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#17
07-22-2015, 08:05 AM
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Not sure where the conv board is. The tdks are mounted on the same board as the fly back. I'll have to check it out later.
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#18
07-22-2015, 08:38 AM
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Not sure where the conv board is. The tdks are mounted on the same board as the fly back. I'll have to check it out later.
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#19
07-23-2015, 07:22 AM
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Should look something like this.
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#20
07-23-2015, 01:09 PM
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Quote:
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#21
07-24-2015, 07:39 AM
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Nope, looked everywhere. It seems the convergeance and deflection or whatever along with the flyback is all the same board. The two black STK chips and heat sinks are on the same large board lying down with the flyback. Board is labeled Conv/Def or something like that. Would a chassis number help? Is it possible for a fuse to be bad even if the element inside still seems intact? You would swear the fuse is blown on this because there is no power at all. Nothing.
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#22
07-24-2015, 07:57 AM
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Does anything look burnt? Pretty much out of ideas now. Were you able to check the PS board for ANY voltages? Not sure if its in shutdown or if the PS board has a problem. A schematic sure would be helpful. Fuses are probably OK if they look OK, but you can check them anyway.
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#23
07-25-2015, 09:00 AM
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Quote:
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#24
07-25-2015, 09:08 AM
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I STILL need some good pictures...of both of the large boards on the bottom of the set. The deflection board and the sigal board. I need to be able to see different connectors and such and i CAN then help you "figure it out. This has been my thing for many years....I weas out of the "scene" for a couple of years due to illnerss...but am getting "back in the saddle a little now.
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#25
07-28-2015, 08:03 PM
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Hope these help.
    
Last edited by pac.attack76; 07-28-2015 at 08:15 PM.
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#26
07-28-2015, 09:38 PM
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They WILL work...GOOD pictures BTW.,..
You need to check that "whatcamacallit"..next to the "whatchmagieer" connected to the "thing a mig."!! Ok SERIOUSLY now... It looks as if you do NOT have a seperate standby power supply here ...so this means that the main SMPS runs at ALL times...or at least it is SUPPOSED to. I see a relay on the COLD side--this is likely to switch off the B+ to the Horiz ckt--in standby. Also what looks like an "SE" voltage reference chip" this is for regulation..it is in front of the relay--looks lke a TO-220 transistor. But in standby...it MAY not have voltage on it--if it is switched through that relay..but likely the relay is AFTER that reference chip. that large transformer is the SMPS power transformer. It powwrs the set. the VERY first thing you need to determine is...if it is even running at ALL. If you can...turn over the chassis and get a voltage reading on that large capacitor behind the SMPS tranny. You need to see if there is at least 150 volts DC on it..ACROSS it's terminals. If it DOES have that on it..(and since you say you see a spark when you plug the set in---it likely DOES)...then you need to see if you are getting ANY voltages out of the power supply. In front of the SMPS tranny...there are several capacitors with diodes near them. ALL of these diodes should have some sort of DC voltage on one side of them...as measured to chassis ground. LIkely 12 volts, maybe 24 volts, 18 volts and perhaps a 9 volt or 5 volt or so supply. A couple will likely shgow a negative voltage to ground--like -18 or maybe -24.. if you see voltages there....move over to the connectors that go over to the signal board (the green one on the left side of the power supply board)..and see how the voltages look on thaty connector. there MUST be at least a couple of voltages there in standby...a 12 volt or maybe a 5 volt supply. These power the MPU and remote ckts...to keep the set "alive". Ground the black probe and check and see what those connectors have on them. with the set off but plugged in...there likely will not be too many with voltages...but a FEW should have some voltages. Your convergence chips are up front on the deflection board..STK 394-250..and do NOT go bad as often as others but they CAN go bad. But it is NOT likely they will totally kill the set. They likely are powered by an +18 or +24 and - source--from the SMPS supply. Just for "kicks"..unplug those three 4 wire connectors in fornt of STK chips...those are the convergence lines...(be SURE to label them in some way...to get them back to the RIGHT connecors..otherwise...when you DO get the set to run...the convergence will be WAY off. ) So....check this out...and we will go from there !! Last edited by rca2000; 07-28-2015 at 10:02 PM. Reason: mistakes
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#27
07-29-2015, 08:02 AM
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large cap was 171 dc. i put the black on chassis ground and most diodes seem to be .000. i had a couple that had something on them as you can see in the pic. Connectors were varying, .002 .001 .005 .43 .349 .003. These are all with the meter set at VDC. NOT VAC. Unplugging the 3 lines from the convergeance did nothing.
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#28
07-29-2015, 08:42 PM
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171 volts DC on that big cap-with no load...sounds about right. This sounds like your power supply is NOT running at all. If you did not see some appricable voltage on those diodes--"the side connected to those capacitors--NOT the transformer side..cathode of most..anode of a few--),with the black probe to cold ground...this means the SMPS is not runni9ng at all--since if it was in overcurrent mode...from a shorted load...it would either be squealing or chirping..but with NO noise...it is just DEAD.
SO...NOW.. I need a better look behind the transformer-- that big heat sink...to see what sort of switch mode driver you have...whether it is a chip or a MOSFET driven by a small chip off of it. I THINK I see an optocoupler--those OFTEN go bad--and stop all oscillation of the SMPS... I ALSO... need to see the BOTTOM of this board...especially the area near that transfoemer...
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#29
07-30-2015, 08:47 AM
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Let me know if these work.
Last edited by pac.attack76; 07-14-2016 at 02:47 PM.
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#30
07-30-2015, 11:24 AM
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They help SOME.
I see you have an "STR"-type SMPS chip. IC -911. Can't see the number--but i KINOW it is one. Go to the negative side of that big cap you got 171 volts on...and take the positive lead...on IC -911. See if those 2 larger pins have that voltage on them. If they do...then check the smaller pins to the same ground. If all show zero or so..the IC is NOT running and is likely BAD. But before you replace it... BTW__get the # of IC-911 for me. ALso check ALL diodes near that IC..ESPECIALLY any glass ones. And check that "optocouler"..that little black thing with 2 leads on each side. On the side near IC-911...check it with the probe on hot ground--that big cap. There should be a BIT of voltage on it--it is is working and IC-911 is good. There is a small transistor in front of the optocouple--check it also. if you do NOT have the 171 volts or near it on IC-911..but you DO have it on that cap...it is likely SHORTED. Take your postiive lead and put the meter on OHMS..and check those 2 larger pins on IC-911...to hot GROUND. It should NOT show low ohms...it should show at lEAST 10K ohms or higher. if it shows an ohm or less or so...the IC is SHORTED. If do...then the two pink-looking resistors beside the sink ar elikelyt OPEN...because of the shorted IC. You notice the "line" around the transformer and IC..it says "live" on one side and 'isolated" on the other. This means that EVERYTHING inside that "box" the line contins is "HOT" with respect to the AC line...and all OUTSIDE Of the line is COLD...with respect to the AC Line. This is why you have to emasuse stuff on the HOT side--with respect to the HOT ground--that big cap and ALL outside of the line to CHASSIS ground..COLD ground. You are mainly concerned with the HOT area right now--since your SMPS is NOT running at ALL. But it IS possible--a fault on the COLD side--is stopping oscillaton.
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Linear Mode
