Roland CSQ-100 Refurb

My CSQ-100

Overview In November 2017 I bought a little Roland CSQ-100 in good working condition for a £150, with a plan to swap out the 2114 RAM memory and upgrade with more memory and the ability to store the sequence when powered off.

My CSQ-100 has a serial number of 183628, which dates it to May 1982 and probably one of the last made, as by the end of 1982 you could buy a Roland SH-101 with a sequencer built in. Then in 1983 with the arrival of MIDI Roland moved onto MIDI sequencers such as the MSQ-100. With over 3500 sold this little sequencer was a big hit for Roland at the time.

CSQ-100 History  Roland released the basic single track CSQ-100 Digital Sequencer with CV and Gate inputs and outputs in May 1979 and made over 3500 before introducing the more power 4 track memory CSQ600 a year later.

The CSQ-100 is micro processor based, using an 8-bit Intel 8048 with a tiny 2k byte operating system, which went through 2 revisions. It was usually paired with Roland’s new mono synths of the time such as the SH-09, SH-1 and SH-2.

The CSQ-100 has no lithium or nicad battery, as there is no memory retention for the single 2114 RAM chip, so your sequences are lost at power off. However with no battery to leak, many have survived in good condition, unlike the CSQ-600 which is a train wreck.

The CSQ-100 has two memory channels of up to 84 notes which can be played separately or in sequence. one after the other.   There are start and step pulse inputs but no DIN SYNC or wider interfacing capability. MIDI happened four years after the CSQ-100 was launched, but DIN SYNC was a standard in the early 1980’s.

Recap Whilst in physically good condition the PSU board needed a recap after 37 years. All the electrolytic and 100nF bypass capacitors were replaced with high quality modern replacements. Testing the power rails revealed the +15V was ok but the +5V had dropped down to +4.85V. So the 7805 regulator chip was replaced and the rail went back up to +5.00V. The electrolytics on the main board were also replaced. I use Panasonic and Nichicon capacitors.

Slider Dust Covers These had perished over the years and a new set were cut from 1mm black EVA sheet. It is important to do this as the old covers break into little pieces that drop into the switches and sliders. Using black EVA rather than a grey means that the hole around the slider or switch blends into the background of the panel cover. I also replaced the front panel screws with either new Philips head M3 at 6 and 8mm or hex cap M3 at 6mm to improve the look of the sequencer. A lot of the old screw heads had been damaged or were rusty.

RAM Adapter PCB

Non Volatile RAM It is rather annoying to loose the sequences you have carefully recorded after power off. I have designed an adapter PCB that replaces the 2114 RAM chip with a new non-volatile FRAM chip. No batteries are needed and sequence storage is 150 years. The 2114 chip is desoldered and replaced with a DIL socket, and the AMSynths adapter PCB with FRAM chip simply plugs in, you can order the PCB from OSH Park here. The SMD FRAM chip is a FM16W08.

Outcomes With the sequencer refurbished it was time to turn in on and check everything worked ok -it was!

2021 Update The OSH Park PCB has been successfully used by CSQ-100 owners, here is an overview by Sunshine Jones on Instagram. The AMSynths web store has the  PCB with the FRAM chip fitted for owners that would prefer not to solder SMD. I am also working on a CSQ600 RAM replacement, which plugs into the 4x RAM sockets and enables the battery to be removed.

A non volatile RAM replacement for the  Roland MC-202 is not easy to achieve as its a Dynamic RAM that is used by the microprocessor in 8-bit serial mode. A possible solution is to use a PIC microcontroller with inbuilt RAM to decode the data and address signals, however I don’t have a Roland MC202 to try this out with.