Fader problems and V-Pots

[Dreamsequence]

I recently acquired a 166 Mhz D8B running v3.0 & the Service Pack.

First issue: Fader banks 1 & 2 (Ch 1-16) do not calibrate to match the monitor display, i.e. they are physically -7.5dB too low. I base this upon pushing them wide open and checking the output levels at the bottom of those faders on the monitor. Bank 3 works fine. Repeated calibrations don't help. Fader bank 1 actually calibrates physically -7.5dB below the +10dB top of stroke where Bank 3 travels; more on Bank 2 coming up.

Second issue: Fader bank 2 will NOT calibrate (no moving faders at all). Instead, they (Ch 9-16) lock up at infinity (bottom of stroke), and will not release after the calibration pass. I moved the Bank 2 cable to Bank 1, and it seemed to work OK (but still -7.5dB low) to rule out the CPU card and/or ribbon cable. For what it's worth, there is some residue on the bottom corner of the PCB that looks suspiciously like a beverage spill. I'm contemplating a rinse with Flux Remover or Deionized water.

I've read some of the threads re: replacing faulty motor drive IC's that seems to work sometimes but not always. I reloaded the OS and the SP just in case. The data cable is not stock, but it works on my other D8B. As far as cleaning the faders, great photos of the process are available in this database, but I'm wondering why no one seems to like a product like Caig FaderLube 5%, which is supposedly made for cleaning and lubing faders. The V-Pots are also really filthy, so I'm looking for a cleaning procedure for them as well. Are they composite wipers or optical encoders?

Any suggestions are welcomed. I didn't want to invest in a fader bank (or two) to find out there is another reason for the -7.5dB deficit.

[Crash]

One thing you could try is either flip the ribbon cable between the two fader packs, or flip the fader physically and see if the problem follows. That will help you determine of it truly is a fader issue put the problem is elsewhere.

[Dreamsequence]

It just occured to me perhaps the encoder circuitry is not referencing correctly. The entire PCB thinks the faders are not at the bottom of the stroke, so they stay powered. One of those IC's must be a latch that won't release...

[Dreamsequence]

Crash:

Bank 2 definitely has a major problem. I connected Bank 1 to the Bank 2 cable and it worked better (still -7.5dB low). I'm more concerned with why both Bank 1 and 2 calibrate low, and by the same amount of error. I even checked the digital trims.

[anyhorizon]

Just as a matter of interest, have you flushed all "start up sessions" down the toilet, turned off "power up with last session" off and rebooted, then run the calibration routine?

Peter

[Dreamsequence]

Peter:

I thought I reset to the factory Session Startup file, but will try your exact prescription. I remember deleting the Session Startup file after reading it might be corrupted. BTW, what about a RAM problem, DB25 Console cable (something about a crossover between TX and RX) or connecting ribbon cables? I still think Bank 2 needs an IC repair. Anything on the fader clean and lube? I have some 5% FaderLube and might clean the Bank 2 faders intact, upside down (after compressed air). At least I can see what happens if it's getting pitched anyway.

[anyhorizon]

The reason I asked previously is that "Modify levels" could have been engaged. "Startup sessions" can end up all over the show depending on what the file path was at the time of saving. You have to delete them all and the d8b will make a new factory default when next booted. Regarding the cleaning agents, compressed air is best and 99.9% Isopropyl Alcohol, 2nd best. The trouble with lubes is that whilst they may work preliminarily, they contain oil which can become gunky over time and exacerbate the problem.

Peter

[McKay Records]

I recently acquired a 166 Mhz D8B running v3.0 & the Service Pack.

I've read some of the threads re: replacing faulty motor drive IC's that seems to work sometimes but not always. I reloaded the OS and the SP just in case. The data cable is not stock, but it works on my other D8B. As far as cleaning the faders, great photos of the process are available in this database, but I'm wondering why no one seems to like a product like Caig FaderLube 5%, which is supposedly made for cleaning and lubing faders. The V-Pots are also really filthy, so I'm looking for a cleaning procedure for them as well. Are they composite wipers or optical encoders?

Any suggestions are welcomed. I didn't want to invest in a fader bank (or two) to find out there is another reason for the -7.5dB deficit.

I would like to know the answer to the question you asked about the fader lube as well, I was told by mackie tech support that the faders are motorized so they dont recommend using it on the d8b, they said fader lube was made for faders with no motors like analog faders but then again I was told by the store manager of a music store (no names mentioned) who ownes a d8b for years to use deoxit fader f5!!!???

[Dreamsequence]

Thanks gents. Is there a specific place where Modify Levels can be viewed and/or turned off? I tried to find any mention of trimming the faders other than Digital Trim, which didn't change anything. There has to be something in common for two adjacent banks to be off the exact same amount.

Comments noted about the faders. The second one says it all...who knows what to believe? That's what I proposed to use.

Anyone care to take a stab at cleaning up the V-Pots? If they are optical encoders, they must be dirty (dust, grime). If they are composition (like an analog pot- unlikely), a little shot of cleaner should help, although composition pots are supposed to be self-cleaning. According to the schematic, they look like conventional composition-film endless pots.

For what it's worth, the trick to replacing SMD (surface-mount device) ICs appears to be with a hot-air rework desoldering station. These can be picked up new online for less than $100 new. Forget about a hand sucker and/or solder wick. There are neat videos on YouTube that show exactly how to do this. Using a conventional vacuum desoldering station doesn't work well with SMDs, but it is far superior to solder wick. And to the member that tried to pry off the IC after solder wick and ended up tearing off a PCB trace...yes, I've seen auto-placement equipment that injects a drop of adhesive on the PCB to secure the device on the pads prior to wave or ultrasonic soldering. That's why the hot-air desoldering works well; I believe the adhesive releases when hot enough.

[anyhorizon]

Anyone care to take a stab at cleaning up the V-Pots?

This post in the database addresses the control room monitor pot specifically but also relates to the V-pots in general. I know it's hard to believe but it works. Make sure you attempt each fix in order.

Peter