[QuadList] Merlin Quads

[Don Norwood]

Hi Park:

Ampex provided a way of dealing with this, so aside from anything else that 
Merlin might have done, the answer to your question is really in two parts.

First, when Intersync is NOT on the main supply (as with the Merlin mod), 
then a jumper on pins 18 & 20 of the power supply frame connector for the 
+/-12vdc supply is removed.  You can check for this by removing the supply 
module, plugging the extender cable into the frame, and measuring between 
the two pins.  On machines with the separate Intersync supply, the pins 
should read open.  This allows any supply module to be used in the slot as 
it automatically changes the load in the supply.

But, beyond that, each supply should be setup for the proper amount of shunt 
load, and that depends on what is installed in the machine.  For instance, a 
machine with the editor installed will be different from one without an 
editor.  Step one is to be sure that the correct tap is selected on the 
primary of the transformer.  There are taps for 105, 115 and 125 volts. 
Next you measure the collector current for each of the two shunt regulators, 
and confirm that it is between 250 mA with full load (record mode, editor 
on, etc.) and 1 A with the machine in stop.  These are constant current 
supplies, so they will run hotter with less load than when the machine is 
operating.  The setup insures that the shunt transistors will operate within 
their design range and the adjustment is done by jumpering out resistors R6, 
7, 8 & 9 as required.

The exact process for doing this is in the manual.  You may find that the 
supplies are interchangeable between different machines.  It just depends on 
what the load difference is among the different decks, but the only way to 
be sure is to check the collector current in each supply when it is 
operating with each machine, and that's kind of a pain!  Probably best to 
check each one with its own machine and leave it there except in an 
emergency.

Don

----- Original Message ----- 
From: "C. Park Seward"

> Ken,
>
> Is there a way to tell the power supplies apart that have been  modified 
> for Merlin use with the extra 12V supply?
>
> I have several supplies from other VTRs and don't know if the previous 
> user has them in the right place.
>
> Best,
> Park
>
> C. Park Seward
> Visit us: http://www.videopark.com
>
>
>
> On Aug 31, 2009, at 10:53 AM, Kenneth Zin wrote:
>
>> Question about the Merlin quads, Ask and I will try to answer them
>> Ken Zin
>
>