| Electronics > Repair |
| Teardown : HP 4263B LCR Bridge meter (and repair) |
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| carl_lab:
--- Quote from: SeanB on April 30, 2014, 07:13:09 pm ---On a lot of those displays the front polariser is a separate item, so you can take it out and flip it around to reverse the LCD. Either turn it 180 degrees or flip front to back and check. --- End quote --- 90 degrees, I think. So you need a new polarizer. |
| MiDi:
Got a unit with OPT 001 & 002 from 2012 in mint condition, unfortunately with Error E-313: Calibration memory. After a couple of restarts it went through POST without error - so there was hope for recovery of cal rom saving $$$ for full calibration/adjustment. Unit cannot be operated with POST error - unless switching it to ignore POST errors (service manual p. 59). Next step was to take backup of cal eeprom A2U1 X28HC64 (X28C64 on other units spotted). Verification showed several errors - wear out or data retention time expired? Comparison of 20 backups showed at least 12 wobbly bits, but luckily only in unused areas with FF - hence spotting the correct values was easy task. Only one of those backups was correct, it was reflashed and several verifications were successful. Seems this guy not only forgot part of its data, but also his datasheet which states 100 years data retention :wtf: Sidenote: the programmer needs to handle the software write protection - I used TL866-II+ with Xicor X28C64 template (after failing with AT28C64 - which lacks WP :palm:). Now unit powers up without errors, several self tests did not show any error - that was an easy fix :-DMM Anyway it seems to be a good idea to get a replacement for this forgetful ic, only awailable compatible PDIP-28 as a new part seems to be AT28C64B. It states only 10 years data retention in the datasheet, hopefully this is worst case with margin and better than 8 years of currently installed one. Cal rom for this unit attached for reference. xDevs repository has latest firmware 1.06 and several cal rom backups. As TiNs pictures seem to have vanished, here the link to the article on xDevs. Part of performance verification was successful - as far as I could get with my equipment. PS: Someone in EU who would lend me cal-kit? HPAK equipment (or equivalent) needed for cal: Standard Capacitor Set 16380A Standard Capacitor Set 16380C 100m Standard Resistor 42033A1 100k Standard Resistor 42039A1 OPEN Termination 42090A2 SHORT Termination 42091A2 1m, 2m, 4m Test Leads kit |
| Le_Bassiste:
haha, extra cookie for the cool cal sticker :-DD any idea what it reads? |
| MiDi:
Unit came from Slovakia, but seems Cal-Sticker is hungarian. "Év Következő Felülvizsgálata ideje Hónap" translates to "Next review time Year Month". I guess that means next cal due 12 2019 ;) |
| MiDi:
Replaced forgetful cal rom A2U1 X28HC64 with AT28C64B without problems. As the keys had a sloppy response the front panel was taken off. The silicone key pad was removed and cleaned carefully with warm water and soap, the counterpart with pcb cleaner. As the front panel was off anyway, I decided to swap the LCD for a black/white one. After setting the contrast with a 1kΩ and adding a current limiting resistor for LED backlight everything was put together again. Keys are now responsive and as new, the display is pleasant with good contrast, but viewing angle could be a touch better. :-DMM |
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