Boonton 4210 troubleshooting

[5065AGuru]

Hi, I just got a Boonton 4210 without a sensor as I need a second power meter. I currently have another 4210 that works well. When I connect the sensor to the new 4210 it wont zero and reads 5 dB off. I looked in the manual and it lists a bunch of U29 EEPROM part numbers that need to match the part number of the sensor being used. The number on the EEPROM does not match any of these ones in the manual. I guess I could try and swap in the EEPROM from the good unit to see but wondered if anyone had any advice?

Cheers,

Corby

Well I found an intermittent that cleared when reseating the DIP IC input switch. Then the meter displayed a +10.00 dbm offset as the EPROM was for a high power sensor. Made a copy of the low power sensor EPROM from my other 4210 and now this unit reads correctly and works great! The EPROM is a 2732.

[Kosmic]

Normally each sensor is AC calibrated with a specific meter. So you can't simply switch the sensor by another one. More evolved version of the power meter had memory for multiple sensors (4200, 4300).

In the manual of the 4210, section 4-18 (Range Adjustments) explain the process of calibrating the meter for a specific sensor. But unfortunately you need a power meter calibrator like the boonton 25A to complete the process.

[5065AGuru]

Yes I understand about calibrating the unit to a new sensor.

The manual states:

"The field replacement of any sensor with another of the same type requires only a simple recalibration procedure"

"If the sensor is replaced with one of another type, a replacement PROM is also required to reconfigure the 4210 to the new sensor."

It also states that the EEPROM holds the low frequency sensor data for the supplied sensor. ( you use the front panel Cal Factor to dial in the High frequency corrections from the chart on the sensor)

So I'm guessing if I swap the sensor and EEPROM from my other unit into the new one it should tell me if that's my problem or if I need to troubleshoot the instrument further.

I'll try that but my hunch is that it has another problem that causing such a gross offset and non zeroing.

Any Boonton experts out there?

Cheers,

Corby

[Kosmic]

Ok I missed that part in the manual. I'm surprise that the 4210 were limited like that. I guess they never expected the client to change the sensor. I't true that they were normally selling the meter and sensor properly calibrated together. It's really unfortunate that most seller seperate the kit and sell them individually.

Still, even with the right rom in the meter if AC calibration is not done you can't really tell if the meter is accurate or not. So not being able to zero and off by 5 dBm is possible.

[fenugrec]

Hi,
I also have a 4210 and was getting strange readings (possibly intermittent contacts in the chopper section), and I got to wondering if I even had the correct ROM for my -4 sensor.

Attached is my ROM dump; I also uploaded it to KO4BB.com (currently not sorted yet, in the "Recent Uploads" folder).

Then I made a quick tool (https://github.com/fenugrec/hp5004_sigtest) to calculate HP 5004A-style "signatures", to compare against the ones given in the service manual.
I think my software works, but I'm getting

Code: [Select]

D0 : 5943
D1 : 306C
D2 : 6763
D3 : 5H1A
D4 : P37H
D5 : 2654
D6 : 9524
D7 : P3P1
which doesn't match any of the signatures listed in the SM.

Anyone else have a 4210 and wouldn't mind dumping their ROM ? (obtaining the signatures in-circuit is difficult since the z80 needs to be disconnected from the databus so it NOPs through all addresses)

I looked at the ROM (Z80 code), and my usual tools (IDA , ghidra) quickly choked on the disassembly. On closer inspection, it looks like the firmware is some kind of FORTH or indirect-threaded code ?

[Uunoctium]

Hi fenugrec

here comes the wanted J0Aa-xxxx ROM (captured w TL866). Should fit the 4210-4A to C sensors acc to sm.
Resistors in chopper board = 1.8k-Ohm for diode sensor.

[fenugrec]

here comes the wanted J0Aa-xxxx ROM (captured w TL866). Should fit the 4210-4A to C sensors acc to sm.

Awesome, thanks ! My signature test tool generates the exact same signatures as the ones given in the SM:

Code: [Select]

$ ./sigtest ~/Downloads/boonton4210_J0Aa_2552.BIN
clocks: 0x01000
constant 1: 826P
D0 : 6243
D1 : H952
D2 : PH2H
D3 : 7493
D4 : 3361
D5 : AU6P
D6 : 82C7
D7 : CA4P

It'll be interesting to compare with my ROM; there's only about 20 changed bytes:

Code: [Select]

srec_cmp boonton4210_J0Aa_2552.BIN -bin  boonton4210_33BAA_12-1984.bin -bin -v
Different:      (0x453 - 0x45a, 0x45c - 0x463, 0x679, 0x67f, 0x685, 0x689, 0x68b - 0x691, 0x693, 0x695, 0x697, 0x699, 0x69b, 0x69d, 0x69f, 0x840, 0x842 - 0x846, 0x848)

I haven't looked much at the disasm, but I did confirm almost certainly that it is some implementation of FORTH; the primitives used are almost identical to those found in this book
http://sinclairql.speccy.org/archivo/docs/books/Threaded_interpretive_languages.pdf

I think it's safe to assume Boonton engineers were very familiar with that document.