The Studer A-820 is a good machine...
The transport is killer, the audio electronics well designed
and overall it's perhaps the one of the best machines Studer ever built.
 
I DO prefer the A-827 over the A-820.
 
Note that Studer does NOT support the A-820
Studer does not sell any A-820 parts anymore
 
In theory you may be able to obtain A-820 parts from
AudioHouse   in Switzerland.
 





Here are some helpful tips I've found over the past years working on Studer A-820 machines...




First off, there are a number of EPROMs inside the machine, and these
can and will go bad - causing a complete machine failure.

Somehow, there was a flaw in the Studer 'self-test' programming, so if one
of the EPROMs fails, the 'self-test' can go through it's entire cycle
and finish up telling you that the machine is in perfect condition - even
though you can't get the transport to do anything....
 
So if this happens to you, it's likely one of the EPROMs.
It could be other things as well, but the first step is to swap out
the EPROMs so replace all of them... if you're lucky that will solve the problem.
Personally, if I owned a A-820, I'd have someone copy the EPROMs in my
machine as a Back-up set, and have them around just in case.
Buying a new set of EPROMs is costly, but depending on which version of
software you have (the programs are stored in the EPROMs)
you may want to buy a new set of latest EPROMs right away
if the machine is older than 5 years old and just replace them now.
 
Note that a upgrade of your EPROMs is dependent on the software version
you currently have AND the hardware... EPROMs are NOT interchangable between the
two basic versions of the A-820.

make a copy of your machine's EPROM set as a back-up...
 
Yes I can make you a back-up set of your EPROMs for you.
 
or buy a back up set   (very costly !!)
 


Replace your RAM Back-Up Battery EVERY 5 YEARS
 
If the battery goes dead, you will lose ALL stored prameters....
all Audio alignments, all Transport alignments, and possibly get wierd
stuff happening....
 
WARNING: when you replace your batteries ALL previously stored
alignment data will be lost - so you will have to realign your machine.
Smart thing is to write down all the various stored parameters - both
transport alignment and audio alignment data.... then re-enter the same data
once you've finished replacing the batteries.   Note that the original Factory settings
will be loaded back into the machine, but not your own settings.
 
Do NOT replace your battery
unless you understand the FULL ALIGNMENT PROCEDURE
- and can do a complete audio and transport alignment yourself,

or have written down ALL the stored values in the alignment 'tree'
and know how to re-enter this data back into your machine   !!!!  
 
We no longer sell Studer Batteries
 
 


Next I gotta tell you that I'm seeing a lot of A-827 and A-820 Multitrack machines
with power supplies that are now malfunctioning.     All the power
supplies in these machines are 'switching' power supplies, meaning they are EXTREEMLY
DIFFICULT to repair.   I've had to repair 4 power supplies in the last 6 months,
and these are pretty dang new machines.   Often the failures are due to the Owners
leaving the machines on for 24 hours a day....   causing the caps to go bad, transistors and FETs
to fail, the MOSFETs to blow up... and so on...
If you own a A-827 or a A-820  
DO NOT LEAVE THEM 'ON' 24 hours a day
!!!
 
Plus saddly the Power Transformers in the Studer A-827 and A-820 Multitrack machines seem to be
under-built, since I've seen a few failures where a power transformer shorts out
and blows fuses.     These cost about $ 1,400 each, plus shipping....
yet another reason NOT to leave the machine 'On' 24 hours a day, 365 days a year.
 
If you will not be using the machine for a while, turn her 'Off'.
 


Next you want to make sure that you do NOT set the wind or play tensions too high...
use the basic specs for tension given in the manual and have the tensions checked
once in a while.   Tensions set too high can force the machine into oscillation in the wind modes
 
Make sure you WRITE down the tensions settings in the manual!!   Engineers WILL change
the tension settings and they will not mention it to you... I've seen this happen too many times.



Also I've been seeing a bunch of A-820's and A-827's that have a huge amount of dirt,
dust and so onunder the transport.   I've even seen razor blades that have made their
way under the transport!   You should be cleaning this out at least once a year!
 
