Marantz service manual - tuner section enhancement
- Thread starter tranguru
- Start date
thxdave
Department of Redundancy Dept. (Retired)
Yes, yes....me too! ;-)
catrafter
Marantz Specialist
Extra notes (source: Tom on Audiokarma):
Intermediate Frequency (IF) signal strength is monitored by H308. If signal strength is above muting level, H308 is ON, H309 is OFF.
If there is excessive noise, then H311 is ON which is wire-anded to H309 keeping H301 (FET) OFF.
If the discriminator is outputting DC due to the tuning being off station, either H314 or H315 is ON which are wire-anded to H309 as well. This also turns H303 ON grounding Pin 8 of the decoder forcing MONO operation.
If the station is properly tuned, not noisy and the signal strength is high enough,
H308 is ON, signal strength OK
H309 is OFF, signal strength OK
H311 is OFF, Noise is OK
H314 is OFF Tuning centered
H315 is OFF Tuning centered
H317 is ON, signal strength , Noise and center tuning OK then:
H301 is ON allowing audio and MPX signal to pass into the decoder.
H303 is OFF If signal strength sufficient for Stereo operation and MONO button is not pressed
H302 is OFF VCO runs (AM not selected)
Thanks to @cjenrick for pointing this out.
Tom
Intermediate Frequency (IF) signal strength is monitored by H308. If signal strength is above muting level, H308 is ON, H309 is OFF.
If there is excessive noise, then H311 is ON which is wire-anded to H309 keeping H301 (FET) OFF.
If the discriminator is outputting DC due to the tuning being off station, either H314 or H315 is ON which are wire-anded to H309 as well. This also turns H303 ON grounding Pin 8 of the decoder forcing MONO operation.
If the station is properly tuned, not noisy and the signal strength is high enough,
H308 is ON, signal strength OK
H309 is OFF, signal strength OK
H311 is OFF, Noise is OK
H314 is OFF Tuning centered
H315 is OFF Tuning centered
H317 is ON, signal strength , Noise and center tuning OK then:
H301 is ON allowing audio and MPX signal to pass into the decoder.
H303 is OFF If signal strength sufficient for Stereo operation and MONO button is not pressed
H302 is OFF VCO runs (AM not selected)
Thanks to @cjenrick for pointing this out.
Tom
I was inspired by Tranguru's and Catrafter's posts above (thanks!!) to work on an enhancement of the Marantz 2230 muting circuitry functional description from the service manual. I posted it at https://www.antiqueradios.com/forums/viewtopic.php?f=13&t=247015
Steven Tate
CEO Flat Forehead Soc.
This is extremely helpful info to me for a problem I’m having on a 2230. I have strong FM reception across the dial, but no voltage to drive the signal strength meter. I have been struggling with the schematic, trying to find why I have no voltage at J557 to drive the meter. This will help me track it better. I have also been focusing on H560/561 area as the possible culprit, but just don’t understand how it works. I noticed what I think might be a typo in your guide. You mention that H560/561 go through a 150k ohm resistor to J553. I think it should be J554 shouldn’t it? Great write-up. Thanks! If you have any ideas why I’m not getting voltage at J557 when signal strength is good, I’m all ears.
Hi Steven. I think you could try the following checks to see why there’s no voltage at J557.
1 - use a 1+ Megohm meter or scope to confirm that the FM IF dc voltage signal strength feed is present at J554 - it should be more positive on strong FM stations, I”d expect a couple volts. If you like I will make a measurement on my 2230 for you.
2 - try playing with pot R561 - maybe it’s set on a corroded spot and needs to be jiggled and then cleaned. This pot was set at the factory so you should return it to its original position.
3 - confirm that +12 vdc supply voltage is present at the collector of H553.
4 - try to isolate failed components or connections by making dc signal level readings at the component level in the signal path starting at J554 and ending at J557. Use a 1+ Megohm meter or scope. All dc signal levels should have less audio ripple as you move from J554 to J557.
