Electronics > Metrology

Datron 4808 Opt. 70 Wideband Source

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perdrix:
Looking at the schematics for the Wideband Source (the only document I have so far for it), the schematic page for installing it it says you need to replace the main ROM in the 4808 digital board and you also need to modify the keyboard (I think mine has been done).

The ROMs on my digital board are labelled:

   400837-3.0   14 Feb 92
   401007-2.10   06/06/94
   401006/1.0   016007

which I think implies overall revision 1.4/ECO 4500 and I think they do support Opt. 70, but I'm not sure as I get Error 9 when I press the WBV button (this could be a fault with my Opt. 70 unit).

Does anyone know what the highest ROM levels available are?   The schematic page for installing Opt. 70 refers to a revision level 1.8 but this may not be the highest.

More worryingly I got an email offline which said:


--- Quote ---Every wideband option 70 unit that I have serviced includes an additional board as well as the firmware and the mod to the keyboard to add the WB button. It is added to the main box at the back on the center metal plate holding the mains transformer. It is installed electrically between the motherboard and the analog connector for option 60/70. The board includes a relay that disconnects the PHI and IHI signals and what appears to be diode clamp protection, though I have not taken the time to look closely at the rest of the circuit.
--- End quote ---

Does anyone know anything about that?

Oh yes, I anyone has any documentation apart from the schematics, I really want to hear from you.

Cheers
Dave

perdrix:
Well, I got it working (sort of).

The 4808 threw "Error 9" when I tried to select the Wideband Source.  When I checked the cables connecting the 4808 to the Option 70 box, I found that pin 9 of the 15 pin digital cable was open-circuit.  This should carry the IDIGBUSON_H (+5v) signal to tell the box that the 4808 is powered on.

Replacing the cable changed the story entirely and it now partly works.

It will allow me to use Wideband Source and it will produce output (at about the right amplitude) at frequencies of 0.34MHz and above, below that frequency it is mute.

Any ideas?

Thanks
Dave

I

manganin:

--- Quote from: perdrix on July 20, 2017, 05:06:36 pm ---It will allow me to use Wideband Source and it will produce output (at about the right amplitude) at frequencies of 0.34MHz and above, below that frequency it is mute. Any ideas?

--- End quote ---

Below that works the main calibrator.

perdrix:
An update:

Poking around and looking at the schematic for Opt. 70 it was clear that the Stellex DDS IC isn't used for all output frequencies.   For frequencies 30Hz to 330kHz inclusive, the signal is supplied on the I+ signal line of the Lemo connector (with the reference voltage on V+ - a sine with nasty x-over distortion).  When I checked this at the 4808, there wasn't a signal on the I+ line at the Lemo.

Checking on the motherboard, the signal was present and correct.   It turns out that the wire to that pin of the Lemo socket on the back panel of the 4808 had never seen solder!   It looked OK because it was covered by an insulating sleeve, but it must have moved sufficiently to break contact when I took the rear panel off to get at the key-lock.

Anyway, all now soldered up and working well.

PS to get higher frequencies out of the Opt. 70 source, you just need to press the Store/x100 button (top left corner of lower left keypad).

Dave

TiN:
This thread is sadly worthless without photos.  ;)

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