d8b Forum

Reading the tech/repair manual: If there is a power surge there is protector switch(?) in the HDR. Do they call that an RCD?
It requires you to pull the main power cord, leave unattached for a bit, then re-install and then the unit will power up.

That is the main thing the HDR is doing. Every time I have to pull the cord & re-attach to have the power-on switch work, but then all goes off in less than 2 seconds.

If I need to replace the Power Supply, does anyone have a link to the exact part I need?

Below is my original post.
thanks for your help.


It has been awhile since I came here.

My 3rd HDR (back-up) has been sitting in a storage rack for awhile. It is a testament to Mackie that my other two HDR units have not failed me these past twenty? years.
I plugged in all the peripherals (keyboard, screen, etc) and pushed the ON button. It would attempt to boot, but freeze at various locations on boot-up screen each time I pushed start button to try again. The lights, screen, fan & hard drive all seemed to be working each time after it froze at bootup AND I had to push & HOLD the stop button to shut it down. (4 second hold option)

I then realized the power cord had been unseated for awhile, so I opened the unit, replace the battery. On next power up I pushed DELETE key, entered and competed CMOS setup. (over the years I have done this multiple times, am most careful and double-check!)

Started the unit again, and voila! it started normally. I opened a few projects on internal, played them, and confirmed all was ok.

Well......here it is almost a year later. This extra 3 HDR has again been on the storage rack. Again, plugging the peripherals, and pushing the ON button, lights come on, noise from the fan, hard drive stars to hum, but this time the unit shuts down completely just like I had pushed the off button in instant stop mode!

Pushing the On button again...nothing. I unplug cord, wait and repeat.... ON button....lights, fan noise and 2-3 seconds it shuts OFF!
I again open unit, again replace battery, thinking maybe like before, but NO! 3 seconds it goes off. Repeated this multiple times. Same result, only now 2 seconds/off.

As per Mike Rivers book, I cleaned all the ribbon cable connections, pulled all cards/contact cleaner/ re-seat them. Still NO Boot! (2 seconds to off)

Thinking maybe an internal hard drive issue, I again followed Mike advice and tested with another hard drive, and then replacing with new the ribbon cable (in case THAT was the issue), but again....NO boot (less than 2 sec off)

Also, in this exercise, I attempted to install OS with new floppies (Tried multiple times with different version 1.2, 1.3, 1.4 AND even with the DOS floppy thinking that maybe there was a magical fix there) At no time did the the floppy drive ever start and the HDR stay on past the 2 seconds. (by this time I was getting obsessed with fixing this EXTRA HDR that I was not using.

Mike had written the power supply has an internal fuse, but he did not say it would "re-set" after power off. Is that the issue? Again, when it shuts off, I have to pull power cord/wait/then attempt another start.

Same result 2-3 seconds off.

Any thoughts?

Bruce / Farmstudio

It sounds to me as if a power-on self-test fails or if a major component that the computer needs to power on, isn't working.

Do you have a monitor connected to the HDR? Does it show anything before it powers off? Can you still access the BIOS or does it turn off too quickly for that?

If there's nothing on the monitor and it shuts down before getting a chance to go into the BIOS, then this could be something like the memory needing to be re-seated (or replaced), no video card being detected by the mainboard or the main CPU/processor isn't working or at least the fan for it isn't. etc. Or the multiplier for the CPU was set to something it doesn't work with (e.g. via jumper... I think this wasn't done via the BIOS, yet, on these old boards) - but you didn't change these settings, right?), or a cable could be hooked up the wrong way and create a short, etc..

It "could" be a power supply or fuse issue, but I think that's less likely, but it's hard to tell with these symptoms.

If re-seating the memory and video card and checking that the CPU fan actually spins up doesn't help, I'd get one of those little internal PC speakers like this and connect it to the corresponding pins on the mainboard inside the HDR:

https://tinyurl.com/4a2fduna

Depending on the type of issue, this could give a different beep-code that you could look up online for this mainboard, to figure out because of what fault it is shutting off.

...or if you changed any cable connections on the mainboard itself, I'd unplug everything that isn't absolutely necessary and try again if the mainboard powers up (and stays on) - if so, one of the cables on the mainboard was likely hooked up wrong and caused a short circuit (but if this problem really started out of nowhere, after the HDR worked fine before being shut down the last time, then this isn't it).

Same thing (but less likely) for external connections... I'd try with nothing but the monitor connected to see if it stays on longer and starts showing something on the monitor (and report back what it says), etc.

So, other than re-seating some mainboard components (I wouldn't re-seat the CPU itself, yet, unless you have thermal paste readily available), I think a little speaker like that would be needed, to get a beep code and a better idea what's going on.

As I posted prior, I had pulled the battery overnight, as per Mike River’s book advice to clear the CMOS, but the same result, 2-3 seconds OFF.

After posting here and the D8b forum, I was beginning to feel the advice of caps in the Power Supply may be the culprit, and I was then researching the correct part number for replacement.

However, as an afterthought, I again followed Mike River’s advice book, and moved the Jumper next to the battery to pins 2-3, waited awhile, then moved the jumper back to pins 1-2. Put power cord back in, pushed ON button and NOTHING! No lights, no sound, no fan….nothing. Did the power cord pull again, and NO, no power, nothing!


As my username says, “Farmstudio” I really AM a farmer by trade 50 years, music studio on the side. Got some warm spring weather this past week and needed to be on the tractor for a bit.


Storm rolled yesterday, so I got back to addressing this HDR, so sorry for not replying & thanking those who responded.


I had a weird thought, that maybe I had not put the jumper back on correctly, or had bent a pin. Opening the case and looking, the jumper looked ok. So I pulled the jumper again, all pins good, then again put it on 2nd pins, then back to 1-2 pins. AND…..

The HDR booted!

I did the delete key, corrected a few odd CMOS settings, it re-booted, all the lights, fan, clicks, and normal noises, & screen ok. Opened a few projects, played them, all seemed normal!

So….I guess the ‘gremlins’ had visited me.


As per the advice from the D8b column, I’m going to leave the power cord in the HDR when it is not in use for maybe a PSU maintenance suggestion.

Thank you again for your help on this issue.

Bruce/ Farmstudio