Hantarex Polo 25 blows c125 470UF 35V

riddler

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I have a Hantarex Polo 25 that continously blows C125 470UF 35V cap. The monitor will turn on and I can hear high voltage but within 10 seconds the cap blows. Anybody know what is causing this and what should be replaced?
 
Checking to see if cap is shorted

I don't mean to sound like an idiot but how do you check those caps on a digital multi meter. I am using a Cen-Tech P37772 multi meter which has a capitance section labeled 20u, 2u, 200n, 20n, and 2n. The capacitor is marked 101J 1 K-V KCK
Thanks for your help
 
I checked both diodes and they tested good. I was not sure how to test these caps so I had another Hanterex Polo 25 donor chassis that I removed these two caps from and soldered into my problem board. I repaced the 470UF 35V electrolytic cap and put the chassis back in. I fired it up and after about 10 seconds there was a pop and I let the smoke out of the 470UF 35V cap at C125 again.
Does anybody know what other things I can check or swap out?
 
In Backwards?

Sure the cap is being installed correctly..

Got any pictures of just that area?

Did you take out during the repair any diodes

and then reinstall them backwards..

Is D117,and D118 shorted or backwards

whats the ohms to ground on the plus side of c125

any traces on the bottom of chassis shorting together

Before you keep blowing up the cap apply an external dc to the

plus side of the cap and see if it kills the dc..

without the chassis plugin..
 
Yes the cap is being installed correctly. I matched the black dot to negative on the cap. I also checked my other chassis to make sure that the board marking was correct and the cap was installed correctly.

I did remove D118 & D119 to check them. They tested .467 on one and the other .455. I made sure they did not test the other way and only shows one on my meter. I checked on my other chassis to make sure they were installed correctly. Both have the negative line on the diode facing towards the board.

I set my meter on ohms to 2M. I put the negative wire on the chassis metal ground and put the positive lead to the blown C125 cap. It reads .221 and drops as I hold the posistive lead on the positive side of the cap. I tested this in circuit.

I checked and I can't see anything shorting underneath. I have taken some pics but do not know how to post them on here.

When you say an external DC do you mean like 12 volts to the positive side of the cap? And I guess it should be a new cap in place when I try this test?
 
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Yes New Cap

Yes the cap is being installed correctly. I matched the black dot to negative on the cap. I also checked my other chassis to make sure that the board marking was correct and the cap was installed correctly.

I did remove D118 & D119 to check them. They tested .467 on one and the other .455. I made sure they did not test the other way and only shows one on my meter. I checked on my other chassis to make sure they were installed correctly. Both have the negative line on the diode facing towards the board.

I set my meter on ohms to 2M. I put the negative wire on the chassis metal ground and put the positive lead to the blown C125 cap. It reads .221 and drops as I hold the posistive lead on the positive side of the cap. I tested this in circuit.

I checked and I can't see anything shorting underneath. I have taken some pics but do not know how to post them on here.

When you say an external DC do you mean like 12 volts to the positive side of the cap? And I guess it should be a new cap in place when I try this test?



Yes. if your dc from the 12vs pulls down then dont bother pluging in chassis,because

theres a short on that line.


but if it doesn't then theres a diode that is leaky allowing the ac from the Smps

to the cap,you have a rare problem,if the diode is not rectifying good then

it will damage the cap everytime..confirm c122,124, are not shorted also.

D117 and D118 the band side should not aim the same way..checking the schematic.

Im not looking at the PCB have to take your word for it that the diodes are in correctly.

Run some more test. and see how it reacts

The vertical ic is on the supply line but shouldn't kill the cap. removing it during

testing is ok.
 
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I replaced C125 and removed the vertical ic. I applied 12 volts to the positive side of cap C125 while I had my meter on the 12 volt line and ground. My meter stayed at a constant 12.23 with no fluxuation. The cap did not burn up either.

How do I check C122 & C124 are shorted? Do I do that on the continuity test on my meter. Can they be tested in circuit?

I found a 3rd Hantarex Polo 25 that is missing the Flyback and after blowing out some dust I can see that the Diodes D117 & D118 are going the same way.

Im really got at shotgunning but not so good at testing.

I really appreciate all your help Ohmerone
 
this is crazy

I replaced C125 and removed the vertical ic. I applied 12 volts to the positive side of cap C125 while I had my meter on the 12 volt line and ground. My meter stayed at a constant 12.23 with no fluxuation. The cap did not burn up either.

How do I check C122 & C124 are shorted? Do I do that on the continuity test on my meter. Can they be tested in circuit?

I found a 3rd Hantarex Polo 25 that is missing the Flyback and after blowing out some dust I can see that the Diodes D117 & D118 are going the same way.

Im really got at shotgunning but not so good at testing.

I really appreciate all your help Ohmerone

Ok good job..
I don't suspect the disc caps, and if the diodes dont check shorted.

Now if someone turn vr101 to high all your secondary

voltages will be high. You can up the dc on the cap to 50v

leave out the vertical because it only uses voltage around 35 vs

during testing monitor the dc on c125 at plugin. whats the voltage?
 
Hello Ohmerone,
I just want to make sure I have this right before testing the cap. You want me to change the cap to a 470UF 50V instead of the 470UF 35V that is in there.
Leave the vertical IC out and plug the chassis into AC Power.
Measure DC voltage on positive lead of C125 the 470UF 50V.
 
Hello Ohmerone,
I just want to make sure I have this right before testing the cap. You want me to change the cap to a 470UF 50V instead of the 470UF 35V that is in there.
Leave the vertical IC out and plug the chassis into AC Power.
Measure DC voltage on positive lead of C125 the 470UF 50V.


yes monitor the dc at plugin if the dc is under 50 then the

the cap should not pop..unless its ac getting to the cap, no dc cap works on ac

coming from the power supply. then unplug the monitor use a jumper

or extend wire to probe so your not so close to the cap if something goes wrong.


Keep in mind the v101 could be set wrong too..over driving the output

voltages..
 
How do I tell if the V101 is set wrong? I see it on the board. It is a square blue pot with a white adjustment. I have never messed with it but I bought the game broken. Somebody before me could have messed with it.

What about the red annode wire? What do I do with that while testing? Should it be plugged into the tube?
 
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How do I tell if the V101 is set wrong? I see it on the board. It is a square blue pot with a white adjustment. I have never messed with it but I bought the game broken. Somebody before me could have messed with it.

What about the red annode wire? What do I do with that while testing? Should it be plugged into the tube?

OMG..what makes you think the anode should be left off

for any reason!! I should bail after that statement.

Yes i want all parts hooked up except the vertical Ic

incase of over voltage we dont damage the Ic.

turn the vr101 counter clockwise so we have not to much

voltage on the secondarys..

Monitor all test point using schematic for the voltages posted on the schematic.
 
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