Servicing a keyboard assembly is a filthy business in many cases. Often, synths are stored without dust covers or have been gigged and the build up a FOD can be disgusting, especially when combined with Roland manufacturing over zealous lubrication. This dirt is a hazard for the keyboard contacts and is to blame for many of the issues. See Jorick’s refurbishment article to see how challenging it can be.
Issues can also occur if it is simply the case that the keyboard has rarely been played, oxidisation of contacts over time happened in our case.
Cleanliness is essential when fitting any keyboard contact PCB, the most common issues that cause problems in priority order are:
- Oil on particles from hands and fingers
- Red epoxy glue used to secure weights in the keys (Roland batch issue)
- Silicone grease contamination
It is essential to source new contacts or thoroughly clean them and remove dust particles before reassembly. Cleaning new contacts can slightly deteriorate contact resistance howveer it is still essential to remove traces of dust using an anti-static brush.
The red glue can be removed by soaking the keys in hot caustic soda solution used for cleaning drains. Take care not to let the solution exceed the melting point of plastic, there are reports of warped keys. It is a pretty nasty process but yields good results. There are various guides and forums on the web that detail this process.
Thoroughly cleaning all parts of the keyboard assembly is strongly recommended.
This page is focused on the important differences when installing the replacement Flexible PCB, plus any important points that ensure success and reliability. It is intended to supplement the Roland Service Notes that can be downloaded from an excellent no-fuss site www.synfo.nl, please make a donation if this site is useful to you.
The keyboard section of the Roland Service Notes is pretty thorough in it’s explanation. It gives plenty of warnings and tips on disassembly and reassembly.
As a whole, the keyboard assembly is quite complicated and contains many parts. The connectors for the Aftertouch and Motherboard flat cable are reused as they are no longer available.
The old connectors from the Roland transition board are removed by desoldering tool. Either electric, as shown in picture, or hand pump are used. It is straightforward because the PCB is single sided.
Fit the Aftertouch connector with a very small amount of superglue taking care not to contaminate the pins or contacts. It will be necessary to straighten the pins for a precise angled fit.
Fit the motherboard connector on underside of PCB, on same side that bracket fits against. The PCB will look as shown in pictures below.
Note the other extra positions for alternative connection methods:
- CN3 – Replacement Flat Cable Option using IDC should the flat cable be damaged.
- CN4 – Different type of FPC should Molex “Top Contact” type become obsolete.
Special note: Do not clean the flux from the white FPC connector. A non corrosive type for a no clean process is used. The danger of contaminants wicking into the contacts is very high. It is possible but a very thorough washing process is required that is usually beyond hobbyist/service tech scope.
Flexible PCB Placement
Take great care not to fold the PCB, otherwise permanent distortion occurs that may be difficult to correct.
Place the flexible PCB on the keyboard frame whilst avoiding touching any contacts or contaminate them with dirt or fluids.
Move the PCB such that the Primary Location hole between contacts S25 and S26 sits over the bump in the keyboard frame. Align the flexible PCB such that it is straight and locates over the other location bumps.
Once happy with alignment and primary location hole is firmly in place, apply some insulation tape to hold in position. Before applying the tape, ensure that the surface is clean and free from grease, remove with IPA if necessary. The lubrication used on the keyboard assembly is silicone based (safe on plastics) and very difficult to remove. If this lubricant reaches the contacts, they will stop working properly.
Checking & Cleaning
Carefully inspect the flexible circuit for any signs of contamination:
- During handling, touching the contacts accidentally can deposit oils from the fingers.
- Lubricants used on the keyboard frame and moving parts can fall onto the surface during positioning.
- Although unlikely, flux residue can be present from the manufacturing process.
If contamination is present, or if in doubt, clean each contact with a cotton bud or Q-tip soaked in IPA before immediately drying off with a dry bud to remove all traces of IPA residue. It is very important that all contaminants are removed before assembly as it is a very long process to correct later. Any adjustment means the keyboard will have to be completely disassembled and rebuilt.
Removing Static Charge & Dust
Polyimide film used in the Flexible PCB is prone to carrying static charge and therefore can attract dust particles during assembly that could ruin performance.
Using a clean anti-static and conductive brush, remove the surface charge plus any dust. Take great care not to place the brush on the metalwork or other areas that may be contaminated with lubricant or dirt. It is recommended to clean the brush with IPA before performing this operation. Brushes like this are often supplied with ESD handling kits and are very low cost on eBay.
Fitting Contact Strips
Contacts must be free from dust before fitting, use the anti-static brush to remove all particles & filaments. The new Polyimide film is prone to rippling due to the manufacturing process, once contacts are in place it is pinned down and held flat. To prevent misalignment, start fitting contact strips around the location hole. There is a mark on the flexible PCB that indicates the edges of the rubber contact strip. Once first contact strip is in place, check alignment of the flexible PCB and adjust as required. If old contact strips are used, clean with IPA then brush off the cotton bud filaments left behind.
