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 of 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, he made an overview of this installation process too.
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
See our special page for an exhaustive examination of failure modes.
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 however it is still essential to remove traces of dust using an anti-static brush.
Dust causes uneven velocity pickup, or occasional mis interpretation of velocity on one or more keys.
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, one of which is here.
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.
There are two types of Flexible circuits in use, it is important to identify which you have in order for us to provide the correct transition PCB. For Type 2, Transition PCB P0016A-04 is specially designed to rotate the signals to suit the different flat cable.
The most common on the Roland JD-800 is Type 1 that has a weak thermal connection and is most likely to fail. Type 2 has a Roland transition PCB mounted upside down. The picture below shows how to identify the two types.
Instruments with Type 1 have a white flat cable with conductors exposed on opposite sides at each end of the cable. Type 2 has a white flat cable where the conductors are exposed on same side at each end of the cable. This means that the Mainboard flat cable connector has to be installed in a different position for Type 2, so that mounting of the new transition PCB is in the same orientation for all types.
Flat Cable & Connectors
The connectors for the Aftertouch and Mainboard flat cable are reused as they are no longer available.
Take care with the white flat cable, it can be easily damaged or contacts contaminated. Disconnect from keyboard assembly and leave connected to Mainboard -or- remove, put to one side and refit last. The white flat cable can be replaced with an IDC type, the method of which is covered in the build guide, Keyboard PCB Adaptors and Cable. When using a 30 way IDC cable method, the transition board needs to have a 30 way IDC cable header fitted instead of the main board connector, it is mounted to same side as where the bracket locates to.
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 Aftertouch Connector
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 Motherboard Connector
Note the positions for different connection methods, there is a high degree of flexibility to accommodate different instruments and issues:
- CN5 – Mounting position for Type 1 flexible cable connector.
- CN6 – Mounting position for Type 2 flexible cable on transition PCB P0016A-04.
- 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.
Fit the motherboard connector on underside of PCB, on same side that bracket fits against. The PCB will look as shown in pictures below.
The Mainboard connector is mounted on the top side of the transition PCB P0016A-04 as shown in the picture below. Contact us for an alternative solution before soldering if you do not have the correct PCB type.
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.
The Roland Service manual recommends a paperclip to engage the contact pillar, however this can be an issue especially for old contacts where the rubber has hardened. Either push very gently or use method as we do below.
One user has recommended not using a paperclip to reinstall the rubber contacts. They always put the rubber dome in the hole and keep pressure on it with a finger. Then with two fingers from other hand, gently pull it through the hole until it pops into place. If using a paperclip you can very easily punch a hole in the rubber or rip the dome off.
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 with velocity pickup. 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 aluminium 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, causes excessive bounce that confuses the scan chip or 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 Aluminium or silver oxide layer that can develop later.
For best performance, a resistive top contact is necessary for the contact de-bounce function and not confuse the keyboard scan chip.
A solution involving carbon top contacts and gold bottom contact is the most reliable method.
A great technique for removing contact strips is by using a silicone sealant tip that has been trimmed so that the hole is 2.8mm wide. The tip is dipped in water to make the surface slippery before applying to the pillar. The contact is pulled very gently from the opposite side, whilst wiggling the sealant tip. Take care not to use much force, a gentle pull is all that is required and the pillar will gradually pop out. If more force is needed then it is because the tip is not aligned with the hole in the metalwork or you are pulling the contact at an angle and not straight out.
This technique was inspired by a beta tester, Carsten, who used a trimmed tip from a de-soldering hand pump. The PTFE surface meant that water was not essential.
Mounting pillars often break off when contacts are removed by just pulling them out. 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 provided that the contacts lay flat. If there is a ripple on the flexible PCB adjacent to a missing pillar, it can cause minor variations on velocity pickup for that key. Some users have placed a small piece of double sided tape close to the area under the flexible PCB, to correct the issue. If doing this, ensure PCB is correctly positioned.
