Author Topic: Hantarex Polo 25 help needed (Read 22249 times)

jeff412 · « **on:** April 21, 2010, 07:47:17 am »

Does anyone know where the test points are on the Polo and what the voltages should be at each test point? I have a Polo with no neck glow and I've recapped it, replaced the flyback and HOT. Any help would be greatly appreciated.

Jeff

smartbomb2084 · « **Reply #1 on:** April 21, 2010, 08:08:40 am »

Check Test Point 6. This is the B+ voltage and should be 138 volts.
Also is the monitor making a 'ticking' sound?

jeff412 · « **Reply #2 on:** April 21, 2010, 08:16:19 am »

No, there is no ticking. Can you give me an idea of where TP6 is? I don't see it on the board.

Jeff

grantspain · « **Reply #3 on:** April 21, 2010, 08:19:27 am »

check the voltage at R227,use frame as ground/set meter to dc volts 200v range/be careful

jeff412 · « **Reply #4 on:** April 21, 2010, 08:21:20 am »

Thanks, I'll check it out tonight.

Jeff

Karetaker · « **Reply #5 on:** April 21, 2010, 02:09:02 pm »

Quote from: jeff412 on April 21, 2010, 08:16:19 am

No, there is no ticking. Can you give me an idea of where TP6 is? I don't see it on the board.

Jeff

About dead center at the very front of the board (front meaning closest to the tube). It's a jumper wire.

arcadecup.com · « **Reply #6 on:** April 21, 2010, 06:08:21 pm »

or check b+ on the middle wire of the yoke .. the jumper wire.. do not measure the yoke voltage or you will tickle your meter to death.
watch out for open traces.. mostly on the flyback pads.. they like to lift as the traces on this board are not th best.. cracks very easilty also in this area.

jeff412 · « **Reply #7 on:** April 21, 2010, 09:23:39 pm »

At TP6 I measure 10 to 20 Volts and it bounces around all over the place. The monitor is still in the cabinet and I can't get to the yoke very easily. But with nothing at TP 6 I assume I have nothing at the yoke either. Any ideas?

Jeff

smartbomb2084 · « **Reply #8 on:** April 22, 2010, 08:06:46 am »

Unsolder and lift the deflection side of L103 ( near TP6 ) and connect a standard incandescent light bulb between it and chassis ground then power up the monitor. If the bulb blinks you have a power supply problem. If it is lit bright and steady you have a deflection problem. Also, check the large color transisitors on the neck board, if one is shorted this monitor won't power up.

jeff412 · « **Reply #9 on:** April 22, 2010, 09:14:16 pm »

Ok I'll give it a shot. I'll try here in a few minutes and see what it looks like.

Jeff

jeff412 · « **Reply #10 on:** April 22, 2010, 10:15:59 pm »

I didn't have an incandesscent socket, so I'll have to try that later. I tested all of the transistors on the neck board they appear to be good. I did make a mistake before when I tested the voltage at TP6. I had failed to plug in the yoke connector. After plugging that in, I get 0 V at TP6.

Jeff

jeff412 · « **Reply #11 on:** April 22, 2010, 10:18:07 pm »

Quote from: arcadecup.com on April 21, 2010, 06:08:21 pm

or check b+ on the middle wire of the yoke .. the jumper wire.. do not measure the yoke voltage or you will tickle your meter to death.
watch out for open traces.. mostly on the flyback pads.. they like to lift as the traces on this board are not th best.. cracks very easilty also in this area.

I checked for open traces and I didn't see any. The board is actually in very good condition. I checked closely around the flyback and everything looks good.

Jeff

smartbomb2084 · « **Reply #12 on:** April 23, 2010, 07:56:49 am »

You don't have an incandescant worklight? Borrow the lamp from the living room end table and use alligator clipped jumper wires to connect the AC wall plug to the monitor. Until you do this test you will likely just keep chasing your tail.

jeff412 · « **Reply #13 on:** April 23, 2010, 08:12:12 am »

Nope, no incandescent work light. I'll pick one up tonight. They're cheap. What does the bulb do that a volt meter won't? Should I not be able to do the same thing with a volt meter and lifting the leg of L103? Unless you are saying that the volt meter is just too slow to register the fluctuations. Just curious.

Jeff

smartbomb2084 · « **Reply #14 on:** April 23, 2010, 08:19:27 am »

POLO monitors have a switching power supply and it needs an unshorted load to run properly. A simple 60 watt light bulb works nicely to provide this load. If the light stays lit the power supply is good and a shorted component on the deflection side is causing the power supply to shut down. If the bulb blinks the power supply is at fault. By performing this test we can narrow down our proplem to one side of the monitor or the other.

jeff412 · « **Reply #15 on:** April 23, 2010, 02:55:28 pm »

Thanks for the explanation. That makes sense. I'll test it tonight.

Jeff

jeff412 · « **Reply #16 on:** April 23, 2010, 06:48:28 pm »

I completed the test with the 60 W incandescent bulb. The bulb did nothing. I guess that means a power supply issue?

Jeff

smartbomb2084 · « **Reply #17 on:** April 23, 2010, 06:58:12 pm »

You are sure it is hooked up correctly? If that bulb doesn't light, then the monitor won't either. Lift the DEFLECTION end of L103 completeletly from the board so it is sticking up into the air. Hook one end of the bulb here and the other end to CHASSIS ground.

smartbomb2084 · « **Reply #18 on:** April 23, 2010, 07:21:48 pm »

If you have no power supply switching activity then T101 and IC101, in that order, are suspect.

jeff412 · « **Reply #19 on:** April 23, 2010, 07:28:53 pm »

Yes I'm sure I connected it correctly. I did lift one leg of l103 right next to tp6. Connected one alligator clip to l 103 and the other to ground.

smartbomb2084 · « **Reply #20 on:** April 23, 2010, 08:05:10 pm »

Measure the voltage at the banded end of D101 and use the UNbanded end of D103 as ground-----BE CAREFUL.

jeff412 · « **Reply #21 on:** April 23, 2010, 08:40:00 pm »

I pulled T101 and it tests open between pins 1 and 3. Yes I tested both directions. Are there any other parts I should test before ordering?

