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Post by mastertech on Aug 27, 2013 10:51:31 GMT -5
But if you touch the 2 probes together you get a short reading, correct?
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Post by mastertech on Aug 27, 2013 10:57:25 GMT -5
Under that A/C input board that has F302 on it, there is a board with a bunch of diode on it. Test some of those diodes with your meter and see what you get. Probably easier to remove the A/C board to get at the 1 under it.
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Post by Michael on Aug 27, 2013 11:20:14 GMT -5
When I touch the two probes, I get 0000 reading. On the lower board, I tested R203, R204 and R205. On all of them I get 0.551.
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Post by mastertech on Aug 27, 2013 11:24:16 GMT -5
You need to test the diodes on that board. There are 4 right in the middle. D204, D205, D206 and D207. Test both directions on each.
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Post by Michael on Aug 27, 2013 11:33:14 GMT -5
Here are the readings;
D204 = 0.494 (OL)in other direction
D205 = 0.493 (OL)in other direction
D206 = 0.498 (OL)in other direction
D207 = 0.499 (OL)in other direction
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Post by Michael on Aug 27, 2013 11:43:39 GMT -5
I am almost certain that there is something wrong with D301. There is an electronic supply shop close by that I can get that. Should I also replace the Q301?
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Post by mastertech on Aug 27, 2013 11:44:47 GMT -5
Ok. So meter is fine and I think you have the testing down now, lol.
If D301 tested open in both directions then it is bad. Probably why the s12v line was fluctuating. Guess were making a list?
Ok, next I want you to test the bridge rectifiers on the board that the main transformer connects to and then connects to the regulator board you removed. There are 2 of them. You shoud be able to do a quick test without having to remove the board. These are the black devices with 4 legs near the outer edge of the board.
Set DMM to diode scale and just test across the outer legs of each rectifier and see if either tests for short. Make sure to switch probes and test in both directions.
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Post by mastertech on Aug 27, 2013 11:46:10 GMT -5
I am almost certain that there is something wrong with D301. There is an electronic supply shop close by that I can get that. Should I also replace the Q301? Just put this issue to the side for now. |
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Post by Michael on Aug 27, 2013 11:59:51 GMT -5
Tested Rectifiers I guess two black cylindrical shape devices approximate size of a "D" size battery;(C201 and C202)two legs on each.
it reads 0.465 on both of them. When I switch probes it shows negative reading and slowly counts down
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Post by mastertech on Aug 27, 2013 12:38:49 GMT -5
No, they are capacitors and I think your on the wrong board. The board is at the front part of the receiver connected to the large transformer. This is a bridge rectifier:  I have to run out for a couple hours so I will check back when I return. |
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Post by Michael on Aug 27, 2013 12:52:24 GMT -5
Got it!! I get reading on outer legs of both which slowly increases. I switched the probes and I get negative reading which slowly decreases. Do you need the range/values?
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Post by Michael on Aug 27, 2013 14:39:16 GMT -5
Well it looks like your the lucky owner of a unit where stuff has to be unsoldered to test further. Blowing F302 indicates the main transformer is being overloaded. I'm trying to find the easiest way to start looking for the problem. Lets try this. On the front of the large heatsink there is a regulator board with 5 regulators attached to it. Set your DMM to diode test and just test to see if any of the individual regulator legs show a short to each other. Post back your results. CORRECTION: Gone back and retested the regulator board on the front of the large heatsink. IC351 thru IC354 does not show any shot between any of the legs. IC355 shows a short between the two outer legs. I dont know why I was getting diffrent readings before but I did!! I am certain that this is a correct reading since I repeated it several times. I guess I was wrong about all 5 regulators being shorted earlier. Read more: repairalmostanything.com/thread/22/yamaha-htr-5280#ixzz2dCRtVXzA |
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Post by mastertech on Aug 27, 2013 16:46:09 GMT -5
Did you get fuses today?
Did you unsolder the wire harness from the regulator board when you removed it?
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Post by Michael on Aug 27, 2013 18:12:09 GMT -5
Yes I got the fuses. The wiring harness was removed before. Let me know what I have to do next and I will continue tomorrow .
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Post by mastertech on Aug 27, 2013 19:19:25 GMT -5
I would next like you to replace the blown fuse, leave D301 lifted, leave Q301 removed and jumper installed, leave the regulator board removed and make sure any disconnected wires are not touching anything or each other and then plug it in and see if the fuse blows. Again, you will not have to hit the power button.
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