Use a paperclip as recommended by the Roland Service manual to engage the contact pillar.
Fit the second contact strip to the right of the first one.
Fit all remaining contact strips making sure there is no dust of contaminants on the contact points. Once all contacts are in place, they are protected from any dust particles.
Rubber Contact Issues
When using old contacts, it is a good idea to clean them thoroughly before installation. This can be done by soaking them in a hot solution of washing powder. Once dry, clean with IPA followed by removal of IPA residue with a dry bud. Any remaining dust and filaments from the bud can be removed with an anti-static brush. At minimum, cleaning with IPA and removing dust is essential.
When using new contacts, it is a good idea to remove any dust because handling of these items can be questionable if not from a Roland distributor.
The contact surface is flexible thus allowing for some dust contamination, but it is the build up of dust over time that adds to the problem. It is best to remove all visible traces of dust before fitting the contact strip. Using an anti-static brush really helps achieve a dust and particle free contact.
The most damaging areas of contamination are:
- Red epoxy glue that has gone soft and run into the assembly.
- Oils from skin particles and dust.
- Lubrication employed on the key mechanism.
Red epoxy glue that wasn’t properly mixed with hardener affected a huge number of instruments for a specific time period of manufacture.
Silicone grease that migrates or gets transferred by dirty hands adds an insulation layer that easily spreads over the contact and penetrates the carbon impregnated rubber contact.
Roland used automatic dispensing of lubricant and too much was used so it becomes a hazard to the contacts when servicing.
There are many “solutions” for contact improvement, many involve adding aluminum foil or conductive paint. However these “fixes” actually add to the problem by either preventing flexibility and reducing ability to cope with dust or worse still; adding a metal adhesive backed foil such as aluminium, actually oxidises over time and prevents low current contact.
The amount of current that passes through the switches is approximately 450 uA at 4.3 V, this is not enough to reliably break through a thin Aluminum or silver oxide layer that develops later. A solution involving carbon or gold is therefore going to be the most reliable.
Mounting pillars often break off when contacts are removed. When some of the rubber contact strip mounting pillars are missing, it can lift up a little during play, allowing dust to work it’s way under and eventually prevent a from contact working. In this case, simply using a keyboard cover when not in use prevents issues. The design can cope with some of these missing.
Using the original plastic rivets and plastic bracket, secure the flexible PCB to the metalwork. It is very important to insulate the sharp metalwork edge from the new PCB. If this was removed, replace with insulation tape. In the picture below, the plastic rivets had broken, so two M3 bolts and shake proof nuts are used instead. If using the bolts from the kit, do not tighten, they must be slightly loose so that they turn freely to prevent crushing the delicate conductors in the PCB.
Fit the new transition PCB to the original position and plug in the Aftertouch flat cable into the 2 pin connector. The original securing tape will be very sticky, if this had touched the connection on the Aftertouch strip, remove sticky residue with IPA. Fitting the Flexible PCB into the locking “Zero insertion force” connector is shown in pictures below.
Prepare the ZIF connector by opening the latch. Pull on both edges very carefully to open the slot.
Insert Flexible PCB connection into the ZIF connector and simultaneously pinch both latches to lock in position. The cable will flip up and down slightly as this is performed.
Turn over the assembly taking care not to damage the flexible PCB connection cable and refit the keys.
Before doing this step, it is recommended to reconnect the assembly to the mainboard, power up and test all rubber contacts.
When refitting keys, it is common practice to lubricate moving pivots with silicone grease. If doing this, use a very small amount of grease, too little is better than too much. This is to prevent it spreading around over time and eventually reaching the contacts.
Do not use petroleum based grease as this will damage the pivot point in the plastic key and it will split over time. It also gradually evaporates oils that can enter the contacts.
We prefer to install all black keys first, it makes for a faster assembly time overall.
After fitting all keys and making sure that they are properly engaged, turn over and lock them in place with the plastic strip pinned down with double sided tape. The plastic locking strips have shallow teeth that sit in each key hole.
Finally, after fitting the keyboard assembly into the Synthesizer and reconnecting the flat cable, place some insulation tape on the metal base under the flexible PCB where it touches the metalwork. Do not use adhesive to attach the flexible PCB to the base, it needs to be allowed to move freely. The flat cable is fragile, take great care with installation as it is irreplaceable, however we do have a solution for replacing it if needed but involves confident electronics skills.
The insulation layer on the top surface of the flexible PCB is only a few microns thick and it’s not guaranteed to prevent short circuits of the keyboard scan chip if touching metal surface. On future flexible PCBs, version 03 onwards, this will be addressed by making them shorter.
Testing is best performed using the test mode in the synthesizer, it is accessed by simultaneously holding down Cursor Left & Right then pressing Exit whilst Synth is in Multi Mode. Once Test Mode appears, hold Exit and press “3”, keyboard test routine starts and each key can be checked and confirm that velocity is being detected consistently.
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