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construction

vk3jh@...
 

Hi I purchased a V5 last year and am only now starting to put it together. I have wired up the DC power plug as per the instructions and the instructions tell me if I apply 12v it should draw between 90 and 110 ma.  Mine draws 3.5ma. Can anyone give me some clues.  Many thanks.
Ray  VK3JH

Ted
 

Hi, Ray.

Is the Raduino connected?




Ted

Paul
 

That's what it should read when the finals have had their bias adjusted iirc


On Thu, 9 Jul. 2020, 10:28 am , <vk3jh@...> wrote:
Hi I purchased a V5 last year and am only now starting to put it together. I have wired up the DC power plug as per the instructions and the instructions tell me if I apply 12v it should draw between 90 and 110 ma.  Mine draws 3.5ma. Can anyone give me some clues.  Many thanks.
Ray  VK3JH

vk3jh@...
 

Hi Ted

 

Thanks for the reply.  No the Raduino was not connected the picture in the documents doesn’t have it connected

 

Regards

 

Ray

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Ted via groups.io
Sent: Thursday, 9 July 2020 11:24 AM
To: BITX20@groups.io
Subject: Re: [BITX20] construction

 

Hi, Ray.

 

Is the Raduino connected?

 

 

 

 

Ted

Evan Hand
 

Ray,

There are 7 2n3904 transistors that should be on in a linear bias plus the LM386 audio amp when in receive.  If you have wired the power correctly (the RED wire is the +12volts to everything EXCEPT the PA)  it should read 90+ma.  I would check your power wiring as a start.  I would also check the power supply to verify that it is providing 12volts.

The readings are without the Raduino connected, per the original wireup instructions.  The PA bias adjustments come later and will add another 200ma + the Raduino current requirements to the readings. 

My v5 is buried in a case with a 3.5" Nextion screen, AGC, and an outboard audio amp, so it is not easy for me to get to the readings from that board for comparison. As stated in the first paragraph above, you most likely have a power supply/wiring issue.

73
Evan
AC9TU

73
Evan
AC9TU

Ray Lenthall VK3JH
 

Hi Evan

 

Thanks for your reply.  I have checked the voltage form the power supply and it is 12.3 v.  I bypassed the diode in case there was a problem there but still came up with the same result of 3.5ma rather than the 90ma.

 

73

 

Ray

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Evan Hand
Sent: Thursday, 9 July 2020 4:01 PM
To: BITX20@groups.io
Subject: Re: [BITX20] construction

 

Ray,

There are 7 2n3904 transistors that should be on in a linear bias plus the LM386 audio amp when in receive.  If you have wired the power correctly (the RED wire is the +12volts to everything EXCEPT the PA)  it should read 90+ma.  I would check your power wiring as a start.  I would also check the power supply to verify that it is providing 12volts.

The readings are without the Raduino connected, per the original wireup instructions.  The PA bias adjustments come later and will add another 200ma + the Raduino current requirements to the readings. 

My v5 is buried in a case with a 3.5" Nextion screen, AGC, and an outboard audio amp, so it is not easy for me to get to the readings from that board for comparison. As stated in the first paragraph above, you most likely have a power supply/wiring issue.

73
Evan
AC9TU

73
Evan
AC9TU

Evan Hand
 

Not sure I understand bypassing the diode.  Per the wire up instructions, the supplied diode is to be used for reverse voltage protection, and if you wired it per the instructions then bypassing the diode would short out the supply.

I would verify that you are getting the 12volts to R18, R38, R52, and R71.  These are the active stages with power when the Raduino is disconnected.  The voltage drops that I got across them are:
R18 = .4 volts  so that is drawing 40ma
R38 = .4 volts so that is drawing 40 ma
R52 = .52 volts so that is drawing 2.4 ma
R71 = .46 volts so that is drawing 4.6 ma

Total = 87 ma close to the 90 ma specified.  There could be other sections that make up the last 3 ma or it could be the meter or resistor value differences.

Also, check that the power connector is plugged in correctly and not offset by a pin or in reversed. 

I really do not know what could cause these symptoms, other than an open on the board or wiring.  I have not seen, nor read of this type of behavior.  

Happy hunting!
73
Evan
AC9TU

MVS Sarma
 

Appears loose pins on the 3 wire power plug. 
Especially if  Red wire is loose  and  some leakage current on the brown Tx wire somewhere could be an answer for 3.5mA

Sarma vu3zmv

On Thu, 9 Jul 2020, 5:16 pm Ray Lenthall VK3JH, <vk3jh@...> wrote:

Hi Evan

 

Thanks for your reply.  I have checked the voltage form the power supply and it is 12.3 v.  I bypassed the diode in case there was a problem there but still came up with the same result of 3.5ma rather than the 90ma.

 

73

 

Ray

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Evan Hand
Sent: Thursday, 9 July 2020 4:01 PM
To: BITX20@groups.io
Subject: Re: [BITX20] construction

 

Ray,

There are 7 2n3904 transistors that should be on in a linear bias plus the LM386 audio amp when in receive.  If you have wired the power correctly (the RED wire is the +12volts to everything EXCEPT the PA)  it should read 90+ma.  I would check your power wiring as a start.  I would also check the power supply to verify that it is providing 12volts.

The readings are without the Raduino connected, per the original wireup instructions.  The PA bias adjustments come later and will add another 200ma + the Raduino current requirements to the readings. 

My v5 is buried in a case with a 3.5" Nextion screen, AGC, and an outboard audio amp, so it is not easy for me to get to the readings from that board for comparison. As stated in the first paragraph above, you most likely have a power supply/wiring issue.

73
Evan
AC9TU

73
Evan
AC9TU

Evan Hand
 

I believe that Sarma has hit on the most probable cause.  I have had issues with the antenna pins coming loose, so the red power lead to the mainboard is a good candidate.  If you add the leakage current of the finals to the 87 ma that I measured you get the 90ma.  Could also be just a bad connection to the pin in the connector.  If you have a pin you could measure the red wire connection to see if there is 12 volts on it.

73
Evan
AC9TU

Bob Lunsford
 

Back in the days of the Commodore 64, there was a recurring problem with the main power connection pin on the board having a hairline crack in the solder joint. All that needed to be done was reheat it. It was a simple repair that caused many techs to have some crazy moments on the repair bench.

Bob — KK5R

On Thursday, July 9, 2020, 11:37:23 AM EDT, Evan Hand <elhandjr@...> wrote:


I believe that Sarma has hit on the most probable cause.  I have had issues with the antenna pins coming loose, so the red power lead to the mainboard is a good candidate.  If you add the leakage current of the finals to the 87 ma that I measured you get the 90ma.  Could also be just a bad connection to the pin in the connector.  If you have a pin you could measure the red wire connection to see if there is 12 volts on it.

73
Evan
AC9TU