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, 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.
One user has reported that aftertouch required rotation of the aftertouch flexible strip by 180 degrees, other users have not. If aftertouch worked before and doesn’t work after this upgrade during testing, then refit rotated 180 degrees. See last section for important notes on this area.
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. When fitting all keys, make sure that they are properly engaged. It is easy to do with version 3 flexi as it has the key numbers marked with “#”.
Whilst fitting the white keys people have noticed that the gaps between the keys can be uneven and they have to move them around to make them look aesthetically pleasing. Maybe keys from particular mold numbers have to be grouped together, but we haven’t tested the theory yet. The mold number is indicated by the second two digits marked on a white key after the letters.
It is a good idea not to fit the locking strips underneath the keys at the pivot points until the assembly is properly tested and you are happy with performance / alignment. Handle carefully as they will fall out easily.
Mainboard Cable Installation
The white flat cable is reinstalled in exactly the same orientation as the Roland method. It is important that it is done correctly as there are many possible permutations that do not work. Note the signal naming on the transition board matches the mainboard, if necessary, these can be confirmed with the Roland service manual.
For both types of original flexible PCB, the transition board is mounted to the bracket in the same way and the blue stripe on the white flat cable always faces the green transition PCB.
The black connector is fitted on the underside of the transition PCB.
Fit the flat cable exactly as shown in picture below with blue stripe facing towards the green transition PCB, i.e. upwards away from the keyboard assembly.
The black connector is fitted on the top side of the transition PCB because the white flat cable contacts are on same side at each end.
Fit the flat cable in exactly same way as it was when removed from original Roland configuration; blue stripe facing towards the green transition PCB, i.e. facing the keyboard assembly.
We do not currently have a picture of this arrangement.
We hope to get more pictures from installers.
At mainboard end, fit exactly as shown with blue stripe facing towards the keyboard.
Finally, after placing the keyboard assembly into the Synthesizer, 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 first 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.
Once everything is confirmed, it is a good practice to fully test using a patch that is severely modified in timbre with velocity, such as “Single Mode I-34: Wet Bass”. With this patch, the filter is strongly coupled to the velocity value and therefore gives a very marked variation that helps to discriminate bad contacts caused by contamination. Consistency can be easily checked up as you work up and down the keyboard.
The “Fault Finding” section below shows guidance on fixing faults and ideas to remedy contacts that don’t perform.
Once happy, the keyboard assembly should be removed and the plastic strips that hold keys in place are put back into place with double sided tape. The plastic locking strips have shallow teeth that sit in each key hole. In the picture below a flat ended tool is used to push them into place.
Strangely, every keyboard assembly we have seen that has been through a UK tech, has these missing. If not present, the keys will fall out easily!
Secure the keyboard assembly in place and retest before putting the synthesizer back together.
Poor Velocity Pickup
The first contacts that are made, top row marked “BR”, are very sensitive to contamination because they determine the critical timing start point for the velocity measurement. Any bounce or high resistance caused by contamination or dust can prevent consistent operation.
If the “BR” contact is not seen then velocity will be deemed “maximum level” when “MK” is made thus resulting in a false impression that the keyboard is “working” for many types of patches. Choose your patch carefully when testing.
The most vulnerable points are where rubber contact strips mate with each other, as shown in the example below where dust and fluff affected the top contact resulting in velocity measurement that appeared to be “high gain”.
The keys could easily be removed in that section because the locking strips had not been installed, then contacts cleaned again. Unfortunately we used “cotton buds” that can leave cotton filaments behind, but we had nothing else and extra care was made to ensure it was clear afterwards. The anti-static brush was used to remove traces of dust.
Keys that require a group of contacts removing can be dealt with by another method. In this case, the velocity pickup issue was only slightly inconsistent and grease contamination was suspected. A strip of extremely high quality paper that doesn’t release fibers was used (high density photocopy paper). It is placed carefully in between the contacts and flexible circuit, whilst avoiding any grease contamination from the springs.
