got a rx21 for 20 bucks, it gives me 'no battery' info when plugged, is the battery removable? or is it soldered to socket? thanks

Thanks for your videos, very helpful. I bought an Opera 6 in 1984 as my first synth, then I sold it a few years down the line and recently bought an Expander with a Tauntek OS but I have a problem and would like your quick view if that's possible. It does not power up after being off for a while - no numbers on the display and no sound; however if I leave it on, the display would appear at some point and by power cycling it would start to work making sounds without any issue via midi for a bit, then it would reset. I managed to load some presets using the tape interface, but it seems that most of the presets have been lost now. I take this might have to do with some problem with the power supply? Kind regards

Congratulations

I installed correctly but i cannot get sync. Seems like tempo is slower

I wish u could fix mine. It’s. Perfect but obviously old. And the coil is slightly rusty looking. But it plays perfect on the boss mains ,,, shall I get rid or keep it

It all sounds the same.

How does one create all 24 subdivisions defined by PPQN?

Hi Mindburner, thank you for the video. I am trying to find the midi kit on ebay, no luck. Could you please give me the contact of MrLogic?

Nice one! Noob Q - Would I be able to use DC coupled outputs from my interface directly into the trigger mod?

At 16:50 it is a switching between control protocols this machine can emulate. On other words it can behave as a VCR being controlled by ordinary edit controller of that time.

The only problem I've had with the Bit is that it constantly loses the factory presets. Which means it also loses connection to the Stereoping controller I have which is highly recommended to this synth btw. Anyone know how to solve this problem? ( I changed the battery and it didn't solve the issue).

I will try this with my SH-09 too. Just one question: Is there no problem with the power switch regarding the higher voltage? According to the service manual there are different part numbers for the power switch (Japanese 100V vs US 117 V vs Europe 220/240).

Hi I'm a fixer for my own stuff but that's due to costs and not extensive technical training. I do have ESD soldering skills and a station, but it's never been a passion just hobby. Can ask you a question? When it comes to SRAM which is what's bad in my HR-16, How much of a variable is the chip number? The chip I need to replace is the cxk58256pf-12L 7K90 C90. Is there any part of that number that is just a variable or newer series of the chip? Or do I need the exact chip with the exact same numbers? I've also heard Hitachi has chips which are better but need to know what number chips those would be unless they're the same chip under Sony. Any help would get me on the right track. I also just bought another HR-16 that also has the ramp chip bad. ALSO, you may find this of interest. both when doing a self test show midi I/O error. Maybe that's inicative of something related to the Sram, not sure. i'm suspecting ram chip since they're not saving data even when the power is turned on. (i.e. changing a voice, save, switch patterns and back to the changed patter, all saved vanishes even while under power. Also I tried ordering a chip thought to be the same, a cxk5864pn, (which I think is wrong now) and that threw jumbled characters on the screen. just like yours. so maybe that chip that was in yours could be incorrect. All my characters came back when I put the OLD Sram chip into it, but it still doesn't save. At 8:52 of your video it looks like the same chip as mine. Maybe my SRAM just isn't saving and your 58256 is more compromised, but I did see a it return with my original non-saving SRAM. And yes both HR16's, I replaced the NEW SRAM (5864) and got the same messed up characters yours got, AND all words return when I reinstall the SRAM. Also both machines in self test say Midi I/O Error. Maybe your machine does as well which may or may not indicate a pattern. Thanks if you have any insight to share!

I have this same exact model. She doesn’t turn on. I bought it for 75 bucks. Do you have a website and repair for the public?

Good job. You must feel good to have succeeded with several problems this synth had.

We got one drum voice that doesn't get any sound out of it, any idea?

Brilliant video for a beginner! Held my hand all the way. My problem still persists though. The portamento is just on constantly. I’ve dismantled and cleaned the potentiometer thoroughly and it still doesn’t work. The only thing I didn’t do was apply the grease. Do I need a completely new slider or is there something further I can do? Thanks again, vid was a massive help!

I'm in Bangor, I have a comatose JV90, various lights went very odd (like they were multiplexed with a slow clock nearly), and after a few weeks it ceased to boot up. I rebuilt the power supply, thinking "90s cap plague" but nada. I'm too fat fingered to ever go through all the test points without shorting something to death, so I gave up. If you think it might be fixable, gimme a shout. Otherwise, she's yours for parts for sod all if you like.

whats the max bpm range? and is there a restart button to resync up all devices live

Very interesting fix, I like to see synths full of stuff rather than 1 board with a processor on it! Apropos nothing at all where do you source your parts from? I'm fixing a Korg DW8000 with a busted Arp speed slide pot, but it's an odd one - 1MC, 1 million ohms!. It's 45mm long. You can get 50k/100k/500k all day long....Any decent source for something like that? Cheers.

