Main Restorations Software Audio/Jukebox/MP3 Everything Else Buy/Sell/Trade
Project Announcements Monitor/Video GroovyMAME Merit/JVL Touchscreen Meet Up Retail Vendors
Driving & Racing Woodworking Software Support Forums Consoles Project Arcade Reviews
Automated Projects Artwork Frontend Support Forums Pinball Forum Discussion Old Boards
Raspberry Pi & Dev Board controls.dat Linux Miscellaneous Arcade Wiki Discussion Old Archives
Lightguns Arcade1Up Try the site in https mode Site News

Unread posts | New Replies | Recent posts | Rules | Chatroom | Wiki | File Repository | RSS | Submit news

  

Author Topic: Need Help on NEOTEC NT-3501  (Read 12620 times)

0 Members and 1 Guest are viewing this topic.

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Need Help on NEOTEC NT-3501
« on: July 09, 2011, 02:27:51 am »
   Ive been doing some leg-work on a "guantlets legends" machine in preperation for this capkit install that is happening NOW, to no avail.  Ive found the schematics, but no monitor service manual "online", but read "MY EXACT SAME SYMPTOMS"  here:   http://forums.arcade-museum.com/showthread.php?t=74838&page=3
 
 
Ken Layton seems to have seen this repair a few times, so I tried to post over there (KLOV), guess my donation hasnt posted yet, so Ill try him (OR any other Technician) here on my favorite board.
 
    This here is one of those Neotec NT-3501 monitors that share a repair manual (and capkit) with the NT 2700-2701-2702-3500-3506.  As far as I can see, there is not a pdf of this available online anywhere, just the schematics.  (HEADS UP! NEOTEC HAS REMOVED ALL SCHEMATICS POSTS AS WELL)  !!!!  (THEY DONOT ANSWER THE PHONE EITHER -  NEW NUMBER IS (626) 858-0802. GOOD LUCK.
 
  I have a "converged screen"  represented with a stripe (DOWN THE MIDDLE (FROM TOP TO BOTTOM)) .  At the above links converstation (2years ago <grin>) a bi-polar cap on a sister "pincussion" board was discussed as a possible culprit, as well as pots on a tether.  I currently have the solder-gun hot, starting my capkit.  There is no "Bi-polar" cap included in Bob Robs kit for that "pincussion board, just one supplied for the main-board "C-550 (WHEREVER THE HECK THAT IS (I HAVE NO CAPMAP)). Wish me luck, guys..... I'm gonna need all I can get here (will be highly appreciated).

 
« Last Edit: August 06, 2011, 05:12:47 am by kampcool »

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #1 on: July 09, 2011, 02:29:58 am »
Here is a Picture of that "pincussion" board in question.
 

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #2 on: July 09, 2011, 02:32:14 am »
And a pic of that armor plated dang neckboard
 

 
  :censored: whatever happened to that piece of cardboard zipptied to the back of this?     ;D
« Last Edit: July 09, 2011, 02:37:32 am by kampcool »

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #3 on: July 09, 2011, 03:58:06 am »
Heads-up already!!!!   Wrong silkscreen polarity label on solderside of board for C-426   (4th on Bobs list).   
 

Correct!!!! (negative to left)

 
 
Incorrect silk image

 
 :soapbox:

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #4 on: July 09, 2011, 05:31:15 am »
I am on the 8th-11th cap reinstall (as per the real Bobrob's list) and wanted to "Heads-UP" on (C-412,502,506,507) Not to mix up the required   4.7uF 50V cap     with the    47uF 25V caps.
 
Take a special close look here, Nt-3501 recappers in the future.  
 

