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Lab Volt Model 790A will not power up

Discussion in 'Troubleshooting and Repair' started by Willard, Dec 3, 2018.

  1. Willard

    Willard

    37
    6
    Dec 3, 2018
    Will do. My problems is not knowing that these are polypropylene capacitors rather than electrolytic or some other type. Also Axial termination style. I could get the Volts and the MFDs but I wasn't sure about the capacitance. I am assuming the oil capacitors that are in there aren't made anymore because of their inherent problems?
    Many many thanks.
    Will
     
  2. Willard

    Willard

    37
    6
    Dec 3, 2018
    Thanks much. I'll check it out and practice tonight.
    Will
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,690
    Jan 21, 2010
    Picking polypropylene is really just a short cut, I know they are good high voltage capacitors with values in the range you require. You could do the same without picking that first.

    Axial simply means one lead comes out of each end. This is the style you're replacing. You could leave this out and your have far more capacitors to consider, and you could pick the axial ones by the image shown.

    For fun you could try following the same procedure, but exclude these two options and see what you get.
     
  4. 73's de Edd

    73's de Edd

    2,646
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    Aug 21, 2015
    Thir Willard . . . . .

    Well I see that my good friend from Bucharest "Hungry" has now come upon the scene.
    He had been asking me repair info about a goldmine of 18 pieces of lab equipment that he has just came into.
    He must have read and liked your topic also .

    Here is my earlier mentioned schematic of the B&K scope that I was prepping up, that we can be assuming is being the closest to that like clone of yours.
    I have the main schema at the left and particular section of interest is being the RED bordered YELLOW inset and finally the resultant deleted irrelevant components with only a totally uncluttered zoom in of just our affected HV supply area.
    It's even being, resplendently complete . . . . with its yellow brick roads.
    With your suggested meager component supply stock and the need to not end up in having bought $5 in total parts cost for repair . . . but your having incurring an additional $75 shipping and handling charges of multiple supplemental orders.
    Lets attack this in an intelligent manner by initially looking only into what we have detected so far.

    Consulting the simplified section, note the also transposed 500VAC @ 5 ma HV winding to bottom left corner.
    and it enters terminal stakes 37 and 38 and uses D5 diode to feed only the stream of negative nodes of the AC to gray C16 filter / storage capacitor. Simultaneously stakes 37 and 38 and D6 diode are feeding a stream of positive nodes of the AC to gray C16 filter / storage capacitor.
    Those caps are non polarized, but I have marked in what polarity of voltage is expected to be found developing across them.
    That should be approx 700VDC across each of them and you can see that the Positive connection of C17 is connected to ground while its Negative connection joins to the Positive connection of C16s developed approx ~700VDC, Thereby . . . the summed series voltages create approx 1400 VDC at the Negative connection.
    The CRT tube is needing descending voltage levels of negative voltage of that Negative 1400 VDC at its electrodes, and relies upon series arranged voltage divider resistors and tapped controls to develop them..

    That Negative 1400 supply originates from the marked in Negative terminal of C16 and it flows upward, along the BLACK arrow supply path to RED A point where it initially encounters a voltage dropping / current limiting resistor R51.Then the A prime side feeds into a junction of 4 possible connections.

    Now I'm seeing a high probability of no faults being found with the D5 and D6 diodes due to their low capacitive reactances being involved with the low value C16 and C17 caps, along with a 60~ supply frequency.
    Next we see the R51 1/2 watt resistor that you have found smoked.

    Just generally dealing with series resistors used in a power supply circuit, if we have lower voltages like in the 12-20VDC range we might expect a 1 or 10 ohm being able to pass enough current at those voltage levels to smoke if being grounded on its load side end.
    If you are dealing with higher voltages up in the 50-200 VDC range, expect like utilized 100 and 1000 ohm resistors to be able and expected to smoke if grounded out.
    NOW . . . lets work with your supplying info of one of the power transformer secondary windings providing a 500V supply at an ~5 ma capability.
    PLUS that supply voltage is being related to the parts that we are now investigating.
    Now 10K and 100K resistors will fall into the smokeable category.
    SPECIFICALLY . . . if you had a 100k 1/2 w replacement resistor in the R51 slot now and shorted its right end to ground, you will then be subjecting it to then receiving 7 watts of power across it !
    Now, don't you think that degree of overload will then make it flip-flop-fly and FLASH !

