Kikusui PLZ603W Troubleshooting Identity Crisis

[Johnny10]

I thought I might post a curious problem on a Kikusui PLZ603W I have on the bench.
It is a 603W unit that thinks it is a PLZ153W model.

The load presented at the terminals is about 4X what is on the display.

Tried recalibrating unit but I cannot select the 603W in the calibration mode only the 153W.
The Calibration data table from Operations Manual can match differences exactly as per 153 to 603.

My assessment would be the firmware eprom.
This is a unit with unknown history.

As I said, everything works it is simply presenting 603 loads while showing 153 display. i.e. when set for .34A the actual load is 1.26A.

While proceeding to order an eprom programmer and asking around for a download of 603 Firmware (Firmware not available from Company), I thought I would post the problem.

The Kikusui PLZ-3W Models look to all have the same CPU board.
The difference being the number of add on load modules.

How the CPU determines which Model number baffles me at the moment.
Talked to a company Rep but they say not much data available for older units.

[perieanuo]

hi,
try to read the eprom
usually things like model/fw are not encrypted, you will see them in clear in ascii
regards, pierre

[DaJMasta]

Not that familiar with the unit, but do you think debug/boot information from the rs232/remote control port could be valuable in figuring things out?  Also is there any evidence of configuration jumpers of some sort on the board?  It could be that a dip switch/jumper/resistor configuration sets the model configuration.

Perhaps less likely, these units probably use the same front panel controller and then modules for the various configurations - maybe the module connected to the front panel controller is somehow reporting itself incorrectly, so maybe troubleshooting any digital links between them could shed some light on the issue.

[Johnny10]

Has GPIB Port

I have just ordered TL866ii+ from China, guess this project will be on hold till delivery.

If anyone has downloaded firmware for the PLZ603W I might need a copy.
EPROM chip is easy to get by removing top cover and it is socketed.

Have not found a jumper to identify model to the CPU.

[Johnny10]

Programmer came today and to test it out I put the AM27C020 in the device and read the contents.

Seems to me this eprom is for all PLZ3W versions. 153W, 303W, 603W, 1003W

Hmmmmmmm

Guess there is a circuit somewhere that identifies the unit to the processor.

[coromonadalix]

please save the content as an hex file, and share it here ... 

[Johnny10]

Kikusui PLZ603W EPROM hex file

[Johnny10]

I am definitely not good with software.
Did anyone notice in the downloaded file where the program looks for Model Type.

I see the request but not the location.