 
 :blah:
« Last Edit: July 09, 2011, 09:09:58 am by kampcool »

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #5 on: July 10, 2011, 02:42:35 am »
wrong silkscreen solderside C121


kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #6 on: July 10, 2011, 11:32:12 pm »
    I want to say Im dissapointed, but I "almost knew" a cap kit wasnt going to fix her.  Went in today and fired up Guantlet Legends, and although my capkit install seemed good "NO SMOKE", I still have the same stripe down the middle from top to bottom.  Thank goodness, before I left ---I repaired a "track n field" with a wells gardner 4900, or Id be worried about my new job.  (I am the "NEW" monitor tech, and my boss needs some games-up A.S.A.P).  Its Summer, and Gauntlet Legends, and this NT-3501 monitor needs to be working.
   This week, I am going to succeed in getting a Neotec Nt-2700-3506 monitor repair manual, AND the caps in the pincussion, AND some neck-board caps, AND a new pot for the "H-hold".  Any other suggestions would be pursued with the utmost gratitude.   Thanks for any input, in advance.
 
                                                                          -KAMPCOOL-        :badmood:
« Last Edit: August 06, 2011, 05:15:42 am by kampcool »

lilshawn

  • Trade Count: (+3)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 7377
  • Last login:Today at 04:40:51 pm
  • I break stuff...then fix it...sometimes
Re: Need Help on NEOTEC NT-3501
« Reply #7 on: July 11, 2011, 01:49:23 am »
maybe the HOT is bad... i have seen instances where the B+ will not shutdown, but display a line... but the HOT tests okay  :dunno

the stress of the high voltage is enough to make it not work under load in circuit.

if you have another to try, it might be worth a shot.

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #8 on: July 11, 2011, 03:31:56 am »
Of course, YES.  This is an option I have been tempted to "explore"  I have a working NFL Blittz (right next door) with the exact same monitor (WORKING).  Robbing from Peter to pay Paul, so to speak.  Dont think for a moment I havnt been tempted.  Maybe I should act upon my impulses to "swap out" that pincussion board as well, just to prove.
« Last Edit: July 11, 2011, 04:40:32 pm by kampcool »

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #9 on: August 02, 2011, 04:27:10 am »
  Hey lilshawn, I finally obtained a manual for this chasis (nt-3500 nt-3502 nt-3602) and my B+ readings at "D106", controlled by the variable "R-111" should be 100  +or- .5VDC.
When I measured this yesterday at the shop, I couldnt believe what I was seeing, as the voltage was extremely high, even at the R111's lowest setting.  I was getting like 174-189VDC.
I think you are the guy I am going to have to buy a beer.    I am truely a new guy to this monitor, and it has been an "eye opening experience", to say the least.  I have checked every single resistor, and cap on this chasis, and everything looks cool.    There are 5 different transistors on this board (8 in total (as there are 4 of the A673's)), and to date I have checked none of them.
  Thanks for the "Leed" that will probably solve this puzzle.  ATM, I do not know which one of these transistors on my main board is the "HOT".  At least you have given me a super sweet nudge in the right direction.  Ill keep it posted here.

lilshawn

  • Trade Count: (+3)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 7377
  • Last login:Today at 04:40:51 pm
  • I break stuff...then fix it...sometimes
Re: Need Help on NEOTEC NT-3501
« Reply #10 on: August 04, 2011, 02:21:19 pm »
hey, i circled the hot in red there for you , as well as circled in green caps that likely need to be replaced.

i also circled in blue, some resistors that often get run hot and burn up a bit. they start to read higher and higher untill they fry on you... best to check them now while you go it out.

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #11 on: August 05, 2011, 05:03:37 pm »
  you rock.    Thankyou very much  Ill keep it posted here   
 
 :cheers:

