| Electronics > Repair |
| Wavetek 2520a 0.2-2,200MHz RF sig gen repair |
| << < (15/22) > >> |
| dazz1:
The problem I am facing right now is how to enable the Phase Modulation option. Replacing the evram has disabled this feature, so obviously something stored on the factory evram was the magic key. I have a number of options to restore the lost feature. The most complex would be to reverse engineer the firmware and find out what test is done to enable/disable the features. The simplest is to load an image of the factory evram contents onto the new evram. DefPom has made the later option viable because he was able to read the evram contents and send me the file. Thank you DefPom. Remarkably, it appears that the 32 year old battery nvram, was still working. So simply writing the contents of the factory nvram to the new nvram should restore the lost Phase Modulation option. I can then calibrate the 2520A and fully restore it to factory condition. To do that I need a parallel ram programmer. Not something I can buy cheaply anywhere. So the plan is to make a ram programmer based on an Arduino Uno. The Uno has everything I need except for a spare serial port to read the file from my PC. I will need to use the one serial port for software development. The easiest way to read the file into the Uno is with a cheap Chinese micro SD card reader, which I have just ordered. That will probably take around 4 to 12 weeks to deliver given the current shipping delays. So I expect it will be a while before I make another post on this thread. If copying the factory evram fails to restore the Phase Modulation feature, then reverse engineering is the only option left. This shouldn't be as hard as it could be. When the 2520A is switched on, it goes through self test routines. That will tell me what test fails when the firmware is checking for added options. There is also a key switch that selects a diagnostics rom. You enter a two digit number and run a selected routine. I suspect the lookup table for selecting the routine will include undocumented numbers for running routines such as enabling options. |
| khs:
--- Quote from: dazz1 on August 18, 2021, 09:59:32 pm ---Hi Definitely different to mine. Your firmware is ver 8.3, mine is 5.1 but the dates on the boards look older than mine. Maybe yours was factory upgraded?? I wonder if any two of the 2520A are the same? I have considered the possibility of modifying mine to have a higher frequency limit but reverse engineering the firmware would be just too much work. Wifi would be within the 2.7GHz range but I don't know if the phase modulation feature I have (currently not enabled) would be useful. It would require a computer ahead of the sig-gen to generate the base band signal, and a receiver. It wouldn't be too difficult to reverse engineer the GPIB board because it is only 2 layered and I have posted a copy of the GPIB firmware but figuring out how enable that option in the main firmware would take time and effort. --- End quote --- Here the FW 8.3 of my instrument. Maybe it enables 2.7 GHz, because it looks the only difference is the RF attenuator control. It can be the standard hardware was able to deliver 2.7 GHz but the standard RF attenuator was not working fine up to 2.7 GHz, so there was only the need to modify the frequency limits of the firmware and the RF attenuator. The additional pc-board with some flying wires looks a little bit quick and dirty so for me it's an additional hint there are minor modifications only.. I'm quite sure it's a factory update due to the modified frontpanel. The RF attenuator relays are controlled by the output pulses of the 74LS123 monoflops, so it looks the relays for the 2.7 GHz are a little bit more delicate compared to the standard relays. You may try the firmware it after making a copy of the NVRAM, but you shoud expect your RF attenuator it not the best at 2.7 GHz . If there is some time left it would be nice to have a picture of both sides of the GPIB board.. :) |
| khs:
--- Quote from: dazz1 on August 19, 2021, 07:14:08 am ---The problem I am facing right now is how to enable the Phase Modulation option. Replacing the evram has disabled this feature, so obviously something stored on the factory evram was the magic key. I have a number of options to restore the lost feature. The most complex would be to reverse engineer the firmware and find out what test is done to enable/disable the features. The simplest is to load an image of the factory evram contents onto the new evram. DefPom has made the later option viable because he was able to read the evram contents and send me the file. Thank you DefPom. Remarkably, it appears that the 32 year old battery nvram, was still working. So simply writing the contents of the factory nvram to the new nvram should restore the lost Phase Modulation option. I can then calibrate the 2520A and fully restore it to factory condition. To do that I need a parallel ram programmer. Not something I can buy cheaply anywhere. So the plan is to make a ram programmer based on an Arduino Uno. The Uno has everything I need except for a spare serial port to read the file from my PC. I will need to use the one serial port for software development. The easiest way to read the file into the Uno is with a cheap Chinese micro SD card reader, which I have just ordered. That will probably take around 4 to 12 weeks to deliver given the current shipping delays. So I expect it will be a while before I make another post on this thread. If copying the factory evram fails to restore the Phase Modulation feature, then reverse engineering is the only option left. This shouldn't be as hard as it could be. When the 2520A is switched on, it goes through self test routines. That will tell me what test fails when the firmware is checking for added options. There is also a key switch that selects a diagnostics rom. You enter a two digit number and run a selected routine. I suspect the lookup table for selecting the routine will include undocumented numbers for running routines such as enabling options. --- End quote --- The aduino uno has 32KB Flash memory (ATmega328P), so maybe you can insert the NVRAM values as character (hex) array into your program and then write it into the NVRAM... |
| TheDefpom:
I would suggest using the ESP32, it has a lot more memory and a lot more functionality than a basic arduino module. |
| dazz1:
Hi I chose the Arduino Uno because it interfaces directly with 5V logic and ram and, because I have one already and, the SD interface pcb is less than $1. So the Uno is far from the best choice but it will do the job with minimal extra hardware. Apart from the Uno, and the SD adapter, I will need some serial to parallel ICs. This will be a single use project so nothing fancy required. Worst case will be if I reverse engineer the firmware code. Dazz |
| Navigation |
| Message Index |
| Next page |
| Previous page |