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Reading 2325 schematic,newb at this. Learning process.

zedex

zedex

Well-Known Member
Hi. So im trying to troubleshoot my 2325. And im tracing a 1k signal through the aux in jacks. Can anyone here guide me to where the signal goes beyond this switch. This is the first time i actually have gone through the trouble of printing off a schematic so i can actually follow it. I dont see too good.:) So the 1k goes into the switch and it branches off to multiple locations depending on where the switch is set. Hmmm
Also. Curious about the # the switch is assigned. S001- 2r and S001- 4r. The service manual is no help determining which switch this is, not that i can see anyways.
So i know i have a 2 good 1k sine waves going in, and i know i have a 1 good and 1 bad sine wave at the pre amp plug before it enters the pre amp. So tracing between these 2 points but am stuck at this switch.
Thanks.
BTW. Im doing this because there are no techs around here , my last tech gave up so im doing this myself with the appreciated help of Bob and Bob.:) Bob talked me into keeping it instead of selling it so im all in.:)
Heres the schematic and i colored the lines pink and green for both L and R channels.
Thanks for the help
Pic one aux in,pic 2 the switches.

7PBeTNq.jpg


5ODHkW8.jpg
 
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The switch designations are a little cryptic. S001-2r is the contacts on the rear side of the second wafer from the front of the switch. S001-2f is the contacts on the front of that same second wafer. S001-4r would be the rear contacts on the fourth wafer from the front (etc etc). There is an area at the lower left corner of the schematic, that designates what each switch does, and the position shown in etc. (SW001 Function switch shown in the AM position in the schematic etc etc)

It is good to hear you are moving along.
 
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Progress, and i have it narrowed down to PH01 board. I dont know what that board is called other than PH01. Anyone?
Its either a transistor or a cap or resistor in between JH02 and JH06. I get about 1/4 amplitude of my 1k input. And in between JH01 and JH05 is full wave but seems flakey. I was getting good signal while i was trying to narrow down which component was the problem and that side started flaking out. Then came back.
Unfortunately these boards dont have markings on the solder side unlike nak boards which are marked both sides. So i have no idea when im probing, what im probing. :(
And very interestingly, right where on the back of the board i have it narrowed down to the problem 1/2" area. There is a repair of looks like a cap was replaced. 2 crappy solder points close together so i assume cap. I cant tell, the board is so jammed with components.

QJNxqih.jpg


LNzHrYg.jpg
 
from the description of the noise you presented, I would suspect noisy semiconductors (transistors). What are the transistor numbers? Are they on the shoot on site list?
 
Shoot on site list? :)

6F-1, A720, C1318

The spot where someone soldered in what is probably a new cap. I reflowed those 2 points(1 solder looked like a cold solder joint) and my bad R channel sine wave changed from a terrible double sine wave, 1/8 the amplitude of the left channel, to a single sine about 1/4 the amplitude of the left channel. So the solder joint was bad on that joint. As you say though still a bad transistor or something . Left channel most of the time was perfect, but did start flaking out and the sine wave would flicker, then came back to a good sine. So L channel problems too. All sines waves at the input of that board always perfect.
Can you tell me what the PH01 board is?
 
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The PH board is the buffer amp. Watch out for the polarity on capacitor CH13. On some models of the 2325 the polarity was silk screened wrong on the actual board. the (-) goes toward the outside edge of the board.
 
If it were me I would likely just replace the transistors, and electrolytic caps on that board. The parts are cheap, and while you have it in a position to change parts you might as well. I generally use 2SC2383 for the NPN transistors, and 2SA1013 for the PNP transistors. BE AWARE that HH05-HH08 are represented in the part number designation on the schematic as 2SC720 (NPN), but they are 2SA720 (PNP) transistors. The schematic drawing is correct but the parts designation is wrong.
 
