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After checking the low RF output in the generator function, I ran the self test. But the self test failed, stopping at item 3 and not continuing.
I am attaching a photo of the test attempt.
I have had this for 5 years and have never updated it. But it has always worked perfectly.
The current firmware is version: tinySA4_v1.4-49-g4f5396a.

Model: TinySA ULTRA
I would greatly appreciate any help.

Just to rule out the obvious.

Did you test with different coax cable?

Is the call output set to 30 MHz visible on a scope?

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Designer of the tinySA
For more info go to

I checked the cables and adapters, they are ok.
I couldn't check the RF signal via oscilloscope, probably because the signal is too low.
But the 30 MHz signal is coming out, I tested it with an amateur radio receiver, on all frequencies, and with the same signal intensity for all.

I followed the procedures in the link sent to my email.
https://tinysa.org/wiki/pmwiki.php?n=TinySA4.FaultFinding
In the test, where 30 MHz is enabled and the analyzer is returned, my tinysa ultra does not show any peaks, it shows nothing.
According to the report, it is reported that the defect must be U22.
I am attaching a photo.

It's difficult to see in the photo but it seems the yellow trace does not go up to 0dBm at zero Hz

If this is indeed the case there is another problem which can not be easily repaired

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Designer of the tinySA
For more info go to

After the U22, it's the pe4312. I managed to find its datasheet. As for the U22, I couldn't find anything, it only has A79 written on its body. Do you happen to know exactly the value of the U22?

Please read last part of this page:

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Designer of the tinySA
For more info go to

One more detail, I made a jump on U22, it didn't work, but I made some measurements on the passive components around U22 and verified that Diode D4 is showing a short, I'll try to lift it to confirm. The other end of D4 doesn't go to ground. I tried to find the TinySA ULTRA electrical schematic, without success. Where can I get the TinySA ULTRA schematic?

On Thu, Feb 27, 2025 at 10:52 AM, Alejandro Zaragoza wrote:

Where can I get the TinySA ULTRA schematic?

The tinySA Ultra is not an open-source design so its full schematic has not been released to the public.? I believe you have to remove U22 from the circuit instead of just jumping it to verify operation:

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In my case, D4 seems not to conduct current at all. My diode test (DMM, applies 2.5V open voltage) does not show any diode voltage, regardless the direction. Perhaps, it's a bidirectional zener device with over 2.5V threshold in both directions.

The diode however is soldered, but it is a bit side tilted. What type should I use as replacement - if the diode is defect (abnormally not as short).

Rob

On Fri, Feb 28, 2025 at 05:29 AM, R. Maris wrote:

In my case, D4 seems not to conduct current at all. My diode test (DMM, applies 2.5V open voltage) does not show any diode voltage, regardless the direction. Perhaps, it's a bidirectional zener device with over 2.5V threshold in both directions.

The diode however is soldered, but it is a bit side tilted. What type should I use as replacement - if the diode is defect (abnormally not as short).

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