开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. QRPLabs
  2. Topics

New Build, No Flash Drive found #build #building #qmx

 

I finished the QMX7build and have applied power,? No Smoke but also not seeing a flash drive,?

Steps so Far:
Limited the supply voltage to 7V
Limited Current to 350mA

Applied power and did not see any voltage or current as expected.?

Pressed the Left Encoder and saw a voltage drop AND the mA jump to the 350mA limit?

Release button and the voltage returns to 7 volts and mA is back to zero.?

No USB Flash Drive shows up.?

Tried Pressing the Left encoder again,? same results,? Voltage drop and mA to 350 limit while the button is pressed.??

I have searched the group for steps to troubleshoot but since I don't? have the firmware loaded I am not sure where to start looking.??

I have looked very closely for any cold joints or bridges or anything that looks out of place.?

Is there a guide I can use to help trace / Trouble shoot???

Thanks?

Bill
 

I found that I had a short with the Right encoder.? The mask under the nut was scratched and was causing a short to ground.? ?Fixed that but still no joy.? Tried another computer and that did not help.? Any Suggestions??
 

开云体育

Hello Bill
?
I had the same problem as did others, mine turned out to be a dead IC203.
?
73
?
Ian G4GIR.

----- Original Message -----
From: Bill - AA4NO via groups.io <beardshaw@...>
Reply-To: <[email protected]>
Sent: 10/06/2024 18:27:44
Subject: Re: [QRPLabs] New Build, No Flash Drive found #build #building #qmx
I found that I had a short with the Right encoder.? The mask under the nut was scratched and was causing a short to ground.? ?Fixed that but still no joy.? Tried another computer and that did not help.? Any Suggestions??

 

Thanks for the reply.? Is there a way to diagnose the bad? IC?? ?And what is the fix if that is the issue.? I am not an electronics expert but I have successfully built radio kits in the past.??
 

I had a short on the 5V supply - T103 was off a bit off position and had shorted D-G. Worth checking.
 

Is that R103?? I don't find a T103 in the QMX or maybe it is time to put this down and take a break :-0
 

I suspect the component is Q103.

If so, see message 123914 from a post by Gabe, yesterday. Especially the link to a video of Hans'.

If I am correct, you need to also check the diode and possibly replace that.?

73 GREG KI4NVX?


On Mon, Jun 10, 2024 at 1:47 PM, ggsubs@...
<ggsubs@...> wrote:
I had a short on the 5V supply - T103 was off a bit off position and had shorted D-G. Worth checking.

 

On Mon, Jun 10, 2024 at 07:45 PM, Bill - AA4NO wrote:
Is there a way to diagnose the bad? IC?
Bill, for a broken IC203 in most cases the resistance between the VDD rail and GND is very low, only a few ohm or less. Here you find a testpoint for VDD (Vdd). Please remove all the boards from the mainboard before checking.
A value around 9 kOhm or more is ok.

And what is the fix if that is the issue.
No fix until now.

73, Ludwig
 

On Mon, Jun 10, 2024 at 07:46 PM, <ggsubs@...> wrote:
T103 was off a bit off position and had shorted D-G.
Bill, I guess it should be Q103. In case of a short D to G diode D101 should be blown during the first switch on.
See also (section "Q103/Q104 drains short on the 5V regulator board").

73 Ludwig
 

On Mon, Jun 10, 2024 at 07:27 PM, Bill - AA4NO wrote:
?Fixed that but still no joy.? Tried another computer and that did not help.? Any Suggestions??
Hi Bill,

here you find a description of the power supply system of the QMX and here of the switch on process. Regarding this you could check until which step it's ok and what is the issue.

73, Ludwig
 

Thank you.? It gives me something to look at when I pick it back up.? With each issue I learn something new and that is the most fun of building. ?



On Mon, Jun 10, 2024 at 4:31?PM DH8WN via <DH8WN=[email protected]> wrote:
On Mon, Jun 10, 2024 at 07:45 PM, Bill - AA4NO wrote:
Is there a way to diagnose the bad? IC?
Bill, for a broken IC203 in most cases the resistance between the VDD rail and GND is very low, only a few ohm or less. Here you find a testpoint for VDD (Vdd). Please remove all the boards from the mainboard before checking.
A value around 9 kOhm or more is ok.

And what is the fix if that is the issue.
No fix until now.

73, Ludwig

 

Ludwig

With all boards removed I get 16.1 Ohm at VDD if I am reading the meter with the correct scale.? See Picture,??

I checked the power board, I have a version 3 board and I do not have a short.? I checked the resister and diode and they both check good.??

With all the boards reinstalled and with power applied....

At PCB#1 I show Vin (batt level) as 7 or 12 volts depending on what I am limiting the supply to.?

Power_on shows the battery voltage that is supplied.? When the left encoder is pressed it does short to ground as expected.?

VDD shows still reads 16 Ohm with the board power supplied.? ?It also shows a connection to ground which I think is correct???

everything else at PCB#1 and PCB#2 shows as 0 volts which I would expect since the firmware has never been loaded so it has not yet booted.??

What else should I be looking for???

Thanks very much for your help?

73 AA4NO
Bill
 

On Tue, Jun 11, 2024 at 07:35 PM, Bill - AA4NO wrote:
With all boards removed I get 16.1 Ohm at VDD if I am reading the meter with the correct scale.
Bill, sorry, it's bad. This means you have a broken element connected to the VDD rail.

