Roland CR-78

This is a restoration of a Roland CR-78 done for a client. The CR-78 was very clean inside with no battery leakage at all. I removed the battery never the less as it is hard to tell the age of the battery inside the machine. Note the EPROM in this version of the CR-78, this might be a later model CR-78, as the large connector to the side near the battery is not present in my version of the CR-78. The wires are soldered directly to the PCB on my version.

Ok, the front panel is off. A lot of dust can be spotted on the push buttons. This calls for some Mr. Muscle ; )

Here is a close up of all that old dust.

Years of wear and tear. Oh well soon this is nothing but a memory ...

That´s more like it should be.

The backup battery. Many times this will be all green and spewing out acid all over the PCB. The N-SB3 is a 3,6 Volts / 90 mAh Ni-Cad cell with Axial leads and can be found all most everywhere today. Do a search on "N-SB3" and you´ll find it for sure. Older batteries might not have the plus or minus ends marked, however new batteries all most certainly have these markings, just install a new one the way you see in the picture above.

Be careful when opening the CR-78, this chip might be a UV sensitive device in some CR-78´s. Make sure it is either of the above type or see to it that the chip has it´s center covered with black thick tape in order not to wipe the program when exposed to daylight.

These have a habit of crackling and making poor connections making the audio suddenly disappear and reappear. Contact spray of different sorts will only make it sound good for a while, after a few weeks the crackles are back. Only solution is to either get new ones which might prove to be difficult or opening the old ones and clean them with Isopropyl alcohol (IPA for short).

You need to de-solder each of them and open them to make them clean. When closing these sliders be careful of how much force you apply to the metallic parts keeping the slider together. Applying too much force will make the slider harder to move or give a uneven feeling when you move the slider arm. If you fasten them to loose you might get loose connection in the slider making the audio suddenly disappear and reappear. One of these sliders is of a different kind than the rest, de-solder and re-solder them one by one in order not to confuse them and by accident solder them in the wrong place.

To open these, I use a flat screwdriver (minus). Gently bend the metallic parts holding the mini pcb in place up from the pcb. Once you get them up a little bit you can bend the rest of the way with a tong (nippers, pliers or whatever you might call them).

The slider opened, be sure not to confuse the way the mini pcb and the slider "slide connector" goes. The image above shows the right way.

This is what is causing all the crackle in the audio, years of wear and tear has made this slider dirty. Clean it all with IPA, add little lubricant like electronics spray with some cotton buds after you´re done cleaning.

This is how clean they should look after you´re done. Note that you can not see any lubricant dripping from the PCB in this image, that is how little you need to add.

Notice how it sparkles now. The secret is plastic polish. You´ll find this chemical at your local gas station, as it is usually used for making you cars instrument panel shine.

More of that shiny result. The black knobs are really black now ; )

None of the plastic parts have been replaced, they are just cleaned.

More of the same shine.

Looking almost new I would say. Time to send it back to it's lucky owner.