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Troubleshooting - Self Test Failures

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In the following troubleshooting procedures, always remove power by disconnecting the 12 volt DC power cable before swapping components.

Q: The Processor Test is failing.
1. If none of the LEDs on the PIC processor board are lit, check for 5 volt power on the PIC Processor Board. Verify that the white push button on the PIC Processor Board is in the up position and that the jumpers on the PIC Board are in their correct locations as described in the Assembly Manual. The normal state of the LEDs on the PIC board is for one red and one green LED to be lit.

2. If you hear a 2 second beep on power-up, and the rest of the processor tests fail, if you see the Modtronix message on the LCD and it does not change,  or if the backlight is not lit in the LCD, check the Processor-to-LCD connectivity as described here.
 

3. If the above steps check OK, check that the LCD daughter board dip switch settings as described here.

4. If the above steps check OK, check that the processor SPI bus as described here.

 

Q: The Front Panel Switch Test is failing.
1. With none of the Front Panel Switches depressed, the LCD message should indicate "NO INPUT SIG DET". If a switch is incorrectly being reported as pressed, check for a ground (0 volts) on one or more of the nine input leads (GPB0 - GPB7, and GPA0) on the I/O Expander chip (MCP-23S17). With no switches depressed, there should be no grounds on any of these pins.

2. If one or more of the switches do not register on the LCD when pushed, confirm that the corresponding switch is applying a ground to the correct input lead of the I/O chip when pressed. If the expected ground is not detected, the problem lies in the related traces on the Switch Board or Controller Board, on on the ribbon cable connection that routes the switch signal to the Controller Board,

3. If the above steps check out OK, check for activity (pulses) on the following pins of the I/O Expander chip (MCP-23S17):
CS,   SCK,   SI,   SO,   INTA.

 

Q: The Panel Meter Test is failing.
Note - If you do not have external meters connected to all four external meter jacks, you can test these ports with a voltmeter. You should see a voltage appear for one second on each of the external analog meter jacks. If you did not install the Expansion Kit components, you will not see any outputs on the external analog meter jacks.

1. If only some of the 6 analog meter outputs are failing to generate a signal and drive the meter needle if connected, check the associated trim pots to make sure they are not at their minimum CCW position.

2. If a signal is missing on only some of the Panel Meter outputs, run the test while measuring the voltage on pin VoutA or VoutB  on the MCP-4922 chip associated with the failure. The self test routine drives each output signal to 1/4th the maximum output value (1.25 volts) for one second. If  you detect this voltage on the chip, but it is not reaching the RCA jack, there is an open between the chip output and the RCA jack including the path through the trim pot. Trace the path to find the problem.

3. If a signal is missing on just one of the two D-to-A outputs on the MCP-4922 chip, disconnect the 12 volt DC power cable from the meter, remove that MCP-4922 chip from its socket, and use a multimeter to determine if the VoutA or VoutB output that has no output is shorted to ground.

4. If the failure is associated with both outputs of the same D-to-A IC, swap a working MCP4922 with the one that has no output to determine if the problem propagates with the IC. If the ICs are OK, check the power, clock, and chip select pins on the device that is failing.

5. If the failure is associated with all six of the D-to-A outputs,  check the power, clock, and chip select leads on all three D-to-A ICs.

 

Q: The Seven Segment Display Test is failing - Internal 7-Segment LEDs
The self test for the 7-segment displays tests both the internal and external 7-segment LEDs. This section applies if you have a problem with the internal 7-segment LED displays.

1. If none of the internal 7-segment LEDs are lit, check for power on the Display Board, which is supplied from the Controller Board to the Display Board on the JPWR IDC ribbon cable which connects the two boards.

2. If the two left four seven segment modules are operating properly, and the two right modules are not operating properly (or vice versa), check for power on the IC power pins, and for pulse activity on the SPI-OUT, SPI-CLK, and chip select pins on the MAX-7219/Max-7221 LED driver IC associated with the malfunctioning modules. (The driver chip located below each group of LED modules is If the chip that controls those two modules.)  If the power and clock signals check out, remove power. Then swap the LED driver chips (MAX 7219/7221) to determine if the problem propagates with the IC.

3. If only one 7-segment digit  has a problem, swap that LED with another to determine if the problem propagates with the LED. If not, check the trace(s) between the seven segment driver and the malfunctioning LED.

 

Q: The Seven Segment Display Test is failing - External 7-Segment LEDs
The self test for the 7-segment displays tests both the internal and external 7-segment LEDs. This section applies if you have a problem with the external 7-segment LED display.

 

If the external 7-segment is not working and you purchased your MB-1 after 10-8-2012, it is possible that you need make a setting change that is easily accomplished. See the section below on changing the external 7-segment display type to determine if a setting change is required proceeding with detailed troubleshooting below.

