angelaudio
Super Member
Thank you much dankik. I noticed you left 24mV at the collector of H002 and 48mV at the collector of H004, which were readings from the right channel P700 board, just thought I’d point it out so it doesn’t cause a mix up.
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Relay not clicking/engaging in a Marantz 2325
- Thread starter angelaudio
- Start date
I think that I have isolated the problem.
Current calculation:
I = V / R = 60v / (560 + 27,000) = 2.18mA
V1 = I * R = .00218 * 560 = 1.22v
V2 = .00218 * 27,000 = 58.86v
- The common line between the positive and negative voltage halves of the amplifier is sitting at 61v instead of 0v (see diagrams)
- You can see that any electrical path that connects to this has 60v instead of the proper voltage (typically close to 0v)
- Both +60v and -60v voltages look like they come into the board through connector J710 and appear on the output transistors at +/-61v, so it is not an issue of no negative voltage
- I would isolate the problem to the circuit outlined in blue.
- 60v goes thru a diode, 560 Ohm, 27K Ohm resistors, then should be 0v
- Then it continues through a 27K Ohm, 560 Ohm resistor and diode and should be -60v.
- If you calculate the voltage drops (assuming 0v drop across each diode for now)
- There is a 1.22v drop across the 560 Ohm, a 58.86v drop across the 27K Ohm, which is now 0v
- Then there is another 58.86v drop across the negative 27K and 1.22V drop across the 560 Ohm getting you to -60V.
- But, we never get to 0v in the center, instead we are at 61V! Looks like an open connection to the -60V rail.
- So, I would suspect one of the following:
- diode H719 is open,
- or R725 is open,
- or R723 is open,
- or bad solder connection or cracked circuit trace
- Please check these three components and report what you find.
- You can just measure the DC voltages (with respect to GND) of each side of the three components.
- The voltage drop across the diode is about 0.6V
Current calculation:
I = V / R = 60v / (560 + 27,000) = 2.18mA
V1 = I * R = .00218 * 560 = 1.22v
V2 = .00218 * 27,000 = 58.86v
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angelaudio
Super Member
Voltage Drops
H719: -61V to -60.36
R725: -60.3V to -58.65
R723: -58.6V to 20.42V
H719: -61V to -60.36
R725: -60.3V to -58.65
R723: -58.6V to 20.42V
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Did you really mean H719?
The R723 voltage doesn't look right compared to the other voltages of -60.4 and -58.6... are you sure about it?
Unless C708 0.1uF capacitor is bad?
What are the voltages for R722 and H718?
Also, what did you do to get those voltages above, they are not the same as before?
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angelaudio
Super Member
Yes I meant H719, edited it above.
I double checked the voltages at R723 and yes they are correct. Should I pull C708 and check it?
R722: 20.4V to 59.6
H718: 60V to 60.55
angelaudio
Super Member
I thought my meter could read capacitance but I tried testing a 3.3uf film cap and it didn’t read anything. 
Looks like the cap would need to go into the sockets at the lower left. You could tack solder on some small wires to the cap and plug the wires in if the leads are too fat or too short.
One more thing to check, H704. Maybe an emitter to collector short causing 20.68v from the emitter to pass through to the collector. Should be close to 0v. It then makes it way through R721 to the common node of R722/R723 and could be the cause of the +20.4v you measured.
angelaudio
Super Member
Sorry for the delay, I will be getting back to the 2325 tomorrow.
I will check H704 as well thank you.
I will check H704 as well thank you.
GRonald
Active Member
You get higher voltages on the early stages of the circuit when you get +-60V on the emitters of the 708/709. When 708 is not conducting you should get -60V and when 709 is not conducting you should get +60Volts. This high voltage carries out to the early stages of the P700. Have you checked 708/709 and any dry solders on 709 on emitter pin.
angelaudio
Super Member
Yea these are the readings for H708/709:
H708 E= 61.5 B= 62.5 C= 62.1
H709 E= 61.5 B= 61.5 C= -62.3
I have not checked for any dry solders on H709 but I will while I’m pulling C708
GRonald
Active Member
+Voltage at emitter of 709, so 709 is not conducting. I would check 709. if it was then the voltage at its emitter should be between -0.5v to -0.7 volts.
angelaudio
Super Member
angelaudio
Super Member
angelaudio
Super Member
H709 tested fine:
B to E = .584V
B to C = .572V
E to B = OL
C to B = OL
C to E = OL
This is what the pins looked like before desoldering:
Hmmm... doesn't look right.
H704 is a PNP transistor 2SA720. What is the part number of H704?
If you connected your DMM leads as shown in the table below, then your measurements indicate an NPN transistor or your leads are reversed.
Please clarify, thanks.
Also, see this?
https://audiokarma.org/forums/index.php?threads/marantz-2325-p700-help.1066948/
Last edited:
angelaudio
Super Member
I measured with the leads reversed, so negative lead on the Base then positive on the Emitter, negative on the Base and positive on the Collector and so on. And good eye on that thread. I’m going to start making a parts list soon, I’ll add those transistors to it.