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New Project Marantz 2250b
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Old 9th February 2018, 09:10 AM   #31
pjf610 is offline pjf610
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No the 90mv goes higher can not get it lower, i will check all my values again should i check them NOT using the DBT??
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Old 9th February 2018, 01:42 PM   #32
Mooly is offline Mooly  United Kingdom
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DEFINITELY not Always keep the bulb tester in place.

So we need to do a decisive couple of measurements now. I can not see on the diagram where these two test points are in relation to the circuit and so I am assuming they are indeed across one of the 0.22 ohm emitter resistors.

Can you check all four voltages across all four emitter resistors and post the result here.
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Old 9th February 2018, 05:42 PM   #33
pjf610 is offline pjf610
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Hi Mooly, please forgive me but I do not have any listing for R641 R637 R643 R639 on my schematic what board or these on??
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Old 9th February 2018, 05:44 PM   #34
pjf610 is offline pjf610
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Is their a difference between the US and UK boards???
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Old 9th February 2018, 06:55 PM   #35
Mooly is offline Mooly  United Kingdom
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I'm sorry that's my fault, used the wrong diagram. Just a minute.
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Old 9th February 2018, 07:01 PM   #36
Mooly is offline Mooly  United Kingdom
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Hopefully back on track.

So you need to be sure that you are seeing this 90mv across both 0.2 ohm emitter resistors. If so then something is wrong because as mentioned, that would mean 4 amps was flowing.

Measure directly across each resistor.
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Old 9th February 2018, 07:37 PM   #37
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OK so i need to check the voltage across R732 and then R733 and they should read 90mv on both correct??
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Old 10th February 2018, 07:39 AM   #38
Mooly is offline Mooly  United Kingdom
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No, that would be much to high. You say you have 90mv across the bias test points and the manual says you should have 10mv.

The method in the manual measures across both resistors in series and so that means you should see 5mv across each 0.2 ohm. Yes

Now, if you measured 90mv then that implies you have a current of 0.090/0.4 which would be 0.225A. Far to much.

So first check the voltage across each of those resistors and see what you get.
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Old 10th February 2018, 02:36 PM   #39
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RC R732=1.4mv
R734= 2.3mv
LC R732= 41.7mv
R734= 43.9mv
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Old 10th February 2018, 04:18 PM   #40
phase is offline phase  United States
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The bulb tester is your friend...
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