How to tell the difference between u2000, u5000, k7400 and k7500 monitor chassis

twistedsymphony

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How to tell the difference between u2000, u5000, k7400 and k7500 monitor chassis

So I wanted to order a cap kit and new flyback for the monitor in my KI2 cabinet looking at some pictures it looked like a u2000 but I soon discovered that the u2000, u5000, k7400, and k7500 are nearly indistinguishable from each other, and not only do they look nearly identical but the capkits and flybacks can be different depending on the model you've got, making for a high probability of ordering the wrong parts.

I figured out a few easy ways to tell the difference and since I had a hard time finding information on the differences I figured I'd post up a guide..

MAINBOARD:

Method 1:
Using the schematics from Wells Gardner the location of a coil near the center of the chassis is a great initial indicator:

u2000:
u2000.jpg


u5000:
u5000.jpg


k7400/k7500:
k7400.jpg

^unfortunately the k7400 and k7500 have identical board layouts so you'll need one other key to identification.


Method 2:
on the left side of the chassis board (the side with the fuse) there should be a board number that starts with a "P" this number should tell you which chassis it is:

P-717 = U2000
P-738 = U5000
P-763 = K7400
P-793 = K7500


Method 3:
Also printed on the board should be a model number that starts with "WGM" for Wells Gardner model, it will follow this format:

WGM####
the first two numbers "##" represent the tube size, 25" or 27"
the second two numbers "##" represent the chassis type as follows:

20 = U2000
50 = U5000
74 = K7400
75 = K7500

for example my number was WGM2520 meaning a 25 inch U2000
if your number was WGM2775 it would mean you had a 27 inch K7500

------------------------
REMOTE BOARD:
The remote board is the small board with all the adjustment knobs on it, that allow you to fine tune the picture on the monitor. there are some differences between remoteboards

Method 1:
just like with the main board look for the "P" number on the remote board
P-716 = U2000
P-718 = U2000 or u5000 (this remote board was used on both models)
P-790 = K7400
P-804 = K7500

Method 2:
This is pretty easy, Count the number of Potentiometers (pots). the u2000/u2000 have 8 pots, and the k7400/k7500 are missing the top left pot (h-hold) for a total of only 7 pots. This only gets you half way there.

Looking at the schematics it appears that the u2000/u5000 remote boards are, for the most part interchangeable, as are the k7400/k7500 remote boards. Don't quote me on this, as I don't have any experience with swapping these out... the minor differences are as follows:

Minor differences between the u2000 and u5000 remote boards:
some u2000 use the same board as the u5000, the ones that are different will have different values on the (non-adjustable) resistors... the older u2000 board has a 4.7K (yellow, violet, red) and 3.3K (orange orange red), the u5000 and newer u2000 boards have values of 2.2K (red, red, red) and 2.7K (red, violet, red). These resistors are used in the contrast adjustment, and could be easily swapped out if problematic.

Minor differences between the k7400 and k7500 remote boards:
the h-position pot is different between these two: the k7400 uses a 20K pot, and the k7500 uses a 10K pot. Theoretically you should be able to use the k7400 remote board on a k7500 but you may be out of adjustment range on the width and horizontal position if using a k7500 board on a k7400, this could be fixed by replacing the pot.


----------------------
NECK BOARD:
I still haven't figured out a good way to determine the differences in the neck boards myself, I'll update this post once I do.

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I was able to use all 3 methods to positively ID my chassis as a u2000. I'm sure most of this info is old-hat to some of you but I spent a couple of hours pouring through posts and images trying to figure it out, so I figured I should post it up to hopefully save someone else the headache.

If I got anything in this post wrong... please correct me... I wouldn't want to be spreading around incorrect info ;D
 
Last edited:
This is pretty sweet. I still have a hard time figuring out some of the newer monitors. The K7000's are easy but these ones can be a PITA.

The next question would be, what chassis are interchangeable with what tubes.
 
The next question would be, what chassis are interchangeable with what tubes.

K7400, U2000, and U5000 all use the same yoke and tube. Chassis can be swapped from the tube of one to the tube of another with no changes.