 

If you have type C modules, you can temporarily ignore the results of this test.  After completing the remainder of the self tests, follow the procedure below to change the setting to a "C" device. Then simply repeat the self test to verify that the 7-segment external display works properly with the new setting.
 

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The following assumes that you are using the 1.5 inch external 7-segment display module that comes with the Expansion Kit. When testing any of the external modules, make sure that you connect the ribbon cable to J1 of the external display module (and not J2). Make sure that the 5 volt power option is selected for both external displays (EXT1 and EXT2) on both of the 3 pin headers on the Controller Board. Applying 12 volts to a 5 volt external display module can destroy it. 

The different size external 7-segment display modules use different software drivers.  if you are using the 1.5 inch 7-segment module included with the Expansion Kit for this test, make sure to set the driver type (field 4 of the 7-Segment menu for LED module 5 (the external 7-segment display connected to the EXT1 rear panel jack) ) to "A". This is the default value.

1. The Default MB-1 configuration is for one external 7-segment display module (driven from the EXT1 connector on rear panel) and one external bar Graph module (driven from the EXT2 connector on rear panel). If the external 7-segment display does not work properly when plugged into EXT1, temporarily configure MB-1 to drive two external 7-segment displays. To do this, power down the unit. Then press Menu 3 (M3) while powering up the unit.

Using the 7-Segment menu, set field 4 of module 6 to driver type "A". Plug in the external 7-segment module that did not operate properly when connected to EXT1 into EXT2. Both EXT-1 and EXT-2 are now configured to drive external 7-segment displays, and both rear panel connectors will be exercised with the 7-segment test pattern when running the self test.

2. Rerun the self test. If the module that did not work properly when plugged into EXT1 now works when plugged into EXT2 , check the voltages and signals on rear panel connector EXT1.

If the problem persists, check the voltages and signals on both rear panel connectors EXT1 and EXT2. These two connectors share some common signals.

 

Q: The External Bar Graph test is Failing.
When testing any of the external modules, make sure that you connect the ribbon cable to J1 of the external module (and not J2). Make sure that the 5 volt power option is selected for both external displays on both of the 3 pin headers on the Controller Board. Applying 12 volts to a 5 volt module can destroy it. 

1. Make sure your MB-1 is configured to operate with one external 7-segment display module and one external Bar Graph module. This is the default configuration.

As a quick check that the meter is configured for External Bar Graph operation, try to select 7-segment module 6 with the Seven Segment menu. If you can select 7-segment module 6, you are configured for two external 7-segment modules and can not exercise the external Bar Graph in this mode.  To reset the default configuration, power down the unit. Then press Menu 4 (M4) while powering up the unit. This will reset the default external module configuration. You can now repeat the test of the external Bar Graph module.

2. If the above tests do not resolve the problem, temporarily configure MB-1 to drive two external 7-segment displays. To do this, power down the unit. Then press Menu 3 (M3) while powering up the unit. Configure 7-segment module 6 to display a value (any setting except off). Make sure to select driver type "A" from field 4 of the 7-Segment menu.

Plug in the external 7-segment module to rear panel connector EXT2. If the 7-segment module connected to EXT2 works properly, the wiring and signals to EXT-2 are OK since the same physical signals are used to control both the External Bar Graph and the External 7-Segment Modules on this connector (just using a different protocol). If the External 7-segment module also does not work in this test, check the voltages and signals on rear panel connector EXT-2.

 

Q: The RS-232 Transmit Test is failing.
1. Make sure the jumper leads from the PIC Processor Board to the 40 pin headers are connected as shown in the Assembly Manual. Also, make sure you have TeraTerm configured properly as described in the User's Manual.

2. During the RS-232 output test, determine if there is pulse activity on the XMT-R lead (on the PIC Processor Board) and the XMT lead on pin 3 of the DB-9 connector). If pulses are present, the problem is probably with the PC cabling or the PC configuration. If you detect a pulses on XMT-R but not on pin 3 of the DB-9 connector, check the traces.

 

Q: The RS-232 Receive Test is failing.
1. Make sure the jumper leads from the PIC Processor Board to the 40 pin headers are connected as shown in the Assembly Manual. Also, make sure you have TeraTerm configured properly as described in the User's Manual. Also make sure that when you send the 'a' character to MB-1 TeraTerm that you have first selected the TeraTerm window (e.g., with a mouse click) before sending the character from the PC.

2. At any time (you need not be running the RS-232 input self test ), hold a character key down on the PC to send a constant stream of data to MB-1. If you do not see a pulse train on lead RCV lead on the PIC Processor Board, but do see a pulse train on pin 2 of the DB-9 connector, check the traces between the DB-9 connector and the PIC Board. If you do not see a pulse train on pin 2 of the DB-9 connector, the problem is probably with the PC cabling or the PC configuration.

