Saturday, 27 September 2014

Synth Repairs


Analogue Systems RS-40 Noise, Sample and Hold, Osc


This came in as 'defective'. After a while it became obvious the noise output was not working. This was traced to an open-circuit LEVEL contol pot (10k lin) which was replaced. Still it didn't work as a sample and hold - i.e. I was expecting to see a stepped output from S\H OUT. Not having used the RS-40 before it took me a while to realise that the noise and clock signals are not normalled to the Sample and Hold circuit like the front panel markings suggest; the lines linking NOISE OUT to EXT SRC IN and INT CK OUT to EXT CK IN suggest to me these are linked in some way but no. 
RS-40
After looking at the jacks it was clear that these are not normalled (I'm not sure if this is the case with all RS-40s but this one looked clean and unmodified so I'm assuming it was factory standard). I used external patch leads and to link the noise and clock outs and ins and hey presto it worked. The first thing that I saw on the scope was at each sample point the sampled signal is present for what I guess is the duration of the sample pulse (about 0.2ms). When using the RS-40 to modulate a VCO I could not tell that the noise spikes were a problem, in fact it is probably above hearing range (at least mine). 
 
Noise spikes

However I didn't much like it and I didn't much like not having the noise and clock not normalled to the S/H circuit. I spoke to the owner and he agreed to have a couple of simple mods applied.

The noise and clock signals are present on the jack board close to where they would have to go for normalled connections. The switched contacts were connected to ground on both EXT SRC IN and EXT CK IN jacks by solder bridges. I removed the solder bridges and fitted links as can be seen here. This worked a treat allowing it to work without patching but still allowing external signals to be patched in if need be.

Solder removed from red arrows and links applied at yellow arrows
The noise spikes 'problem' although not audible was fixed by placing a 10nF cap across the S/H output amplifier's feedback resistor (27k) making it a low-pass filter with a cutoff of 590Hz. This got rid of the spikes without adding noticeable slew.

10nF capacitor

Spike free steps



Saturday, 13 September 2014

5 into 1 Analogue Systems to Doepfer Bus Adaptor/Expander

The new 5ASM2DB Analogue Systems Module to Doepfer A-100 Bus Adaptor/Expander is now in stock and available to order. 

NEWS UPDATE 25 Oct 14: SchneidersLaden have stock and can be ordered from their website at http://www.schneidersladen.de/en/manufacturer/synovatron.html. RhythmActive also have stock and can be ordered from their website at http://www.rhythmactive.com.au/

For DIY enthusiasts it is also available as a kit or as a bare PCB. 

The 5ASM2DB offers five Analogue Systems sockets on one small circuit board with low-current LED indicators to show that ±12V and +5V power is available. It comes with a ribbon cable to connect to the A-100 bus and four self-adhesive nylon PCB mounting pillars (you can of course use screwed in pillars so a drilling template will be provided).

If you have several Analogue Systems modules in a Euro rack then the 5ASM2DB could be a better alternative to using several ASM2DB Adaptors because it expands the bus and frees up A-100 Bus connectors for Euro modules; it costs roughly the same as three ASM2DB Adaptors. ASM2DB and DM2ASB Adaptors are still available.

5ASM2DB Adaptor/Expander
What you get with the 5ASM2DB Adaptor/Expander
What you get if you order the 5ASM2DB DIY Kit

Price info and ordering

For sales, support and combined shipping enquiries please contact synovatron@btinternet.com.  


The base price is without delivery and VAT.
The UK and EU prices include delivery and VAT @ 20%
The ROW price only includes delivery; VAT is not applicable. 
Model                                        Base            UK              EU                ROW
5ASM2DB Adaptor/Expander    23.00 GBP   30.06 GBP   32.58 GBP   27.45 GBP
5ASM2DB DIY Kit                      16.00 GBP   21.66 GBP   24.18 GBP   20.45 GBP
5ASM2DB Bare PCB                  Available from www.thonk.co.uk
UK delivery by Royal Mail First Class; elsewhere by Royal Mail International Standard.

