Re: HP3586A 5V supply overheating
|
Bad Molex. Multiple Ground Paths or on Hot Side thru¡¯ Molex. Some Paths thru Molex Higher Resistance than others. Burns up the Connectors. This has been seen before. ? Regards Bill Lauchlan ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Raymond Boute
Sent: Monday, November 26, 2018 12:32 AM
To: [email protected]
Subject: [HP-Agilent-Keysight-equipment] HP3586A 5V supply overheating? My HP3586A suddenly lost its 5 V, with neither red nor green 5 V led on the A80 board.
I traced the?problem to overheating pins in the connector between the transformer and the A99 motherboard (burn marks around the pins).
Wiggling the connector reestablished 5 V, but the overheating is nearly immediate and severe . It does not occur in standby, nor do the connector pins on the A80 board show any overheating when the unit is on.? One would expect the current limiter to cut in if there were a short on the bus.?The rectifier diodes also get very hot. Evidently?troubleshooting cannot last more than a few seconds at a time lest the connector is destroyed.
Questions: (a) is this a known issue, (b) what is the normal current drawn from the 5 V supply, (c) might the rectifier diodes be switching improperly (e.g., causing shorts at switchover), (c) would replacing them by Schottky diodes be indicated?
|
