Assorted pics of the actual boards.. might be useful to someone.
That good old recappin’ blues:
Since one of the boards was GLUED to its standoff, i had to solder some caps on top of the older ones.. now one of the caps had leads so short i thought it might be useful to remind myself where does each lead went (see pic w scribble).
And the odd freaky transistors that didnt have its legs cut off (and indeed they were perilously almost touching)
The FR8L can produce 13 drum sounds-and very crispy too, thats why i decided to modify it..
Circuitbenders.co.uk’s trigger module: wires aplenty, but this will allow me to trigger each drum sound from a midi to trigger highly liquid board, that has been assembled back in the day to control my fr3-a build/mod and brilliantly carried out by circuitbenders.co.uk (you can see it HERE and HERE TOO).
The trigger board for the fr8l can be ordered HERE but remember, stock is limited.
Please note a male/female hex spacer (m3 22mm) is needed to screw the trigger board to the existing hex nut.
I decided to put the trigger input jacks in an external box-lots of fun soldering all the tiny jacks!
Due to the nature of the machine it is best to reduce background noise as low as possible-and an external power supply may be a better power sourcethan the provided transformer since the filtering in the power supply section is basically nil.
I had to make a quick mod here so if you may, bear with the crudeness of these connections-i was also low on cables so pardon the lacking colour scheme..
Remove the transformer (WARNING: Dangerous voltages around this area)
First of all take a nice picture or two of where the transformer cables were originally.
The plastic thing where the red orange and black wires go is a diode bridge-check the schematic from the FR8L service manual, it has to be removed along with the transformer. We’ll reuse thosw wires so just cut them and leave them hanging for now.
Then when everything has been unscrewed and cables cut, make a bridge connection between the two pins of the on off switch at the tagboard end (pink cable).
Red and orange cables soldered to the positive side, grey cable connecting all black leftover cables to the negative side.
To attenuate noise from using a switching psu i put a choke in series with the positive pole, and a 2200uF 50v capacitor in parallel between + and – like this:
Remember the resistor between + at the psu and the orange cables (you can barely see it in the picture because i used some spare shrink tubing to prevent shorts).
Each input requires a dedicated preamp/transformer module, for microphones there’s preamp, 1588B or preamp+12v phantom power, model 1588C.
I had to do a massive recapping job on the 1592B- the original caps values were all over the place-and i mean not only electrolytics-the only ones that were still measuring ok were the tropical fish and some of the lower values disc caps- though most of the electrolytics were good quality, Mallory or West Germany made, ROE (Roederstein). I replaced them all with Elnas (they seem to be the standard nowadays).
Also, the resistor after power transformer 7818 (that feeds part of the tone section, so if you have an unit that powers up but does not produce a sound, check for +18v at pin 6 of the tone board, that is linked to the power board after (out) the aforementioned 7818) was burned-clear sign that some damage had taken place. The schematic calls for a 10 Ohms resistor-i decided to put a 100 ohms substitute, much better.
Sounding good, i decided to recap also the 1588B module i have here (more are on the way, and when factory new, they were fitted with 3 modules).
After using a small screwdriver to pry the enclosure open, i took a look at this interesting blog (check it) for the schematic-i also took the time to sub the carbon comp resistors with metal film and yes-noise went down.
For your reference, here’s the resistors network:
Q1 and Q2 pinout:
If the preamp is not working, check carefully the resistors-they break easily. One immaculate looking (inside and out, the spongy filler still in good soft condition, no leakages on the plastic screen etc) 1588B i have had a resistor broken at its base, and since the components are so squeezed together it was impossible to see it-i decided to test the transistors (thats why i took the q1 and q2 pics above) since everything was looking proper-and there-i spotted the broken resistor! The preamp would still burst in noise if i knocked the mic gently on the capsule, yet it wont amplify it properly. Thats the resistor connected to ground on the white wire-a pain to desolder too.
