P750 Illustration
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Steven Tate
CEO Flat Forehead Soc.
What are you trying to determine?
Here is a colorized version of the 2230 P750 board layout, done from a clean scan.
bibota
New Member
Wow, this is absolutely beautiful, many thanks runningdog. Such a difference!
Any chance of more of the same for other boards?
BTW, I got the transistors you suggested and have them on board now together with many other new bits.
During the last month or so I've been kept busy replacing bads on the P750. Something went wrong there and fried a whole bunch.
I may put it to the test today, with the Variac. Which again is a first, just bought it for this very project.
bibota
New Member
I know Tom, I went far and wide myself looking for a better resolution and there were all identical; so glad to see runningdog's, can't have enough of it now.
I find that having a print of the layout as reference is very useful when identifying the points to be de-soldered on the back of the board.
On a related issue, I remember you making a comment somewhere about the diode attached to the heat sink. It is the only component I couldn't trace anywhere and I sort of went ahead hoping that the fault may be somewhere else.
If the functionality test proves that I didn't get to the bottom of the problem after all the new parts put in, there may be the case for me to replace the diode as well.
Any chance you could suggest a source please?
catrafter
Marantz Specialist
First thanks to Randy (runningdog) for the great colorized layout!
bibota,
The only place I know of to get the exact diode (SV-3A) that is used as the bias temperature compensation in the 2230 is from a donor Marantz. Models 1030, 1060 and 2230 use the same one AFAIK.
Tom
bibota,
The only place I know of to get the exact diode (SV-3A) that is used as the bias temperature compensation in the 2230 is from a donor Marantz. Models 1030, 1060 and 2230 use the same one AFAIK.
Tom
bibota
New Member
Really thrilled that I can myself have a contribution to AK. Minor one admittedly and a mere amendment to the hard work done by somebody else, but I'm rather proud of it anyway.
In the colorized version of the 2230 P750 board layout kindly provided by Randy, H753 should be facing like this:
as opposed to this
Bringing the overall picture to this
Speaking of TO-92 transistors on this board: am I the only one finding that KSC2383 works much better than KSC945C for the H751? Although I've seen them both recommended for that position, KSC945C seemed to bring with it a sizeable loss in the mid to low range. Things come alive as soon as KSC2383 replaces it.
But of course, KSC945C does a perfectly decent job at H753.
In the colorized version of the 2230 P750 board layout kindly provided by Randy, H753 should be facing like this:
as opposed to this
Bringing the overall picture to this
Speaking of TO-92 transistors on this board: am I the only one finding that KSC2383 works much better than KSC945C for the H751? Although I've seen them both recommended for that position, KSC945C seemed to bring with it a sizeable loss in the mid to low range. Things come alive as soon as KSC2383 replaces it.
But of course, KSC945C does a perfectly decent job at H753.
Steven Tate
CEO Flat Forehead Soc.
Interesting. The recommendation I was given on my first 2230 was to use KSC1845 at H751. That's what I have always used. I may have to do a comparison next time.
Were you replacing the transistor because it failed? Or is known to fail often? Or were you replacing some/all of the transistors? I'm trying to gauge if H751 should be replaced routinely during a rebuild.
Thank you for the correction to the board layout and good catch! I just compared the updated document to a couple of amps and sure enough H751 goes the other way.
The colorized board layout comes from ak'r TimCartier and I agree it is awesome. And now even more so, thanks!
Steven Tate
CEO Flat Forehead Soc.
I think on my first 2230, I got a parts list form MBuras and replaced everything on his list, which included H751. Since then, I have done a couple of others and only replaced the electrolytics. Right now, I'm leaving well enough alone in the way of semis on the power amps if everything adjusts out well.
bluehills5
Active Member
I just finished a 2230 and here are some more cleaned up scans of the P400 and P800 boards that are clearer than the scans in the SM I have.. They were copied from other posts but I can't remember where so thanks should go to whoever uploaded them first.
bibota
New Member
Nice ones, thanks for sharing.
Still, I have a feeling the P800 doesn't quite fit the 2230. Could it be a 1060, possibly?
You got it. Both scans are from the 1060 service manual.
From AK'r TimCartier comes this scan of the 2230 P800 board layout:
bibota
New Member
Another nice one for the collection, thanks runningdog.