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #12 on: August 06, 2011, 05:08:41 am »
  Allright then, looking at the "HOT"  I just pulled this bad boy, and right off the start I have discrepancies.  I ACTUALLY "Witch hunted" down a manual, and at Q402 (there is no description except for a "BU2532AL"(The manual doesnt even describe this as a transistor).  No big deal, but the transisitor I did pull out of there was a "BU2532AW".  I am currently scoping the datasheets, and see no difference.  Now, mind you, when I first opened up this "Guantlet Legends" machine, there was no monitor chasis board.   I found this board in a box of junk under a desk.  I have been scoping this HOT, and it doesnt seem right.  
 From the datasheets I have looked at, (both pn# al and aw)  its a BASE, Collector, Emitter configuration, 1, 2, 3.  The only readings I can achieve on this transitor are from the negative (AT the base) to the (collector), and from the negative (at the base) to the (emmiter).  EVERYTHING ELSE IS WIDE OPEN IN ALL CONFIGURATIONS.  This means this transistor is bad news.  This means that we have good news.     10 dollar freakin part.  
  Its 5 am, and I have just put in a 50 hour work week in the worst hell hole known to industrial America, and I CANNOT wait to show up at my new source (to see if they have one in stock)  If they do, I will be so stoked!  Then I can show up to my love job, and get this thing right, punch out, and play this game for free, till my boss tells me to "GO HOME".  Totally STOKED.  This has got to be the culprit.  
  Will "KEEP IT POSTED HERE"!!!!
« Last Edit: August 06, 2011, 06:03:51 am by kampcool »

lilshawn

  • Trade Count: (+3)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 7377
  • Last login:Today at 04:40:51 pm
  • I break stuff...then fix it...sometimes
Re: Need Help on NEOTEC NT-3501
« Reply #13 on: August 06, 2011, 07:09:43 pm »
 Allright then, looking at the "HOT"  I just pulled this bad boy, and right off the start I have discrepancies.  I ACTUALLY "Witch hunted" down a manual, and at Q402 (there is no description except for a "BU2532AL"(The manual doesnt even describe this as a transistor).  No big deal, but the transisitor I did pull out of there was a "BU2532AW".  I am currently scoping the datasheets, and see no difference.  Now, mind you, when I first opened up this "Guantlet Legends" machine, there was no monitor chasis board.   I found this board in a box of junk under a desk.  I have been scoping this HOT, and it doesnt seem right.  
 From the datasheets I have looked at, (both pn# al and aw)  its a BASE, Collector, Emitter configuration, 1, 2, 3.  The only readings I can achieve on this transitor are from the negative (AT the base) to the (collector), and from the negative (at the base) to the (emmiter).  EVERYTHING ELSE IS WIDE OPEN IN ALL CONFIGURATIONS.  This means this transistor is bad news.  This means that we have good news.     10 dollar freakin part.  
  Its 5 am, and I have just put in a 50 hour work week in the worst hell hole known to industrial America, and I CANNOT wait to show up at my new source (to see if they have one in stock)  If they do, I will be so stoked!  Then I can show up to my love job, and get this thing right, punch out, and play this game for free, till my boss tells me to "GO HOME".  Totally STOKED.  This has got to be the culprit.  
  Will "KEEP IT POSTED HERE"!!!!

the difference between AL and AW may only be as small and one is lead free designated, while the other isn't. or a different revision...no big deal.

it does cross to an NTE part# NTE2533 which is a brand commonly available at most electronic parts distributors. (IE NOT radioshack)

best way to test the transistor is to set your volt meter to ohms, and check for continuty (short) between the middle leg and the two outside ones. it should read very high or open, if it reads a short, it's bad. sometimes (depending on the surrounding circuitry), you have to actually remove the transistor to check it. (if you are getting negative resistance reqadings, it sounds like you have a capacitor discharging into the meter, throwing off your reading.... sounds like you need to take it out to test.

keep in mind ive had lots of these test good (even with a B&K transistor tester) but still be bork when powered up. this is just a quick and dirty test.

