Neotec NT-500DX issues

hatrick

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I'm working on a Golden Tee with an Neotec NT-500DX tri-res monitor. It would only display the little colored "no signal" box when in CGA or EGA mode. I hooked it up directly to the VGA out of the video card, and it has a beautiful picture.
What would cause it to work only in VGA mode?
Also it clicks 2 or 3 times when you first turn it on. Is this the power supply, or the monitor switching resolutions?
This is my first time messing with a newer digital tri-res monitor.
 
there's to sets of three pins with a jumper on the RGB sync board. (the little board on the side or back) move the jumper on the top i believe to the other two and try it again. I know it's something with those pins. that control the resolution.
 
C3A7694C-1B2C-4E52-9476-7FDF1122C06F-604-000000FBF05EDB71.jpg


Here's the board. I was under the impression that all you had to do was hook up the proper input, then switch the output wires to the appropriate plug (EGA/CGA or VGA).
The 3 pinned switches, Sw1 & Sw2 are glued in place and labeled: H/V and COMP.
 
Any more info on this monitor? Are the switches on the input board for sync? Comp or H/V?

I changed one of the switches from H/V to COMP, changed the inputs to CGA/EGA and it still had no signal, but it clicked a lot more times at startup.

I hate new monitors that have a lack of documentation.
 
Caps?

if signal interface board is good and cables hooked up right.
Check the X901 is solder in good for the micro.
Next check for a shorted mosfet like q709,q707 irf640
also reading th FH or frequency table on schematic will tell
you what mosfet drive trans is turned on..for each res.
Test point is S0,S1,S2 to the base of each transistor{2sc945}
then to a mosfet for scan,If no shorts in the scan circuit
then replace the Caps
Have to search for a cap kit if needed.

if you can't find a made up list then
start pulling them to replace, record the location's
and uf list for each cap.
after you done add your list and caps,to a bag and start making
millions of dollars selling a NT-500 cap kit!! LOL
Good Luck!
 
if signal interface board is good and cables hooked up right.
Check the X901 is solder in good for the micro.
Next check for a shorted mosfet like q709,q707 irf640
also reading th FH or frequency table on schematic will tell
you what mosfet drive trans is turned on..for each res.
Test point is S0,S1,S2 to the base of each transistor{2sc945}
then to a mosfet for scan,If no shorts in the scan circuit
then replace the Caps
Have to search for a cap kit if needed.

if you can't find a made up list then
start pulling them to replace, record the location's
and uf list for each cap.
after you done add your list and caps,to a bag and start making
millions of dollars selling a NT-500 cap kit!! LOL
Good Luck!

That's good info, thanks. As far as I know, I'm hooking things up right, and I assume the interface board is good, but I guess I can't know for sure.
I'll pull the chassis and start looking for bad solder and bad caps, then check the mosfets.
Hopefully, I'll have something to report back here.
 
Found this thread while looking for a list. Didn't find a cap list so I made my own. I made the document viewing public but if you have any problems let me know.

https://docs.google.com/spreadsheets/d/1VU6cxyHT0mOKN7f3SbSuhLj03VrZj_IuaZZAhT24NEg/edit?usp=sharing


your listing is wrong because you have three caps on the neck that are BP/NP caps and you can't use polarized caps to replace them so you should fix that otherwise it will cause damage to someones chassis if they use your list. i did this kit about 5 years ago so i am only going off memory so i only check for critical information like that.
 
I made this list based on the caps that were on it, and the monitor has been running well for 2 days after full swap. The neckboard I have shows polarity for the the 200v/1uf caps, and the caps that were on it were not clearly marked as bipolar. I installed polarized caps according to the marking on the board (and the direction of the writing on the cap). I will make a note about the caps being bipolar just to be safe.

Initially the monitor would not power up and a relay was, for lack of a better term, machine-gunning. In the past I have swapped caps in the power supply to remedy this, but couldn't find a list so I made one.
 
Last edited:
I made this list based on the caps that were on it, and the monitor has been running well for 2 days after full swap. The neckboard I have shows polarity for the the 200v/1uf caps, and the caps that were on it were not clearly marked as bipolar. I installed polarized caps according to the marking on the board (and the direction of the writing on the cap). I will make a note about the caps being bipolar just to be safe.

Initially the monitor would not power up and a relay was, for lack of a better term, machine-gunning. In the past I have swapped caps in the power supply to remedy this, but couldn't find a list so I made one.

Ok, I see why you replace them with polarize caps


Yes they need to be Biplolar.

They are normally found in series and the polarize Cap's

is mostly found in parallel to ground.

And the Negative side on the board would be above ground reference

if a Biploar caps needs to be there.

and mostly found inline with a signal or drive pulse.

Be sure to confirm all locations for your part list.
 
Is there a readily-available capacitor listing that is more accurate than mine? Not trying to be a dick, but had I been able to find it, I wouldn't have wasted my employer's time making a list. If that's the case, I would be happy to mirror it with credit given, or we can link to it here.

I am waiting on a couple of these caps yet to arrive, so I know there is one that has a value but no location. That one will be updated when I get it out so I can read the silk screen. It's in tight by a heat sink. At that time I will be sure to check to make sure the locations/values match.
 
Is there a readily-available capacitor listing that is more accurate than mine? Not trying to be a dick, but had I been able to find it, I wouldn't have wasted my employer's time making a list. If that's the case, I would be happy to mirror it with credit given, or we can link to it here.

I am waiting on a couple of these caps yet to arrive, so I know there is one that has a value but no location. That one will be updated when I get it out so I can read the silk screen. It's in tight by a heat sink. At that time I will be sure to check to make sure the locations/values match.

First off, Thanks for posting a list.

I don't see an issue with your list beside what I already said.



I personally have found wrong caps in cap kits. that were in stock

at company's I was helping.

and cost me more time, but I don't need to look back if I just replace what was

there if original. So its not a waste of time to detail each chassis with a different

tube.

I would not assume each chassis with different tubes

has the same Caps. with only one schematic found.

need to check the board, because they are using different Tubes

on the chassis.

I'm pretty sure there is a cap kit, I just haven't bought one pre-made yet.

and I would not just swap in caps because a pre-made cap list

I would confirm the one's are correct from a technical view point.

Or look for others to confirm it was correct for their chassis.
 
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