PA-100D Fan always on?

[JK1QLQ]

I just received my PA-100D and absolutely love it; however, the fan is always on and frankly has a whine pitch that drives the XYL nuts. Reading the manual page 10 under Fan Cut-In Temperature, it seems to imply that on Normal setting the fan does not even turn on until Cut-In Temperature. Mine comes on as soon as I power on the amplifier, irrespective of heat-sink temperature. Is this normal?

[EDIT: Update; only a few hours later, now my PA-100D will not transmit, fan stopped turning and temp shows 0C. All settings were default and working fine. Amp was on but had not transmitted in a hour when I tried to transmit again and it would not. Amp controls and configurations fully functioning otherwise. No smoke or other indications of abnormality.]

[EDIT#2: To make matters even more odd, now my PA-100D will not power back up using the power button after powering down using the power button. Yet, if I do a hard reset with the power cord (i.e. unplugging and plugging back in) the amp will power up. Above issues remain.]

73
Scott JK1QLQ

[5B4AIY]

Those are an interesting set of symptoms. What firmware are you using? Is it the original or my firmware? In order to proceed, I presume you have the full schematics, if not, please download them as we will need to make some measurements, as well as run some tests.
Adrian, 5B4AIY

[JK1QLQ]

Adrian, thanks for the quick reply! It shows version 4.1a on startup. Yes I have the schematics, however, since I literally just received the unit new from roWaves I'm more than a little afraid to open it up and start poking around. I'm currently awaiting a response from their support team. I threw it out here on the remote chance it was a known and easily fixed quirk.

73
Scott JK1QLQ

[5B4AIY]

I can understand your reluctance to open the unit, and, if it is still under warranty, then it would indeed be best to await Rowaves response. Rowaves is actually using my firmware, so if it comes to it and you have to diagnose the fault(s) yourself, then we at least start from a well-known point. From your description, you seem to have several problems:

1. Inability to power up from front panel;
2. Fan continuous operation;
3. Temperature reading always 0C.

There is no common factor here, other than the +5V bus, but if the microprocessor is on, and you can switch to the calibration and configuration menus, and change things, then the +5V bus must be OK. The 'least intrusive' thing I can suggest without invalidating the warranty would be a complete hard reset. Before doing this, however, make a note of your calibration and configuration settings. Since you are running my firmware, these can be dumped via the serial port using a terminal program. Once you have done that, then you can proceed with a hard reset, if you have not already done it that is.

If Rowaves cannot assist, then let me know and we can investigate.

73, Adrian, 5B4AIY

[JK1QLQ]

Adrian,

I truly appreciate your interest and support! Here is the current situation (only one slight clarification):

1) Inability to power up from front panel
2) Fan does NOT operate (Initially the fan was in continuous operation despite temperatures showing below 40C (default cut-in) and Fan Control set to Normal; but, after only 3 hours the unit failed)
3) Temperature reading always 0C

Yes, I can enter and navigate the configuration menu; but, I have not tried the calibration menu. I do not currently own a USB RS232 to 3.5mm cable, so just ordered one (should have by next week). I have not tried nor familiar with either how to do a hard reset or settings dump. Quickly scanning the manual, is it fair to presume they are terminal Command D and E respectively while in serial test mode?

73
Scott JK1QLQ

[5B4AIY]

In order to connect to the amplifier's RS-232 port you will need to make a cable with a 3.5mm stereo (Tip-Ring-Sleeve) plug on one end and a female DB-9 connector on the other end to connect to the male DB-9 connector of a standard USB to RS-232 adaptor.

With the internal jumpers on the Frequency Sense board in the NORMAL position, the tip of the 3.5mm plug is RX-Data, the ring is the TX-Data. The tip has to be connected to pin-3 of the DB-9, and the ring to pin-2, and the sleeve or screen connected to pin-5 of the DB-9 connector. (This is for a standard USB to RS-232 adaptor.) If the internal jumper is set to the PROGRAMMING setting the tip and ring connections are reversed.

