The Studer A-810 is a GREAT machine...
The transport is killer, the audio electronics well designed
and overall it's perhaps the best small portable 2 track machine Studer ever built.
It is NOT the best 2 track Studer ever built, but it's a good solid
machine, and is selling for reasonable prices on the used market
Almost all of the Studer A-810 machines need work

Here are some helpful tips I've found over the past years working on Studer A-810 machines...

First off, there are a number of EPROMs inside the machine, and these
can and will go bad - causing a complete machine failure.
Personally, if I owned a A-810, I'd have a copy of the EPROMs in my machine made
as a back-up in case I need to replace them in the future.
  The latest EPROM version is Studer Part Number (1.810.999.24)
== there were 2 kinds of EPROMs used in versions of the A-810 ==
And there are about 6 or 7 different sets of EPROMs over the years.
You MUST have the correct EPROM set for your own version machine!!
Once an EPROM goes bad your machine will not function correctly
SO Make or GET a back-up SET OF SPARE EPROMS
We can make a copy of your EPROMs for you
  (  if you can't find anyone local who can do it for you...)
 Cost is $ 100.00 which includes 3 new EPROMs
Note: you MUST send in your EPROMs for me to copy   !!!
What are the EPROM’s ??
They are a set of 3 or 4 memory chips that contain the full machine program info
that runs the A810 main microprocessor on the MP board.
The EPROM is a programmed ROM that is ‘burned’ electrically once and then can last between 10 – 15 years
before it needs to be refreshed or re-burned.   Some EPROMs last longer than others.

But   ALL A810’s are now 20 - 30 years old  - so the likelihood of an EPROM error is pretty high these days.
Once you get errors in the operation of the machine - often random - you may have a failing EPROM.

Studer updated and improved the code in the EPROMs from time to time...
to not only improve the functions and fix minor errors,
but also to add extra functionality to the machines...

There are basically 6 EPROM set versions...

07/83 – a 4 chip set   -   13/83   -   25/86
01/88   -   46/90   -   25/91
Note the last 2 numbers indicate the Year of the EPROM set

You can update the versions as follows depending on what board number you have.

the early A-810 4 EPROM chip board can only take it's own version, and cannot be upgraded
unless you get a new 3 EPROM chip board - not worth it...

EPROM versions 13/83   or   25/86 can upgrade to the 01/88 set

EPROM set 46/90 can upgrade to version 25/91

There isn't much of an improvement in upgrading your EPROMs... most changes were minor.
If your machine is running fine - Keep using the same EPROM version !!

Most A-810 machines MUST have their internal Battery changed ASAP !!!
Change your back-up batteries every 5 years.

We no longer sell batteries   !!!

  There are two different types of batteries in the A-810 units...
One is a long battery similar to a AA cell, the other is pictured above
and has three solder pins.... this one can be replaced with a
Varta 3/V150H or a Varta 3/100DKO-PC
Once your battery goes bad you cannot store any audio alignment parameters
so your alignments can go crazy or revert to the original very old Factory alignment data

WARNING: when you replace your batteries
  ALL previously stored alignment data will be lost  
so you will have to realign your machine... For the A-810 it is audio only!!
You MUST write down all the various stored parameters audio alignment data....
BEFORE you replace your existing battery

then re-enter the same data back into the machine
once you've finished replacing the batteries.
  Note that the original Factory settings
- from the Date your machine was built - 1983 to 1991
will be loaded into the machine from the EPROMs
until you re-align the audio system   !!!!
Do NOT replace your battery unless you understand the FULL ALIGNMENT PROCEDURE
- and can do a complete audio and transport alignment

or have written down ALL the stored values in the alignment 'tree'
and know how to re-enter this data back into your machine   !!!!  

Almost ALL Studer A-810 early version machines MUST have their Motherboard
power supply caps replaced ASAP.... the Franko brand caps are now failing and
will often explode inside your machine - not a nice sound to hear - or will
open up or short out one of the power supply rails.... thus rendering your
machine unuseable.
The Philips caps are lasting much longer than the Franko brand ones, and
there is no need to rush out and have them replaced - wait until your machine
needs service and have your tech replace them when you need other work done.


Note that a few A-810 machines have the newer 1.318 heads installed which are
upgrades.   As Studer says... "No A-810 machines ever left the production line
with built in amorphous heads (1.318 series heads)"
But they were an aftermarket upgrade provided by Studer.
The 1.318 heads REQUIRED circuit board modifications...
here is the Service Info on the mods that need to be done... in a PDF file.
  Amorphous Head Mods...  

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 will cause your heads to wear out fast.

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-810 is a micro-processor controlled machine....
it's basically a computer, but it's getting OLD... it's a 10 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!!

One of the MOST IMPORTANT and overlooked thing
is oiling the Capstan Motor...

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 at two places listed on this Page...   :
  Studer and Revox  CAPSTAN  OIL
Read this ASAP   !!!

Use ONLY THE CORRECT OIL for your motor !!!
There should be a colored sticker on the rear of the capstan motor
which will tell you which oil to use....

AudioHouse - the present supplier of Studer parts - still has SOME the parts for the A-810

Note that the cost of Studer heads is 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!!


One of the NICE things about the A-810 is that the Repro heads are connected
via very short cables, to a well designed LOW NOISE head amp right near the heads.
This amp is DIRECT COUPLED to the Repro head....This is great.... and not so great.

One of the problems is that it IS possible - in fact likely - that if the tape
is against the heads and you turn ON or turn OFF the tape machine - with tape against the heads -
the machine may put a nice horrible recorded POP onto the tape via the Repro head.

This comes about because there is a quick fluctuation in the power voltages
on turn-on and turn-off in the Head Amp.... which is direct-coupled to the record head.

So you MUST make sure tape is removed from the heads
   - better to take the tape off the machine -
  BEFORE you turn ON or OFF the tape recorder  !!!!!

Finally make sure that when you set the audio parameters, the setting Hex Codes between the
Right and Left channels are somewhat close together... if you find one channel
requires a significant increase in level or high-frequency EQ or bias,
swap the audio cards and see if the needed increase (or decrease) follows the card
or stays with the channel.   You will need to swap cards one-at-a-time.
NEVER take out or put in a card with the machine turned 'On'  !!!

Finally, almost ALL Studer A-810's need to have their Audio and Power Supply
caps replaced.... and there are a bunch of caps that are hard to get to !!!
See my 'What Bad Caps Look Like" page :
   Bad Caps !!    


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