If you must desolder stuff, be patient-these boards wont take a 300 degrees hot iron-the circuit tracks will lift if you heat them up too much-use care.
Since someone over at the Tape Operator forum has raised the warning that the power supply may have been ill designed, i am powering it using an external psu (using the battery option), 24v dc.
Terminal: from left, my battery (external psu) connections (- and +) and pinout to wire an XLR balanced jack to the output: hot, cold and ground… in the mess between high and low impedance i went with, 600 ohms, good for any mixer or recorder input. PLEASE note 2 and 3 terminals are bridged (connected) at the terminal post. The signal is nice and strong.
I will not mod this unit, i like it as it is. Nice and retro sounding.
I saved it in location 20 (empty) and made it the startup template.
To use the drumpads to send cc (mod depth 1,2,3,4,5,6) on the novation zero SL you must first press REVIEW and then use the drumpads-you will see their assigned value increasing because we are using them as step switches.
For your reference, heres a crudely PAINT assembled wildcard:
I opened my newly acquired Akai S612..to check for spiders and animal residue from its previous owner – i was intrigued by the “cassette interface”. Mine was screwed behind a closed metal door.
I realized right away it is the same cassette port as the Commodore 64.
And yes, you can save, verify and load your samples using an old (non)trusty tape Datassette!
I sampled a sound, got some tape to record, went fast forward 004 counts on the tape counter, pressed rec and play and then pressed save on the Akai panel. Red light, it’s recording.
Counter reading 044, the Datassette automatically stopped. I rewound the tape, switched off the Akai (remember with these old machines it is better to switch them off before plugging or unplugging devices from serial ports..), on again and Load. Pressed play on tape, and yes. It’s working. Easy.
No need to buy the MD280 rack to load discs on the S612.. you just need a Commodore Datassette (clean its heads and fix azimuth before doing anything)!
Ok this is as basic as it gets, but still it’s nowhere to be found on the actual Akai S900 manual, since it deals mostly with pitched sounds and how to spread them on the keyboard.
How do you make a drum program from recorded samples on the Akai S900, and play those sounds from a controller in midi in?
Well, first of all you must understand what a keygroup is.
The keygroup is the number of samples in the program. Or something like that.
Here the guide, how you do it, step by step:
-press the function button sample rec, press “letter” function and enter the name of the new sample, scroll down and set the sample rate: choose 16000 for best definition (it will be punchy nevertheless) then scroll the page down until you can assing that specific sample to a key on the keyboard- I normally start from A1. For easier operation, use a keyboard plugged in the midi in port.
-press edit sample function, since they are drum samples you dont want any scaling of the single hits so deactivate any transpose function, then set the sample start and end points.
Scroll the page down and choose (right arrow twice) to discard whatever is before the start and after the end points (aka sample truncate).
-press edit program and choose (right arrow) the name of the sample you just recorded.
At Program screen 03, KEYGROUP, add one more keygroup to the total keygroups by pressing + on the COPY line. Then scroll page down, assign the keygroup to the sample you just edited, and set the sample pitch range-since it is a drum sample, you want the range to be of just one key, so set it to the key you assigned upon recording for both range figures. If you assign it to another key, the sample’s pitch will be affected. You will not be able to listen to the sample as you do this so make sure you write down what note the sample was assigned to.
-press save, scroll down page to (right arrow twice) save prg and samples.
That’s it, plain and simple, easy guide to make drum programs on this legendary sampler.
Remember to drive the inputs a bit when recording-i always record at 16000 (best quality) but sometimes in a drum kit i like to have also low fidelity drum hits, so i record also some kicks and snares at like 8000-they add some dirt, just dropping them in the pattern, they add character.
I bought some soft touch button replacements for my RS7000, because the keyboard had to be banged on to operate..
Here’s how i carried out the button repair.
Disclaimer: please carry out this repair only if you have electronic skills such as soldering, desoldering, handling pcbs and know how to handle electronics. Remove the mains plug on the RS7000 and use care. Do not touch the power supply components. I shall not be held responsible if you hurt yourself or other people or the machine in the process.