    In order to have minimal investment of parts purchases, how about using this test procedure.. . . .


    First you pull out ye olde Fluke . . . Duke . . . .and initially have no power to the unit and measure across C16-17-and 18 caps to see that no DC voltages are present across them. If finding any, short them out to get 0vdc.
    Then you ohm across the smoked R51 to see what the present ohmic reading is being. Then you very carefully unsolder the A Prime end of the resistor, and lift that end free from circuitry and confirm what resistance it is then, thus, eliminating any other potentially adjunct shunting circuit resistance in that manner.
    Either its being open circuit or has some potentially altered resistance value.
    Next you want to lift the lead of BLUE C18 that connects to RED A Prime junction to float free of circuitry..
    Now it is time to test the two voltage supplies that are hopefully still being created by the 500VAC winding and the D5-C16 and D6-C17 components.
    Hopefully you have some clip leads that will let you initially clip the Flukes leads across C16 at the marked polarity at 1000VDC range. That then leaves hands free to flip on the AC power just long enough to see if a voltage builds up to approx 700VDC. If so . . .goooood . . .shut down.
    Then move the clipped on meter leads on over to C17 and test in the same manner.
    Should you hen find that both sets of voltage are being developed . . .VELLY-VELLY good.

    Now we need some feedback from you, as we now need to measure across the summed voltages at the chassis ground potential lead of C17 and the RED A test point, where we should get approx 1400VDC. Whooooooooa Nellie !

    Now your Fluke is probably only rated at up to 1000VDC ***,as two of mine are, so we need to do a workaround to scale its voltage capabilities up a bit.
    That would be by using some high value 1/2 watt resistors ( for minimal circuit loading down) to make a voltage divider.
    If you place a 1 meg resistor across the meter leads and swing a 10 meg off the positive lead, the floating end of the resistor will then be used to apply to circuit to be able to read that voltage and scale it down to a 140 volt reading being read at the 1400 VDC test point.
    Probably you won't have the 10 meg and also ? on the 1 meg. . . . .so . . .if you happen to have TWO of 4.7, 5.1, 5.6,6.2, 6.8,7.5 megohm resistors they could be used instead, with the resultant halved reading being 1/2 of the actual voltage. 1400VDC is then reading out as 700VDC.
    Also there might be a chance, that you have either a Triplet or Simpson analog meter, that will let you plug in your + meter lead into its 6KV receptacle and read on its then created 6000 VDC scale.

    I pause for fill in on the above test capabilities.

    The following procedure to come would be to confirm the 1400 presence and then install a 100K 1/2 watt resistor in place of the "bad" one ?
    Then you use clip leads to reconnect across R51and still have its right lead floating, as well as the A Prime lead of C18 which is floating free.
    THEN you power up and and will be seeing no voltage monitored across R51 and then you use an insulated clip lead to make a fast connection between those two flying leads. If all is well, there will just be a quick meter jerk as that cap takes on its inial charge up.
    IF THINGS ARE BAD . . . . like the capacitor being leaky or machine gun arcing internally a meter reading will show up.
    If in excess of 225VDC shows up on the meter, you are in excess of the 1/2 wattage rating of the resistor and need to shut down !
    If this test of C18 is passed then the power can remain and a second insulated clip lead used to connect into the RED A Prime circuitry for just an instant.
    You are still looking for in excess of 225 VDC across R51 which would now signify that the ORANGE-BLUE-GREEN Arrow path circuitry pulling excess power from that R51 resistor.
    Then we would have to isolate those lines to see which one is at fault.

    A quick peek ahead . . .in fast forward mode . . . .

    Tracing up the ORANGE arrow route . . . HEY ! . . . there is a 390K resistor, which would only have 1/4th the power demand of the R51's 100k's demand. Then it's being followed by a series 470K up above . . .I think that we are on a cold path for our problem. There is an even less likely added on path to the left where the ORANGE SQUARE path would have to encounter a shorted C19 which ends up going to ground thru a super high 2.2 meg via the LIGHTER SHADE of ORANGE SQUARE path.
    Also there are some no consequence . . .side paths of the ORANGE SQUARE paths to CRT electrodes and controls,
    SO . . .our ORANGE SQUARE fault path seems to not be able to create an excess power pull thru R51.