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #14 on: August 11, 2011, 06:57:43 pm »
   Replaced the hot, and I still have the same symptoms.      :badmood:       So where do i go from here?   the Regulator transistor?  Does anyone know where that one is located?   

lilshawn

  • Trade Count: (+3)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 7377
  • Last login:Today at 04:40:51 pm
  • I break stuff...then fix it...sometimes
Re: Need Help on NEOTEC NT-3501
« Reply #15 on: August 11, 2011, 07:22:43 pm »
not the regulator... you have b+ and you have high voltage (as evidenced by the vertical line.)

you have something amiss in the horizontal deflection circuit... you should have a chip or something "upstream" from the HOT. on the other neotecs it's an LA7850 or 7851. the LA7850/51 provides the pulse to fire the transistor that fires the transformer that fires the HOT that makes the flyback and the beam "flyback"

on and on and on....




kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #16 on: August 12, 2011, 05:14:44 am »
   Roger that.  At   "IC401" 
 

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #17 on: August 12, 2011, 05:16:42 am »
  We have a "LA7851" which I just pulled.
 

 
LOOKING AT THAT THING, IT SEEMS TO HAVE DONE A TOUR IN IRAQ (hopefully its bad)
« Last Edit: August 12, 2011, 06:29:32 am by kampcool »

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #18 on: August 12, 2011, 05:38:41 am »
  So Lilshawn, (BTW, thanks for all your time helping me out on this little monster)  You have been the only guy around with experience, willing to share.  I cant thankyou enough, you are being super cool, and I appreciate. :notworthy:   Is there a laymans way of checking this deflection circuit chip for failure, or do I rush up to my parts dealer tommorow and lay a $20 on him?

  I found one online and that seems to be the going rate here: 
 
http://www.wellgainelectronics.com/sanyola7851.aspx
 

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #19 on: August 12, 2011, 06:26:28 am »
  No matter what happens, at this point (thanks to LilShawn) we have the most in depth forum coverage on this (very common) symptom (for this monitor) ANYWHERE!  I know, because I have been scouring for months  :banghead:  (Its bad, when you do a search and find your own post)!  This particular Neotec Nt-3501 has stirred a love-hate emotion into my view on this hobby.  I now know I need to get my arse back to school, and finish my electronics degree, so I have something to do when I retire from automotive hell (thats the LOVE part).  I  have definately lost the initial need to save and resto any machine after 1992.  The things I am discovering in the industry, are taking the luster off, real quick.  The fact that Neotec (and many others in this era) are purposely tight lipped and tight assed about backing their product, and the overall non-info campaign they pursue turns me way off.  :angry:
  Probably a good topic, elsewhere, but thats where I'm at.   I love monitors, video, color, Graphics, and pretty much anything visual-related.  At 10 yrs old trying to uhf tune in "Benny Hill", from Canada, and tuning my radio shack self-built radio to listen to a book reading of J.R.R tolkiens "The Hobbit", when I should have been long asleep.  Everyone here knows exactly what I'm talking about.   Back when Air (waves) was free. ;D

lilshawn

  • Trade Count: (+3)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 7377
  • Last login:Today at 04:40:51 pm
  • I break stuff...then fix it...sometimes
Re: Need Help on NEOTEC NT-3501
« Reply #20 on: August 12, 2011, 10:11:19 am »
once you have an understanding on how monitors work, you will find they are all pretty much the same (with some minor parts differences.)

As for your chip, there isn't much of any testing you can do on the output side unless you have an oscilloscope... even then, i don't really know what to look for.  :lol i have a couple of scopes and only bust them out for really tough issues.

You can check an make sure you have 12 volts on pin20 of the chip which is the voltage input to power the chip..... that would be the top left pin when viewing the chip writing right side up. if no volts you must go further up stream.

Generally if I have no horizontal deflection that changing the HOT doesn't cure, I go ahead and change the chip. (mind you we have a board full of parts so swapping is no problem for us) if still no dice, there has to be an issue with the 12 volt supply to the chip that I was too lazy to check for.

