HP 8753B Ver 3.0中的CAL系数位于何处？

嗨，所有的社区，我有一个旧的HP 8753B Ver。
使用选项006的3.0，突然所有Cal系数从菜单CAL消失，即C0，C1，C2，C3边缘电容系数已经变为零;
在所有情况下显示都显示为零。
VNA内部的所有CAL套件都有相同的问题，问题是：每个Cal套件的Cal系数记忆在哪里？
*固件内部或EEPROM *内部？
在此问题之后，我的旧HP8753B拒绝工作，我的所有前面板LED都亮起（见图），并显示HP LOGO和固件（见图），此时VNA卡住了。
每按一次键，都会显示一条错误信息：警告无效KEY（见图）。
我怀疑A1 / A2前面板数字控制，带状线是好的。
VNA拒绝使用HPIB控件，例如，
CAL KIT Manager程序拒绝控制VNA。
我还搜索旧的A9 CPU板，部件号为N°08753-60067。
任何帮助都将是伟大的，非常感谢。
CPU上的ON1EV比利时LED.jpg593.2 KB当按下一个键时，该消息无效key.jpg578.2 KB



     以下为原文

  Hi ,all the community , I have an old HP 8753B Ver. 3.0 with the option 006, suddenly all the Cal coefficients have disappear from the menu CAL , i.e.  the C0 , C1, C2, C3 fringing capacitance coefficient have  changed to zero; the display show  zero in all cases. all the CAL kit inside the VNA have the same issue, the question is: Where are the Cal coefficient for each Cal kit memorized?  *inside the firmware or inside the EEPROM*?  

After this issue, my old HP8753B have refused to work, all my front panel LED are ON(see the picture)  and the HP LOGO and firmware are displayed(see the picture) and the VNA is stuck at this point. each time I press a key , an error message is displayed : caution invalid  KEY(see the picture).

I have suspected the A1/A2 front panel digital control, the ribbon cable is Ok. The VNA refuse to operate with the HPIB control, e.g. CAL KIT Manager program  refuse to control the VNA.
I also search an old A9 CPU board with the part N° 08753-60067.
Any help will be great and greatly appreciated.
ON1EV
Belgium   
附件

• front panel with all the led ON.jpg527.2 KB
• LED on the CPU.jpg593.2 KB
• when a key is pressed the message is invalid key.jpg578.2 KB