    The BLUE ARROW path is seen encountering a 1 meg INTENSITY CONTROL pot and then across a 270K resistor and then thru a 1 Meg FOCUS pot and then three series 1 meg resistors to ground.
    Then there is the G2 electrode of the CRT.
    None of this string of parts pull any significant power either, to be able to overload the R51.

    The GREEN ARROW path just goes up and connects to the 6.3 VAC filament winding of the power transformer, which goes up to feed the filament of the CRT.
    That looks like a nothing circuit to pull excess power thru that R51.

    If that initial test connection of R51 to RED A Prime has excess current pull and >225 V across it, the ORANGE BLUE and GREEN connections need to be removed and connected back in one at a time to see which one is causing excess current pull.

    And then there is the never- never expected fault . . . .

    If finding a fault on one of those then isolated load lines.
    Experiencing one of the controls that is grounded to the chassis metal is having an insulation breakdown across its phenolic / bakelite insulation and a carbonized resistive path has developed to ground.
    Or, there has been an arcover within the power transformers 6.3VAC winding thru waxed paper or fish paper / or / fiberboard and therein developed a carbonized path to ground or to another winding that is connected to ground.

    So digest all of this and come back with answering of the metering situation

    *** Fluke meters . . . .
    I have used 3 of my different Fluke DVM's in static- non destructive testing of the evaluation of 1N4007 rectifier diodes (Why would anyone order / keep / buy their 1N4001-2-3-4-5-6 series . . . for the minor or same price of the 1N4007's .
    Of upwards of 100 new ones tested and the handful of my loosie-goosies tested . . .the 1300-1400-1500 on up to a 1600VDC was the norm, with there being the rare 1100-1200 VDC.
    Soooooooooo my meters have felt up 1600 VDC.

    You say . . .
    D8 and D9 are zeners correct?

    Yeth . . . .and how do you like those rare case profiles?
    One diode is regulating a low voltage supply and the other one is holding a supply voltage above ground to get a regulated voltage reference from that junction.

    OUR high voltage diodes of interest are being the D5 and D6 which are in black molded cases that look like tantalum caps with their rounded /or/ yellow dot ends being their cathodes .
    HIGHLY suspicioned . . . . . . to be using series selenium junction stacks inside . . . . so they will test HIGH in junction fwd VR meter testing.

    Now I ask you ? . . . .how much of yer hard earned munneys from your CORN squeezin's . . . is being spend-ed-ed with this simple test procedure ?

    YOUR RELEVANT TECHNO REFERENCING . . . . .

    [​IMG]



    73's de Edd . . . . .
    . . . . . . . . . . . .


    I am doing / aging s o o o o o o . . . . MUCH- MUCH- MUCH . . . . better than this . . . .

    SUCCESS
    At age 4...success is... NOT peeing in your pants.
    At age 10...success is...cooking your own meal.
    At age 12...success is...having friends.

    At age 16...success is...having a driver's license.
    At age 21...success is...having sex.
    At age 35...success is...having money.
    At age 50...success is...having money.
    At age 60...success is...having sex.

    At age 70...success is...having a driver's license.
    At age 75...success is...having friends.
    At age 80...success is...cooking your own meal.
    At age 85...success is... NOT peeing in your pants.
     
    Last edited: Dec 28, 2018
    Richard9025 and bushtech like this.
  5. Willard

    Willard

    37
    6
    Dec 3, 2018
    Wow! I'm on read through number 5 trying to take all this in. When this is all over I believe I will owe you guys big time. Which is okay if you like honey. I happen to have about 12.5 gallons of the stuff. Message me with your address and I'll get some moving your way if you want. The honey comes with two free stings, which this being the Christmas season, I have already taken for you. Do you have any idea the pain involved with a bee sting to the eyelid? It is really quite extraordinary but I digress.
    I have a Fluke 179 so I will double check out the top end of the voltage ratings. I also have an analog Sperry snap 8 snap around volt-ohm-ammeter but it looks like it only goes up to 600 volts. I will make a couple of calls but I may be able to come up with a Simpson analog meter. Would that be a big square black box with a very large dial on the front? If so I have a couple of electrician friends that probably have one of those sitting on a shelf. They have all gone digital but they never throw anything away.
    As always thanks for the work you are putting into this. It is quite prodigious.
    meter.jpg
    Would this be the Simpson analog meter you are asking if I have access to. If so yes.
     
