From KeepWalking188 at ac0c.com Tue Feb 18 14:06:35 2025 From: KeepWalking188 at ac0c.com (Jeff Blaine) Date: Tue, 18 Feb 2025 13:06:35 -0600 Subject: [Skimmertalk] QS1R rescue - almost there... But not quite Message-ID: <8b56b853-c0c2-469a-8aff-29524d4e6248@ac0c.com> I've been working on a QS1R and have it mostly operational. Unfortunately in the case of an SDR, "mostly" also means "not yet" operational from a "does it do something useful" standpoint. Wanted to see if anyone had any comments on the symptoms observed.? At this point I'm out of ideas... Background:? The unit was subjected to reverse voltage and was thought to be operational.? There was shipping damage with some adhesion-attached heat sinks coming loose in transit and banging around in the box enough to knock a couple of the larger electrolytic loose.? The reverse protection diode had exploded but the voltage regulators are all operational and functioning correctly.? physical component damage has been repaired with replacement caps and a close examination for physical damage under magnification has been performed. General operation - current draw are consistent with an operational unit; several hundred mA at idle, and about 1.3A with Skim Server loaded, without a big spot loading.? Voltages on the several regulators are stable and noise levels are the same as the operational unit.? Heating and cooling and flexing the board shows no impact to the operational status. On the chance that the often cited USB chip was at fault, I did manage to replace it (which initially was "how hard can that be" only later to become "I'll never do THAT again...") with no change in board behavior.? So that's not part of the problem. LED:? In the operational unit, LED D2 (LED most near the board edge) is lit, and adjacent LED D3 (2nd from the edge) is not lit. But in the defective board, LED D3 is lit as well as D2.? This is the only visually observable difference seen.? Power LED is on, CLIP light is off as normal.? From the VERB manual, I think the illumination of D2 means "program loaded" (VERB manual, page 14). This seems to imply that the FPGA and the USB are in fact functional, at least from the ability to handle USB transactions and get the FPGA loaded. Further on the CLIP led.? I was thinking maybe the ADC function could be established using the CLIP as an indicator of overload so that I would know the ADC is doing it's thing.? However I could not get a CLIP indication with even +15 dBm on the board which caused me to think maybe the ADC was dead.? Unfortunately this is not conclusive as on the operational (known good) unit, the CLIP indication does not fire either at this level and given the cost of the ADC, I'm not interested in possibly destructive testing of the ADC...? So for now, I'm assuming the ADC is working although that's a stretch. External clock:? both units are configured for external clocking.? This provides an additional diagnostic via the CLIP LED.? When an application is loaded, and there is no clock signal, the CLIP light will light.? With the clock signal connected, the CLIP light extinguishes.? This behavior is the same in both the operational and defective unit.? I'm assuming this means the ADC is at least somewhat operational as the CLIP light is run directly by the ADC. Running Skim Server, the USB device shows up in device manager. The FPGA loading window comes up and completes, and skimmer opens.? Then skimmer toggles between "SDR RECEIVER OK" and "SDR_FAILURE: USB_BULK_READ FAILED" on a several second basis. From a prior post, there was a comment about the voltage regulators cutting out and causing this effect but monitoring the regulators at the time this is occurring shows stable power on all regulator outputs. Running the QS1R SDR app, the server applet loads with success. The GUI loads as normal.? But when RUN is clicked, there is no further response by the app. Appreciate any advice or insights from guys who may have been there, done that and got their QS1R to rock and roll for another day.? Thanks! -- 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com From N9CO at aol.com Tue Feb 18 14:46:10 2025 From: N9CO at aol.com (Charlie Ocker) Date: Tue, 18 Feb 2025 13:46:10 -0600 Subject: [Skimmertalk] QS1R rescue - almost there... But not quite In-Reply-To: <8b56b853-c0c2-469a-8aff-29524d4e6248@ac0c.com> References: <8b56b853-c0c2-469a-8aff-29524d4e6248@ac0c.com> Message-ID: <4e65e6b2-a2b9-4d9c-b309-f56d343146fd@aol.com> On 2/18/2025 1:06 PM, Jeff Blaine wrote: > Running Skim Server, the USB device shows up in device manager. The FPGA > loading window comes up and completes, and skimmer opens.? Then skimmer > toggles between "SDR RECEIVER OK" and "SDR_FAILURE: USB_BULK_READ > FAILED" on a several second basis. From a prior post, there was a > comment about the voltage regulators cutting out and causing this effect > but monitoring the regulators at the time this is occurring shows stable > power on all regulator outputs. Hi Jeff, I recall seeing this when I was getting my used QS1R up and running a couple of years ago. I believe it went away once I applied 6vdc to it. Before, I was trying to use 5vdc. I've heard from others that a sure way to fry a QS1R is to apply 12vdc to it. 73, Charlie N9CO