 

Q: The Front Panel Pot Test is failing.
1. Check the voltage on the center tap of the front panel pot and verify that it changes from 0 to approximately 5 volts as the pot is turned CW through its full range

2. Verify that the voltage on lead CALIB-POT-FILT that connects to the RA1 pin of the PIC Processor Board varies from 0 volts to approximately 4.1 volts as the pot is turned CW through its full range.

3. Verify that the voltage on VRef+ that connects to pin RA3 on the PIC Processor Board is approximately 4 volts (4.096v).

 

Q: The Coupler Port Test is failing.
1. Make sure that none of the coupler trim pots is set to its minimum travel. If this is the initial test after assembly, and if you have not yet calibrated any of the coupler trim pots, adjust each trim pot to approximately half its travel (7 1/2 turns CW - exact setting not critical.)

2. With no signal applied to any of the 8 coupler inputs, if you are seeing a coupler port being reported as detected (e.g.., SIG DET ON COUP 2 ON FWD PORT), check the voltage on the MCP-6S28 Amplifier/Mux chip pin corresponding to the signal that is being reported in error. In the COUP 2 FWD PORT example above, it would be the C2-FWD-IN lead on the CH2 pin of the MCP-6S28 chip. The voltage should be close to 0 with no input is applied to the corresponding RCA jack. If that is not the case, determine the source of the stray voltage.

3. If only some of the coupler input ports do to not properly declare a "signal detected" condition when a signal is applied to the corresponding RCA jack, check the corresponding input pins on the MCP-6S28 to determine if you see a voltage when a signal is applied to the RCA jack. If you do not see a signal on the CH0 - CH7 pins of the  MCP-6S28 with a signal applied to the corresponding RCA jack, check for a short to ground or an open in the path between the CH-n lead and the RCA jack, including the coupler trim pot.

4. Make sure that the ground connection on the associated coupler trim pot is soldered properly. An absent ground on a coupler trim pot will cause that coupler channel to report incorrectly during the self test.

5. Check the power pins, and the clock pins SCK, SO, SI, and CS on the MCP-6S28 for pulse activity.
 

 

Q: Forward Power is always reading 0. 
Make sure that the meter is not in the Reflected Channel Calibration mode (indicated by an flashing yellow LED on menu button M2). If the LED is flashing, apply a long push to M2 to turn the Reflected Channel calibration mode off.

 

Q: My meter sometimes displays low power values with no transmit power being applied. 
You have a coupler that is not sensitive enough to generate an adequate DC voltage at very low power levels. When you calibrated the coupler at these low power levels (e.g., .05 watts), the ADC value for the corresponding power level, while non-zero, is operating in the vicinity of the A-to-D noise floor for that power level, and therefore some nonzero measurements may be displayed when no transmit power is being applied. When such calibration points exist, even small induced voltages on the antenna can cause these readings.

Use the DISPLAY function for the coupler in question to examine the ADC values associated with the very low power calibration points. If these numbers are very small (<10), your coupler is not generating enough voltage for reliable operation at these low power levels. The solution is to edit the coupler and simply DELETE these low power calibration points.

Power levels with associated ADC values greater than 20 should not encounter this problem. Just for comparison, the MB-HF1 coupler is a fairly sensitive coupler and generates an ADC value of approximately 150 at the lowest power calibration point (.05 watts) when calibrated for a full scale value of 1000 watts.  The "Interfacing your own Couplers" page has some guidelines that will help you understand the restrictions when using your own couplers with MB-1.

 

Q: I am applying a signal on coupler port 1, but I am seeing measurements displayed when I select other coupler ports that are not connected.  
The corresponding coupler trim pot adjustment for your coupler (coupler 1 in your case) is set too high causing that signal on that coupler port to overdrive the corresponding input lead of the Multiplexer/Amplifier chip (MCP-6S28).  The input leads of this device have a maximum rated voltage range of -0.3 volts to 5.3 volts when powered from 5 volts. If you overdrive any of the eight input leads of this device beyond the rated limit of 5.3 volts, that signal will be coupled to the output of the multiplexer even though the software is not selecting that input lead.

Since the maximum output of the 15 bit input chain is 32,767, if you follow the calibration procedure of adjusting the coupler trim pot to achieve an ADC output of approximately 30,000 when the input device is generating its maximum full scale voltage, you will not have this problem. The maximum ADC output occurs when the coupler port input signal  (after being reduced by the voltage divider formed by the 100K input resistor and the setting of the 200K coupler trim pot) is exactly 4.096 volts at the input lead of the MCP-6S28. (4.096 volts is the voltage generated by the MCP-1541 voltage reference chip and used by PIC ADC converter to define its full scale output.) Therefore, setting the ADC count to 30,000  with the coupler trim pot when the maximum DC voltage from the input is being applied to the coupler port guarantees that the corresponding signal on the multiplexer input lead will always be less than 4.096 volts.