5 - with the Function Select rotary switch set to anything other than FM you should be able to check the B-E and B-C junctions of H553 without removing it from the pc board.
6 - the meter or the electrolytic capacitor around it may be shorted.
Good luck. And thanks for the correction to my write-up. I’ve added some clarifications to that sentence.
1 - use a 1+ Megohm meter or scope to confirm that the FM IF dc voltage signal strength feed is present at J554 - it should be more positive on strong FM stations, I”d expect a couple volts. If you like I will make a measurement on my 2230 for you.
2 - try playing with pot R561 - maybe it’s set on a corroded spot and needs to be jiggled and then cleaned. This pot was set at the factory so you should return it to its original position.
3 - confirm that +12 vdc supply voltage is present at the collector of H553.
4 - try to isolate failed components or connections by making dc signal level readings at the component level in the signal path starting at J554 and ending at J557. Use a 1+ Megohm meter or scope. All dc signal levels should have less audio ripple as you move from J554 to J557.
5 - with the Function Select rotary switch set to anything other than FM you should be able to check the B-E and B-C junctions of H553 without removing it from the pc board.
6 - the meter or the electrolytic capacitor around it may be shorted.
Good luck. And thanks for the correction to my write-up. I’ve added some clarifications to that sentence.
Steven Tate
CEO Flat Forehead Soc.
I have done some of those things, but I was kind of random in my testing as a I tried to figure out the circuit. But I will go back and be a little more orderly about it. The meter is OK because it works fine in AM mode. I do remember testing DC at J208, which is the same as J554. I compared the voltage to a 2245 I had. It’s been a couple of weeks, but I think I was getting about 200mV on a strong station on the 2230, and maybe 800mV on the 2245. I wondered if that difference might have been keeping H553 from going ON, thus nothing out at J557. But tracking back in P200, I cant find a bad component or where my voltage should be going higher. I definitely had 12V on H553 collector. It would be helpful to know what max voltage you get at H554 on your 2230. Thanks a bunch for the suggestions!
Steve
Steve
Hi Steven here are vdc measurements I made at J554 and response of the Sig Strength meter with a FM RF signal generator at the antenna terminals:
RF input J554 Meter
0 uV 0 v 0%
3 uV 0.27 v 0%
10 uV 0.55 v 0%
30 uV 0.75 v 10 %
100 uV 0.85 v 20%
300 uV 0.95 v 35%
1000 uV 1.1 v 50%
3000 uV 1.75 v 55%
10,000uV 1.2 v 60 %
Also with a clear FM station (the strongest I can get in the basement)
J554 Meter
1.1 v 50%
I can see that the J554 voltage response to RF input level flattens out as the RF level increases. I think this is due to how the signal at J554 is generated - it is a mix of the rectified and smoothed outputs of four FM IF circuits on P200. The mix is made at the junction of R248, R256, R255 and R254, and is routed to J554 via R258. R254 is a positive output from the AGC amplifier H206 which is not a clipping stage. The other 3 sources to the mix are from IF stages that are intentionally increasingly clipped (for example, by H207 and H208) as the RF signal strength increases. I think this might explain the flattened response. I thank you for suggesting these measurements because I think I now understand the reason for this mixer. It could be it was tailored using the various values for those mixing resistors to give the desired response characteristic for the Signal Strength meter. Interesting. Of course I could be wrong.
Also I can see that there is a minimum threshold of RF signal strength below which the meter is at 0%. I think this is due to H553’s turn-on threshold as there is no positive bias on its base.
Hope this helps.
