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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Tue Jan 31, 2012 7:15 am Post subject: Marantz sr7002 locked in standby mode |
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I am working on a Marantz sr7002 for my grandson. I am not a tech, but have managed to fix many electronic devices over the years - TVs, stereos, PC motherboards, flat screens , auto diagnostics, etc. However, I don't do it very often and it takes a quite while to zero in on the problem. But, I usually get them fixed. This sr7002 looks far more complex than anything I have looked at before and at first take I said it was way too complicated for my skills. After downloading a schematic and reading about several other similar problems, I am beginning to think that maybe with some expert help there may be hope. Anyway I would like to give it a shot. Heres what's going on. Apparently there was a flood in the basement where this thing was setup, it didn't get wet. However, I believe the power source was shorted out and maybe other components may have gotten wet. My guess is speaker wires. The unit is locked in flashing standby with @ 2 sec intervals. When you hit the power button I can hear a relay kick and the flashing stops for few seconds and then returns to the same standby flashing mode. No display! I've been looking at the power and standby boards. Any help as to where to start looking would be greatly appreciated.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Jan 31, 2012 3:49 pm Post subject: |
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Try disconnecting CN73 on the amp board and see if it will power up.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Tue Jan 31, 2012 5:19 pm Post subject: |
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No such luck, still have the exact same results, same standby flash, relay click and then standby flash, 2 sec interval and no display.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Jan 31, 2012 7:03 pm Post subject: |
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DSP board, connector CN30, test for +5v on pins 6 and 7.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Tue Jan 31, 2012 11:06 pm Post subject: |
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If I got them tested correctly, I got about .1 v on each 6 and 7 using 5 as a ground. Honestly, I don't know the proper way to do this, but I just loosened the boards above the DSP, stood them up and encased them each in baggie. I've never dealt with stacked boards before. In order to get the boards out of the way I had to remove the ribbons at CN42 and CN43 on DSP. I didn't think they would affect the test.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Jan 31, 2012 11:16 pm Post subject: |
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Put that all back together and I'll be back with the next step.
How easy is it to get at the regulator PWB?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Jan 31, 2012 11:19 pm Post subject: |
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Test fuses F901 and F902 on the regulator PWB.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Jan 31, 2012 11:42 pm Post subject: |
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If those fuses are ok then go to the standby board and check fuses F701, F702 and F703.
Does the florescent display come on or flash at all when it first tries to come on?
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Wed Feb 01, 2012 4:56 am Post subject: |
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Great job!
Sure enough had @7.5AC at CN92 and nothing at D902. Pulled the card and found that f901 was @.02 ohms and f902 was @2.8 meg ohms. Will check our one local shop tomorrow. If not, I'll try a few TV repair shops. Otherwise, I will have to order it. Like I said. I don't do this very often and feel like I am reinventing the every time I work on something. Hopefully this will fix it! If not, I'll keep going.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Wed Feb 01, 2012 9:38 pm Post subject: |
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Not what I wanted! Replaced the F901 fuse, hooked everything up and plugged it in. The flashing standby was now solid red, whatever that means. I powered it on and nothing happened, no display at any time. Powered it off. Back to solid red. Then powered it on again, I hear the relay drop and we are back to 2 sec. flashing. I assume it took the new fuse out. Apparently there is a dead short somewhere. I'm wondering should I replace the fuse and leave all jumpers disconnected and bring them on one at a time. Or is there some things in particular I should look at. Maybe IC's on the board. I guess maybe I should have checked all of the voltages before powering it on. What do you think?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Feb 01, 2012 9:43 pm Post subject: |
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Test the fuse first and let me know if it's gone.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Thu Feb 02, 2012 1:24 am Post subject: |
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Yes, fuse F901 is gone. I will buy several tomorrow. It was only 125v 5a, that's all they had. They don't have a 250v. I didn't think that would really matter. considering the low voltage involved. What could be shorted?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Thu Feb 02, 2012 1:33 am Post subject: |
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| jmdigges wrote: | | Yes, fuse F901 is gone. I will buy several tomorrow. It was only 125v 5a, that's all they had. They don't have a 250v. I didn't think that would really matter. considering the low voltage involved. What could be shorted? |
We will have to trace it out and find it. No problem though. 
Do you know how to test a rectifier? You first need to test D902. If you know how to test a diode you can test a rectifier. DMM on diode scale. Google will show you I'm sure. If not post back and I'll explain it tomorrow. I'm sighing off for the night soon.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Thu Feb 02, 2012 7:46 am Post subject: |
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I tested D902, IC91 and IC92 using ohms and reversing polarity. They look good to me. I do understand diodes and rectifiers, however, I have never used the Diode tester on a DMM. I have a Fluke with that on there. How do you use it? I think I am testing them correctly but, may not be. I assume we will eliminate the possiblity of a problem on this board.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Thu Feb 02, 2012 7:56 am Post subject: |
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Do you think I should take that D902 out of circuit to get a good reading?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Thu Feb 02, 2012 4:21 pm Post subject: |
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I test almost every thing on diode scale. Resistors are about all I test on resistance scale.
Yes, pull that rectifier. I would like it out anyways for some more testing.
Once you have it out and retested and it's ok then set your DMM on diode scale and connect it to the DC points of where the rectifier was on the board and give me the reading. Reverse leeds also so I have the readings both ways.
Make sure the board is fully connected when you do this. All boards for that matter.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Thu Feb 02, 2012 11:20 pm Post subject: |
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OK, tested rectifier out of circuit and it still tests good. Just like site below. Using diode test on DMM tested across DC pos/neg terminals on board with nothing connected and got 1.47v with + test lead to + DC post on board where rect was and neg test lead to neg DC post on board. Got .573v with + test lead to - DC post where rect was and pos lead to neg DC post. Got almost same readings ( 1.47v and .569v) with card plugged in. I wouldn't expect that, although I don't understand what the voltage is implying. I am lost on this. I expected something drastically different somewhere.
http://www.youtube.com/watch?v=dqkT6hF0O3E
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Fri Feb 03, 2012 12:18 am Post subject: |
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Normally I would now say test this and test that but I'm sensing unsureity in whether what your testing comes out correct or not. So we're going to try this in simpler methods.
Put D902 back in and make sure fuses F901 and F902 are good.
Locate CN96 on that board and remove the wire from the connector of pin 1. Or just cut the wire and you can fix it later.
Now reinstall everything and try turning it on. Lets see if the fuse still blows.
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jmdigges
Joined: 31 Jan 2012
Posts: 43
Location: tulsa, Ok
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| Posted: Fri Feb 03, 2012 4:51 am Post subject: |
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Finally got back to it. Put D902 back in and new F901. Unpinned pin 1 (8v) on CN96 and plugged everything in. Blew out F901 when powered on. Back to flashing. Got tired of pulling that card and jumpered in a new F901 with all connectors unplugged, tested fuse as I plugged them one at a time and tested power on. Finally blew it with only the following pugged in: BN91 - POWER PWB, BN92 - POWER PWB, CN93 - INPUT PWB, and BN61 POWER PWB. It didn't go right away - I turned off and on a couple of times and blue diodes were illuminated above the dials, first time I've seen those. Is there a resetable fuse or circuit breaker I can jumper in?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Fri Feb 03, 2012 7:13 pm Post subject: |
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So what did you learn from this? 
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