DEC H7260 PSU fault

[Rob Jarratt]

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Jules
> Richardson via cctalk
> Sent: 27 January 2018 23:39
> To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
> Subject: Re: DEC H7260 PSU fault
> 
> On 01/27/2018 04:02 PM, Ethan Dicks wrote:
> > On Sat, Jan 27, 2018 at 4:34 PM, Jules Richardson via cctalk
> > <cctalk at classiccmp.org> wrote:
> >> Success!
> >
> >
> > Congratulations!
> 
> ish... :-)
> 
> It seems that my DHV11 board is bad - the system stalls on the PSU tests
with it
> plugged in.
> 
> The TK50 drive sits there with a rapidly-flashing light (I saw someone
saying
> that's likely the tape feed band or just dirty heads, so it might be
fixable).
> 
> The RD53 drive... hmm. I tried powering it without it plugged in, just to
see if it
> at least sounded healthy; it spun up to a "sensible-sounding"
> speed for maybe 15 seconds, then spun down again. I tried again, and it
> remained spun-up, but the initial spin-down was hardly encouraging.
> 

Did you hear the heads move? Spinning up and down again likely means it
couldn't find the first track. Very likely to be stiction from the rubber
bumper inside which has turned to goo.

> With the drive actually hooked up to the controller, I'm getting "?54
RETRY"
> messages when it's trying to boot - however, I'm not entirely sure what
device
> it's trying to boot from! Maybe it's attempting the TK50, or via Ethernet.
I still
> need to read up on that and work out how to force it to attempt a disk
boot.
> 
> One other issue is that the RD53 was in the second bay (and hooked up to
the
> associated cables) - it makes me wonder if it was just an auxiliary disk,
and the
> system originally had another drive in the first bay (containing actual
OS) which
> has been removed.

Can't remember exactly, but not necessarily. You need to try commands like
BOOT DUA0/1/2/3, but if the heads are sticking you won't get far. I would
suggest net booting the machine as a satellite and then seeing if the local
disk is visible to the OS.

> 
> > Just be sure to follow the grant chain
> 
> Yup, I *think* I've got my head around how that works! (along with the
special
> slots for CPU/RAM)
> 
> cheers
> 
> Jules