Tascam M-3500 mixing console

The mixing console is 32 channel inline mixer which means that there are essentially 64 input channels to take care of.

m-3500-part1.jpgI'd call it semi-modular since you can easily remove a set of 4 channelstrips at once. The PCBs all look pretty clean and there are no capacitors that look bad. The pots will need some cleaning since some of them crackle a bit, as do the faders. A treatment with DeoxIT D100 hopefully will cure the crackling pots and faders. I'll use contact cleaner for the switches. Some of them crackle when activated or deactivated.

There are all together 542 small parts to clean. Every channelstrip has 2 faders and 14 knobs. The master section consists of 8 bus faders, 4 aux return faders, 1 stereo fader and 17 knobs.

m-3500-cleaning-parts.jpgNow, if you lookup the term “lazy” in a thesaurus, you will most likely find my passport photograph right next to the definition. 542 small parts to clean, a toothbrush and me don't mix very well so it's going to be the dishwasher with the parts in the compartment where you put knife, fork and spoon. I did all parts at once 40°C “express mode” and put half of one of those dish washer tabs in. Almost all parts were clean but some had still some muck on it that went away when I dried them with a kitchen towel. I think I could have run the dishwasher a second time since “express mode” doesn't last very long but I just went ahead with the drying.

m-3500-potshot.jpgI cleaned the console surface with a wettish lint-free cloth and off the shelf dish liquid. To make cleaning easier and to allow access to the pots and faders, I removed a quadro-channelstrip module and an 8 channel fader module. The knobs had already been removed, so you just need to remove all the nuts from the pots, disconnect the line faders from their respective PCBs and you're good. Now you can clean the surface, and treat the pots and line faders with DeoxIT D100. Look at the picture to the left where I tried to sneak the DeoxIT in. In addition to that I treated every switch / latch with contact cleaner. Fitting the cover over the pots and switches was quite difficult. You need to be very careful not to bend or break something. Maybe it would have been easier to completely remove the channelstrips from the console and pull one PCB at a time working from the bottom instead of the top.

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m-3500-faders1.jpg On the picture to the left you can see where the 8 faders are attached to the console. You need to disconnect them by pulling the sockets to the front while applying a little pressure from the right side. It should not be difficult. If you can't get them loose easily, you're doing something wrong and might damage the connector or PCB. Anyway, cleaning the 8 channel fader module was a lot easier than the channelstrip module although you need to be careful removing the 16 screws that attach the faders to the cover. You need a small philips screwdriver. Be careful not to ruin the heads, some screws may only unwillingly come loose as they might be by a little rusty from sweat and locked by the grime that certainly accumulates around the heads of those screws after some years of usage.

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After removing anything that doesn't belong in the fader housing (see last picture of the following three to see what can be found inside the faders' housing after some 15 to 20 years of use), you can apply a short burst of DeoxIT D100 onto the “runway” and use a Q-Tip to carefully sweep it. If the fader doesn't crackle, there's no need to use the D100.

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Proceed with the remaining 3 fader modues, 7 channelstrip modules and the master section in the same manner and the console should look and feel almost as if it were new ;-)

before after
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m-3500-master4.jpg The master section does not contain as many knobs as a channelstrip and therfore removing the cover plate is a little easier. Removing the nuts from the pots isn't sufficient though. You need to remove four L-shaped brackets from underneath to get the plate removed. Be careful when re-ataching the brackets; not every bracket fits every position. The brackets are matched to fit the upper or lower end of eiter the left or right group of four PCBs. Either take notes or just compare them, when reinstalling. If it doesn't fit, it's not the right bracket. You can look at the pictures above for reference. Cleaning is the same procedure as with the channelstrips. After you're done your brand new master section will match the looks of your channelstrips again ;-)

before after
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I think about changing the op amps of the channelstrip and maybe the bus and master section. I haven't checked the whole board but at least in the input and eq section there are JRC 4580D used.

m-3500-channelstrip2.jpg m-3500-channelstrip3.jpg