HP 3852A, Memory Lost, Repair and other stuff (o; - Page 1
Forum section: electronics / repair

author: davorin
author_rank: Unknown
timestamp: February 07, 2015, 02:41:15 pm
content: Recceived a 3852A this week....powering it on...it reports: "Memory Lost"....but self-test is okay and functions seem to work on panel and via GPIB...The controller board has a 3.7V lithium cell soldered onto it....which is empty....and oddly...powering it up again without cell shows that there is no built-in chargin circuit for buffering the 4 6264 SRAMs....Can it be HP forgot to add a charger circuit?Seems this is just a one-way cell....not even mAh printed on it...

author: davorin
author_rank: Unknown
timestamp: February 07, 2015, 03:38:20 pm
content: Guess this type would be the best fit besides building in a hacky charger circuit for a rechargable cell (o;http://www.distrelec.ch/en/Lithium-battery-3-6-V-2400-mAh-Tadiran-Batteries-SL-360-PT/p/16932078?q=%09972545&page=1&origPos=1&origPageSize=10&simi=99.3Hooked up a charged 3.7V cell now...and after 2nd power-up the "memory lost" is gone...

author: davorin
author_rank: Unknown
timestamp: February 07, 2015, 05:52:28 pm
content: Just out of curiiosity...I traced some signals on the controller board to the edge connector...not sure how easy it would be to add the 4MB memory extension (o;So here is the pinout of the 100-pinn edge connector:Code:HP 3852A Edge Connector1NC2NC3NC4NC5NC6NC7NC8NC9NC10NC11NC12NC13NC14NC15GND16GND17NC18NC19NC20NC21NC22NC23GND24GND25NC26NC27NC28NC29NC30???31NC32NC33NC34???35GND36GND37RESET38NC39GND40GND41NC42NC43LDS44UDS45R/W46AS47GND48GND49NC50A151A252A353A454A555A656A757A858A959A1060A1161GND62GND63A1264A1365A1466A1567A1668A1769A1870A1971A2072A2173A2274A2375GND76U27 1820-4147 Pin 4 (74HCT573 Octal Latch?) -> D277D078D179D280D381D482D583D684D785VCC86VCC87D888D989D1090D1191D1292D1393D1494D1595NC96NC97NC98NC99NC100NCHaven't found out yet what the missing 3 signals are doing...one going towards data bus transceivers to D2. Some assuming ti checks the presence of a card inserted, as pin 77 is connected to GND, but with a finer trace than power traces.The other two I don't know yet...somehow DTACK is missing....and not sure yet if CLK is routed out...but must somehow...The ROM images are available here...seems 4.22 is latest version...and I got 4.21 only *sniff (o;http://www.dalton.ax/hp3852a/

author: kawal
author_rank: Frequent Contributor
timestamp: May 05, 2024, 03:38:26 pm
content: The memory card seems to be the same as the cards used in the Hp 9000 computers. To be more specific the card is a HP 98257Ahttps://www.hpmuseum.net/display_item.php?hw=213.The interface pin out you provided has some mistakes. I attached the pin out for the HP 9000 DIO card . Not all the pins are used on the 3852A.

author: kawal
author_rank: Frequent Contributor
timestamp: August 26, 2024, 12:24:14 pm
content: In case someone else tries this - the HP 9000 card has exactly the same pinout but the addressing scheme is not the same. The card will not be identified correctly in the HP 3852A.I created a modified version of the card that works with the 3852A based on the HP9000 design.I will be offering these up for sale at some point. The unit will accept up to 4MB of SRAM cards. The board allows the card to function as 1MB, 2MB or 4MB boards depending on the amount of SRAM used and solder bridges.