A&H Spectrum Mixer Refurb 4

Overview During the summer of 2020 not much progress was made. This was down to the fact that whenever I turned the Spectrum on, it was noisy and there was no getting away from how noisy it was. Whilst I had bought effectively another Spectrum as spares and started to refurbish some cards, I had to sort the noise out! Looking at the noise floor in the original A&H Spectrum brochure and a new ZED428, I knew I had a hard job on my hands and I nearly gave up and bought a ZED428.

I decided to buy a second hand Allen & Heath RPS14 power supply to see if we can get to a lower noise floor. It will also provide lots more current for the upgraded op amps and maybe an extra 8 channels. The RPS14 eventually arrived and what a beast it is! A massive and heavy toroidal transformer and very nice voltage regulation with large capacitors. Time to make a custom cable to power the Spectrum up and see whether a modern power supply can get the Spectrum back in the game.

 

Alesis DataDisk Refurb

Alesis DataDisk

Overview I picked up an Alesis DataDisk in May 2020 for £25, so I  can store and retrieve SysEx data from my hardware synths rather than having to power the computer on and use software. The 1U rack  connects up to my MIDI hub and uses a 3.5″ floppy diskette to store 800 KB of data.

The DataDisk was launched in late 1989 at a rather steep £299, but was quite popular for musicians touring and wanting to restore all their patches across multiple synthesizers. In the studio an Atari 520 was more effective with the right software, and that is what I used in 1990. The high cost of the DataDisk put me off buying one, until now!

Recap Complete

Refurb The DataDisk looks like an x-hire unit; connections have been hot glued and there is lots of wear to the casing and buttons. All the casing screws needed replacing with new ones, and the LCD mount has broken. It also needed a 9V external power supply, which is the same as used with the Quadraverb with a 4-pin plug, bought from eBay. I replaced the 16×2 LCD with a new OLED display and glued the mounting back together (two parts were broken) and unglued the ribbon cable.

The original LCD is 16×2 characters with 14 pins, here is the Quadraverb schematic which uses the same LCD. Note that there is no contrast potentiometer but a fixed contrast voltage of -0.6V at Pin 3. Pin 2 is the main GND connection and pin 5 is set low to enable write to the display. Pin 4 is the mode control for either data or an instruction and Pin 1 the +5V.

New OLED Display

I have fitted a new blue character OLED display, the Winstar WEH001602DBPP5BN which is available from Rapid Electronics. It has the same 14-pin connector and PCB size and is a drop in fit as Pin 3 is Not Connected. There is no contrast needed on an OLED display. To be extra safe the cable to pin 3 can be cut or the diode and resistor removed from the main PCB.  The new OLED fits on the same plastic mount but is thinner than the original and therefore the front of the OLED is set back 5mm from the bezel.

The three large 4700uF 25V axial electrolytic capacitors were replaced in the power supply along with 3x 4.7uF 50V and one 100uF 16V capacitor. The OS is 2.10 and does not need upgrading. There was no floppy drive in the unit, so I tried my spare diskette drive but it was not compatible, and I don’t want to hack one. There is not much space in the case left free for the diskette cable at the rear of the drive but there is plenty of room for a Gotek drive.

In the Studio I use the DataDisk with my MIDI polysynths to save and restore patch banks; the Wavestation, OB-6, XTk and D-05 using the iConnectivity MIO as the MIDI hub. All these synthesizers can initiate a SysEx dump of patch data, which the DataDisk simply listens for and then reads the data stream and puts it on the diskette. The DataDisk cannot handshake with my MKS-80, so I use the my MC-300 with the MFB-500 Bulk Librarian software which works perfectly.

The DataDisk can also initiate a SysEx Dump request, provided the Manufacturer and Device ID’s are known by the DataDisk software. You simply select these two parameters from the display, however the OS has not had an update for 30 years, and there is no free form editing of the Device ID which would be very useful – see below.

Storage Limitations the DataDisk is limited to 764 KB of patch data storage and a maximum of 53 files. In 1991 the storage limitation was not significant (a D-50 Patch Bank is 36 KB, the Wavestation is 64 KB and the XTk is 70 KB) but today synthesizers can generate much larger SysEx files, such as the OB-6 at 576 KB! Large SysEx files generated by fast PC’s may overwhelm the old synth processors, so I use pauses when sending to the Wavestation. The DataDisk uses a slow processor my today’s standards and therefore should not overwhelm the synths with SysEx, but maybe new synths will overwhelm the DataDisk, we will see!