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The problem with 2SA1015 is they are obsolete and not available at Mouser or Digikey. The Ic for 2SA720 is 0.5A, so they seem to want a pretty robust transistor there. I have seen KSA1013YTA recommended as a replacement. Bob, do you think that is a reasonable sub there? I’m asking because I want to keep my transistor sub guide as accurate as possible while quoting readily available transistors as subs. Thanks!
https://audiokarma.org/forums/index.php?threads/marantz-transistor-diode-sub-guide.926805/
 
You are correct, 2SA1013 is a better sub (although they are not specified as low noise).The max collector current on the 2SA1015 is only 150 ma where the 2SA720 is 500 ma. the 2sc1318 is also a 500 device. You could use 2SC2383 (compliment to 2SA1013). (I also keep those in stock in quantity).

I would use 2SC1815 for the 2SC1345 (HH01-HH04)

I edited my previous post to prevent someone using the improper device.

Looking at the circuit, it appears that the NPN device (HH09) sets up a constant current source for the PNP device (HH05), (which is operating in class A).
 
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Awesome. Thank you guys.

So when i order transistors, there are 3 different types. Which substitutes for which?
Also on the schematic, the arrows on transistors, some pointing in, some out. Which denotes NPN and PNP? I will try find them Monday as well as the 5 electrolytic caps.
Cheers
 
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While not germane to the problem at hand, I would also replace HH11 with two 1N4148 or 1N4448 diodes in series.

Tom
 
zedex said:
Awesome. Thank you guys.

So when i order transistors, there are 3 different types. Which substitutes for which?
Also on the schematic, the arrows on transistors, some pointing in, some out. Which denotes NPN and PNP? I will try find them Monday as well as the 5 electrolytic caps.
Cheers
Click to expand...

Transistors shown with the arrow pointing in are PNP and those shown with the arrow pointing out are NPN.

All 2SAxxxx and 2SBxxxx transistors are PNP, and all 2SCxxxx and 2SDxxxx transistors are NPN.

2SA720 can be replaced with 2SA1013.........2SC1318 can be replaced with 2SC2383........ 2SC1345 can be replaced with 2SC1815.
There are other parts that could also sub for those transistors, but these should work well.
 
Thanks Bob. I guess i should test the pre amp now before ordering anything. :) Something wonky going on back there. Or can i procede? As i would have to plug that 14 pin connector back in. Can i pull out the 2 leads that supply the faulty signal and feed in my good 1k sine wave?
 
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PNP : Points iN Proudly
NPN : Not Pointing iN

I also know a mnemonic for the resistor color code but it violates current social graces.
:)
Tom
 
A nice safe one: Better Be Right Or Your Great Big Venture Goes Wrong.

A trick I use to better figure out what I'm doing is to photograph both sides of the circuit board. Then I use a photo editor to mirror one side and combine the two. Since I'm usually probing and soldering from the copper side I make that the correct view. Then I add the mirrored component photo, maybe lightening things for good legibility. Adding text is optional for when I'm really confused. Then I print it, color or B&W, as makes sense, and I might print it larger than lifesize.

The same technique works when the service manual has drawings of both sides of the board. Copy and combine as above so you can work from one simple sheet.
 
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Thats a good idea. My problem is your looking at the component side,then you have to flip it over, so now its upside down. Its attached by wires you can just flip it probably 110 degrees and thats it. I need a fine paint marker to mark the solder side of the board. My fine sharpies wont mark on that slippery surface. The regular sharpies are too fat. I used to have a fine gold paint pen but cant find it. I think when i replace components im going to cut all the wires so i can have the board on a stable surface. Splice when i install.
 
I would not cut the wires if there is any way to avoid it.

"I guess i should test the pre amp now before ordering anything. :) Something wonky going on back there."

The parts are really very inexpensive. I would just buy plenty so you will have the transistors and capacitors you need if there are issues on another board.
 
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Wow. Getting transistors in Canada is like pulling teeth. Digikey cant/wont get me 2sc2383 (NTE31) as they wont ship to Canada.Only ship to the US. Mouser "might" be able to get them for me but have to wait for a quote. I remember having this problem before. Normally i can have anything shipped to my US address(which is why i have a us address) but borders are closed and will remain closed for the unforseeable future. You guys in the US have it good.
 
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