2020. december 13., vasárnap

HP 8903B Audio Analyzer - WIP 1.

 I started to work on my instrument control software months ago (http://pakahuszar.blogspot.com/2020/09/instrument-control-1-beginning.html). When my audio analyzer related things started to work, I realized that the analyzer itself is off from the specifications, so I can't really continue the work on it as I planned. Actually I put the whole project aside for a while.

Now I feel it is the right time to continue to work on it.

The unit functionally working correctly, just some calibration (maybe recapping needed). For the calibration I would need a few raiser cards, to be able to measure things on the boards. The original raiser cards (08901-60084, 08901-60085, 08903-60018) are unobtainable. Even for the last one the schematic diagram is also missing. Fortunately the unit has no functional problems, so the processor board doesn't need troubleshooting (the last card is for this).

As the cards are not available, I ordered the matching 44 and 30 pin 3.96mm pitch connectors on the aliexpress, and designed suitable raiser cards. To make my work easier, added two things to the new cards:

  • additional 44 (30) pin 2,54mm headers to be able to measure easier on the bus.
  • additional 44 (30) pin edge connector to be able to break out the cards in 90 (instead of 180) degree (I don't know if this will be useful, we will see)

The boards at jlcpcb for manufacturing:

In addition to those, I have doubts on the EPROM long term stability. Unfortunately those 2k x 8 EPROMs doesn't exists at the regular suppliers I use. So I ordered some from the eBay.

Waiting for the things to arrive, to be able to continue.