testing voltage detector and WG7302

[kardenm]

Can anyone tell me how to test an "error amplifier/voltage detector", #SE120N (NTE7216) ??

lilshawn-?? Really appreciate all your expert help!  

[lilshawn]

unfortunately, i can't locate any useful information on that IC, so i can't give you an answer on how to test it.

judging by your other posts, your trying to track down an issue.

if you post the make and model of the item you are having problems with and the symptoms you have, or had before it stopped working, we might be able to figure it out.

some of us are kinda smart.....

[kardenm]

lilshawn.  See my previous post "WG 7302 is dead".  Still beating my head against that wall.  Still seems to be a power supply problem.  I802 (STR-S6707) was bad (not the bridge rectfyr).  I can measure an on/off voltage at L802 (B+ voltage) and can hear a ticking of about one second freq.

Have been in touch with Wells Gardner tech support.  Had already replaced several components which he said were likely culprits such as zener diode D805, Q801, R809 (which was open), and C807.  Have replaced a few bad caps and tested almost all components in the power supply section.  Guy at Wells said to test Q802(voltage detector SE120N or NTE#7216) and the optocoupler(I802/PC123Y11). 

That's where I'm at with this.  Unfortunately I have no history on this board as I inherited it in it's present, nonworking condition.

Thanks again for your help.

[kardenm]

lilshawn.  The NTE cross reference site will produce a spec sheet on SE120N if you enter that part number.  Can you tell from that how to test it?

[qrz]

assuming the Hot is good , disable the 24v line ( i.e. lift one end of the diode )
the vert out ic could be loading down the supply enough to cause a startup fault.
if it starts , replace the la7833

common problem in several brands of analog tv  
even seen audio out ics do the same...

the sanken se120n is a error detection ic .   
in this circuit, when voltage exceeds 120.2v (+/- .8v)
the output is pulled low,  lighting the led and in turn activating the photo xistor which then adjusts the pwm
pulse from the driver ic = regulation 

[kardenm]

Thanks for the explanation qrz.  The HOT is good.  I will try what you suggested and let you know.

Thanks again!

[kardenm]

Tried what you suggested.  No joy. Still not fire up.

See also my previous post http://forum.arcadecontrols.com/index.php?topic=102255.0

(wg7302 is dead).

[qrz]

note : an isolation xformer SHOULD be used for any LIVE testing on the PRIMARY side of a SMPS 

pse keep in mind my print isn't the clearest ....
check c805 ( 220uF/25),c806 (10uF/100v),c807 (47uF/50)
q801 2sc2073, r812 (68ohm),  d303,4,5
r809  a value increase here WILL cause regulation issues
 
if ok ,  isolate the smps

disconnect pin 4 on the flyback.
lift the anodes of d809 (24v) d808 (15v,12v reg)
a load should be placed on the 123v line .  (a 60-100w 120v incandesant lamp works in a pinch)

this removes outputs not needed for supply operation.
if all is well with the supply , the lamp should illuminate upon pwr application and stay lit ....

[kardenm]

I'll try.  Thanks!  I'll let you know what I find.

[kardenm]

qrz:  please tell me if you would where to connect the light bulb.  I'm assuming it should be connected between 123v connection to pin-4 and chassis ground?  Thanks for your help.

Have you perused (sp?) my post on this monitor?
http://forum.arcadecontrols.com/index.php?topic=102255.0

Also, cannot find a D305 on board or schematic.  Are you sure abou that one?

[kardenm]

Trying light bulb test as suggested.  Have lifted D809 and D808 and disconnected the 123v line to FBT by lifting a jumper wire (43) between pwr supply and J71. 

Connected bulb to 123v line and grounded to I802 heat sink or to W802.  Neither one resulted in a lit bulb, pwr supply ticking.  Not sure I'm grounding properly.  Can you advise?  I did not hook up any other connections to board (neck board, CRT, video sig., etc) only the ac pwr in.  What to do with two grounding wires which normally screw onto frame (W802, W302)??

[qrz]

W802 is "HOT" gnd . the 123v source is on the SECONDARY side of the xformer . a "cold" ground is is the required reference ...usually chassis gnd
 
these components tested and ok ? :

check c805 ( 220uF/25),c806 (10uF/100v),c807 (47uF/50)
q801 2sc2073, r812 (68ohm),  d303,4,5
r809  a value increase here WILL cause regulation issues (doesn't take much)
either side of opto-coupler open/shorted...

"Also, cannot find a D305 on board or schematic.  Are you sure abou that one?"
 alas, a poor resolution print      so no , am not sure of ref numbers ...

[kardenm]

qrz-Thanks

Yes, all those components (and others) have been tested and/or replaced.  All test good at this point.  Have tested or replaced most components in pwr supply area.

Would heat sink of I802 be correct ground (chassis ground). 

During this test must I connect W802,W302 to frame like they are during normal operation or does it matter?

[qrz]

there are two grounds here .
the HOT ground is strictly for the mains/primary ( 120vAC ) side of the supply and
cold ground will be the secondary side - crt ground / chassis ground , etc.

under NO circumstances should these grounds be interconnected and line voltage applied ( defeats all line isolation )

if the test is very brief ( <2 seconds max ) a load isn't that critical . just checking to see if have secondary output voltage.

[kardenm]

still no joy   

[qrz]

this " shouldn't " be such a challenge 

pm or email direct....