First of all, check the new buttons. There are a few tutorials on how to check switches’ functionality using a digital multimeter on the net, google that up.
Remove all the knobs from the front panel.
Wash them with soapy water using an old toothbrush!
Turn the unit face down, using some soft padding to relieve the knobs from the weight.
Keep this pic as a reference: the position of the midi sockets.
There are 3 types of screws..Put them somewhere safe (i used three fruit jam lids) and remember where each type goes. An additional set of two very thin screws belong to the scsi port.
As a rule of thumb:
short ones-> they hinge the metal sheet that separates the top from the bottom pcbs. The top left and middle left ones secure the bottom to the metal cover of the power supply as you will realise opening the unit.
Remove the bottom lid.
Unscrew the midi assembly and the buttons holding the input/ output panel in place and take it off.
Take pictures of the pcbs.
Pay extra attention to the cables, what goes where. How they are turned, and move them the least you can. They are the right lenght to be assembled, very neatly laid out, Yamaha style😉👌🏻.
The bottom cables are all tied together and they originate from under the shielding metal sheet..right where we want to get! Carefully, gently rock them to pull them out of their sockets.
You will have to remove the card reader assembly, the flat wire (just pull it) and all the screws that link the metal sheet to the case will have to go (pay no mind to my pics cos mistakenly i unscrewed also some of the pcb’s)..
Below, this is the central layout, the wiring harness pops out from underneath the metal sheet shielding.
The plastic motherboard shield will have to go. Please note how its left side kind of sits on top of those surface mounted chips.
Gently lift the shielding metal sheet, get your girlfriend or boyfriend or your best caring and patient relative to hold it up for you.
Remove the cables that hold the keys assembly in place, and carefully slide it out from one side.
Here is the ugly mother.. Turn it around and take a look at how the key covers are snapped in their places. It takes a little inward motion using two fingers from the bottom side, push and they will spring out.
Put them in a sink and wash them with shower soap and water. Brush them with that old beaten toothbrush. Carefully, but with authority.
Please note that generally there are soft touch and clicking buttons, maybe you want to dust the encoders too, i took a rag and dusted the pcb too, TAKING EXTRA CARE.
If you are feeling tired and the stress of the procedure so far has got you on your knees, put the board in a padded cover and go to sleep.
When you are in the right mood and focused, you may proceed.
Take a look at how the soft buttons are put, their position from all angles. Your new ones will have to be laid out just like that. Maybe even better, if they all look twisted like mine!
Turn the board over, using a hot soldering iron heat up one of the two soldered poles of the switch and using a desoldering pump suck the solder off. Do the same for the other.
The nice folks at Yamaha have bent the two poles in opposite directions, one upwards – the other downwards, so that to remove the button you must heat up a bit the two points (solder side) while gently applying a circular motion to the button, taking it with two finers, component side..
Using the same procedure, you could also replace a few LEDs if you feel inclined, just be careful with the LEDs height.
Once you are done replacing the faulty keys, put the button masks back on.
The tap button does not have an LED, but its mask is like all the others (check pic)-it’s all right.
Putting everything back in its place, take special care with the central wire harness: the cables have to reconnect to their original sockets, so beware if they get stuck somewhere they should not-you might not be able to plug them in. Reassemble everything with care in respect to the wires.
It is quite a long procedure, also given how many screws you will have to work with-panic may take over you once you realise there are two pcb levels in this machine, but fear not. It CAN de done!
I do not think it is a difficult nor long build – i spent a couple of hours on every day off from work on it, for about a month.
The excitement of being able to own an 808 drove me, and gave me the needed focus and patience boost.
When building the Yocto, it is very important to measure every component before soldering it.
I decided to buy the resistors needed each time I was going to start a new section. This relieved me from measuring hundreds of resistors in one tiring session, putting them in order all at once, etc.
