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My scope is only analog with 60 MHz bandwidth. Not very helpful for that.
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A 60Mhz analog scope will do. The problem is likely in the PLL control circuitry, which is relatively slow-responding. And the PLL clock output to the sequencer is no more than 40MHz anyway.
Since you don't have a spectrum analyzer, you won't be able to verify the RF output is actually correct. But it should be possible to troubleshoot the PLL lock.
If you decide to proceed with opening the unit, here is a test you can perform on the PLL:
Set up the dual arb generator using MODE Mutli-tone.. The default is an 8-tone carrier with 10kHz spacing. It will display temporarily it is creating a waveform. Then turn off multi-tone. You can turn on the RF or not. It doesn't matter since the arb generator continues to run with the RF off.
Go back to MODE and enable dual-arb. Choose Select Waveform and pick the waveform AUTOGEN_WAVEFORM. This is the multi-tone waveform it just created. Turn on dual-arb using the internal reference. Loading the multi-tone waveform in dual arb mode allows you to play with the various clock settings, which you can't do in multi-tone mode.
Take a look at the following test points. I have the same board as you, E4400-60187. Note that testpoints (TP) are available on both sides of the board as pads. You can probe them directly or solder small jumpers to them so you can clip your probes to them.
Here's what I see on my board with the above dual-arb waveform:
TP200 PLL reference clock in = 312.5kHz, 0V to 5V square wave.
TP201 PLL clock out = 312.5kHz, 0V to 5V square wave.
J5 pin 2 PLL VCO tune = 8.48VDC, steady.
TP204 PLL derived waveform clock = 5MHz, 0 to 4V square wave. This should be the "ARB Sample Clock" setting divided by 2. (TP204 is near the middle of the board, far from the other TP2xx pads).
Your PLL clock out and tune voltage will probably not be right since the PLL is not locked. The VCO tune voltage may also be oscillating as the PLL tries to lock, so look at it with a DVM and a scope. The red LED next to U212 should also be lit on your board, indicating no PLL lock.
Try changing the ARB sample clock from 10MHz to something else, say 8MHz. Do you see any change at TP204?
Try moving jumper J5 to the PLL test position, shorting pins 2 and 3 (normal is pins 1 to 2 (lower position)). This applies a fixed 7.40VDC to the PLL VCO tune input (i.e., no feedback). On my board, this results in approximately 469kHz at TP201. The no lock LED should definitely be lit.