The paper was wetted on an inch of it’s length with IPA.
Then dragged the wet area underneath the contact whilst pressing very gently. Be sure to drag a dry section to remove IPA residue.
The other methods involve removing the rubber contact section again, which is time consuming.
If no keys are detected then a misunderstanding of Type 1 or 2 flexible PCBs has been made or a different orientation of Mainboard white flat cable is present.
When debugging it is important to note that the white flat cable and mating connectors only have electrical contacts on one side. This can lead to a lot of confusion if something is wrong. Type 1 white flat cables have a very clear blue designation line to identify the non-contact side. A picture of the end of the connector below shows a “top contact” arrangement.
Check the contacts between the mainboard and transition PCB test points as per “Keyboard Signals” guide below. It may be necessary to change the position of the connector on the transition PCB but this should be a last resort.
All signals are marked on both Transition board and the flexible circuit, it is straightforward to confirm that these run through to the mainboard correctly. It is important to get the mainboard connection correct as it can connect to either side of the flexible circuit and if wrong will reverse the signals. One side of the contact is designed to clamp the plastic backing and the other is a contact point, it is therefore essential to get orientation of the flexible circuit correct for reliability.
The picture below summarises pages 13, 17 & 18 of the service manual that show how it is connected up.
The new PCB kit does not fix issues with the After-Touch (AT) connector, however, the end of the sensor has contact points that are made of carbon and mate with nickel plated connector can become more resistive with time. The AT sensor is only a resistive type and can pass current in either direction so connection orientation does not matter.
One user has reported that twisting the AT flexible connector 180 degrees before insertion fixes this issue as it utilises fresh contact areas. However, it is possible to rejuvenate this by rubbing graphite powder onto the contact. Usually, cleaning with IPA is all that is needed to get this back to life.
An important note is that when unplugging the AT connection, the adhesive tape used by Roland is very sticky and the adhesive can touch the end and contaminate it. Cleaning is therefore often necessary.
The kit doesn’t fix the After-Touch sensor performance, that can be difficult. On JD-800 Center, there is a modification described. The components used in the fixed resistor type are too big for attaching to SMD pads safely. Go to bottom of the page of the modification page for a nice solution using a potentiometer and wires. Ideally a miniature multi-turn trim potentiometer and 30 AWG wire of the type used in wire wrapping prototyping should be used.
Here is our version of the Aftertouch Modification in our instrument using 30 AWG wire and a Bourns 12 turn 500K trimmer potentiometer 3266W-1-504LF glued to the motherboard PCB. When glueing, take care not to get any on the adjustment screw.
Note that we had to clean the aftertouch connector contacts with IPA otherwise it wouldn’t give any reading at all. Using a multimeter on resistance range, we also noticed open circuit even when keys were pressed hard. The socket was cleaned using a piece of card slightly wetted in IPA. This shows that some issues can be with the connector arrangement, not necessarily with adjustment or sensor itself.
Adjustment is using a trimming tool and the lid propped up just enough to allow adjustment.
Testing is best first 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 “1”, aftertouch, modulation and bender test routine starts.
Adjust the sensitivity on the potentiometer to taste by pressing a key and observing the aftertouch value, the maximum value is 127. Trial with a number of keys pressed together too.
Once done, exit test mode by simultaneously holding down Cursor Left & Right then pressing Exit. Test a patch such as “Classic Sweeper” for sensitivity, re-adjust if necessary.
In this particular instrument, the keyboard had been rarely played since the mid 90’s and suffered from red glue on the aftertouch sensor; resulting in poor performance. Sensitivity adjustment on this instrument essentially makes the behaviour of the sensor more like a switch (unlike the U-20 that we modified in same way). If other users report similar, we will do another article showing how to circumvent this issue.
Copyright © 2021 Super Synth Projects, Guy Wilkinson & Jonathan Williams