I'd like to see this, since I have several TV tubes I'd
like to start using. I've considered his tubes, and based
on what he asked to be measured, it seems like a fairly
easy tasks to mate the tubes with his respective new
chassis.

Scott C.

Pac-Fan wrote:

All --

This post is intended to be a summary (though it still got long) review of
Victor Genao's (8liners.com)'s replacement CGA/low-res analog RGB arcade
monitor chassis. A much more thorough review with numerous pictures and
explanations will be posted to a web site (anyone have space?) when time
permits.

If you have personally tried one of his chassis as well, please contact me
and confirm/contrast anything noted below. If you reply you MUST include the
word 'chassis' is the title otherwise your mail will be lost in the spam
deluge, or preferably post to the group.

I am not in anyway related to Victor or his company, just an enthusiast with
enough CRT background to be safe and to be able to try out numerous tubes on
a chassis over a couple evenings. All I have in this is $73 for the chassis,
shipped, plus some old donor tubes, and about 10 hours work (also doing
swaps in a WG arcade chassis). My review is intented to be fair and
impartial based upon MY experiences only. Yours may vary based upon tube and
yoke variations.

Remember: Safety first. Don't attempt this unless you know and understand
all risks of working with CRTs and high voltage.


Summary: A cheap, quick and easy way to make an arcade monitor with (nearly)
any old TV or Arcade tube with their yokes attached.

Results: Vary depending on donor tube type, brand, model, quality, previous
(ab)use, yoke characteristics and other factors. Overal very positive with a
few caveots.

Unit purchased: I purchased the "low impedence" version. Meant for use on
tubes with yokes with vertical windings measuring around 15 ohms DC voltage.
(Technically, yokes work and vary based upon impedence [AC resistance, not
DC] but that's another topic for another post) Low impedence versions are
similar to a Wells-Gardner K4600 series monitor NOT an Electrohome G07 which
is high impedence (~55 ohms, DC).

I have yet to find a TV set with a high impedence yoke that also has the
correct tube pinout. With 5 tubes total, plus testing a WG chassis too,
making for 10 combinations, I didn't want to get into swapping yokes for
"perfect" combinations leading me to do 100+ ? tests along with
reconvergence/etc.. The intent of these chassis is for a quick setup
with a tube and its existing yoke...

Overall comments, in no particular order (remember far more detail will be
posted later, with pictures)

- Original RCA 19VJTP22 tube + yoke from a WG K4600 presented a super sharp,
VERY highly focused pixel screen at nearly any (resonable) contrast and/or
brightness. As good or better than the K4600 it came from. However the yoke
suffered from pincushion on the horizontal left and right part of the tube,
bowing inward about an inch in the center making it annoying to use. No way
to adjust it out. (Tube had burn-in but looked good in the chassis with the
new picture on it.)

- 4 different donor TV tubes. A Matsu****a dark-tint screen from a mid-80's
Quasar knob tune set (very very faint overall burn-in), 2 Orion tubes from
late 80's Emerson quartz mini-dial and PLL synth tune sets (different tube
model #s), and a Magnavox/NAP/Philips tube from an early 80's Magnavox knob
tune set. Other 3 tubes showed no visible general burn-in.

- All 4 tubes presented colors very well, except the dark tint one that
seemed to be somewhat 'gun worn', which makes sense given the light burn-in
and darker glass. Overall on the all 4, the colors were vibrant and very
adjustable. However all 4 tubes exhibited an overall blurriness that could
NOT be removed using the focus control, even though the edge of the focus
pot was never hit. The only way to get the clarity in each pixel to match
the original WG tube was to adjust the brightness control very low (too low
to place in a game however) At normal brightness levels, basically there
was significant "blooming" around the pixels, especially white, making it an
overall soft, yet, not out-of-focus image.

- All the drive controls, cut-offs, screen and focus were adjusted in every
way trying to 'fix' these problems. However, a bit of background told me it
wouldn't help. You see, I also tested each of these tubes in the WG K4600
chassis and all of them had nearly the same highly focused pixels on the WG
chassis (though they had yoke problems there, where they had outward bowing
pincussion, opposite of what the WG tube did on the 8liners chassis...which
makes sense). I also compared the sharpness against a NOS, basically
unused, Hantarex MTC9000 monitor I have that is brilliantly sharp at even
high contrast/brightness as a basline comparison. (No, I didn't want to swap
that tube in to test...yet)

- Two of the tubes (the dark Matsu****a and the Maganvox tube) exhibited
slight pincushion in the lower right corner (assuming the anode cap was on
top for orientation). The horizontal lines were slightly drug towards the
corner in the corner, but it was not so annoying as to make it unplayable
like the large pincusion exhibited by the RCA/WG tube.