 

Q: If I place my transceiver into transmit, and sweep the frequency dial across the full 500 kHz spectrum of one of the Amateur bands, I see several frequencies within the 500 kHz range where the analog meter seems to momentarily drop out.  Is this a bug?. 
This is not a bug. When I first saw this, it surprised me as well.  (At the time, I had two of the other popular meters inserted in series with the MB-1 and neither one picked this up, convincing me, initially, that this was a software bug.)

Here is the explanation. When tuning across a band on some modern transceivers, the VFO implementation is such that some switching takes place at discrete frequency points. As you "roll through" these frequency points and the switching takes place, you will see a momentary signal loss of a couple of milliseconds if the transceiver is transmitting, or you will sometimes hear a click at these frequencies if the transceiver is receiving. Because the MB-1 has a very high update rate and measures  instantaneous power, MB-1 will capture these short dropouts and you will see their effect on any of MB-1's  fast acting display devices such as the analog meter or bar graph. The Min/Max feature will also pick up these "hits" if you configure the Min/Max feature to monitor TUNE (instantaneous) power.

 

Q: The linearity of the front panel pot seems to have changed. The step size at the high end (max CW) of the pot travel seems to be smaller than I recall.
You have connected a low resistance load to one or both of the RCA jacks labeled FR POT on the rear of the meter. These jacks are designed to provide a high impedance variable voltage source of approximately 0 - 5 volts for prototyping or test purposes.  This voltage is controlled by the front panel pot.

The wiper of this pot feeds these RCA outputs through a 5.1K resistor. It also feeds an A-to-D channel on the controller, which is read by the software during calibration and parameter adjustment functions. The low resistance load from the RCA jack is therefore affecting linearity as seen by the A-to-D channel on the controller.

Even with a dead short on the FR POT RCA jack outputs, you should be able to obtain the full range of meter control and calibration functions using the front panel pot, although the step size will be smaller at the high end of the potentiometer's travel. It is therefore suggested that these FR POT utility outputs on the rear of the meter be disconnected during normal operation to avoid this problem.

 

Q: I am trying to program the simulation values for one of the virtual couplers (coupler 5) using the Coupler Setup. I have the coupler menu displayed on line 4 of the LCD, but when I enter Setup, I am only able to choose the real coupler numbers (1 - 4).
The coupler setup (calibration) function applies to the real couplers only (1-4). To program the simulated full scale power and SWR values for any of the virtual couplers (5-8), select the DEMO menu instead on line 4 of the LCD. Then press the Set-Up button. (i.e., the virtual couplers are a subset of the Simulator, and therefore associated with the Demo (simulator) menu, not the Coupler menu).

 
 
Q: I plugged an external analog meter into a rear panel RCA jack on MB-1, and the meter needle now looks like a pretzel.
You inadvertently plugged the meter movement into one of the two 5 volt auxiliary power RCA jacks. These are the only RCA output jacks that are capable of damaging a meter movement to that extent. It is recommended that you place two blank RCA plugs into the 5 volt auxiliary RCA power jacks to prevent this from happening again. Remove them only when you need to access the 5 volt auxiliary power source.  (Two blank RCA plugs are included with the Expansion Kit.)

 

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7-Segment External Display Modules - Modifying Default Setting

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SURE Electronics, who makes the external 7-segment display modules, has two different designs for the 1.5 inch 7-segment  modules that MeterBuilder provides with the Expansion Kit, both of which will work with MB-1. MB-1 is shipped with a default  setting for a type "A" device. However, some of the SURE 1.5 inch external 7 segment displays are type "C" devices, which require a different setting.

To determine if the type of external 7-segment module, look at the rear of the 7-segment module. If it has surface mount resistors (see below) it must be configured as a type C device. If it has discrete resistors, the default setting of type "A" is correct and does not need to be modified.

 

Steps for Changing the Default setting for the external 7-segment display for type C  for 1.5 inch 7-segment Display Modules

1. Turn the meter on. Select the Digital (Seven Segment) Display menu by tapping the the second button from the left on the bottom row of buttons.
    
2. With the 7-segment display menu selected on line 4, select module D5 on the menu line by tapping M1 (menu button 1) repeatedly until D5 is displayed. This selects the first external display module. You will see that the fourth field in the line 4 menu is set "A" (type A device). This should be changed to "C" (type C device). Do this by tapping M4 (menu button 4) repeatedly until the value in the fourth field changes to "C".
    
3. To save these settings so that they are automatically restored the next time you power up the meter, apply a long press to M1 (menu button 1). You will receive a confirmation message that settings have been saved.

If you plan to use two 7-segment external displays with MB-1, simply repeat the above procedure for module D6 (the second external display) after configuring the meter for two external 7-segment displays. See the User Manual for details on configuring MB-1 to work with two external 7-segment display modules.