nashou
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Post by nashou on Apr 11, 2020 16:51:50 GMT -5
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Post by mastertech on Apr 12, 2020 17:26:09 GMT -5
What amp fuse did you choose for replacement?
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nashou
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Post by nashou on Apr 13, 2020 7:46:11 GMT -5
1.25 amp fuse. So I tried to add a thermistor in series on the input side , the side that leads to the rectifier but it still blew on second power up, but power was there to light up the Display and leds etc. When fuse blows it looses the LED's and the display , but the cue lights still work . But I had another issue now, I noticed all the led's light up to half way the light track. none should be on unless sound is passing. Soi I connected it to an amp and head phones and now there is no sound. So something else is up with it. I had this working before just by replacing the fuse. it worked for him for a few days till I got it back with same fuse blown. For him it blew on power up and he used it the night before a short while. Fuse I used, green.  Led's lit up half way.  |
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Post by mastertech on Apr 13, 2020 14:33:42 GMT -5
Well it looks like after that fuse the line feeds 3 regulators: ic550, ic551 and ic552 and also continues to another board feed. A strain on any of those regulator outputs could cause a delayed failure of that fuse. Do any of those regulators seem hot when it is on?
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nashou
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Tech in Training.....
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Post by nashou on Apr 14, 2020 16:59:26 GMT -5
Well it looks like after that fuse the line feeds 3 regulators: ic550, ic551 and ic552 and also continues to another board feed. A strain on any of those regulator outputs could cause a delayed failure of that fuse. Do any of those regulators seem hot when it is on? I checked IC551 as its right next to it and that did get somewhat hot. I removed it and re greased it just incase. But it still blew. The others are just mounted on metal plate and that plate is screwed to the chassis . I don't have many of those fuses left and don't want to keep blowing them, Anything I can use in its place like a resistor to help diagnose it more. I have some 1/2 ohm 1/4 watt I think. Nashou |
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Post by mastertech on Apr 14, 2020 19:29:33 GMT -5
Putting in a resistor you would loose your safety. You could increase the fuse amperage for now while testing. I would then remove D550 and then if the unit stays on for a while try testing the voltage output on those 3 regulators to see if any are low, especially the one that is running hot.
Edit; Also, if you have an inline fuse holder laying around you can solder that in, in place of the pico and just use glass fuses for now.
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nashou
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Post by nashou on Apr 15, 2020 7:29:35 GMT -5
Putting in a resistor you would loose your safety. You could increase the fuse amperage for now while testing. I would then remove D550 and then if the unit stays on for a while try testing the voltage output on those 3 regulators to see if any are low, especially the one that is running hot. Edit; Also, if you have an inline fuse holder laying around you can solder that in, in place of the pico and just use glass fuses for now. Ok, I'll see what Buss fuses I have. Might have a 2 amp and I can remove a bus holder from that Sharp TV I never got fixed. So remove the diode, I think its D560 not 550 if its the one near the 4.7uf cap C571. I see that would remove the feed to CN209 Pin 7 ( MUTEB) I'll do that later tonight possibly . Finishing up a Yamaha B2 V-Fet amp, should get the Lamps today to finally finish her. Athanasios |
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Post by mastertech on Apr 15, 2020 10:15:40 GMT -5
Yes the schematic is a little blurry there and it does look like D560. At least you know what I mean, lol.
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Post by tibimakai on Apr 17, 2020 9:55:01 GMT -5
Good to "see" you around, Mastertech.
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Post by mastertech on Apr 17, 2020 11:45:52 GMT -5
Thanks. Good to see you still here also.
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nashou
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Post by nashou on Apr 22, 2020 16:00:09 GMT -5
Ok Got back to this today. One of the regulators gets really hot!!! I'm using a fuse fuse holder and a 2 amp fuse, this seems to hold while powering off and on. Here are the output voltages and temps using an infrared Ryobi thermometer. I didn't have to remove the diode. | IC | Out | IN | TEMP | | IC550 | 3.5 | 20.44 | 200° | IC551
| -16.5 | -22.33 | 98° | | IC552 | 8 | 20.33 | 105 | | IC553 | -8 | -22.33 | 105° | | IC554 | 5 | 7.88 | 98° | | IC561 | 7.94 | 20 | 80° | | IC600 | -14.86 | -22.33 | 105° |
In the SM they have the power assembly IC numbered wrong, it should be IC554 with the 4 pins. I measured the input there and its 7.88. I'll go check the inputs for each as well now, But I think IC550 on the REG Assy is bad. All voltages corrected . Nashou |
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nashou
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Post by nashou on Apr 22, 2020 19:12:38 GMT -5
Ok I ordered a 15 volt regulator and some fuses, I used the the fuse from a 1.25 to a 1.5 as I don't think that much will hurt , if it does once we are sure everything else is ok then we'll go with the 1.25 fuse. I am thinking of removing the bad regulator and feeding it +15 volts from my DC power supply and see if that gets it to work properly . This is the regulator  Athanasios |
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nashou
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Post by nashou on Apr 22, 2020 20:04:34 GMT -5
Ok I used my DC power supply to feed the out line. No luck, It wouldn't hold the 15 volts it go down to about 4 vdc and i had to turn the current control up and it got up to 9 vdc but dropped to about 7 vdc. I didn't leave it to long. maybe less than a minute to 45 seconds.
So Is something up stream bogging it down?
nashou
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Post by mastertech on Apr 23, 2020 10:27:34 GMT -5
Yes, most likely somewhere past the regulator. When you are feeding that output line with your external power supply the bad part is most likely getting hot so feel around while supplying that voltage even if it is not the correct voltage.
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nashou
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Post by nashou on Apr 23, 2020 13:56:35 GMT -5
Yes, most likely somewhere past the regulator. When you are feeding that output line with your external power supply the bad part is most likely getting hot so feel around while supplying that voltage even if it is not the correct voltage. That should be fun, this thing is layered boards connected with ribbon cables . And it has tons of IC's . Looked at the schematics last night and got a headache searching for anywhere the V+BB lines goes to. And the Find function doesn't work well here cause the schematics aren't tied to it, only some parts are. Nashou |
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