  6. Willard

    Willard

    37
    6
    Dec 3, 2018
    I checked for voltage at C16-17-18. None found.
    R51 ohm reading is OL or open lead. R51 has no continuity.
    I unsoldered A prime end of R51 and checked for ohm reading. It is still OL or open lead.

    I have the blue lead that was connected to the A prime junction unsoldered and am now ready to test for voltages. BUT , BUT I would like clarification of one tiny aspect. I am assuming that I need to put the board back together in the chassis. To get the pictures you needed I had to unsolder some of the wires so I could remove and flip the board. Do I need to make everything pristine like it was before I started disassembly? As in replace the board. Resolder the unsoldered wires and reinstall the CRT, OR do I just make sure nothing will be shorting out and then hook up the alligator clips and run some power to it. By unsoldering the C18 I haven't completely removed power to the rest of the board correct?
     
  7. Willard

    Willard

    37
    6
    Dec 3, 2018
    Scratch the previous question about reassembly. I went ahead and soldered the board grounds back to the chassis like it was before I entered into this journey. So to reiterate what I have done before.

    I checked for voltage at C16-17-18. None found.
    R51 ohm reading is OL or open lead. R51 has no continuity.
    I unsoldered A prime end of R51 and checked for ohm reading. It is still OL or open lead.

    This morning I dug up some alligator clips and checked the voltage on C16. Turns out the transformer is putting out 762 Volts.
    So far so good.
    C17 is reading 755 Volts.

    I am now off to dig through my cabinets and find some resistors that will hopefully work for the voltage divider. I'll get back to you.
    PS: It is interesting to see the charge left in the capacitors. I have read about the hazard potential and have accepted it as gospel - don't screw this up and touch anything- but it is interesting to see the voltages actually drop as you are shorting the capacitors. It just reinforces what I have read. Thanks.
     
  8. Willard

    Willard

    37
    6
    Dec 3, 2018
    It looks like I am going to have to order some resistors for the voltage divider. I have gotten on digikey and working on finding an acceptable resistor.
    My question is what are they made of? I can't tell by looking at the pictures. I am assuming they are either a carbon film or a metal film based just on how many 1M 1/2 watt resisters that are offered on the site. I also chose a + - 5% tolerance. I thought I would order the resistors for the voltage divider and also the R51 replacement at the same time to avoid ancillary shipping costs.
     
  9. Richard9025

    Richard9025

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    May 24, 2016
    Aren't there any other ways to get the required components? Such as a local electronic component store.... Like a RadioShack? Here in Bucharest we have a lot of these kind of stores, and I can go there wheen I need something.

    You can ask them how they procure their components, or if they have and can give you.

    For DC voltages, it really doesn't matter. For Audio, carbon film resistors are more noisier than metal film.

    R51 is open, that means that you have the following problem with your scope:
    - No high voltage driving the CRT.

    You can measure the 700Volts, but you don't need to risk your meter's life by measuring 1.4kV, because if you have 1.4KV then the CRT will light up and show a dot or trace.

    But for voltage to pass and to get doubled (to 1.4kV) you need:
    New R51
    and
    New caps (the old ones are oil-impregnated polypropylene) you can replace them with normal polypropylene.
     
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,690
    Jan 21, 2010
    More important might be the voltage rating of the resistor. If the voltage across the resistor is high (as it may be in a high voltage voltage divider) you need to be aware of this.

    Check the datasheets. You may find that you need to use a higher wattage resistor due to this (higher wattage, and generally larger components typically have a higher voltage rating).

    The voltage rating of a resistor is not a heat dissipation issue. Both power and voltage ratings may need to be considered, but with high resistances, you'll hit the voltage limit before the power limit.
     
  11. Willard

    Willard

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    Dec 3, 2018
    I wish I could go to Radio Shack. That is where I used to get all of my few components when I needed them. Unfortunately the company went out of business and the stores were closed.
    I have two different kinds of electrical friends. The local guys who work on mains voltages and then the electronics people. Generally I have found that the two are totally different. I already know that If I start talking about capacitors and resistors to my mains people, their eyes tend to glaze over. They just don't work in that area. My electronic source died about 3 years ago and I haven't found a replacement person who is interested and knowledgeable in electronics. Rural west central Illinois just doesn't attract many electronics types of individuals. There just isn't much work for them here unfortunately.
     
