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Post by sunnyfl on Aug 20, 2015 11:40:05 GMT -5
I have a Denon 1612 that is going into protection mode:
Here a brief history of what I've attempted to do.
I changed out all of the transistors on the regulator board(7805, 7905, 7812 and 7915 as a precaution). The voltages are correct @ cn931 feeding the input B'D( Preamp board)
The voltages are also correct coming off of the SMPS B'D( Transformer Board)@bn903 to the Digital Board( HDMI\Microprocessor Board)
I've also changed out all of the Thermistors because I was getting a Thermal A and Thermal B shutdown error.
I 've measured the voltage on the output transistor's collectors of 1560 and 2390 and I'm getting -54v on 1560 and +54v on 2390 on the 5 pairs.
Additionally, in order to get the receiver to power on fully with the speaker relays engaging I have to somewhat tilt the CN252 connection which holds the: Front Relay,C/S relay, H/P relay, ASO DET, DC PROT, ThermalDET A and ThermalDET B( But what I think I'm doing is removing the (DC, Thermal A and B) out of detection mode for the receiver to fully come on.
When everything boots up(I'm a PC guy) I measure all of the speakers outputs and the front left speaker output is seeing +13volts at peak, then it counts down to zero, then the receiver shuts down.
Any help will be appreciated. I have the service manual
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Post by sunnyfl on Aug 20, 2015 14:22:11 GMT -5
Same process I used to turn the receiver on, by tilting the cn252 connector,( I believe it feeds the DC DET circuit from the amp board to the microprocessor board.) So I measured the front left channel speaker output and the voltage is zero now(normal) I guess. Also I fully connected the cn252 connector now and receiver has been on for 25 minutes whereas it would shut off immediately when the Thermal and Dc offset circuit is connected(in cn252).I'm lost by the lack of experience when it comes to phantom circuitry.
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Post by sunnyfl on Aug 20, 2015 15:01:15 GMT -5
Replaced all the capacitors on the HDMI board, also checked the voltage on the 3 pairs of resistors in the dc circuit, 1 pair(r7720, r7717) is at 54 volts the other 2 pairs(r7716, r7719 and r7718,r7715) are at 22 volts.
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Post by mastertech on Aug 20, 2015 16:34:29 GMT -5
I need a little more time before I can look at the schematics on this. I have a few projects of my own here that are not getting my attention, lol.  |
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Post by sunnyfl on Aug 20, 2015 16:47:05 GMT -5
Mastertech any help is appreciated, I don't expect to be placed ahead of the line. I've been working on this a week I can wait.
Additionally, I have a louder idle hiss in the left speaker. Measuring the mv I'm getting a 100mv, the right speaker jacks I'm seeing around 29mv. All other channels I'm getting 3.2mv. I've been playing music on it for about 2 hours and no shutdown, The minute I turn it off, I go back to scratch.
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Post by sunnyfl on Aug 20, 2015 17:02:08 GMT -5
I'm getting the same mv on the emitter legs of 2390 and 1560( front left and right) as I'm getting on the speaker outputs
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Post by sunnyfl on Aug 20, 2015 20:40:13 GMT -5
I was reading that when it comes to mV's on speaker jacks (outputs), under 40mV is ideal, and under 15mV is superb. 6 hours of music and no shutdown, just that heavy hiss out of the left channel with volume @ zero. Dread turning it off. I know I'll run into the protection mode again.
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Post by mastertech on Aug 20, 2015 20:52:52 GMT -5
Shut it down, make sure all connectors are secure. See if it turns back on or goes into protect. If it goes into protect then turn it off and remove Q7105 and Q7106. Then turn it on again and see if it still goes into protect or not. If it stays on see if your LF hiss is gone but before you connect a speaker there, test for any DC on that line.
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Post by sunnyfl on Aug 20, 2015 21:12:35 GMT -5
I forgot to mention early, that a day or two ago, I swapped out Q7105 and Q7106 along with Q7104 from the center channel, but ran into the same protection mode....I'll remove them again. brb 10 minutes
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Post by sunnyfl on Aug 20, 2015 21:30:19 GMT -5
Yes it still shut down q7105 and q7106 out, getting old here I remember removing all 5 pairs of 2SB1560 and 2SD2390 along with KTC3114A and still having it shutdown.
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Post by mastertech on Aug 20, 2015 21:37:06 GMT -5
Go to connector BN702 on this same board and test for DC voltage on pins 4,5,6 and 7. Post your results.
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Post by sunnyfl on Aug 20, 2015 21:40:47 GMT -5
Did my usual bypass to get it on and the Left Channel is seeing 43-45mV the right is seeing 34-43mV
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Post by sunnyfl on Aug 20, 2015 21:50:19 GMT -5
1.FRONT_RLY 3.217V
2.C/S_RLY 3.147V
3.H/P_RLY 0.001V
4.ASO_DET 0.001V
5.DC_PROT 3.273V
6.THERMALDET_A 0.60V
7.THERMALDET_B 0.60V
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Post by sunnyfl on Aug 21, 2015 10:10:32 GMT -5
There is an interesting short all channels. With the main amp board upside down I'm testing from the main line feeds (Red and Black wires) off the 6800uf 63V capacitors. Negative 54V feed to both 2SB1560 and 2SD2390 give me a short on the collectors the same happens off of the 54V Positive feed. However, the short is temporary on the opposing transistor; when I alternate the orientation of the leads from the multimeter the short happens for a few seconds again. For example, the positive feed 54V with the red lead of the MM there, then the black lead of the MM on the 2SB1560 collector( then I alternate the position of the leads) and the short reoccurs for a few seconds, and vice versa with the 2SD2390. Is that suppose to happen? I though the collectors on each transistor is supposed to be isolated from the other. One positive and the other negative.
Additionally I've tested a few Zener diodes and these are the readings:
+ P to Anode and -N to Cathode Reverse
D7601 .524 .791
D7603 .264 .264
D7604 .259 .259
D7602 .263 .263
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Post by sunnyfl on Aug 21, 2015 12:09:55 GMT -5
Using another MM I got these readings
+ P to Anode and -N to Cathode Reverse
D7601 1.016 1.851
D7603 .751 .759
D7604 .754 .761
D7602 .779 .786
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