Friday, 29 August 2014

New product preview

This is a design that has been hanging around for over a year in a 95% complete state but I have now taken the bold step of finishing it and going into production. It is called the 5ASM2DB and is a 5 socket version of the popular ASM2DB Analogue Systems module to Doepfer bus Adaptor. It is fabricated on a small circuit board and has 3 LEDs that indicate the presence of ±12V and +5V. The 5ASM2DB will be supplied with 4 self-adhesive nylon mounting pillars and a short ribbon cable so it can be placed adjacent to a busboard and linked via the ribbon cable (standard Euro rack 16 pin cable). It is not recommended for use with the Analogue Systems RS-370 as this draws a whoppng 680mA from the 5V rail.

It will be priced at roughly that of 3 ASM2DB Adaptors so the aim is you get 5 for the price of 3; which will be of interest to those of you with many Analogue Systems modules to go in a Eurorack case.

Availability is from mid-September and will also be available as a DIY kit and as a bare PCB for the more adventurous DIYers. Here's an image from the CAD package - it will not be red BTW!






Confused by Cwejman ribbon cables?

I received an order to build some Cwejman standard ribbon cables that were 40cm long. Up until then I had no idea they were different to standard Eurorack cables. So here is what I found out and hopefully this takes the mystery out of it for anyone who is lucky enough to own one of these top modules (and it's also a sales plug - no pun intended).


Saturday, 12 July 2014

Eurorack DIY Prototyping Cards Rethink

The Eurorack DIY Kits have been quite successful and when the last DIY1 PCB was sold several weeks ago it provided a great opportunity to reassess the PCB design rather than just reorder more of the same.

What has emerged is a revised and rebranded Eurorack prototyping solution that is more usable and more elegant than before. The revised product revolves around three PCBs in the Synovatron Proto series: ProtoPotz, ProtoJax and ProtoXp

The new Proto PCBs' holes line up with each other to allow each board to be stacked one on the other using header plugs and sockets; allowing power and signals to be routed between boards without resorting to linking ribbon cables. Here is an example board stackup; this all fits neatly behind the Synovatron 8HPJ front panel (8HP wide with pot and jack holes):-

ProtoJax, ProtoPotz and ProtoXp boards stacked together

Examples of headers and sockets used to stack the boards

ProtoPotz

ProtoPotz is the direct replacement for DIY1 PCB (as used in DIY Kit 1 and DIY Kit 2). It is designed to hold up to five 16mm P160KN series pots using brackets. What's new about it?
  • Plated-through holes for robustness and convenience, essentially it's a double-sided PCB. 
  • Better supports the A-100 bus with dedicated positions for 10 or 16-way open or boxed headers, small electrolytic capacitors and protection diodes (to protect against reverse power connection.
ProtoJax boards with 5 pot brackets are available from Synovatron for 7.50GBP + delivery + VAT @ 20% (UK/EU only). ProtoJax will also be supplied in DIY Prototyping Kit 1 as a replacement for the original DIY1 PCB.

ProtoPotz pot breadboard PCB
Here is the range of pots available from Mouser that Synovatron recommends for use with ProtoPotz:-

ProtoJax

ProtoJax is an evolution of DIY2 and DIY3 PCBs. It is designed to hold up to five Cliff CL1384 3.5mm mono jacks. It is almost identical to ProtoPotz except it has footprints for jacks instead of pots and another two rows of breadboard holes. What's make it more advanced than DIY2 and DIY3 pcbs?
  • Larger breadboarding area. 
  • Supports the A-100 bus similar to ProtoPotz.
ProtoJax is available from Synovatron for 7.00GBP + delivery + VAT @ 20% (UK/EU only). It will not replace DIY2 PCB in DIY Prototyping Kits 1 or 3 except as a requested option.

