm saying is that the bulb on the GRANT isn't directly connected over the 0V and +12V line when the radio is on . The voltage difference/drop to the bulb Is dependent on what resistor combination is switched in when pressing either DIM or BRITE . TR401 dims the channel display . The actual voltage across the bulb when the DIM is on is around 8V . I know , as I take advantage of this button/circuit when I wire up the +10khz .

Capture.JPG
Lots of other radios are just directly connected to the ON/OFF switch and 0V giving them the full +13V across it . .

The JACKSON , according to the diagram that I have , is similar to the GRANT in that it seemingly has a 47 ohm resistor in series with the 12V line to the bulb. Although I don't remember ever seeing the -ve line of the bulb going through a resistor .. That's why I don't understand why the meter bulb is going out when the guy switches to USB . If it was shorting the whole 12V line out , and not just the 8V regulator voltage to the mode switch , then I would expect maybe something to blow ....

Anyway . Let's see what the guy says when he posts back . If he ever does ....

Cheers
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Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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Re: President Jackson OLD shutdown in USB mode

Post by 13EL121 » 10 Jun 2019, 18:14

Correct Paul, misunderstood you or you me. 😜👍
Yes, not directly 12v from PSU.

Let's wait what the OM finds out. 🍻

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Re: President Jackson OLD shutdown in USB mode

Post by 14CS06 » 10 Jun 2019, 18:21

Hello

C 169 22μ 10V is probably shorted

wait and see

@+
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Re: President Jackson OLD shutdown in USB mode

Post by cb4ever104 » 11 Jun 2019, 09:38

14CS06 wrote:
10 Jun 2019, 18:21
Hello

C 169 22μ 10V is probably shorted

wait and see

@+
Claude
Could be Claude , but would that cause the S/RF meter bulb to power off ? That's been my question all along . We need the original poster to clarify .

Sammy
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Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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Re: President Jackson OLD shutdown in USB mode

Post by 14CS06 » 11 Jun 2019, 10:23

Bonjour Paul

Another schematic with anotation A 8 volts

Image

Image

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