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Post by mastertech on Jan 14, 2022 12:55:52 GMT -5
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Post by mmartell on Jan 14, 2022 14:07:59 GMT -5
When I click the image to enlarge it the link gets blocked by uBlock Origin, something about the hoster "viglink" maybe...
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Post by mastertech on Jan 14, 2022 14:23:56 GMT -5
I have no problem accessing it so the link is good. Try this link. Try selecting the tracer link or the image itself. tracerAttachments:
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Post by mmartell on Jan 14, 2022 14:40:23 GMT -5
Wow I have no room for all that stuff on or even near my bench. Would I be able to use the 1khz calibration tone from my scope as in input to BN502 ?
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Post by mastertech on Jan 14, 2022 15:26:05 GMT -5
You are only adding 1 receiver and a source device to play preamp audio. Besides my volt meter, this was the most used test piece back when I was repairing daily. And it does not have to be on your bench. Just have 2 long wires coming from the good unit. This device would be used to test the initial audio signal and the volume and switching ic along with audio going in and coming out of the volume ic after returning from DAC. Not for sending signal into the power amp section.
As far as your other question regarding your scope I would say probably not because the preamp signal would have to be controllable. For testing the power amp section I always use to just have another receiver with preamps out. Then just cut a preamp cable, put on some test leads and inject before the cap. So it has volume control because the power amp is always running full.
I actually had 1 receiver set up for both above uses.
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Post by mmartell on Jan 14, 2022 19:01:47 GMT -5
I will have a look when I get home.
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Post by mmartell on Jan 14, 2022 22:14:51 GMT -5
Interesting. No protection necessary for this setup ?
Would this not work equally as well with a modified headphone plug into a mobile phone ?
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Post by mmartell on Jan 17, 2022 11:55:45 GMT -5
Ok I had a little time and built the probe. Before I go using it and blow up my expensive audio equipment I will await your instructions.
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Post by mastertech on Jan 17, 2022 13:26:55 GMT -5
Ahhh, well........ you are suppose to use a cheap receiver that you bought at a yard sale or had laying in a closet collecting dust, but it should be fine, lol.
What are you going to use for a source device?
Are you able to test right on the pins of ic891?
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Post by mmartell on Jan 17, 2022 13:54:43 GMT -5
Am I able to use the tuner as an input or is it necessary to use an external input ?
Yes I can test directly on the pins.
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Post by mastertech on Jan 17, 2022 14:02:47 GMT -5
Am I able to use the tuner as an input or is it necessary to use an external input ? Yes I can test directly on the pins. The reason I do not like to use the tuner for testing because how do you know how well this receivers tuner works and do you have a good signal and does it mute the output if it is not a good signal? A lot of if's to not know if the tuner is actually working without having sound. But if that was your only option then the first place you would have to test for sound would be pins 24 and 25 just to see if you have good sound from the tuner. Now as for the test receiver, which input are you using for your test probe +? Does the outer metal of that input connector show continuity to chassis gnd?
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Post by mmartell on Jan 17, 2022 14:49:50 GMT -5
The tuner has a "Tuned" and "Stereo" indicators. I have found with other receivers when both are lit you are assured to have audio but I get your point.
Yes the jacket of the input on the working receiver shows continuity to ground. I think that's what your asking ?
The jacket (barrel) of the input is connected to the spk- of the non-working receiver as per your diagram which also shows continuity to ground.
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Post by mastertech on Jan 17, 2022 15:17:06 GMT -5
Ok, good. I only asked because it may have been easier to just connect an alligator test lead from chassis to chassis. So which ever is easier for you.
I would next try turning on both receivers to make sure they do not have an issue being connected to each other.
Then just be sure your test unit is set to the correct input for where your test wire is connected, and set the volume to approximately normal listening level.
On the defective unit, I would set the sound mode to "Direct". I would also say set it to "stereo" mode if it was a separate selection but I dont think it is in this unit. And set the volume to mid point and make sure mute is off.
Then if your tuner is playing, test pins 24 or 25 and see if the test unit plays sound.
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Post by mmartell on Jan 17, 2022 15:29:50 GMT -5
Pins 24 and 25 are active! Music playing through working receiver fine.
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Post by mmartell on Jan 17, 2022 15:33:56 GMT -5
Nothing on pins 1-5
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