[QuadList] Transistors for Ampex AVR-2?

[Chill315 at aol.com]

The AVR-2 will make better pictures and provide better audio.  It also  takes 
a lot less power.  There are a couple of things that you need to look  at.
 
First and foremost is what recording standard was used.  The AVR-2 is  a high 
band only machine.  There were board sets available for other  standards.  
These are hard to come by but the instruction book always  included the other 
boards so you could make your own.  It will take  time.
 
Second, What condition is the transport.  Look at all the rollers and  guides 
on any machine.  How about the compliance arms?  The rollers  and compliance 
arms can be rotated to get rid of the cuts.  Do the rollers  even turn?  What 
condition are the audio and erase stacks?  Do the  reel hold downs on the 
VR-1200 hold a reel?  These are all pieces that you  will want to consider 
replacing because they can cause edge damage.
 
After that, look at the serial number and modification history.  The  early 
AVR-2's had a lot of modifications.  By the time they were in the  500's. it 
was pretty stable except for the Triac assembly.  The VR-1200 had  a long 
history.  The Inter-sync went through about 11 (?) different  versions.  The 
assembly number has a -xx and that tells you the  version.  
 
The VR-1200 Auto Chroma was a band by band system.  The AVR-2 was a  line by 
line system.  It makes a difference.  The VR-1200 had as an  option, the 
Differential Gain module.  This is something that makes a whole  lot better 
pictures.  The AVR-2 had that built in.  I could get an  AVR-2 to look better than a 
1 inch Sony.  It was because I took the time to  tweak the DG controls and set 
it up correctly.
 
The AVR-2 has a better RF system.  The filters used were better  designed.  
The VR-1200 had numerous filters available.  There were  four different 
versions listed in the schematics.  Most came with the  better filter but not all.  
Also most came with the AFC modulator but again  not all.  These things make 
subtle differences in the performance.
 
The VR-1200 can play back some tapes that the AVR-2 has issues with.   Or you 
have to go into the AVR-2 and change a few jumpers.  Most of these  are very 
early tapes that were made on poorly maintained machines.  
 
So what does it come down to?  I would not worry that much about the  
transistors but more about what do you want to do with the machine.  Yes  the AVR-2 
is a better performing machine and will work forever.  The  VR-1200 is a little 
easier to get to but you have to spend a little more time  keeping it up.  
The biggest thing is you are going to have to look at all  the big electrolytic 
capacitors in each.  The get a stock of certain  transistors for both.  The 
AVR-2 will go through the power transistors on  the back panel a lot.  That was 
the major item that I dealt with.  The  VR-1200 it was just general ones in 
all different areas.  Mostly keep the  servos aligned.  
 
Hope this helps your decision.
 
Chris Hill
**************The year's hottest artists on the red carpet at the Grammy 
Awards.  AOL Music takes you there. 
(http://music.aol.com/grammys?ncid=emlcntusmusi00000002)
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