With all the boards reinstalled and with power applied....
...VDD shows still reads 16 Ohm with the board power supplied.
???, did you measure resistance with power connected and left encoder pressed? This brings wrong results and your DMM is endangered.

You should measure voltage at Vdd with power supplied and left encoder pressed.

73, Ludwig
 

Bill, btw is this at the picture a yellow fabric? If yes, is it antistatic?

73, Ludwig
 

it is a fabric, not specifically anti-static.??

So new symptoms.? I tried to power it up again and this time I noticed that after the left encoder was pressed the voltage did not drop and I could see a current draw of about .3 amps.? I connected the USB cable and a QMX drive showed up.? Happy Days..... but a after about 30 seconds the drive disconnected.? Powered the qmx off and then tried again.? Same results, Drive shows up but only for 30 seconds,?

Then I noticed some heat from the QMX and found IC101 on the power supply was HOT to the touch.? Close inspection and no solder bridges.? Also no more USB drive showing up even briefly.? ?

Looking at the group messages but don't see anything similar yet.....?

Bill
 

On Tue, Jun 11, 2024 at 10:27 PM, Bill - AA4NO wrote:
it is a fabric, not specifically anti-static.
Bill, maybe it could collect electric static charges. This would be dangerous for the QMX and other modern electronic parts.

and I could see a current draw of about .3 amps.
0.2 A would be fine. But lets go forward. The whole time before the firmware is working IC101 regulates the 3.3 V (see here). When using 12 V you have a voltage drop of around 8 V. This makes around 2.4 W loss by IC101 and will heat the circuit more than for 0.2 A.

?IC101 on the power supply was HOT to the touch.
but a after about 30 seconds the drive disconnected.
Inside IC101 is a thermal overload protection. I guess this kicks in and switch IC101 off.

So you have to search for the to high load at VDD rail. Check visual around the VDD rail. Check the resistance from VDD to GND (see here Debugging - No 1)

Later for tests you may use only 7 ... 9 V input to lower the thermal power at IC101. But don't load the firmware. First search the cause for the 0.1 A additional current. Check the relevant elements for higher temperatures. It's only 0.33 W, not so much heat and maybe not enough to find it. Check the exact voltage at VDD (see here).

73 Ludwig
 

On Tue, Jun 11, 2024 at 11:39 PM, @Ludwig_DH8WN wrote:
Check visual around the VDD rail. Check the resistance from VDD to GND (see here Debugging - No 1)
Please check it again to see is there a difference to 16.1 Ohm before.
 

Thanks for all your help,?
The VDD is up to 23.5?

I don't see any shorts,? I am not sure how to follow the rails.? I am looking at the schematic but don't really understand it that well.? I have the voltage limited to 7 volts and current to .350 amps.? I connected a USB cable but I no longer see a USB drive.? ?
 

On Wed, Jun 12, 2024 at 02:00 AM, Bill - AA4NO wrote:
The VDD is up to 23.5?
Bill, I guess this is the resistace 23.5 ohm?

In this situation the controller could be faulty, no repair (until now.) But you found some short USB connections. So the controller maybe not broken, good mesage.

To get a consistent picture please collect a consistent set of data.
Use 7 V supply limited to 0.35 A for Step 1 to 5.

Step 1: measure the real supply voltage using your DMM when left encoder pressed.
Step 2: measure the real supply current using your DMM when left encoder pressed.
Step 3: measure the real internal voltage at "+12V" using your DMM when left encoder pressed.
Step 4: measure the real internal voltage at "VDD" using your DMM when left encoder pressed.
Step 5: Check temperature of IC101 after pressing left encoder for 20 seconds or so. Hot like decriped before?
Step 6: Without supply check resistance from "+12V" to GND with all the sub PCB connected to the mainboard.

73, Ludwig
 

>>>> Bill, I guess this is the resistace 23.5 ohm?

YES 23.5 ohm,? what should it be??

>>> In this situation the controller could be faulty, no repair (until now.) But you found some short USB connections. So the controller maybe not broken, good mesage.

To get a consistent picture please collect a consistent set of data.
Use 7 V supply limited to 0.35 A for Step 1 to 5.

Step 1: measure the real supply voltage using your DMM when left encoder pressed.
? ?Voltage in was 7V,? when the left Encoder pressed it dropped to 6.8V?

Step 2: measure the real supply current using your DMM when left encoder pressed.
? ?Current was Zero, when left Encoder pressed it was .35 which was the limit.? I increased the limit slightly and it stabilized at .365 amps

Step 3: measure the real internal voltage at "+12V" using your DMM when left encoder pressed.
? ? 6.62 volts measured

Step 4: measure the real internal voltage at "VDD" using your DMM when left encoder pressed.
? ? 2.72 volts

Step 5: Check temperature of IC101 after pressing left encoder for 20 seconds or so. Hot like decriped before?
? ?It is still warm, You can touch it but if you hold your finger on top it gets very warm.?

Step 6: Without supply check resistance from "+12V" to GND with all the sub PCB connected to the mainboard.
? ?22 oms was measured?

I also noticed that the STM 32 processor is a slightly warm to the touch.?

No USB Drive shows up so that only worked for a few minutes a few times.? ?

Thanks very much for all your help,?

Bill
? ??

1 - 20 of 31