  12. 73's de Edd

    73's de Edd

    2,646
    1,075
    Aug 21, 2015
    Sir Willard . . . .


    Nope that Simson doesn't have that high of a voltage capability, it's basically for 500V, but plugging into right bottom corner doubles the range up to 1000V.

    On any one of my 1-2-3-4- Five TRIPLETT 630NA's . . . .akin to your unit, has one plug in receptacle that extends my high voltage range up to 6000 Volts.
    If you have any more electronically oriented friends they may have those higher value resistors I had given you .
    That would let you make a voltage divider bridge to extent your voltage reading capabilities up a bit..either 10x or 2x minimally.
    Tube equipment / antique radios are the main users of those higher megohm values.
    Any REAL ham radio builder probably would have them, yet a guitar freak that builds maintains tube amps is another candidate.

    The 100K 1/2 watt replacement should be a carbon film type . . . to still retain the pop open "fusible aspect" in case of an overload again .
    Since you said have already ascertained their being the 700VDC across ONE of the existing gray capacitors, just confirm the other polarity on the other gray then you can surely be assured that they will be combining to get their 1400 summed voltage .
    The IMPORTANT part is my mentioning that you keep the 100k presently out of circuit.PLUS if you consult the schematic, you will see that there are two places that a 120K . . .or two series 47 could be "borrowed" and used for this HV sections testing.

    It would be easier to consult an older photo of the area of concern now . . so I am transferring it to just below.

    You would want to get a 100K equivalent replacement soldered to the B connection and have its free end floating THEN you lift the C PRIME connection of the BLUE capacitor that would be storing the 1400 VDC. Since we don't want it into placed circuit just yet.
    Also it looks like the GREEN wire and the paler YELLOW or PALE GREEN wire just below it need to be lifted from their connections , as they must be the two ARROWED path units on the other schema. Then you can see the other load path being at " X " with that 390K resistor above it .

    In order now . . .

    The meter in 1000VDC range gets connected across the new 100K with clip leads.
    The fail point is any voltage above 225VDC reading on the meter.
    Power up . . . .
    The free lead of the new 100K resistor gets jumped to the lifted BLUE HV cap. If no constant reading in excess of our spec, the cap is not leaking, constantly arcing internally or being dead shorted. Plus the new 100K did not "fuse" out.

    Shut down and discharge . . if any.

    The BLUE HV cap must not be what is PULLING too much power.

    Then a connection is made between one of the wires pulled and the free 100K and and blue cap junction you just previously created .
    Power up and do the same test. If the 100K doesn't blow and the voltage stays below 225 , then that line must not be at fault for overload.

    Power down and bleed voltage if present.

    Then there is the other wire that was lifted, needs reconnecting into that enlarging junction.
    Power up and . . . .to blow or not to blow is the question ? . . . . if no problems power down.

    Now, only that " X" points 390K resistors string is left to be connected into the cluster.
    Connect and power up and test . . . . . . now if any chance that there is no failure this time from
    sequentially adding all of our possible four load lines.

    Instead of leaving on just long enough to confirm metering as you have done before, give it about 30 seconds warming time for the filament of the CRT.
    Then you run brightness / intensity control up to max and swing thru all possibilities of vertical and horizontal positioning controls.
    If you see a trace or even a dot show on screen . . . .promising !

    The other possibility is that the excess loading SHOULD have shown up at one point in the progressive adding on of the load lines to the HV supply.

    MOVING OF PRIOR INFO TO THIS PAGE . . .

    [​IMG]

    73's de Edd . . . . .
    . . . . . . . . . . .


    * * * * The Standard Law of Mechanical Repair * * * *
    After your hands become coated with grease, your nose will begin to itch
    and you'll have an uncontrolled URGE to pee !

     
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  13. Willard

    Willard

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    Dec 3, 2018
    Thanks Edd. I'll study this tonight. I have resistors coming in from Digikey on Thursday sometime so I will get back to you then with the appropriate readings.
    As always your help is appreciated! And seriously I have 12.5 gallons on honey. A diabetic has no use for that much liquid gold.
     
  14. Willard

    Willard

    37
    6
    Dec 3, 2018
    I received my 1 and 10 M resistors. They are both withing 5%
    To recap what I have done earlier.

