Roland FP-8 Keyboard Repair (Capacitors and Hammers)



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This was quite an easy fix.

To sort out the keys that were not going up, I needed to open the keyboard by undoing 8 screws underneath (4 on each end).

Then the keys assembly is removed by undoing some more screws underneath (towards the bottom of the assembly), and some screws to the top of the assembly.

After undoing the ribbon cables from the keys assembly to the main board, you remove the assembly from the rest of the housing.

Use a flat screwdriver at the top of the problem key to gently open the tabs outwards and lift the key out at the same time.

The Hammer assembly’s were broken at the usual point just above the weight. Epoxied the hammers. After drying, reassembled the keys.

To sort out the low volume was simply a matter of replacing several electrolytic smd caps (10uf 16v, 47uf 16v, 100uf 6v) on the main board itself. Replacement caps were sourced from an old DSTV decoder.

Replacing the 2 Capacitors near the main processor also fixed the long start-up time (from the time the unit was switched on, until the time it showed anything on the display.

After this the volume was now at an acceptable level. However the Left speaker set was at full volume no matter what the position of the Volume fader is.

Cleaned out both faders. Noticed that the Monitor fader is damaged and worn out. Swapped it with the one for the Line Output (as that one is not used as often).

The ‘Strings’ button needed to be pressed hard to activate. Replaced the tactile switch on the board

The top ‘C’ key (the rightmost key) intermittently works. After further dissasembling the keys assembly, it was determined that it is the conductive pad and rubber assembly that is worn. This will probably require a workaround or replacement, but that is for the customer to decide if he wants full functioning of that key.

SMD Reflow Oven – DIY Build

Decided it is time to get a reflow oven together (my boards are too tiny to solder with an Iron (I guess. But this will be easier anyway).

Step 1:

Find a cheap, 2nd hand mini oven.

Done – This thing is Tiny. I would be surprised if you could even cook a mini-pizza in this.

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Put a thermocouple in this oven, and tested the temperature. It takes a long time to get up to the reflow temperature. So time for some mods:

1) Strip out the Timer and Controller.
2) Take out the bottom elements, and reinstall them in the top.
3) Install a PID Temperature controller.
4) Insulate around the cavity to prevent heat loss.

Ok, So Time to start stripping :

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Oven has been stripped, New holes drilled, and the bottom elements have been relocated to the top (sorry, no pics yet).

Wired the elements in parallel and hooked up a PID temperature controller in place of the Timer/Switch combo. I also bypassed the thermal cutout on the sidewall of the oven.

Put a populated SMD board in the oven, heated up to (what the controller says) is 165 degrees centigrade, with the thermocouple in contact with the PCB, and the solder melted. I was able to remove all the components with a gentle tap.

Oven actually got up to 250 degrees c, but the door was rather hot.

And this was without any additional insulation in the oven (and the top cover still removed),

I have taken plenty of old boards I had lying around, and after sticking them in this oven for a bit, As soon as the solder melts, I pull them out (with a pliers) and bang it on the workbench.

The results : An almost Empty and Clean board, Solder Splatter all over the workbench, and small parts all over the garage!

For Fun I cranked up the temp, and had a GPU chip (from a monitor card)on the rack, After tapping it, the ‘lid’ came off the processor, and i could see all the bond wires. That was unexpected