From time to time - say once a year - lift the transport up and remove the connectors one at a time,
spray clean the sockets and press the connectors firmly back into their sockets....
(of course with the machine turned off !!!)
Then after all the connectors have been cleaned,
you MUST test ALL the audio and transport functions!!!

by the way I use "LPS-1 Greasless Lubricant" as my spray-cleaner of choice



 
One of the MOST IMPORTANT and overlooked thing is oiling the Capstan Motor...
 
Most Studer A-820 machines use a 'sintered bearing' sytem in the Capstan
which needs to be lubricated about every 6 months, even if the machine
is in storage and not used.
Special Studer lubricant is required   !!!
A drop or two of the CORRECT (and expensive) oil will keep your
Capstan Motor running for years.... don't oil it and it will go bad   !!!
Please read the Studer Memo on Lubricating the Capstan Motors
Here's the Link:   Studer Oil Info  
 
You can purchase the correct Oil from Jeff at Precision Motor Works.   :
     Studer Oil  
 


Note that
later versions of the A820 and A827 use Ball Bearing bearings and
do NOT need lubrication!
   

There is sticker on the bottom of each capstan motor
that indicates which kind of oil is required or if it is a ball bearing type.
 
Here is the page on Capstan Motor Lubrication for the A820 MCH machine:
  A820 MCH Capstan Lubrication Info  
 
You MUST use ONLY the CORRECT oil   !!!
 




There are a lot of fuses in the A-820.... and you want to make sure you
have some in stock at at all times - it would be a shame to have to cancel
a session at 10pm just because you don't have a replacement fuse!
 


From time to time lift the transport up and remove the connectors one at a time,
spray clean the sockets and press the connectors firmly back into their sockets....
(of course with the machine turned off !!!)
Then after all the connectors have been cleaned,
you MUST test ALL the audio and transport functions!!!

by the way I use "LPS-1 Greasless Lubricant" as my spray-cleaner of choice



Next you need to learn the 'feel' of the transport control buttons -
they have a tendency to go bad now and then, and you need to know when one is about to fail...
there should be a good solid 'click' to the button, and it should bounce back after being pressed.



Note that the A-820 is a micro-processor controlled machine....
it's basically a computer, but it's getting OLD... it's a 15 year old computer now,
and chips do fail, EPROMs loose their memory, and strange things can start to happen.

Make a list of the various chips in the control system, and make sure that
you have a couple chips of each kind sitting around... some you may find hard to find,
but it's better to try and find them now, then when the machine's not working...
some chips will take hours of searching to find, but do it now!!



Various components in the A-820 are now getting old - the power supply caps, the
specialized caps in the Switching Power Supplies, and so on...
Heat over the years is also destroying such items as the tops on the Adjustable coils
in the Capstan Tach Card, which may just fall off if you even touch them... so
you really need to be careful with everything you do in a A-820.
Note that Studer does NOT support the A-820 in any way anymore -
no Parts, no support, no anything....




Also note that the cost of Studer heads is very high - too high for most studios
to afford to replace heads once they're gone....
so make sure that the tape lifters are pushing the tape away from the heads in wind modes!!
 
Remember that in the 'auto-mute' mode, you will NOT hear the repro system in the fast-wind modes....
meaning that if the lifters were allowing the tape to touch the heads, you would never hear it !!!
So physically check the lifters, or undo the 'auto-mute' and listen in the wind modes.
 


 
 


  Many Electrolytic Capacitors in the audio cards are
starting to lose their values and need replacement.   I just worked on
3 different Studer A-820 24 track machines all of which needed their
blue Phillips electrolytic caps replaced, particularly the 220uf 10 volt ones.
Other blue Phillips caps are going as well, so I suggest you think about
getting all the blue small Phillips caps replaced when you can...
Note that at least in the machines I recently worked on, the larger sized
caps were fine, and the brown ones perfect - so you don't need to replace those.
 


 
Also make SURE to buy a box of buses for EVERY fuse that's in the Machine !!
 
get 5 each: T style fuses - 250mA / 1 amp / 6.3 amps / 16 amps
get 10 each of T 3.15 amp fuses
 

Finally..... I never use the Auto-Alignment in the A-820.
I always align the machine track by track.
 

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