EDIT TO ADD:

If you check the voltage and find it low 9 or 8 or 6 volts, try removing the chip and testing the voltage again...if it's 12 or 13 or 14 after removal it's likely bad. (short inside dragging down the voltage.) if it's zero then something is up with the power supply.
« Last Edit: August 12, 2011, 10:36:01 am by lilshawn »

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #21 on: August 12, 2011, 06:26:51 pm »
     O.k then, thats cool.  Looking at my last photo posted, you can see chip 1 and 20 are screened right on the chasis board.   :cheers:

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #22 on: August 22, 2011, 04:10:46 pm »
  ok, I threw that chip back in there and measured a 11.68 at the 20 pin., so my powersupply seems good there.   I had my electronics guy order me a horizontal chip for $5.67. , we will see by this weekend.

MKFan4Life

  • Trade Count: (+2)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 300
  • Last login:July 24, 2023, 08:18:00 am
  • My arcade machines...
Re: Need Help on NEOTEC NT-3501
« Reply #23 on: August 25, 2011, 01:36:38 am »
Hi.  Just perusing your topic here.  I have a GL dedicated cabinet with a Neotec 2701 (labeled in one spot as an NT-27E).  Neotec's are a mixed bag or confusion it seems.

Just following your progress.  I did a cap kit to mine 2 years ago and had to replace the bipolar pincushion cap at location C-19 on the pincushion board.  Ended up using an axial bipolar (in place of the normal radial) cap from the local Radio Shack as Bob's kit didn't include one then.  It fixed my pincushioning problems to this day.

At that time, I sent Bob some high-res scans of some of the pages from my 2701 manual, and he made a kit just for the pincushion board.  I think he is still selling it separate from the standard cap kit for these Neotecs.

Also, for sure, I have come across some of those incorrect polarity silk screenings on the Neotecs.  They'll be right on one side sometimes, but wrong on the other side of the chassis.  I have a video I need to upload to YouTube of a complete cap kit and flyback replacement I did for a fellow YouTuber the end of last year where I found one of those wrongly-screened cap positions and pointed it out in the clip.

Sorry for the diversion.  Just following your progress.  Carry on!  :)

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #24 on: September 04, 2011, 10:23:11 pm »
  Ok, I installed the new chip at "IC401" (LA7851) with a NTE7062, with no success.  I have the same Line down the middle from top to bottom.  I measured 11.78 at pin 20.    Any suggestions where to look now, would be highly appreciated.

lilshawn

  • Trade Count: (+3)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 7377
  • Last login:Today at 04:40:51 pm
  • I break stuff...then fix it...sometimes
Re: Need Help on NEOTEC NT-3501
« Reply #25 on: September 05, 2011, 11:55:30 am »
if you still have no deflection there must be something wrong with the HOT or its appreciated circuit. since you replaced the deflection chip. there isn't much left. you are almost in the home stretch.

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #26 on: September 08, 2011, 01:22:28 am »
  Ok, so after the 401, and the La7850 (which is all the horizontal stuff) (phase position hold and frequency), my block diagram shows it flowing towards the "IC 301", and "LA7836" (Which I do believe is all the vertical display).  It also flows to a H.Driver, and a H.output (which I have replaced).  Then it flows from there,  to the pincussion board, and to a transformer "t402". 
 

 
What is this H Driver, and should I be looking into it for this problem?   Should I also be looking into this T402 transformer as a culprit, or should I go straight to the pincussion.   Alot of people have mentioned a bipolar cap as the culprit for this pincussion board as a problem on other neotecs, but I have looked everywhere and cannot find a bipolar cap on this model, and there isnt one on the parts list either.

MKFan4Life

  • Trade Count: (+2)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 300
  • Last login:July 24, 2023, 08:18:00 am
  • My arcade machines...
Re: Need Help on NEOTEC NT-3501
« Reply #27 on: September 08, 2011, 10:35:57 pm »

   Alot of people have mentioned a bipolar cap as the culprit for this pincussion board as a problem on other neotecs, but I have looked everywhere and cannot find a bipolar cap on this model, and there isnt one on the parts list either.


Do you have a cap at position "C316"?  I have that position screen-printed on a Neotec Med Res NT-2701 chassis (no cap there though), and did a cap kit to a friend's Neotec, and it had a bipolar at position "C316" I think.  It wasn't in the kit from Bob back when I did that for him (almost a year ago).  Not sure what that one is for though.  My Medium Res chassis has the pincushion board with a bipolar cap at position "C19".