- Other than the slight bends noted above, the chassis seemed to handle a
wide variety (9.8 to 14.5 ohm DC vertical) yokes keeping the pictures
straight and only very light geometry issues, but the 8.5 ohm one from the
WG was apparently too different in impedence to work without pincushioning
(and vise versa--the TV yokes in the WG chassis all had pincushion due to
impedence mismatch)


Conclusions:
- Depending on your donor tube luck--If you are looking for a monitor to
present a nice smooth screen, especialy with newer games that have numerous
solid colors and large fonts, you probably will be very happy with the
results. For the MAMErs it will blow away any attempt to use NTSC composite
or Svideo on a standard TV set, it will be better

- If you have older games with not much background and very clean/concise
lines (pac-man, galaxian, etc..) and LIKE seeing very sharp (but round, not
computer crt 'square') pixels, then you may have to look longer for a better
matching tube and/or do a yoke swap to make things match best. (e.g. if my
old RCA tube didn't have bad burn in, I could just swap on any donor yoke
from a TV set and have a really really nice monitor for what I like--sharp
pixels)

- It seems to like the impedence of TV set yokes best, but I only had one
compatible arcade chassis/yoke to compare against so my test sample is
admittedly small.

- The chassis has a wide range of controls and isn't anywhere as limited as
a WG 46xx or EH G07 series chassis. You can control virtually everything
with pots, and there is a "small/medium/large" jumper block to gain even
more size if the HWIDTH and VSIZE controls don't give you enough or too much
size. Unlike many monitors there are THREE drive and THREE cutoff controls,
giving you full (and easy) control over RGB grey and white balancing, which
is good if the donor tube may have a weaker gun than the others. Focus seems
to be very wide..I didn't ever reach the 'edge' of the pot in either
direction when I switched tubes. I did run into that on the old WG chassis
where a donor tube would just be in focus at the extreme left or right of
the pot.

- Built in switch-mode isolation transformer is nice so you don't need a
huge heavy copper wound iso. It includes a very cheap line cord with AC end.
I was annoyed it was not keyed hot (small) and neutral (wide), as techically
it's safer to run the hot in through the fuse first and not the neutral. But
I just labeled the end to be extra safe and plugged it in the same way each
time.

- For those with odd positive sync game board: This monitor only accepts
composite negative sync. You will need to get a hex inverter and a 5 volt
line and invert your old sync if you can't adjust it on the board in order
to get a picture. Many boards use negative separate (easily
combinable--just combine the wires) or negative composite, but some use
positive separate or composite and need adapting.

- There are 2 yoke jumper rows so if you mount the tube upside down, you can
easily flip the image 180 degrees by using the other jumper row..without
having to remount the tube or de/re-solder the yoke wires. (This is a common
problem with old vertical games that each rotated the tube differently.)
[Note: in practice I have seen some SLIGHT color shifting when a yoke is
flipped due to the way the beams hit the phosphor slightly differently, so
perfectionists may want to find the way to mount and control the yoke that
looks best and is the best adjustable with the pots.]

- For $73 shipped (for the 19" version), it's a pretty good deal if you have
a/many donor tube(s) and don't have the time, experience or want to spend
money fixing up broken or "untested" old chassis. However be aware it may
take some trial and error finding a 'perfect' match. If more people have
tried this and could report their results, along with tube model #'s we
could figure out which ones work better or worse given an individuals
tastes.

- Bad: I found that no matter how long I let the chassis sit unplugged
(admittedly 24 hours at most), it did NOT auto-discharge the tube, like both
of my K4600's and my G07 and my Sanyo EZ20's do. I was actually amazed at
this fact given new technology. I have NEVER gotten a "zap" when
discharging any of my old chassis+tubes before removing the anode cap.
However I got THREE healthy zaps in a row each and every time I discharged
each tube I swapped in and out of this chassis. The first zap jumped from
the clip to the screwdriver when they wern't even touching, the second and
third (after waiting a few secs) required touching the clip. Therefore
people 'used to' not getting zaps discharging will be in for a surprise if
you do a few swaps on this. Yes, ALWAYS ALWAYS ALWAYS assume there is a
charge and discharge three times, even if you don't hear/see anything after
the first time... you may have 'missed'.

- Good: The anode wire clip is VERY easy to clip in and remove. (Unlike the
horrible one in the WG K4600 that is very hard to work with, especially to
remove). This clip seems to stay very tight and any anode 'crackling' went
away shortly after turning on (a sign of a poor connection).


That's all for now... When I get time, I will post numerous photos of the
results of each tube on each chassis. Please reply (to the forum preferably
so it isn't lost in spam) with any comments on the review or your
experiences if you've tried them yourself.

-- Pac-Fan