You will also have to enable the Serial Test suite in the User Configuration setting, as it is normally defaulted to OFF. In order to enable it, you must also select a non-serial frequency sense mode, also in the User Configuration menu. (See Serial Port Mode on page 8 of the User Manual)

Once you have done this, connect your serial cable to the USB to RS-232 adaptor, plug the adaptor into your computer and identify the COM port, and then launch a serial terminal program. For all my testing and software development I used Simple Term. By entering '?' at the terminal you should get the response from the amplifier as shown in Annex A, pages 21 through 27 of the User Manual.

To display the calibration and configuration settings, enter 'E', and you should see them dumped. Simple-Term allows you to copy the screen contents to a file, or else simply make a note of the settings on pages 42 and 43 of the User Manual.

Once you have made a note you can now perform a hard reset. With the amplifier powered OFF, press and hold the BAND+ button and turn the amplifier on. (As you cannot turn it on from the front panel, you will need to place a jumper on J4, and then turn the main power supply on.) See page 6 of the User Manual.

Once you have reset the amplifier, see if that has changed anything.

As for the temperature always showing 0C, if a hard reset does not fix this, it indicates a fault in the Bias & Temperature sensing logic, and you would need to make some measurements. This would be somewhat intrusive, so wait for a Rowaves response.

You can always test to see if the amplifier will go into transmit, plug a standard 3.5mm to 3.5mm stereo patch lead into the T/R socket, select the OPERATE mode, and ground the tip to the chassis, the amplifier should go into transmit. If the bias supply is operative, then you should see bias current when you switch to the current display. If in transmit there is no current displayed, then this confirms a bias fault.

Adrian, 5B4AIY

[JK1QLQ]

Adrian,

Thank you for the very detailed instructions. Hopefully the USB RS232 to 3.5mm cable I ordered will work. The only one I could find pre-made was designed for use with the Intel Galileo; however, the pinouts tip-RX, ring-TX, sleeve-GRD are the same. If not, I will have to go the route you describe to fabricate one.

In the meantime, I did try your last suggestion to see if I could get the unit to go into transmit. Sadly, it appeared to not. I tried grounding the T/R tip to chassis and the unit showed no change in Amps nor make any sounds.

Andrei at roWaves did contact me and I've already forwarded more details, photos & videos to him. I hope we can come up with a solution soonest.

Thanks again!
73
Scott JK1QLQ

[5B4AIY]

You have more than one fault here. With electronic equipment, there is a phenomenon called 'Infact Mortality Failure'. If you were to plot the failure rates of a large number of samples of a device versus time you would see a large number of failures early on, decreasing to a small amount over the majority of the lifetime of the equipment, and then rising due to wear-out and end-of-life failures, the well-known 'bathtub' shaped curve. This is why we have a warranty period. If it is going to fail, it is likely to do so early on in its life. In your case whilst I could accept a single fault, say, with the bias supply, or the power logic, or the T/R logic, to get all of these points to a much more serious problem, and in this case, I think that you will need to send it back to Rowaves.

I would be more than happy to assist you, but if these faults involve failures requiring replacement of SMD components, as seems likely, then unless you have had a fair amount of experience in doing this you could end up with badly damaged amplifier. In the worst case, if the microprocessor requires replacement that would be a VERY challenging exercise requiring a great deal of skill.

Nevertheless, if I can be of assistance, then please let me know. In any event let me know what Rowaves have to say.

73, Adrian, 5B4AIY

[JK1QLQ]

Adrian,

Truly appreciate your time and thoughts. I will definitely let you know what roWaves says.

Thanks for what you do for the community!

73
Scott JK1QLQ

[JK1QLQ]

Adrian

Quick update. I had not received any ack or reply to my original photos/videos/answers to roWaves questions on Monday, so followed up yesterday. They asked for another video and said they would respond on Friday.

My USB RS232 to 3.5mm cable arrived early and I was able to connect to the PA today, dump the USER & System Configuration settings, then hard reset the unit. Sadly, there was no change to how the amplifier operates. Still shows 0C temp, 0.1A, no fan activity, no transmit and inability to power up unit from front panel power button.

I will let you know what roWaves responds with on Friday.

Thanks & 73's
Scott JK1QLQ