I recognize that carpet design from "The Shining".

Are you based in London I need to service my maestro and aelita and don't know where to do it..

I've my Juno-1 from '94, bought locally in a market in Belfast for £110. And still going strong.

Belfast 🤘

Dude said 'knackered" and shoved it off to the right. Dude said RAM board and shoved it off to the left.

A DCO is not digital. A digital Oscillator is when the sound is generated digitally and output via a DAC. A DCO is actually a VCO that has it's frequency timing controlled digitally. Instead of using a comparator to measure the voltage and then trigger the capacitor discharge when it reaches a certain level it uses an ADC to count the steps and then triggers the capacitor discharge when it reaches a certain value. This has the effect of quantizing the oscillator timing and making the frequency much more stable.

Hi, I've just acquired one of these and I'm thinking of replacing the display. You mention the info on changing it is on your website. Could you possibly link it please as I cant find it. Many thanks

Almost unknown and last synthesizer from the former GDR, first shown at the Leipzig autumn fair in 1987 and available until 1989, when the wall brakes down. I love the unique sound and the timeless design.

did t know this model before from akai.. example sounds are fat.. thanx

I’ve been after one of these for years now

How’d this work out in the long term, MB? About to do the mod to mine and wondered if you had any additional thoughts 2 years later?

Good video m8, keep up the good work. I also love the cover on your workbench, it reminds me of the carpet in the Shining Movie. 👴🏻👍

Hey m8.. I know this is an old video but I have 2 ax80s I'm trying to get one working. Got it to the point where if you turn it off and on many times eventually you will luck into it coming on... random if the keys trigger sound but midi always does. When it doesn't boot all the way up it just has garbled output on the 7 seg displays. I checked all power from the supply board.. regulator.. all working. Any ideas?

Great video. Just wondering, what desoldering tool do you use ?

Hello, how can I email you ? Have some equipment needing serviced.

at around 2min you adjust for around 0 V but which trimmer on the back do you use? The Dynamic/Sense probably. Great vid btw. i try to learn as much as possible as i have now bit01, Bit ONE and Bit99. and might come handy at some point.

Good Video , by the way where can I get the plastic wheel in yellow color that one , mine one is broken ! Thanks

I love 80s Roland keyboards, this was peak Roland IMO '80-'90. My reasoning? Sure 70s Rolands are cool, but in 1980 we had the TR-808, '81 the Jupiter 8, '82 the Juno 6/60, 1983 the JX-3P, 1984 the TR-909 and Juno 106! In '85 we got the JX-8P, in '87 the D-50, '88 the S-Series samplers, '89 the R-5 and R-8 drum machines and the JD800 in 1990!

You outbid me you bugger! Glad you got it running properly, like a crunchier TR606...but much cheaper!

Mouser still sells those 909/303/606 pots. The once I bought had a D shaft, though.

I just did up my Mono/Poly and poly6. Most of those bleu, slightly metallic looking caps had corrosion on the leads. Just an FYI.

Nice work on the restoration, mine was a wreck when I got it too, with the panel ribbon in a similar state. Glad the NVRAM tip worked out! On the tempo pot you may be able to swap in the wiper / shaft from a mechanically similar one (TB-303/TR-606?) but re-use the orignal carbon track to retain the intended range and taper.

It would be so nice if you could enable subtitles on your video. As a non native speaker, I have sometime difficulties to properly understand what you say.... Cheers and thanks for your upload.

Thanks for the video, wondering if you’ve any idea as to what causes sounds to continually play as soon as the synth is powered on? I can switch between presets and for the most part it keeps playing constant sound as if I’m pressing on a key but not a key has been touched. cheers!

This synth didn't have aftertouch, did it?

Is that a Casio Z series underneath the Akai?

You have become the Bit One Guru!

I generally agree that when replacing an ic you should use a socket. There are exceptions, however. Analog video circuits tend to not like ic sockets because they introduce capacitance, which video circuits are particularly susceptible to problems do to this introduced capacitance.

The piece of plastic at 11.07 looks to me like one of the two little triangles that are underneath the sliding tray.

Bob Grieb from Tauntek is an absolute genius and a nice guy. I had the pleasure of having my Digital Keyboards Synergy repaired by Bob and I sent the main boards of the Synergy to him. Many techs here in the UK would not touch the Synergy and seemed scared of it. Bob had it for a few days and totally repaired it all using about 0.000000001 % of his brain power lol. Boards came back to me and worked straight away. Bob Actually re-writes operating systems for synths in assembler for fun and improves the original manufacturers code and adds new features. Imagine the brain power to do that :) Very clever guy.