Gotek Drive Setup It is easy to fit a Gotek drive and here is the setup, you need to customize the firmware:

  • Track Type: MFM, Two sides floppy, GAP3 auto GAP3
  • 80 Tracks, Sector IC Start: 1, Sectors size: 1024, 5 sectors per track
  • RPM: 300,  Bitrate: 250,000, Total sector: 800, Total size: 819200
  • HFE file interface mode: Auto (IBM PC 720kB)
  • Shugart device
  • Hardware Jumper settings: MO and ID0

File Naming The DataDisk reads the inbound MIDI SysEx message and extracts both the Manufacturer and Product ID’s. The Manufacturer ID is either one or three bytes with the DataDisk capable of recognizing the big manufacturers from the 1980’s using a single byte;

  • Sequential 01H
  • Roland is 41H
  • Korg is 42H
  • Waldorf is 3EH
  • Behringer is 00H 20H 32H

The DataDisk is over 25 years old and therefore has not kept up with more recently issued manufacturer ID’s in its ROM based look up table> If the manufacturer ID is not recognized the default is xxH. The Device ID’s are also a problem, as these single byte numbers correspond to a product name which the manufacturer has determined. Once again a look up table is needed and the DataDisk is stuck in 1991!

The DataDisk names the files with 3 set of characters:

  • XXXXXX is the manufacturers name
  • YYYYYY is the product model name
  • ZZZZZZZZ is the name of the file and can be edited

I may extract the ROM code and do an update if there is room in the ROM.

SQ Display

SQ Upgrade Alesis updated the DataDisk to a new SQ model in the Autumn of 1990 with a new firmware version 2.0 (and higher price of £349). SQ stands for SeQuencer as the upgrade enables the DataDisk to record and playback MIDI sequences, with the usual store and retrieval to floppy disk using DS/DD diskettes. MIDI sequences from a keyboard or a MIDI sequencer (like my Roland MC-300) can be recorded and then played back locked to the MIDI clock.

Sequence recording also allows SysEx to be recorded and played back with pauses, which is often how long data streams are managed.  MIDI data is recorded and played back in real time from the diskette with no copying to internal RAM, so there is no lag between hitting MIDI start and the notes being generated, this made the DataDisk as an attractive MIDI song player for live bands.

Buttons These are touch sensitive (multi-speed) versions and not the usual single click momentary buttons, therefore the best I can do is clean the surface of the buttons, and even polish them, but the damaged ones remained pale. A common issue with these buttons after 30 years of UV light.

Inside the DataDisk

Technical Bits  The DataDisk is based on an Intel 8031 microprocessor running at 12 MHz which does all the MIDI handling, front panel scanning and disk access work. It loads the OS from a 27C256 EPROM (32 KB)and uses 32 KB of static RAM as a work area. There is no battery as the RAM is only used during operation and no data needs to be saved across power downs.

A Sony MPF11W-10WP 3.5″ DS/DD diskette drive was used in the DataDisk, which can now be replaced with a Gotek drive – see above. Some hardware bugs were sorted out in the DataDisk manufacturing life, some to do with MIDI timing and signal levels. Mine has a few kludges.

OS Versions The latest OS versions are 1.03 (non SQ) and 2.10 (SQ) and there are many versions below this final numbers, so its well worth getting 2.10 which cures all the known bugs. It was released in November 1991. The service manual explains the version history and bugs, the OS EPROM is available on eBay.

 

 

Roland SH-5 Patch Archive

Patch Sheet

Introduction  In November 2018 I was lucky enough to win a VEMIA auction. Not a vintage analog synthesizer, as they are too expensive, but a set of original Roland SH-5 Patch Sheets. 231 patches for this amazing synthesizer, written by hand on official Roland patch sheets between 1977 and 1983.

Each patch carefully documented and grouped into 13 categories from BASS to ANIMALS. There is unfortunately no record of who created this amazing archive of sound, but I guess they bought their SH-5 in 1977, a year after it was launched in Spring 1976. They would have paid around £900 new (around £5k today!), which was well beyond my means at the time as a university student.

Patch Sheet

Patch Sheet Detail These are printed in monotone with a light grey header featuring the Roland logo on the right and Sample Sound Synthesis to the left in caps. Must be the first time Roland used the word Sample, and the contemporary 100M and 100 patch sheets do not use this name.