RF input J554 Meter
0 uV 0 v 0%
3 uV 0.27 v 0%
10 uV 0.55 v 0%
30 uV 0.75 v 10 %
100 uV 0.85 v 20%
300 uV 0.95 v 35%
1000 uV 1.1 v 50%
3000 uV 1.75 v 55%
10,000uV 1.2 v 60 %
Also with a clear FM station (the strongest I can get in the basement)
J554 Meter
1.1 v 50%
I can see that the J554 voltage response to RF input level flattens out as the RF level increases. I think this is due to how the signal at J554 is generated - it is a mix of the rectified and smoothed outputs of four FM IF circuits on P200. The mix is made at the junction of R248, R256, R255 and R254, and is routed to J554 via R258. R254 is a positive output from the AGC amplifier H206 which is not a clipping stage. The other 3 sources to the mix are from IF stages that are intentionally increasingly clipped (for example, by H207 and H208) as the RF signal strength increases. I think this might explain the flattened response. I thank you for suggesting these measurements because I think I now understand the reason for this mixer. It could be it was tailored using the various values for those mixing resistors to give the desired response characteristic for the Signal Strength meter. Interesting. Of course I could be wrong.
Also I can see that there is a minimum threshold of RF signal strength below which the meter is at 0%. I think this is due to H553’s turn-on threshold as there is no positive bias on its base.
Hope this helps.
Steven Tate
CEO Flat Forehead Soc.
I have a very early serial number 2230 (#1309) that I have been using to try to compare voltages. The problem is that P200 and P550 are more rudimentary than the later models on both boards, so many components are missing. Makes it hard to compare. I also have a 2245 with similar circuitry that I have been comparing voltages with. What I'm finding is that the problem seems to be on P200. I get 0.8V at J208 with a strong station on the 2245. I get 0.2V on the 2230 with no meter deflection. I believe 0.2V is not enough to turn on H553, so I get 0V at the emitter of 553 whether the station is strong or weak. I changed H553 to see if it could be a bad transistor, but got the same result, so put the old one back in.
What I'm finding in P200 is that everything feeding into J208 (which sends voltage to J554 that is processed to run the meter from J557) is roughly 1/4 the voltage that I get at the same spots on another 2230 and a 2245. I just don't have enough circuit design knowledge to understand what is causing that. All of the spots in the P200 schematic measure 1/4 of what is expected (green circles). All transistors test with proper ECB voltages. There are many germanium and silicon diodes, and all test the proper voltage drop. I've tested every resistor in that area of the schematic, and all test near spec. Again, FM reception is pretty good (although no stereo), but I get near 0V out of H553, I think because P200 only puts out 0.2V at J208. Grrrrrr!
What I'm finding in P200 is that everything feeding into J208 (which sends voltage to J554 that is processed to run the meter from J557) is roughly 1/4 the voltage that I get at the same spots on another 2230 and a 2245. I just don't have enough circuit design knowledge to understand what is causing that. All of the spots in the P200 schematic measure 1/4 of what is expected (green circles). All transistors test with proper ECB voltages. There are many germanium and silicon diodes, and all test the proper voltage drop. I've tested every resistor in that area of the schematic, and all test near spec. Again, FM reception is pretty good (although no stereo), but I get near 0V out of H553, I think because P200 only puts out 0.2V at J208. Grrrrrr!
Hi Steven. You said that “everything feeding into J208 ... is roughly 1/4 the voltage that I get at the same spots on another 2230”, also that “FM reception is pretty good (although no stereo)”.
This suggests to me that the problem may be a fault in the FM antenna input, RF or IF signal stages that is reducing your receiver’s FM sensitivity. Here is why: My 2230’s FM antenna is in the basement. Some stations come in clear in mono without any movement of the signal strength meter, but are too weak to present in stereo, meaning that H303 is OFF. This sounds like your observations, possibly?
This suggests to me that the problem may be a fault in the FM antenna input, RF or IF signal stages that is reducing your receiver’s FM sensitivity. Here is why: My 2230’s FM antenna is in the basement. Some stations come in clear in mono without any movement of the signal strength meter, but are too weak to present in stereo, meaning that H303 is OFF. This sounds like your observations, possibly?
Steven Tate
CEO Flat Forehead Soc.
