Tektronix AWG20xx power supply R174 value

[aeg]

Does anyone know the resistance of R174 in the Tektronix AWG2041's power supply? Mine is smoked - open circuit . Tektronix didn't publish schematics. The same power supply is also used in the AWG2005 and in AWG2021 S/N J300101-J320100.

[BlownUpCapacitor]

I see several other similar looking vertically mounted PCBs on that main board. Desolder those and see if the two working and non working boards have identical layouts. If so, look at the value of the resistor on the good one and you got your resistor value.

While you're at it, check the other components to see if they are faulty or not. Resistors don't just burn out randomly. Something sorted in this PSU...

[aeg]

The board with the open resistor is different from any of the others. They all have a resistor in series with the 2SA1220A collector, but the values vary. I already checked the semis on the small board and none of them are shorted. There are two bad caps on the primary side but I can't see how they would cause a resistor in a postregulator(?) on the secondary to fail.

[BlownUpCapacitor]

In that case you can try to reverse engineer that PCB with the burnt resistor and create a schematic.

Using this schematic, you can try and find possible values for that resistor.

ei:
If it's a pulldown resistor for a FET, generally nearly any resistor value between 10k and 50k would work fine.

If it's a voltage divider that's meant to create a specific voltage, and you know that specific voltage it should output, you can calculate the value of the resistor.

etc...

Make an educated guess and choose the largest value and go down from there. Largest, to smallest resistance value.

[aeg]

Thanks for the suggestion. I would prefer to wait and see if someone with the same instrument can tell me what resistor the factory installed.

[gianrisa]

Hey I hope this will help you the resistor is a 51 ohm here the picture !

Let me know if you need any other values. I have my awg2021 open because I have a trouble on the chain  Waveform Mem -> DAC, I don't know yet if the ram data is stuck or the ram address doesn't get selected correctly or the DAC is faulty
I've discovered that the board A21 has all the D0-D12 clock and CE CS exposed there so my next try will be to connect the Logic analyzer there and check what's going on. I hope it is the ram and not the DAC, that will be quite hard to find it.

Let's see.

Cheers Gian

[aeg]

Thank you Gian! I hope you get your AWG2021 working.