CRT:BKM-68X

From ConsoleMods Wiki
Jump to navigation Jump to search

BKM-68X

BKM-68X.png

Information
Manufacturer Sony
Type Input
Optional Yes
Inputs 1x RGB/YPbPr
Outputs 1x RGB/YPbPr
Links
Operation Manual File:BKM-61D BKM-62HS BKM-68X Operation Manual.pdf
Service Manual File:BKM-61D BKM-62HS BKM-68X Service Manual.pdf
Compatible Models

BVM-A32E1WU

BVM-A24E1WU

BVM-A20F1U

BVM-A14F5U


The BKM-68X is a rare optional input board used for adding RGB/YPbPr component inputs to a BVM-A series monitor. While they are rare, expensive, and often have sync related issues - there exists Martin Hejnfelt's BKM-68X clone (source files) which has all the same functionality but for a fraction of the price and with less sync issues as shown in the picture below.

68xVShomebrew-1024x357.jpg

Sync Issues / Potential Fixes

Many consoles seem to have sync issues with the 68X, as the A-Series BVM's don't have the "VCR Mode / Automatic Frequency Control (AFC)" that the previous BVMs offered, which cleared up a lot of the horizontal problems. Different settings for the card's configuration, as well as a lot of "tricks" to fix the sync. A sync regeneration device could potentially fix all issues with A and H series BVM's, but at the moment, there's no true "fix" for the 68X.

Here's some tips if you're a current owner of the 68X:

  • Try routing your RGBS signals through a device that converts sync to RGBHV, then back through another device that converts it back to RGBS. One example might be using an LM1881-based device to convert to RGBHV, then an Extron RGB interface (203xi, 501, etc) to convert back to RGBs.
  • You can run your consoles through an OSSC or RetroTINK 2x in passthrough mode, then use an HDMI to component converter. This breaks compatibility with some light gun games and Sega 3D glasses, but it's certainly better than not being able to use it at all.

VCR Mode / AFC & Sega Master System

Here's some screenshots from the D-Series BVM manual, explaining what VCR mode does:
BVM VCR Mode01.png BVM VCR Mode02.png

Another description provides a more technical description of the issue that Automatic Frequency Control will correct: "It will also occur when the receiver is operated from a signal which does not have horizontal slices in the vertical sync block". Apparently, the Sega Master System doesn't have horizontal slices in the vertical sync block, which explains the root cause of the issue. Without AFC, or a way to re-generate the horizontal frequency (such as by using a 580xi), the SMS can never sync to an original BKM-68X. The BKM-68X clone does not have this problem.

BKM-68X Maintenance Menu

Note The main A-series maintenance password is 53415.

This is how you access the BKM-68X maintenance menu and also the options that are available (I don't believe these options are listed any either of the operation manual or service manual for either the A20F1 or the BKM-68X). If anyone has any suggestions on what options to enable / disable to get it to sync properly with consoles like the AES, please speak up.

  1. Press the MENU button and select "SYSTEM CONFIGURATION...".
  2. Select "MAINTENANCE...".
  3. Enter the password 53415 and press Enter.
  4. Select the "BKM-68X..." option.

Options:

BKM-68xMaintenanceMenu05.jpg BKM-68xMaintenanceMenu06.jpg BKM-68xMaintenanceMenu07.jpg

Media

BKM-68X clone developer log on ImmerHax website

File:BKM-68xPics.zip