ProtoJax jack breadboard PCB

ProtoXp

ProtoXp is a completely new PCB. It is an eXpansion board designed to add more breadboarding area to ProtoPotz or ProtoJax boards. It's features are:-
  • It has a cutout that allows the A-100 bus ribbon cable connector to fit without fouling on the ProtoXp board. 
  • The same ±12V power bus structure as the ProtoPotz or ProtoJax boards.
ProtoXp is available from Synovatron for 5.00GBP + delivery + VAT @20% (UK/EU only).

ProtoXp expansion breadboard PCB

 What else?

Data sheets will be prepared for the Proto series PCBs and download links will be posted online over the coming days.

DIY2 and DIY3 boards will be available for the foreseeable future. These can be used on their own or with the Proto series boards but the PCB holes do not align exactly so a linking ribbon cable is the best way to pass power and signals around between Proto and DIY series boards. Consequently the price of DIY2 and DIY3 PCBs will be discounted while stocks last. 

Sale price for DIY2 is 3.75GBP + delivery + VAT @ 20% (UK/EU only). Was 5.00GBP.

DIY2 jack breadboard PCB

Sale price for DIY3 is 5.00GBP + delivery + VAT @ 20% (UK/EU only). Was 6.75GBP.

 
DIY3 jack breadboard PCB

Please contact Synovatron for order enquiries, delivery costs and quantity/combined order discounts.

Sunday, 30 March 2014

Website updates

Due to being very busy trying to keep up with orders and developing new modules this blogsite has been sadly neglected. I was thinking I'd get round to putting up a proper grown-up website but that will not happen for a while yet as it requires careful consideration; I hope to setup an e-commerce type site with a basket and checkout facility. So apologies this is long overdue - I have updated details and pricing info for DIY Kits (Prototyping Kits and CV Tools Kit). More will be added to the DIY Kits page over the coming months including front panels and PCBs that can be ordered separately. I have also updated the Adaptors page and added a CVGT1/cvgtMM page.

Saturday, 11 January 2014

cvgt MM Buchla Translator ModuleModules are now shipping

The first cvgt MM modules have started shipping to clients at the top of the pre-order list. If you want to be added to the list then please make contact on synovatron@btinternet.com

I will build in small batches and work through the list in chronological order and will then contact you when your order is ready to ship. Only at that point will I request payment (see prices below). Please note that this does not form any contract between us and you are not in any way commiting yourself to making a purchase until such a time that you make a payment.
 
Initially the cvgt MM will be only available directly from me but if there is enough demand then it is possible they will become available at all the usual distributors in due course. 

The current variants are:-
  • Buchla-Euro (round or hex nuts on 3.5mm jacks; please select)
  • Buchla-Serge*
  • Buchla-BugBrand*
  • Buchla-Fenix*
*These are banana socketed variants and only the colour of the banana sockets is different (to match the target system); All are variants (inc. Euro) are to translate from Buchla to 1V/octave systems.

The User Manual is being worked on and will be ready very soon and will posted here in an update. Please checkout the Eardrill website for more info on the ModuleModule concept and other great products from Chris Muir.

The price for the cvgt MM is as follows:-
UK is 180.00GBP plus 9.00GBP delivery (prices include VAT at 20%)
EU is 180.00GBP plus 15.00GBP delivery (prices include VAT at 20%)
ROW 150.00GBP plus 13.00GBP delivery (import duties and taxes may apply).

Either one or two modules can be sent within the quoted delivery price for the UK but add 2GBP per exra module for the EU & ROW. 

It is estimated that it will take up to 2 weeks from registering on the pre-order list before your module is ready to ship and the shipping time from the point of payment could be 2 working days ( UK ) or 5 working days (EU/ROW).
 
Payment is by PayPal to synovatron@btinternet.com
Bank transfer is available on request.

Euro variant
Serge variant
Euro (top), Serge (bottom)