Tag Archives: 4192a eprom

HP 4192A LF Impedance Analyer: a few final fixes, and 14(!) EPROMs copied

Finalizing some repairs on the 4192A – there were two tasks remaining, replacing one of the front buttons that were damaged, and making a copy of the EPROMs, because none could be found in the web and the various forums.
The EPROMS are MB2516 type, 1982 vintage, with a white ceramic package and gold pins. Better not damage them, so I removed them after good sleep and after a cup of coffee, using some good tools.

Reading such old EPROMs can be a bit tricky with modern programmers, so I didn’t want to take chances and used a custom reader, reading every address several time. No uncertainties showed up, all reads identical.

The serial, suggesting 1981- vintage. According to the date codes, made in about 1982.

Just in case you need a copy, see here, hp4192_eprom.

Next, the defective button (at the left display) – did a thorough search in the German workshop, but no such button around (a dark brown, LED type button cap). But I did find a “LCL” labeled button. The original 4192A “Local” button has no print, so I did a little swap as indicated on the picture. Now all looking good.

To handle all the data and sweep function of the 4192A, best to use it in combination with some software. Fortunately, there are some great tools available for free, working right out of the box.

A set of resistors, left side are my 0.01% precision resistors (using them for calibration and adjustments of LCR meters), Vishay S102C/S102K, AE (Alpha Electronic) XT series. Next to it, some other resistors, all 1 kOhm.

The precision 1k resistor…

A 68 nF ceramic cap…

1 k low cost axial resistor…

1 k standard good quality metal film axial…

1 k metal oxide 4 Watt resistor (green, POS400 Vitrohm series) …

All in all, the 1 k resistors have very little parasitics up to 13 MHz, say less than 1 pF parallel capacity, and inductance, below what can be reliably measured.