Hp8112a service manual

View and Download HP A operating, programming and servicing manual online. A Pulse Generator pdf manual download. Check the Delay Generator operation against Table The microfiche package also includes the latest Manual Changes supplement and all relevant Service Notes. Answer This is the time taken by the HP Ato transmit a message when error reporting or learn mode. Jp Points on the Main Board A1. The possible error codes are: Transition times can be increased by increasing the overshoot.

During this interim period donations and continued membership are greatly appreciated while we transition to our new space. O A key is stuck in the depressed position. Should your computer be too fast for the HP A, it will be necessary to force the computer to wait gp few hundred milli-seconds before reading the response after an interrogate command. Refer to Figure for the part numbers of the available cables. This amount is subject to change until you make payment.

Inform Hewlett-Packard of any repeated failures of any of the checks, or any other safety features. Page - 0. Period Generator ramp signal pin 20 3. Check the trigger output signal at pin 2 1 of U against Figure Check the Delay Generator levels against Table 1 0.

Width Generator ramp signal 4. Check the input signal from the width generator at pin 1 of U against Figure JUST Figure 1 0. Page The operating principle is lb.

Current Mirror The pre-attenuator circuit is controlled by the microprocessor via Pre-Attenuator latch U R N.

R R R l. Sl CSl2 l. Check the output on TP6 against Figure The voltage is Amplitude-vernier measured at the board connector side of R Control-voltage Table 1 0. Page Output Amplifier If there is distortion, check the output-amplifi e r input signal at TP4. Then do the following: a.

If the input signal is clean but the leading edge of the output signal is distorted, check Q and Q NIER nG.. R: ll! The main board supplies power to the control board and the microprocesor board A3 supplies the digital control data.

Page The timing range decoder U2, controlled by RCT from U l , latches Timing Range Decoder data from the data bus which is then used to select the timing ranges required by the period, delay, width and transition time control sources. The offset DAC U20 is a 1 2-bit multiplying device which provides l out l two output currents. ZSK l. Page 1. Check the offset DAC's output-voltage against the following table.

Check U26 pin 3 for a Hz signal. The counter is then clocked by output pulses from the period generator on the main board Al. The 1 1-bit counter consists of two 4-bit counter ICs Ul l l and U 1 1 2 and three flip-flops U and UA which handle the three least-significant bits. The component layout and locator for the burst control part of board A2 is the same as Figure Page 3. Desolder wire W3 on the control board A2 and resolder it to the "test" position.

Connect Al U pin 10 to ground. Switch on the HP 8 1 12A and check that error number E52 is displayed. Press LCL 7. Introduction The microprocessor monitors the keyboard and HP-IB , interprets the key-presses and commands, and implements them by sending control data to the control circuits and updating the front-panel display and LEDs. These bus management lines are used to control the flow of data on the HP-IB data lines.

Enables a data bus driver U36, which allows the remote programmer to read the address set on the HP-IB address switch. Servicing the Microprocessor and Front-panel 1o. Page Address decoding for the control board functions is partially carried Control Board Address out on the microprocessor board.

Page Table 1 o. Page MP! Page Table A Page Main Board Table A Page Control Board Table A Page Keyboard Table A Page Note Some components may have been changed more than once during production of the HP 8 1 12A. Therefore Hewlett-Packard suggests you make the modifications to the manual in pencil as you work through the changes for your instrument. Page Table B Page For instruments with serial numbers G and lower, make the following change to the parts-list for the Main Board assembly Al in Appendix B , Table A Change 1 7 For instruments with serial number G and lower make the Page 2.

Modify Chapter Page 4 1 for more information. Page Standardisation of rear frame assembly introduced new part number. No backdating action for earlier instruments is required. Changes to circuit diagrams Figure B-5 shows the change to Figure 1 0. Figure B-6 shows the location of U28 and other additional components, modify Figure Figure B Page 6. Modify the schematic Figure Figure B-9 shows the microprocessor reset circuit on microprocessor board , modify the schematic Figure Page 8.

In Chapter If the instrument becomes totally inoperable switch it off and disconnect the RAM back-up battery for at least 30 seconds.

Page This change introduced a standardisation of switch part numbers, no backdating action is required. Page For instruments with serial number G and lower: l. The address switch is set at the factory to 1 2 decimal. Remove all four feet at the rear of the instrument by unscrewing the fastening screws. Page Figure B Exploded view of HP 8 1 1 2A rear frame Turn off the instrument and disconnect the power cord.

In Chapter 1 0. Mechanical Parts - 1 B Backdating Mechanical Parts Backdating B Page Updating I ntroduction This appendix contains information to correct errors in the manual, and to update the manual for instruments with a serial number higher than that shown on the title page of this. Please file all update information behind this page. If any text or drawings are affected, it is useful to indicate whether that update information has been incorporated in the manual.

The item may have some signs of cosmetic wear, but is fully operational and functions as intended. In the applications section, examples are given of how the HP A can be used in common manyal and test situations. Slope test setup 2. May 29, version: Replace the transistor s. If necessary, repeat steps 30 to 37 and adjust if necessary. This website uses cookies to improve your experience while you navigate through the website. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are as essential for the working of basic functionalities of the website.

We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. Every single button shows "o" in the display when pressed at power on. Therefore, the complete front panel indicators and buttons is working properly. The voltage rails on the main board and on the microcontroller board are within spec.

The symptom "only LCL is working" matches with the following description in the manual: "When in remote control mode all the front panel keys, except LCL , are ignored by the microprocessor. If the local lockout command has been received on the HP-IB then the key is also ignored. I have removed the GPIB controller chip and rebooted the unit. But this does not change anything. At the moment I suspect the RAM.

How trustworthy is the RAM check at power on? Perhaps the check does not find an error, but the data read by the controller is garbage? I will try to hook up the logic analyzer to the RAM. Perhaps this will reveal some information.

I don't know how thorough the RAM test is on these units. It sounds like it's stuck in local lockout mode. In local lockout the LCL button is ignored service manual page That was a good idea to try removing the GPIB controller.