Is this the D8b “rail cap” issue or something else?

[juanbanzai]

Thanks to several of the members of this forum, the D8b I rescued from my work has been chugging along pretty well for the most part. But with that said, lately the board has been acting very flaky. Sometimes, in the middle of a session, it will go completely dead and start exhibiting the symptoms associated with the rail cap failure; clicking coming from inside the board, various VU meters bouncing up and down rhythmically, and no output whatsoever.

More often than not, when I turn the board on after not using it for several hours (or several days), I’ll hear a faint click… click… click… and some of the VU meters faintly display up and down movement. The software doesn’t load past the main D8b graphic. Every time, I seem to solve the problem by unplugging the master power supply cable hock from the back of the D8b and reinserting it. The other day, I pulled the hock out completely and sprayed DeOxit into each of the pin holes. Once I do this, the board almost always powers on. On those occasions where it doesn’t, I unplug the power supply hock again and reinsert it. Then the board powers up. I’ve got some major archival work to do with old Mackie drives but I’m afraid to do it if the board is on it’s way to a total meltdown.

Am I looking at a rail cap replacement or is something else going on? I have everything I need to replace the caps, I just don’t want to do it.

Thanks for any help.

Aaron

[Phil.c]

Before you do anything drastic I would do a ribbon clean and reseat, this will eliminate cable problems which is very common, but when you take off the connectors, run your thumb nail in the join front and back to lift the cable off the spikes, put in some circuit cleaner and pinch back tight with a pliers. Also, make sure the white power connectors are tight for a good connection.

Phil

[doktor1360]

Thanks to several of the members of this forum, the D8b I rescued from my work has been chugging along pretty well for the most part. But with that said, lately the board has been acting very flaky. Sometimes, in the middle of a session, it will go completely dead and start exhibiting the symptoms associated with the rail cap failure; clicking coming from inside the board, various VU meters bouncing up and down rhythmically, and no output whatsoever.

More often than not, when I turn the board on after not using it for several hours (or several days), I’ll hear a faint click… click… click… and some of the VU meters faintly display up and down movement. The software doesn’t load past the main D8b graphic. Every time, I seem to solve the problem by unplugging the master power supply cable hock from the back of the D8b and reinserting it. The other day, I pulled the hock out completely and sprayed DeOxit into each of the pin holes. Once I do this, the board almost always powers on. On those occasions where it doesn’t, I unplug the power supply hock again and reinsert it. Then the board powers up. I’ve got some major archival work to do with old Mackie drives but I’m afraid to do it if the board is on it’s way to a total meltdown.

Am I looking at a rail cap replacement or is something else going on? I have everything I need to replace the caps, I just don’t want to do it.

Thanks for any help.

Aaron

Aaron... following Phil's advice is SOP from the get-go, it should put things in a state where it'll be less difficult to mitigate any issue(s). At that point, you can almost disregard anything that would involve opening and closing the console. It also helps anyone attempting to help know that the integrity of the electrical connections are burnished and intact...

Another thing I can add for starters, which you seem to be doing albeit slightly differently, is that when you unplug the power from the unit do it at the AC outlet on the wall. This serves the purpose of allowing the non-volatile electrolytic caps onboard to drain. They tend to 'hold a charge' on a lot of TTL logic used on the power supply, motherboard and other peripheral components. Again, what I personally do in the odd event this occurs (and highly recommend to anyone in this type of situation) unplug at the wall, walk away for 5-10 minutes and get yourself something to eat and/or drink. When you return, plug the AC back in and reboot. It should boot normally... this is especially true if you use a CF card for boot media. There aren't any moving parts, and it essentially 'journals' things making it very reliable for real-time computational operations of any kind - it doesn't cache data like a mechanical hard drive does...

As far as the rail cap(s), when something lets go designed to regulate power all kinds of f*ckery would then likely ensue. I can't speak personally, I've never experienced this particular malady (*knocks wood*), but that really seems like an extreme edge case tho too...

In summary, just follow Phil's advice for Step #1, and then post up anything else that arises...

Of course, you had to know it was coming, so here it is:
[Standard Mgmt Disclaimer] - "Your actual mileage may vary..."

[juanbanzai]

Thanks for the responses, guys.

I found out yesterday from one of our radio producers who worked with the D8b when it was new that it ALWAYS did that weird thing sometimes when powered on. He (and everyone else who used the board since it was in one of our control rooms) figured it was quirk with the D8b and just accepted it. He also said that our D8b was one of the first ones out of the Mackie gate when our Chief Engineer saw it demoed at the Las Vegas CES. In other words, it was so advanced for its time that the Chief HAD to get it into our studio. Of course, this made me wonder if the earlier versions of the D8b did indeed have some flakes that were eliminated in later runs.

I can live with the thing not booting up when it's first powered on, but what really makes me incredibly nervous is when it simply goes into that fault state when it's turned on and HAS been on for a while. Case in point, I was doing an SFX mix on the D8b for an upcoming episode of my podcast and thing just went "DOINK!" A loud POP came from my monitors, random VUs started blinking and the rhythmic clicking was under the hood as well. I'd love to be able to keep the D8b powered on all the time, but if I connect my studio speakers to it, I'm afraid of them getting killed if the board goes into fault.

I've been doing a lot of reading on the ribbon-cable issue and I think it's time to dig into that piece of necessary maintenance. I just have to remember where I saw how to get to them!

I also have all of the original floppies so I may finally upgrade from OS 3.0 to 5.1.

Thanks again.

Aaron

[Phil.c]

First, an upgrade to v5.1 is a must, just do it, have you got the installation code?

Ok, the ribbon procedure,stand the desk on end, take the bottom cover off, take a picture of the cables, also, it’s a good thing to number the ribbons and where they go with a felt pen, just to be sure. Pull one connector at a time off, run your thumb nail between the connector and the ribbon both sides to lift the ribbon off the spikes, drop in some IPA or similar, squeeze the connector back on the ribbon with a pliers, clean the mail connector with IPA and push back into place, it only goes on one way.

Do as many connectors as you can get at.

There are also a few power connectors, these are usually white, take them off, clean and push back making sure the are a tight fit, if they are loose, press a screwdriver against the silver piece on the side, this will tighten the fit.