    I checked for voltage at C16-17-18. None found.
    R51 ohm reading is OL or open lead. R51 has no continuity.
    I unsoldered A prime end of R51 and checked for ohm reading. It is still OL or open lead.

    This morning I dug up some alligator clips and checked the voltage on C16. Turns out the transformer is putting out 762 Volts.
    So far so good.
    C17 is reading 755 Volts.

    Now for the readings with the 1 and 10 M resistors.
    I am reading 125 on my meter with the 1M resistor attached across my leads. I attached the 10M resistor to the positive end and alligator clipped that to the Chassis ground end of the C17 capacitor. I then alligator clipped the negative lead to the Red Point A end of the R51 resistor. It was at that point I was reading 125 V on my meter which should translate into 1250V correct? This is a tad lower than the 140 that I should be seeing. If I take 95% of 1400V I end up with 1300V. I am reading 1250 V. Is this close enough? I will continue on with the replaced R51 when I get it. I originally ordered a metal film capacitor so I am now waiting for the carbon film resistor to arrive.
    I am assuming I should continue on with the test for C18. Correct?
    I apologize for the delay. Work tends to get in the way from time to time. Hopefully the resistors will show up on Saturday and I can get back to you with C18 or the directions you provided for a C18 that passed.
    As always, many thanks.
    PS: I think we are getting close!
     
  15. Willard

    Willard

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    Dec 3, 2018
    I just received my 1/2 watt carbon film resistors. I am assuming the new resistors are a lot smaller than the original burnt R51. I purchased the 1/2 Watt carbon film resistors with a 100K ohm rating.
     
  16. Willard

    Willard

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    Dec 3, 2018
    Update. I soldered my new carbon film 1/2 watt 100K resistor in place of the toasted R51. I left the lead at A' flying and connected it to A which runs to the HV D5 diode. I then clipped my meter leads across the resistor and powered it up. I got no meter reading at that time so I installed a clip to the A' end of C18. The meter immediately started climbing but not with a quick jerk. It started scrolling at a very slow pace. I kept an eye on my new R51 and didn't see or smell any difference. When it went past 225 V I shut it down and shorted out the capacitors and unclipped everything.
    I am assuming that I should now replace capacitors C16, C17, and C18 and then repeat this test. Is this correct?
     
  17. Willard

    Willard

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    Dec 3, 2018
    Edd. The test of the C18 capacitor failed so I replaced C16, C17, and C18. I then tested C18 again and man what a difference.
    There was a slight jump on the meter going across the newly replaced R51 resistor and then it zeroed out. I powered down and shorted out the new capacitors and they had a LOT more charge in them than the old ones did. I then went ahead and connected the C18 capacitor and the R51 into the A prime location on the board and powered it up again. It read in the vicinity of 32 volts across the R51. I am assuming this is behaving the way it should be. I still have the 12K slightly toasted resistor to replace at R20 and one more .1MFD 630 V oil type capacitor to replace and then I think I am ready to put the CRT back in and see if I get a response. If I need to do anything else let me know otherwise I will post pictures of my results.
    Thanks
    Will
    PS: I am changing the 3 .1 MFD 630 V capacitors just because they are an oil type and It sounds like they are extremely likely to fail. I left the electrolytics alone.
     
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  18. Richard9025

    Richard9025

    205
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    May 24, 2016
    Yes, those caps are oil-in-paper Japanese capacitors that like to short.
    Good job! Keep up the good work!
     
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  19. Willard

    Willard

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    Dec 3, 2018
    Thanks!
     
  20. Willard

    Willard

    37
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    Dec 3, 2018
    Okay, it's official. To everyone who has taken time out of their own lives to help a person that they don't know, well this is for you. YOU GUYS ROCK!
    greenline.jpg
    It looks to me like this is what I should be seeing.
    final.jpg
    I replaced the oil film capacitors with PP capacitors. These are in the large red balloon. I also replaced the smoked 100K resistor which was located in the top red circle and the slightly toasted 12K resistor which was located in the bottom red balloon.
    You would think at this point I would be done with questions but alas, no tis not the case. Does anybody have any suggestions on the type of probe I should be acquiring? Also it is time to start using this bad boy. I would appreciate any and all suggestions on how to proceed so as not to screw up a lot of work on both our parts
    Once again, I want to thank you guys for sticking with me and teaching me as we proceeded through this quest. It has been a LOT of fun and quite educational.
    Will
     
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