Schematic for neotec 2702, 3602, and 3501

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Started by Amusement Repair -


Can anyone post these.  I would appreciate it.

Thanks

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By Cactusjack -


I have it only in hard copy.  That is the only way Neotech has it too.  I have no way to scan it.

If no one else comes through, I can snail mail you a copy of NT-2700(1)(2) and NT-2702A.

CJ

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By Amusement Repair -


Thanks I will wait and see who else can come through.  These chassis are very easy to repair, but I would like a schem for reference.

Thanks

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By channelmanaic -


Hey CJ,

We have a great print server at work that I can send a job to and it sends me back a .pdf file... so if you can scan it, send it my way and I'll .pdf it.

RJ

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By kbert -


Has anyone posted this schematic, I'm in need of the NT-2701 to try to fix my monitor.

Thanks

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By Amusement Repair -


I dont think its posted, but you can call Neotec at 909-626-9889. Ask for service and the guy there can fax it to you.  Whats wrong with yours and maybe we can help you here.

Thanks

S J K

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By kbert -


The problem with my NT-2701 is that it won't power up.  I get nothing when I plug it in, no static, no noise, nothing.  I've checked the fuse and it is good. Voltage is getting to the monitor, checked it at the fuse.  I don't see a test pin for the B+ voltage, found the adjustment for the B+ voltage, just no place to check it.

Any ideas?

thanks,

Ken

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By Jay -


Sounds like the CPU board is not getting its power. My analogy is that you have Video1 going but no disk in the DVD player...

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By Cactusjack -


How much monitor board repair experience do you have?

This type of monitor board uses a switching power supply.  It is normal procedure to isolate the power supply (lifting B+ from the rest of the monitor) and try powering a 55-60 Watt Incandescent light bulb as a dummy load.  This will allow you to test the B+.  And helps to determine if the problem is a power supply problem or a deflection problem.

That would be the starting point if the switching power supply made no sound, or was ticking or chirping like a bird (which would indicate either a P/S problem or a no-load or over-load situation on the other half of the monitor (deflection).

CJ

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By kbert -


I've done some more testing by using the NT2515 schematic, which looks very close to the nt2701.  Found a place to measure the B+  (off of pin 2 from the flyback) and was able to max adjust the voltage to 112.5 volts (up from 105).  I think it needs to be 125+.  The screen is squashed to the middle (Horizontal left and right 4" show nothing).  The last monitor that I had a low B+ voltage on was because the big cap was bad (c104 on the nt2515 schematic).  I'm thinking that this may also be my problem with this one.

Ken

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By Cactusjack -


You might be right.  It is difficult to tell from one board to another as the Cap #'s don't seem to match the schematics. If your monitor has the add on board on the side, that is where most of the deflection caps are (the high voltage ones).  There is also a Bipolar cap that almost always goes bad there (5.6 or higher at 50V).  That will cause no horiz width adj.

Here are some other things from my notes on various ones related to Neotec

NT-2702A (not 2702) C407 0.68ufd @ 400V
NT-3501 C423 0.94ufd @ 400V

For a standard 2701, check the caps around C419, 420, 421.  I am starting to see C423 burn up now (563/250V) it is actually for the ground on the secondary side of the flyback.  On the ones that have failed, it is located in front of the Vertical Driver IC (heat sink).

CJ

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By kbert -


An update for all those who may have a simular problem with a monitor.  I did a cap kit, replaced IC501 and Q501 and had the same problem, but the picture was nice and bright.  I checked out the caps C419, C420 and C421 which looked good, so I started thinking that the problem may not be on the board.  I had another monitor (without chassis which was a nt-2701) which I decided to check out the yoke.  I compared that ohm reading of the yoke to the readings on the current monitor and they were different.  Once I moved the chassis to the other monitor, everything works fine.  So my problem was the yoke on the monitor having a higher ohm reading which means that it had the wrong chassis.

Thanks for everyones help.

Ken

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By pinshoppe@aol.com


I have schematics for the NT-3501 if anyone would like them in pdf form.  -Mike

[frep420]

Please fwd the pdf or link to me. I have 3 chassis, two tubes and at least one bad flyback.

JFBArcade@gmail.com

Thanks!