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #28 on: September 09, 2011, 12:49:00 am »
  MK, Yes I do have a capacitor at C316 (its on the main board), and it is a 220uf/25v.   HOWEVER, I do not believe my monitor (NT-3501) is comparable to your monitor 2701.........On my manual, it says it covers NT-3500, 3501, 3602 models, so I dont know if above info is applicable.  The bipolar cap I have heard rumors about was supposed to be on the pincussion board, for my converged screen problems, but I dont think this is the case with my NT3501, as there are only 2 ec capacitors listed at this mini board.  CF01(100uf/25v) Cf04(47uf/25v)., and neither are bipolar.           

lilshawn

  • Trade Count: (+3)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 7377
  • Last login:Today at 04:40:51 pm
  • I break stuff...then fix it...sometimes
Re: Need Help on NEOTEC NT-3501
« Reply #29 on: September 09, 2011, 02:59:44 pm »
just upstream from the HOT you should have a drive circuit (h-drive in the block diagram)

basically your 7851 doesn't have the power to drive the HOT and flyback alone so they switch an intermediary transistor or small transformer  that is capable of switching the higher load of the hot and flyback.

whatever the circuit it will be connected to pin 12 of the chip.... that is the output drive for the horizontal. it should run through maybe a rsistor/capacitor then to a transistor then a small transformer, then to the HOT for final output.

on the 27 series chassis which are pretty close to these, it's q401 its a 2SC2688.

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #30 on: September 09, 2011, 11:17:12 pm »
Cool  l'll look into that next then , thanks.   My Q401 is listed as a D669A, and Ill check out the board tommorow, to see where that 12 pin (from the LA7851) leads to.   

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #31 on: September 13, 2011, 03:41:41 am »
  Just to keep things up to date, and visually current, we have changed the HOT, the horizontal deflection chip, and all capacitors.  We are now looking downstream of the 12 pin of the H-deflection chip, to the H-Driver (Q401) D669A Transistor, pictured below.
 

 


lilshawn

  • Trade Count: (+3)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 7377
  • Last login:Today at 04:40:51 pm
  • I break stuff...then fix it...sometimes
Re: Need Help on NEOTEC NT-3501
« Reply #32 on: September 13, 2011, 06:48:43 pm »
could you scan the manual...or upload your document here?

if you have a hardcopy, if you scan it, i can turn it into a PDF for you for ease of sharing.

its hard to find, lets make it available to everyone who might need it.

kampcool

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 164
  • Last login:September 22, 2011, 04:43:59 am
Re: Need Help on NEOTEC NT-3501
« Reply #33 on: September 15, 2011, 12:06:00 am »
   The Q401  (D669A)  cross referenced into a NTE373.  $2.00.   
 
   As far as the manual goes, I have no problem sharing it, as a matter of fact lil shawn,  when I get this monitor done, the hard copy is yours.  I have reservations about posting the whole thing as a pdf, here for this sites welfare.  Neotec is a company that is in business currently SELLING these manuals, so for copyright purposes we cannot post it here.  PM me, and I will send you my copy, for all your help.  Does it suck, they way this company backs it's product by charging the poor recipient of their JUNK by profiting more?  YES.   Does it suck how this company doesn't even answer its phone, or return messages?  YES.   Does it suck that this company would probably go after this website for helping people fix their product? YES, but I.M.O, that's the kind of company we are dealing with here. 

piiifast

  • Trade Count: (0)
  • Newbie
  • *
  • Offline Offline
  • Posts: 1
  • Last login:September 23, 2013, 04:23:51 pm
Re: Need Help on NEOTEC NT-3501
« Reply #34 on: September 23, 2013, 04:23:51 pm »
I was just wondering if you still had the NT-3501 manual you could send me a copy of?

Thanks,
Don