Jeff

jeff412 · « **Reply #22 on:** April 23, 2010, 08:44:34 pm »

Since I know T101 is bad, do I need to do the voltage test between D101 and D103?

Jeff

smartbomb2084 · « **Reply #23 on:** April 23, 2010, 08:51:31 pm »

T101 is a MOSFET not a Bipolar and is tested differently. Check out this link http://www.utm.edu/staff/leeb/mostest.htm

jeff412 · « **Reply #24 on:** April 23, 2010, 09:09:29 pm »

based on that test t 101 appears to be good

Jeff

smartbomb2084 · « **Reply #25 on:** April 23, 2010, 09:24:39 pm »

Back to D101/D103. We need to check for a source voltage to switch on an off. T101 doesn't even need to be installed for this test. While you are at it check the voltage at the unbanded end of D105 (TP2).

jeff412 · « **Reply #26 on:** April 23, 2010, 10:38:52 pm »

I have no voltage between D101 and D103. I have 131 V AC on the negative side of D105.

Jeff

smartbomb2084 · « **Reply #27 on:** April 24, 2010, 08:13:48 am »

You should have DC VOLTAGE. D101 banded end positve meter lead. D103 UNbanded end negative meter lead, If your meter is not AUTORANGING you must set it for 500 volts DC not 200. If I remember correctly this should measure around 300 volts. Again----BE CAREFUL.

For D105 positve meter lead Unbanded end. Negative meter lead leave on the UNbanded end of D103 as above.

If you still have 0 volts DC R103 may be open. It is a disc shaped pinkish colored resistor connected to D101/D103 and should be 10 Ohms.

On a side note, keep using the light bulb as a load until the power supply is good.

jeff412 · « **Reply #28 on:** April 24, 2010, 08:16:03 am »

I tested on 200. I didn't realize I was looking for 500. I'll test again.

Jeff

jeff412 · « **Reply #29 on:** April 24, 2010, 08:40:11 am »

D101 and 103 still have no voltage. I measured across the pink resister and got 12 ohms in the circuit. Do I need to remove it to test it? Also, I noted that the heat sink for t101 has 131 volts ac on it. Found that one the hard way. Is that correct?

Jeff

smartbomb2084 · « **Reply #30 on:** April 24, 2010, 09:20:24 am »

The heatsink for T101 is connected to primary (power supply) ground. I have to check on why you are getting shocked from it. Hopefully some other memebers have a take on that one because I am not sure.

You are going to have to follow the power path from AC Line In up to D105.

My time for today is up as I will be gone from now until early tomorrow evening.

Good Luck and try not to get electrocuted.

jeff412 · « **Reply #31 on:** April 24, 2010, 09:24:52 am »

I greatly appreciate your help. This is going to be an awesome troubleshooting thread if we can get it fixed. I will see if I can find the cause of the ac on the heat sink.

Jeff

grantspain · « **Reply #32 on:** April 24, 2010, 09:46:39 am »

t101 should have an insulation sheet between it and the heat shield

jeff412 · « **Reply #33 on:** April 24, 2010, 09:52:27 am »

It does. I have the connector hooked up wrong. I have to back up and regroup.

Jeff

jeff412 · « **Reply #34 on:** April 24, 2010, 11:40:02 pm »

Ok. Here's the deal. As much as I hate to admit it. I screwed up. Somehow I ended up connecting the hot leg to the center pin of the 3 pin connector instead of ground. That is why I was getting 131 V on the heat sink. I now have it connected properly. This monitor wasn't working before in another cabinet, so I know that wasn't my issue. Hopefully I didn't toast something else because of this error. After reconnecting it properly, I now have 171 V DC at TP6 and 338 V DC between D101 and D103. Where should I go from here?

Jeff

smartbomb2084 · « **Reply #35 on:** April 25, 2010, 06:08:58 pm »

I found out that you should not have AC on the heatsink of T101. I measured for voltage on it saturday and found none. Then I bravely (read foolishly) touched it with my bare hand and... nothing. So I am glad you found the cause. One thing about working on monitors is that mistakes generally are not tolerated.

We need to redo the light bulb test with the deflection end of L103 lifted. We still have not officially narrowed the problem down to the power supply or the deflection circuits. 171 volts at TP6 is high, it should be about 138 volts.

jeff412 · « **Reply #36 on:** April 25, 2010, 07:26:08 pm »

The light bulb stays lit with L103 lifted.

Jeff

smartbomb2084 · « **Reply #37 on:** April 25, 2010, 07:39:17 pm »

Excellent. One step closer. What did we learn? Has the monitor been powered up completely assembled since our bulb has been burning bright?

jeff412 · « **Reply #38 on:** April 25, 2010, 07:42:47 pm »

Yes. It is currently fully assembled. I am reading 171 V at TP6 with it assembled.

Jeff

smartbomb2084 · « **Reply #39 on:** April 25, 2010, 08:00:31 pm »

I assume you have the drawings for this monitor. Have you checked for all the other power supply voltages at their test points as shown in the power supply drawing. Are you sure the HOT is good?


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