I bought a paper note book on which I would position the components, writing down their value and taping them, as I prepared for each part of the build. This helped me double check them before and while soldering them to the boards.
I decided to socket all the IC’s and the noise section transistor.
The germanium diodes provided in the half kit are rare, treat them with care. I cut the curvy terminals to have a straight lead as per this picture.
Check the pictures I am posting here to note certain ic’s position.
I made the mistake of putting all the pots at the end, do not do it, it is a mess. Just follow the build guide-do it as recommended, at the end of each section.
Remove the encoders’ tabs before you solder them in!
Please note that you do not have to cut the lead cables at the end of the build (i did it!), what Vincent meant in the last paragraph of the build guide is, you can make them shorter.
I had some issues with the flat cables, aka they broke, so i socketed them too. It is advisable to have a suitable enclosure ready before you get to link the two pcbs with flat cable, otherwise having the boards moving around will cause them to break. I would recommend you to buy this brand and sku: TE Connectivity-fsn-3a-10-3″ ribbon cable. They are the best. I socketed the connection point as per picture here, and i just slid the ribbon cable in the sockets-it works great.
Usually the boards sit a bit shallow in the enclosures, do not use led covers and cut LED leads so that mounted, they rise about the height of the sequencer’s coloured buttons.
Use 5mm spacers to lift the board up and have it sit properly, the keys will stick out properly through the holes.. i would suggest you buy a set of various spacers and screws etc that can be found on Am*zon, they come in their little handy boxes and experimenting with those will allow you to mount your precious yocto properly inside the enclosure.
More on that further down..
(see pic at the top of the post)
A few more tips to build the yocto, not a mod guide by any means, more like a ‘watch out for’ list, for instance where to look if you would like to change the value of some resistors to change the tuning of the instruments.. and other useful things to know as you go along.
A lot of these ideas are to be found in the yocto forum, but here is whatever I found essential to complete the build without headaches.
For a more in depth mods’ list, google dsl-man yocto.
Side note: please take note of these mods that allowed me to fine tune my build-i am not implying that these will be needed for your build, but keep these in mind:
Hats noise filter: for R58 use a 1K trimmer, multiturn
Cymbal noise filter: R56, use a 1K trimmer, multiturn
Cymbal decay: R93, use a 470K trimmer
Clave filter: R322, use a 20K trimmer
Clave decay: R313, use a 470K trimmer
SD noise filter: R202, use a 50K trimmer
TM1 and TM2 better adjustment range (Cowbell): at R44 put a 100K (or 56K if needed, see below the cymbal section) resistor, R45 put a 68K.
I put them on a veroboard or two, see at the bottom of the guide..
Also make sure you have many SC828 transistors to choose from for the noise generator!
THE NOISE SECTION
As opposed to the building guide, a more effective functionality of the noise generator can be achieved with this mod, as per the official Roland service manual (page 15):
R 129 use a jumper instead of the resistor listed
R 131 100k
R 127 10uF electrolytic: see this pic for correct orientation (positive side left)
R 130 22pF in parallel with resistor 130 (it means on top of the resistor, using the same soldering points – check the pic, i soldered it on the other side of the board)
I socketed Q35 as it is a very substantial part of the noise generator. Remember that for the noise section to work properly, 2SC828 transistor’s hfe must measure more or equal to 300.
NOS and new production 2SC828 values are all over the place, but ultimately you will realize most of them have a hfe thats lower than needed. Buy different sets from different sellers and take your time to measure them. Get your PEAK transistor tester out and measure them.
It can be time consuming, that’s the reason why Roland had them selected by the producer.. when stock finished, 808 production ceased-sometimes a 2SC945 was used as noise transistor. 2SC828‘s noise is grainy, as opposed to other transistors. There’s this mystique surrounding the selected transistors used by Roland, the same procedure has been used for the TR606 and CR8000 noise transistor-they were selected and are easy to spot if you would see a gutshot of said machines because the transistors have a white painted top. But remember: they are nothing special-they are just transistors whose hfe fall into range with the noise circuit. Dig into them and you will find one or two that will have the right specs.
