Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Television Broadcast Gear

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 02-27-2015, 08:01 PM
N2IXK's Avatar
N2IXK N2IXK is offline
Technohippie
 
Join Date: Apr 2011
Location: Sittin' on the "Group W" bench...
Posts: 799
Link Electronics PRC-970 Proc Amp--Manuals available?

Just scored a couple of these guys on the auction site, and was wondering if anyone had manuals for them. All I can get from the web is the spec sheet/catalog page.

Looks like a really nice unit, with 2 banks of DIP switches to pass/replace any line in the vertical blanking interval, PERFECT for stripping macrovision or other nasties. Plus all the usual proc amp functions like pedestal, sync, chroma level controls. Looking forward to playing around with these.
Reply With Quote
  #2  
Old 03-14-2015, 02:48 PM
N2IXK's Avatar
N2IXK N2IXK is offline
Technohippie
 
Join Date: Apr 2011
Location: Sittin' on the "Group W" bench...
Posts: 799
Obtained a copy of the manual from Link, who are still selling these units.

http://www.linkelectronics.com/catal...ct_Info&ID=294

Got the units in and have been playing around with them a bit. As the seller described, they powered up, and one actually worked right off the bat. The other unit, had a shorted tantalum cap on the +5V rail, which took out the 7805 regulator. Replacing these restored full operation. Both fans were (as described) very noisy from worn bearings. Little tiny 25mm x 10mm muffin fans, which I was able to find cheaply enough, and replaced them both.

The units work wonderfully for stripping macrovision encoding from DVD or VHS. Setting the switches to dump lines 10-17 on both fields does it. Dumping line 21 will strip closed captioning, and line 19 dumps a VIR test signal I produced from a Sencore VA62.

The units have so many adjustments that it is possible to do some real funky stuff to a video signal. Separate adjustments for black and white clip, sync level, burst level, pedestal level, luma and chroma gain, plus subcarrier and horizontal phasing adjustments, and overall AGC loop that can be applied to whatever parameters you select. Have to try hooking up the lousy Chinese VGA/NTSC converter box I bought a few weeks back. I wonder if I can polish that turd enough to produce a compliant signal?

Link was able to provide the manual as a .pdf, but unfortunately no schematics, (proprietary information) which struck me as unusual considering the excellent theory of operation (complete with references to specific component designators) section the manual contains. They describe the circuitry in pretty good detail, but they can't include a schematic?

A nice addition to the shop video rack all in all.
Attached Images
File Type: jpg PRC970 guts.JPG (134.6 KB, 12 views)
File Type: jpg 001.JPG (115.2 KB, 13 views)

Last edited by N2IXK; 03-14-2015 at 02:58 PM.
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 12:13 PM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.