Thanks, I finally figured this critter out last night. I found the P/N on that SCR barely readable, but there. It was the 2N681, that Astron told be it was. Further checking shows it to be 25V/25A. Light! That's probably why they went to that 50V/65A unit that crosses to nothing!
I found all I needed at Digi-Key rather than going through Astron. Hey, when I can't even send email, do they think I am going to order parts? NOT! Does anyone know what is used for the AMMETER? I want to add V and A meters. I have a large Ammeter (feed through) but the schematic shows current being sampled and run through a 500 Ohm pot. I have many 1 milliamp meters. If I can find the right pot and/or fashion a by-pass wire across the meter then re-scale it that would be nice. I never have liked the idea of feeding full current through a meter! The lightning appears to have gone around the outside of the unit. All 8 pass transistors shorted. 5 of 8 emitter resistors open. The MOV blown right off its leads! Best of all, one mounting on a pass trans appeared to be stripped, no turning it from outside or inside with pliers. I then realized the trans was loose! I pried it out and saw the screwhead WELDED to case! The control board, filter caps, rectifier diodes, driver trans, power transformer and all else appear to be OK. Thanks again for the help All! Bruce (PooterWizz) (CallSign coming soon) (Tech Test 3-20-08) >I had this same issue about a year ago. Their replacement SCR required minor >>modification to the enclosure in order to mount but otherwise worked ok in >>my RM50M. In my opinion Astron does a very poor job of documentation >and >support (especially phone support) so I often stay away from their >products. >Gary >---- pooterwizz <[EMAIL PROTECTED]> wrote: > Hello Group! > i hope some one can help me here. I have An Astron RM-50A Power > Supply that took A lightning hit! All 8 pass transistors (2N3771) > are toast, but the 2N3771 driver is OK. The rectifies diodes are OK > and the power X-Former is OK. > > My problem is the crowbar SCR. This is a TO-48 case with MICA > insulators. > > I phoned ASTRON and got conflicting answers. The schematic I have > calls for a SO565J SCR. Astron says this is an INSULATED case device > rated @ 65A 50V. When I told him mice had mica, he said I had an > older unit (circa 1983 and the SCR is A 2N681. I checked this critter > and it is 50V @25A. That seems light for a 50A peak crowbar! > > Does anyone know of the correct P/N or proper cross reference? > > BTW, the email link at the Astron website is dead. I was told (By > ASTRON), the CORRECT email is: [EMAIL PROTECTED] When I tried to > send mail to that address it came back also. WHAT GIVES!!! .