Hfe lower than 300 will result in duller sounding, shorter decay, drier snare.
C 27 1n2 for 1ms pulse, needed for an effective accent
R 165 tuning resistor
R 234 47k (positioned in the Low Tom section)
R 188 check its position carefully
R 195 tuning resistor 1
R 196 tuning resistor 2
R 202 noise filter resistor
R 231 to lower pitch, use a 4k7 resistor (or increase value to lower pitch)
R 257 tuning resistor
R 284 tuning resistor
R 312 tuning resistor
R 315 tuning resistor
R 334 and
R 373 are part of the Hand Clap circuit, although they are to be found here
R 342 and
C 137 may have a solder bridge, it is ok
Do not rush to solder the BA6110 ic, it is better to socket it and add it at a later time, please check the picture here to have it positioned correctly.
R 63 decay resistor 1
R 65 decay resistor 2
The sound of this trademark instrument will be tuned once you get to the cymbal section, also please note the resistor values as pointed further up on the post.
Look at this section before trying to find the position of the components. It is L shaped.
R 56 noise filter variable resistor 1
R 58 noise filter variable resistor 2 (this is in common with the HiHat)
C 6 and
C 42 and
C 44 and
C 46 I did not have any 22nF caps in my stash so I used, 27nF instead.
This is the only section where it is mandatory to have a scope at hand-to tune the cowbell sound, using the two trimpots TM1 and TM2.
I used a Hantek 6022BE computer based USB scope.
Use one channel-probe on R44* resistor like this:
And ground crocodile on the above pot post like this:
Above: rotating slowly the trimpot, the values you want to see are 1.86mS, 526-540Hz and below, this wave:
If your trimpot cant get within range, change R44*. I had to lower its value to 100K first, but 56K finally got me in the range!
Time to probe TM2, like in the picture here, always grounding the nearest pot post too:
And the values you want to see, rotating carefully the variable resistor are: 1.25 mS, 800Hz:
And thats’s your cowbell sorted!
INPUT OUTPUT BOARD
Please note the position of IC4 on the i/o board..
IC4 is a optocoupler, 6N138 and it controls incoming midi signals, so if your yocto 808 has got any issue with midi like it will not sincronize to midi in, change this IC, maybe it would be better to go for a beige original:
Before you put the keys in, make sure your enclosure will let them stick out properly (as stated before, they sit a bit shallow), and use spacers the right height to suit your eclosure.. As described here..
Before you put it in the enclosure
Prep the enclosure by screwing the spacers in the front panel- i used 5mm spacers but 10mm spacers’ screws (aka the ones that came with the mouser order) that go in for like 3/4 of the spacer’s lenght. Screw the top panel side all the way in through the spacer.
Please note there are two sides to the spacer, one is hollow and the other flat. You want to have the hollow part as receptacle to screw the pcb side in (aka at the back of the front panel) as much as you can (it is not much, a few mm’s but that will suffice to have the pcb steady in place). This means, flat side of the spacer on top.
Look at the picture:
Nuts of the two encoders will have to be placed on top of the front panel not below.
My Yocto fired properly first off.
I made all the trimmer’s adjustment upon finishing it.
I am very satisfied by the result. Vincent has been very helpful too, and the YOCTO forum is an invaluable resource.
Thanks Pawluk for the sturdy enclosure!
Also, if you feel inclined, i would suggest you add a little daughterboard to fine tune the noise generator, to allow for correct voicing of the snare, hats and cymbal (check out the relevant resistors above and swap them with trimmers)..
I arranged them on a small veroboard and i am very happy with the results!
Lately (2019-2020) an unofficial custom firmware boasting amazing features as found on the original 808, such as instrument TAP writing, prompting users to update the ATMEGA ic.
For people who are modern pc challenged like me, i made a quick guide that you can find at this link: