Dave Denyer: The Reel-to-Reel Rambler

This is a tale of how a relatively simply upgrade to Neville Roberts’ Studer A810 turned into a major problem, and how it led him to find a company that specialises in Studer MPU boards – solving all his issues! Over to Neville…

While scanning interesting pages on eBay recently (as we do!), I happened to come across someone who was selling a non-volatile RAM chip upgrade for a Studer A810 open-reel tape deck. “A what?” you might be asking. Allow me to elaborate…

As the proud owner of a Studer A810 tape deck, I’ve invested in having it fully serviced and have upgraded all of the key components in the audio chain.  I’ve then carefully set the machine up using MRL test tapes.  These tapes allow you to set the playback and record equalisations for your machine, and all of these settings are stored in a volatile RAM chip on the MPU (multiprocessor unit) board. The memory remembers all of the settings and is kept alive with a rechargeable battery that’s soldered to the MPU board. Nowadays, you can get non-volatile memory that doesn’t need a battery, but such memory wasn’t around when my Studer machine was designed.

The Studer’s original battery was NiCad and was known to start leaking after a few years, causing disastrous corrosion of the PCB tracks and adjacent components. Fortunately, I was able to replace the battery with a newer Nickel Metal Hydride battery. The issue for me is that even this newer battery has a limited lifespan and should be replaced every 10 years. After a few battery replacements over the years, the PCB track was beginning to look a bit worse for wear, but my trusty 15W Antex soldering iron and a solder sucker did the trick and I was able to replace the battery.  However, I was very excited to find someone who had designed a direct replacement for the volatile RAM chip, which would mean an end to regular replacement of the on-board battery. The NV (non-volative) RAM uses F-RAM technology that will hold the data for many decades. Result!

I placed my order via eBay and found that my non-volatile RAM chip upgrade was being sold by an appropriately-named company called ‘Studer MPU Boards’, who have a website at www.studer-mpu-boards.com.  The chip swiftly arrived and all I had to do was to remove the battery from the board and swap the chip over.  This time, I used my snazzy temperature-controlled soldering iron and a solder sucker for the job of removing the battery. I then changed the IC6 chip on the board with the NV RAM chip and finally, I replaced the MPU board in my machine.

Original Studer MPU Board with the replacement NV RAM chip

Original Studer MPU Board with the NV RAM chip fitted and battery removed

Of course, when changing the memory, all of the settings are forgotten. So, before doing this, I had stored all of the machine settings onto tape using a home-made lead and the procedure documented in the Studer manual, hence restoring the machine’s parameters after changing the battery wouldn’t be a problem. Another option is to write the settings down to enter them manually afterwards, which was especially important for me since I had taken great pains to set my machine up using MRL calibration tapes. So, now, my next job was to read my parameters stored on tape into the new NV RAM. Or so I thought….

Alas, my machine wouldn’t boot up!  When I switched it on, it lit up, but the MPU board didn’t reset as usual. In fact, it was dead, it was no more, it had ceased to be, was bereft of life, it rested in peace – it was indeed a late MPU board! Putting the Pythonesque references to one side, I tried replacing the battery and the original chip, but it still failed to work.

I then got in touch with Petronel Butuc of The Audiophiles Clinic who kindly offered to look at it for me, but sadly, he found that several of the chips on the board had failed. My initial thought was that I hadn’t taken enough care to earth myself when I was de-soldering the battery. I remembered that CMOS chips of that vintage are prone to damage from static electricity. However, in a further discussion with Petronel, I learnt that he has found that some temperature-controlled soldering irons can have quite a high static voltage at their tips – enough to destroy early CMOS memory!  Petronel recommends the use of a soldering gun for such de-soldering work, because the tip is at a low impedance to earth for safety.  I now have one on order, but horses and stable doors come to mind!

Anyway, Petronel told me that the most cost-effective solution for my predicament was to replace the MPU board and that Studer MPU Boards also specialise in manufacturing brand new replacement boards. I contacted the very helpful owner of the company, Steve Fensome, and he told me that they have two versions of the board available, one with the original chip set and backup battery for those who want to retain the authenticity of the original design, and one with the new NV RAM chip fitted and no backup battery. I, of course, opted for the latter, which is available for the very reasonable price of £280 with free UK postage. I’m delighted to say that the board arrived swiftly and worked perfectly.  All I had to do was restore the machine settings, and I had no problems loading in the parameters from tape.

Studer card cage

Studer MPU board replacement

Rear of Studer MPU board

New MPU Board installed in the left slot

I’m delighted to have my Studer working again and relieved to know that I will never have to change an MPU battery again! If you’re thinking of replacing a RAM chip yourself, do make sure that you’re properly earthed (wear an earthing bracelet while de-soldering the battery) and that your soldering iron has a fully earthed tip, or get an expert to do the job for you.  As for the components and boards, I can thoroughly recommend Studer MPU Boards for their helpful service and manufacture of high quality products that come at a very reasonable price.

Neville Roberts is a man of many interests and talents. As well as being a regular contributor to Hi-Fi Choice magazine, he’s a retired UK National Health Service (NHS) director, electronics engineer and physicist. He’s also a lifelong audio enthusiast with a particular interest in valve/tube audio design, vinyl and tape. Neville enjoys an eclectic range of music including classical, especially baroque, light orchestral and jazz. He lives with his wife near Bournemouth in Dorset, UK, where he grows orchids and is a keen photographer.