20 Sep
2016
20 Sep
'16
10:49 a.m.
So the DSD-440 I got at VCF is completely unresponsive. All of the LEDs are on and never
go out, which is bizarre - they are supposed to go out in 1/10 of a second after power
on.
I tried disconnecting everything but power to the card, and it still lights all LEDs. No
jumpers that I could find are in the wrong spot, but many are seemingly undocumented ( I
looked in both the 1981 user manual and 1984 service manual on Bitsavers).
The drive just spins and does nothing else. Altering the switches on the control board do
nothing to change the state of the LEDs.
I measured voltages at the power supply, and they seem to be within spec according to the
manual.
Are there any other things I can try before I start digging into things on a component
level?
20 Sep
20 Sep
11:34 a.m.
On Sep 20, 2016, at 12:49 PM, Julian Wolfe <jrw at lolqb.us> wrote:
So the DSD-440 I got at VCF is completely unresponsive. All of the LEDs are on and never
go out, which is bizarre - they are supposed to go out in 1/10 of a second after power
on.
I tried disconnecting everything but power to the card, and it still lights all LEDs. No
jumpers that I could find are in the wrong spot, but many are seemingly undocumented ( I
looked in both the 1981 user manual and 1984 service manual on Bitsavers).
The drive just spins and does nothing else. Altering the switches on the control board
do nothing to change the state of the LEDs
I measured voltages at the power supply, and they seem to be within spec according to the
manual.
Are there any other things I can try before I start digging into things on a component
level?
This is a failure of the DC Power Up/Down circuit - See page 3-10 + 3-53/54 in June 83
Service Manual. If the components in this circuit (capacitor) are out of spec, then this
may be the cause.
Congrats on picking it up. I was tempted to bid for it as well, but I already filled had
my boat anchor quota.
Is the Green LED on?
Jerry
11:37 a.m.
Both green LEDs are on. They're ALL on.
This is a failure of the DC Power Up/Down circuit - See page 3-10 + 3-53/54 in June 83
Service Manual. If the components in this circuit (capacitor) are out of spec, then this
may be the cause.
Congrats on picking it up. I was tempted to bid for it as well, but I already filled had
my boat anchor quota.
Is the Green LED on?
Jerry
12:02 p.m.
After reading this section, I should probably bring up that when I checked the PSU
voltages, the 5v+ line was low, at 4.7v or so. I adjusted it back to 5.05v on the pot as
defined in the manual, and there it stayed steady, but it didn't seem to help. Before
I adjusted the pot, it was fluctuating.
---- On Tue, 20 Sep 2016 11:47:17 -0700 Jerry Weiss <jsw at ieee.org>wrote
----
On Sep 20, 2016, at 1:37 PM, Julian Wolfe <jrw at lolqb.us> wrote:
>
> Both green LEDs are on. They're ALL on.
>
>
As LED 9 is on (sorry for not being clear), then the CPU is active. That?s a good sign.
Definitely look at the DC Power up/down circuit first.
Jerry
12:25 p.m.
On Sep 20, 2016, at 2:02 PM, Julian Wolfe <jrw at lolqb.us> wrote:
After reading this section, I should probably bring up that when I checked the PSU
voltages, the 5v+ line was low, at 4.7v or so. I adjusted it back to 5.05v on the pot as
defined in the manual, and there it stayed steady, but it didn't seem to help. Before
I adjusted the pot, it was fluctuating.
Given the age of the unit, its not surprising that the potentiometers are a noisy, have
drifted/aged and/or are contaminated with crud.
SYSTEM Reset L should be High. If Not then Check for 1.1V on THR.
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