Poower supply HP54845A ,Infinium OSD ,Schematics CD Technologies  pn 0950-3252  - Page 1
Forum section: electronics / repair

author: INFINIUM
author_rank: Contributor
timestamp: November 01, 2018, 04:19:17 pm
content: Hello,I want to repair the PS in my osciloscope HP54845A , I need the schemats, I checked with the 200 ohms in the pin 3-11 inhibit signal ,infos from here and the manual but only get the DC voltage 200 volts but nothing in +- 5 .12 v only I get the 15v for the start signal. nothing is burned and classic things.?there is a similar problem here MY HP WON`T START whith a similar OSD one person put an extra 5Vols in paralel with the bad original PS and it seems that the OSD START :popcorn:VOI do not to buy a power supply may old or bad in the internet my idea is to adapt an universal power supply with the plus minus 5 and 12 volts to the conectors J3 J7 And forget the power on off in the osciloscope that is also dificult to repair in the front panel.I burned one finger with the HVoltage in the PCB 200 VOLTS !I am looking for the connectors in the PS Voltages and colors.

author: INFINIUM
author_rank: Contributor
timestamp: November 01, 2018, 04:42:51 pm
content: Connector photo PS PN 0950-3252 From the HP 5845A

author: INFINIUM
author_rank: Contributor
timestamp: November 01, 2018, 04:50:30 pm
content: The vertical module gets the inhibit signal or start voltage from +15 v this is OK but the PS Does not startnothing gets out the 15 and 5volts ….in reality there are 2 Power supply in oneIt won`t start unless I find something easy condensers , etc.Somebody knows how to start this PS ? I Try the 200 ohms trick nothing , with the finger is dangerous and less blind without schematics.

author: Tony_G
author_rank: Super Contributor
timestamp: November 01, 2018, 04:55:56 pm
content: Based on previous requests for schematics of similar era HP power supplies I suspect you won't find them.You might want to try and start with a standard PC power supply to get the motherboard running and then see about providing power to the rest of the scope.TonyG

author: INFINIUM
author_rank: Contributor
timestamp: November 01, 2018, 05:03:33 pm
content: Thanks I suspectedthis I am trying to identify the pins if somebody has this basic pin code color voltage please send it to me ..

author: nctnico
author_rank: Super Contributor
timestamp: November 01, 2018, 08:47:52 pm
content: I'd trouble shoot the power supply. Look for the controller chip, get the datasheet to get an example schematic, apply power to the controller chip and see what comes to life or not using an oscilloscope. Switching power supplies are mostly the same so if you know one you know 90% of them.

author: INFINIUM
author_rank: Contributor
timestamp: November 08, 2018, 01:04:29 pm
content: I suspect something in the vertical module card with dozen of components no chips like the new ones , I get 220 volts DC in one place where I put my finger by mistake. the inhibit signal looks good , I tried also with the 220 ohms resistor in pin 3- 11 in the control inhibit card, nothing is coming out , somebody here try it on putting the 5 volts in parallel with another power supply , in my OSD I need + -12 volts + - 5 volts and another secret + - there are in total 5 pairs or +_- lines to the OSD PCB card. looks very easy with another PC cheap P .Supply , but also there are synchronization cables maybe for the 50 hz self test in the only module schematics I found in the internet.the OSD was abandoned for 10 years , I suspect the condensers are gonechecking with a FLUKE Component testing ,I see the curves in this magic voltmeter with a small oscilloscope correct.there is a laching relay in the front panel and PCBs cards that prevent the PS to power on , but again with the 200 ohms the manual said it can power on the PS If not change the PS ( 500 dolars and maybe I get one worse).anyway thanks I live in Alkmaar nownear the cheese marketI am looking for an electronic atelier , before in ALMSTELVEEN the HP repaired and calibrated it , now is gone , any help will be appreciated .

author: INFINIUM
author_rank: Contributor
timestamp: November 08, 2018, 01:08:17 pm
content: This is the address for the FLUKE Component test , the ideal is to have to PS and compare the signals from the good one to the bad one.http://assets.fluke.com/appnotes/multimeters/gmm-app4.pdf

author: INFINIUM
author_rank: Contributor
timestamp: November 08, 2018, 01:25:51 pm
content: Here you will see Schematics Power supplies from TEKTRONIX the filter condensers in the entrance connected to 220 v , blow up and everything smell to coal , HP does not give any schematicswithout schematics ,blind , old andis a little complicated to repair the Ps.

author: INFINIUM
author_rank: Contributor
timestamp: November 08, 2018, 01:30:25 pm
content: Power supply TDS TEKTRONIX

author: INFINIUM
author_rank: Contributor
timestamp: November 09, 2018, 08:28:09 am
content: Nice book about Power supplies :PowerSupplyCookbookSecond Editionhttps://www.researchgate.net/publication/277814092_Power_Supply_Cookbook