RE: DEC H7140 (11/40) power supply revisions and general advice?

k-boun...@classiccmp.org] On Behalf Of Josh Dersch > Sent: 10 October 2015 16:46 > To: General Discussion: On-Topic and Off-Topic Posts > Subject: Re: DEC H7140 (11/40) power supply revisions and general advice? > > > > On Oct 10, 2015, at 4:15 AM, Mattis Lind <mattisl...@gmail.co

Re: DEC H7140 (11/40) power supply revisions and general advice?

> On Oct 10, 2015, at 4:15 AM, Mattis Lind wrote: > > 2015-10-10 5:42 GMT+02:00 Josh Dersch >: > >> Hey all -- >> >> > First of all I haven't poked around in the PSU of my 11/44 since it worked > fine when powered up.

Re: DEC H7140 (11/40) power supply revisions and general advice?

2015-10-10 5:42 GMT+02:00 Josh Dersch : > Hey all -- > > First of all I haven't poked around in the PSU of my 11/44 since it worked fine when powered up. But the design of the H7140 is a lot similar to the design of the H7104, the PSU of the VAX-11/750 which I worked quite a

DEC H7140 (11/40) power supply revisions and general advice?

Hey all -- Once again, I find myself in over my head debugging a power supply, this time an H7140 from a PDP-11/44. Here's the skinny: I examined the supply physically before experimenting and found a capacitor on the Bias/Interface board that was leaking, bursting and rather burned-out

Re: DEC H7140 (11/40) power supply revisions and general advice?

On 10/9/2015 10:42 PM, Josh Dersch wrote: > > Capacitor C4 looks to be involved with the START-UP DRIVE signal > circuitry (which drives the relay) so the behavior I'm seeing makes > sense if C4 died and took a couple of things with it (or if something > else died and took C4 with it). > >

Re: DEC H7140 (11/40) power supply revisions and general advice?

On 10/9/15 9:13 PM, Jay Jaeger wrote: On 10/9/2015 10:42 PM, Josh Dersch wrote: Capacitor C4 looks to be involved with the START-UP DRIVE signal circuitry (which drives the relay) so the behavior I'm seeing makes sense if C4 died and took a couple of things with it (or if something else died