Friday, October 22, 2004

CRT Analyzer/Rejuvenator

Looks like I started a new trend!

One of the most useful devices for the workbench of a video arcade enthusiast is a CRT Tester/Rejuvenator. This device allows you to test the CRT of a Television/Monitor to make sure that internally, it's in good working order. I managed over the course of time to pick up three of these things, including two B&K 467's and one B&K 470.

A couple weeks ago, I decided to clean out some of the extras in my garage, and the 470 was one thing that could go (since I use my working 467 almost exclusively). So, I sold it on eBay, but instead of marketing TV/RADIO repair folk, like other people do, I went after the Arcade Collector. I spent a good deal of time preparing a lengthy description that included usage instructions, because most sellers of these things simply buy them at estate auctions and turn around and sell them, stating "I have no way to test it".

The auction was a success in my mind, because of the description, marketing to the arcade group, and also because I threw in a CR-23 adapter, which is used on the majority of popular arcade monitors (I picked up the CR-23 a few weeks back for $5). I realized a return on my investment, and came out ahead, even with losing a little bit of money on the fixed shipping cost that I quoted in the auction.

Well, this week, I'm noticing a lot of people selling rejuvenators on eBay who are targeting.... yup, the arcade group. One guy (QUARTERMANCO) even ripped off my auction description almost verbatim. Granted, he added a few words and took out some too. I complained a little on RGVAC, and his auction ended early for "error in description". Now, I didn't really mean for him to shut down the auction, but I was a little taken back by someone using my unique marketing scheme without at least crediting where the description came from.

So the description doesn't get lost once the auction gets out of eBay's archive, here it is:

Here's a WORKING B&K 470 CRT Analyzer/Restorer (Rejuvenator) from my spare collection. I verified that the unit works by analyzing and restoring a Wells-Gardner K4900 that was in my shop. It does not include all of the default adapters, and is missing a knob (actually the center function selector knob is missing, but I moved the heater voltage knob over, as is visible in the pictures). Also, there's typical cosmetic flaws, like foam rot in the adapter storage.

What is included is the all-important CR-23 adapter, which fits most arcade monitors like the G07, K4600, K4900, 25" K7000 (not the 19", which needs a CR-31), and the Sanyo 20EZV just to name a few. This piece is worth $40 new, and can sometimes be found here on eBay by itself or part of a collection of adapters.

I work on a lot of coin-op arcade monitors, and it surprises me just how many come in with weak emissions. Sometimes, the picture will be dim and it's obvious that the emissions on all guns are low. Other times, there might be a missing color (or one color significantly dimmer than the others). Still other times, they will have a decent picture, but the analyzer will show that they are actually bad.

Arcade monitors see a lot of abuse in that they are left powered on almost all day every day. It seems that the larger tubes (25" and bigger) are the most consistent in needing restoration. And if you happen to lose a color due to a dead transistor on the neckboard or something, you can almost guarantee that the corresponding gun will have weak emissions after the problem is fixed (especially if the monitor was left on for a period of time after the failure).

What the B&K 470 will do is analyze the emissions of each gun (red, green, and blue) and show you via a meter if they are good or bad. It will also let you check tracking, which is how each gun operates compared to the other two, and will check for leakage, which is caused by tiny short circuits inside the tube, specifically H-K (Heater-Cathode) and G1-K (G1-Cathode) shorts.
If there is a problem, then there are restoration modes that allow you to attempt to correct the problem, which includes removing shorts, clean-and-balancing, and full rejuvenation. For the most part, all that I ever have to use is the clean-and-balance function, which uses low-power to try to clean up a gun's emissions. G1-K shorts can be fixed by this unit, but H-K shorts cannot.

Here's how a typical restoration session goes for a CRT using the CR-23 adapter (voltages used in this example may vary for other CRT's, so be sure to look up the numbers for the CRT you are working on before starting):

  1. Start with the function selector set at the "Power Off" position, and the monitor unplugged.
  2. Attach the CR-23 adapter to the 470's cable, then connect the CR-23 adapter to the neck of the CRT. Set the heater range to "4-7".
  3. Turn the function selector to "Set Heater".
  4. Turn the heater voltage dial until the needle on the meter points to "6.3" on the HTR scale.
  5. Turn the function selector to "LEAKAGE-HTR".
  6. Turn the gun selector knob to each color, and observe the meter. The needle is supposed to be in the yellow "OK" section on the Leakage scale (otherwise, you have a H-K short).
  7. Turn the function selector to "LEAKAGE-G1".
  8. Turn the gun selector knob to each color, and observe the meter. The needle is supposed to be in the yellow "OK" section on the Leakage scale (otherwise, you have a G1-K short).
  9. Turn the function selector to "SET G1 VOLTAGE".
  10. Turn the G1 Voltage dial until the needle on the meter points to "50" on the G1 scale.
  11. Turn the function selector to "SET G2 CUTOFF VOLTAGE" and the gun selector to "RED". Start with the Red Cutoff knob turned fully counter-clockwise. Note where the needle is pointing (in case it does not start on a tick mark). Slowly turn the Red Cutoff knob clockwise until the needle moves one full tickmark on the top scale (if it started in between two tick marks, make sure that it ends up in between the next two ticks)
  12. Repeat the previous step for the Green and Blue guns by first turning the gun selector to the color, and then adjusting that color's cutoff knob.
  13. Turn the function selector to "READ EMISSIONS".
  14. Turn the gun selector to each of the colors and observe where the needle points on the meter. All guns should have emissions in the green "GOOD" section.
  15. Turn the gun selector to the color that had the strongest emissions.
  16. Turn the function selector to "SET COLOR TRACKING".
  17. Turn the Tracking dial until the needle points to "SET TRACKING" on the meter.
  18. Turn the gun selector to each of the other colors and observe where the needle points on the meter. All guns should fall within the yellow section.
  19. If a gun was weak in either the emissions or tracking, select that gun with the gun selector, then turn the function selector to Clean-Balance.
  20. Wait 20-30 seconds for the heater to completely warm the cathode, and then press and hold the rectangle Restore button.
  21. Watch the meter, and when the needle falls into the red "BAD" section, release the button. (If the needle does not move after 30 seconds or so, go ahead and release the button anyways--you might need to use Rejuvenate instead of Clean-Balance).
  22. After restoring a gun, go back to step 11 and reset the cutoff for all guns, read emissions, and check the tracking. Clean/Balance other guns as needed.