The patch sheets are nicely printed on a traditional Japanese Shirokuan paper size of approximately 189 x 262 mm. They are single sided and contain two patches, using a graphical representation of the SH-5 front panel.

Patch Index

Patch Archive I have written up all the patches into a spreadsheet, and reproduced the complete set of patches on newly created SH-5 Patch Sheets (designed in Adobe Illustrator). This will be available as a digital download book, along with blank SH-5 Patch Sheets.

I have also translated the patches (and tried them out!) on an AMSynths SH05 Modular version of the SH-5, and these patches are also available as a digital download book. This means musicians using either the original SH-5 or the new SH05 can explore and enjoy over 200 sounds from a very creative individual.

SH-5 Schematics

SH-5 Service Manual The patches came with an original Roland service manual, printed on thin almost clear paper. A higher quality than the photocopied version on the Internet (which is a Roland scan), with fold out large pages for the circuit diagrams.

It is exactly the same document from 30 October 1976, with hand written Japanese annotations. This original manual was stapled together but the staples have been removed, and there is no front cover, which would have been like the SH-3A service manual cover.

Boss PH-2 into a Jupiter VCF

Introduction  The Boss PH-2 Phaser pedal contains two valuable Roland IR3109 OTA chips. This post explains how they can be carefully removed and used in the AMSynths AM8109 JP8 VCF or the AM8060 JP6 VCF module. The PH-2 was manufactured for nearly 20 years, from the early 1980’s until at least 2000 by Boss (Roland) and is available second-hand from 20 – 90 GBP depending on condition, try not to pay more than 40 GBP.

Customers following these procedures do so at their own risk and there is no guarantee of success made by AMSynths.

Buy a Boss PH-2 We bought this pedal on eBay in November 2014, it is serial number FN21896 and was produced in March 2000.

Stage 1 – Circuit Board Removal
The first stage is to remove the paxolin PCB from the pedal.

  1. Undo the 4x black posidrive screws in the base of the pedal.
  2. Remove the base plate and clear plastic protector.
  3. Pull the PCB out of the case, it is attached via a grey ribbon cable and 10 wires.
  4. Cut the wires and ribbon cable near the PCB and there you have it – the PCB with two IR3109 chips. Nice!!

Stage 2 – IR3109 Chip Removal

  1. The second stage is to extract the IR3109 chips from the PCB. We prefer to cut the chips out before then carefully desoldering the pins.
  2. Using a coping or fret saw cut around the two chips very carefully, you may want to remove some components by clipping them out with cutters, so that you get straight and safe cut lines.
  3. Now remove each IR3109 attached to the PCB as 2 separate sections.
  4. Mount the small PCB section in a pin vice upside down.
  5. Cut through the back of each PCB very carefully between each set of 4 pins. Make sure you don’t cut down into the IR3109.
  6. Heat the solder pads of the first section and using a pair of fine nose pliers gently ease the PCB section off the 4 pins.
  7. DO NOT OVERHEAT the Pins or IR3109.
  8. Alternatively you can use a de-solder pump and not cut the PCB into sections.

Note: We have found the IR3109 to be a robust chip which is not over sensitive to static or heat. But PLEASE take care! They also seem to last many years (decades in fact), it is rare for us to find one that has failed. Of course it’s worth testing your pedal before you extract the chips, so that you know the chips are working.

Stage 3 – Clean Up the IR3109

  1. Once you have removed each IC from the PCB section….
  2. Using de-solder braid remove excess solder from the front and back of each IC pin.
  3. Straighten up the 16 pins with fine pliers.
  4. Optionally use flux remover to brighten up the pins.
  5. Wash the chip in water if you do this procedure, and allow to dry.
  6. You now have a nice clean IR3109 chip!
  7. We usually put them in IC holders to protect the pins, and to enable them to be quickly fitted to a PCB.

Mistakes do happen!

  1. You may break an IC pin on removing the chip or the pin may break because it is fragile.
  2. Don’t worry, they are easy to repair.
  3. Mount the chip in an IC socket and feed a resistor wire into the top of the socket and align to the damaged pin.
  4. Then carefully solder the wire and pin together.

AMSynths Web Site Returns!

The AMSynths web site is back with a revised WordPress based site with the fantastic slider theme.

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