K7500 uses a completely different yoke and needs to be matched with it specifically. I've seen two different K7500 yokes - one with the rings and yoke as all one piece and one with them separate. I think the whole is the K7501 and the separate is the K7502. Mixing incorrectly (K7502 chassis on K7501 yoke, for example) can sometimes lead to major purity issues.

Btw - the U5000 can also be easily identified by the two large connectors in the middle of the chassis that are used to select standard or medium resolution inputs.

And you might want to add some info on the different remote board numbers, since they are model specific and people sometimes cause problems by connecting the wrong one.

And maybe a mention of the differences in neckboards. They aren't all the same, despite what many people think...
 
For whatever reason, I always notice the difference in them at the flyback. The U2000 and U5000 have the flyback very close to the edge. On the 7400 and 7500 they moved it back farther, so you can tell very quickly if it's the older (bad) or newer (good!) board by how close the flyback is to the edge.

board-1.jpg


U2000, notice the fly is right at the edge of the pcb. Once you see that, you know it's a 2000 or 5000, if it has the jumper plug in the middle it's a 5000, if it doesn't, it's a 2000.

k74kit.jpg


K7400 chassis. Notice how far back from the edge the flyback is? Really easy to notice at a moment's glance. So you know it's a 7400 or 7500, I usually have to check the tag at this ponit. You'll see 2574 or 2575.
 
Hey Modessitt,
You wrote,
"K7500 uses a completely different yoke and needs to be matched with it specifically. I've seen two different K7500 yokes - one with the rings and yoke as all one piece and one with them separate. I think the whole is the K7501 and the separate is the K7502. Mixing incorrectly (K7502 chassis on K7501 yoke, for example) can sometimes lead to major purity issues."

By Chance do you have pictures of these yokes or numbers so I can match up a yoke for a K7500 chassis I have. Can a tube from a U5000 be used also? Just curious. Thanks again for
any insight into getting another project going. I also need the remote board number or ones that will work on the k7500 as well as ones that will work with the k7400 too.
 
I can't do specific info now (on my phone) but the K7500 yokes are 09A3xxx-xxx. I have the specific numbers written somewhere, but it might take a bit to find them.

As for remotes, I have thread around here somewhere about converting a K7500 remote to a K7400 remote (or vice versa) with the numbers for each type in the thread...
 
Thank You Modessitt,
Last question regarding the Tube.
Will the U5000 tube work?
Thanks again, I will track down that
string regarding remotes.
 
The U5000 tube SHOULD work, although almost all K7500's were 27" and most U5000 tubes are 25"...
 
And maybe a mention of the differences in neckboards. They aren't all the same, despite what many people think...

I've added a section on the remote boards based on what I could gleam from the schematics, I'd appreciate it if you looked over what I posted :)

I haven't found any easily discernible differences in the neck-boards. according to the schematics all 4 chassis use the same "P719" neck board but that doesn't seem right to me. the few differences I do see in the schematic are VERY subtle (ie: jumper here, extra resistor there, etc.)

if you have good pictures of the neck-boards I could make up some images highlighting these variations. Or if you know of some easier method of detection than I do...
 
What about u3000 neck boards and u5000 chasis?

they don't go together. they're not remotely close. the U3000 shares more with a K8000 -- their overall designs are similar, including the 120/27V needs, external power supplies, square neckboards, and equally shitty construction.

U2000 has a small white plug in the middle, U5000 with 2 different headers (as noted previously by mod) .. and if ever you're stuck on K7400/K7500, the K7500 will have a black wire wrapped around the core of the flyback.

that's how I know the differences. you can go deeper with the K7400/K7500: one has a cap at C729 and the other has one at C731 instead. (going off my hazy memory)
 
U2000 has a small white plug in the middle, U5000 with 2 different headers (as noted previously by mod) .. and if ever you're stuck on K7400/K7500, the K7500 will have a black wire wrapped around the core of the flyback.

that's how I know the differences. you can go deeper with the K7400/K7500: one has a cap at C729 and the other has one at C731 instead. (going off my hazy memory)[/QUOTE]

width coil locations on the PCB is also a way to tell them apart.
 
Thx, for response. Can a u5000 drive a 30" monitor? I read in specs on WG support page that it can do 25,27 & 33..

Probably wrong thread for that question. I'll do some searching.
 
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