Could be. Just to rule out the transistors in the IF amp, I replaced H201-H205. I still have the same relatively strong reception with no stereo and no meter movement. This is a new to me receiver. My next step will be to touch up the alignment and see if that gives me a stronger signal. It’s just strange to me that I can pick up stronger signals very well, with very quiet backgrounds, and can’t get any decent voltage at J208.
USMC Spike
Well-Known Member
I didn't read through the thread, however what the site doesn't know, it doesn't know.
May I suggest two things.
1. Please save as file type .doc. Why Lowest common denominator and it just plain works.
2. When you go to upload the file do the following, shhhhh don't tell the site.
2a. Remove (delete) the dot before the .doc; AFTER you saved the file and before you upload here.
2b. Then after the doc add the following .pdf
Example the file might be named something like this:
Saved file: 2230writeup_rev2.doc
Renamed file: 2230writeup_rev2_doc.pdf
Upload the file.
Then for Everyman,
Download file: 2230writeup_rev2_doc.pdf
Change file name back: 2230writeup_rev2.doc
Any version of word will open up the file.
Last edited:
USMC Spike
Well-Known Member
The PDF maker you are using there should have
an tn option of a Searchable PDF.
Instead of everything being a PDF Graphic Image,
only the pics are images and the text is treated as text.
This feature makes PDFs a manageable size.
To test, find a pdf with text in it and click on a text page, if the whole page turns blue
every page is treated as a graphic image (very large) and the document will be very large.
If you can click on a word and only it turns blue, it is a searchable text pdf and only
graphic images in the PDF will be large, the rest will be treated as text (small by comparison).
Hope this helps,
an tn option of a Searchable PDF.
Instead of everything being a PDF Graphic Image,
only the pics are images and the text is treated as text.
This feature makes PDFs a manageable size.
To test, find a pdf with text in it and click on a text page, if the whole page turns blue
every page is treated as a graphic image (very large) and the document will be very large.
If you can click on a word and only it turns blue, it is a searchable text pdf and only
graphic images in the PDF will be large, the rest will be treated as text (small by comparison).
Hope this helps,
USMC Spike
Well-Known Member
I know, four years since last post.
QUESTION:
Does any one have a Modern version of the 2230 Service manual?
An original?
A good clean scan?
Or
Have good clean drawing of the boards, etc in the manual?
I've got a good flatbed scanner and I know how to use it.
If someone trusts me enough to send it to me and I'll send it
back when I finish scanning it.
I would do the following scans for every page:
PDF scan, hi rez, scanable text.
PDF scan, hi rez, pdf image.
OCR scan, to pick up all the words.
JPEG scan to have editable graphics.
I could then assemble a word doc and sent it around for
edits, (post here as ".pdf" and YOU make the change)
additions to the knowledge base, make it simpler to
follow along on that stuff that seems to give folks WTF
moments, etc.
I've also been developing "New Media" where you had to use
a Mini computer PDP-11, + with very sophisticated interfaces
and lots of sophisticated software (think big $$$$$$$) to teach
people how to do "stuff."
The only current Issue I have is with ADOBE and HP screwing everybody
around! Adobe wants everyone to use their cartoon versions of acrobat/pdf maker
so they can spy (er, support) on everything you do. HP took the worlds largest
retailer to task (wally world) to force them to stop marketing their house brand
of ink and force every one to use HP Ink ($$$$$). HP downloaded code
to their printers so if HP doesn't recognize the cartrige, YOU CANNOT PRINT.
It's the same scheisse that Bill Gates used to pull--that is when his pants were up.
So right now I can't print pages of a PDF without making a screen print,
then resizing either saving as JPEG or putting many JPEGs into
either Word or PowerPoint.
This was the last version of acrobat/pdf maker that would read some
older uncleSam documents, that uncleSam would rather us PFCs (Poor Effing Civilians)
not have access to any longer.
It fits right along with what is happening
in our country and around the world including various initials depending on
branch letters of the alphabet: abc, nbc, sports channel, what you need to identify it,
make it safe etc; or if there are disturbances/protests etc, what steps
are taken to quell them, at local, state, national levels
including strategy, tactics and laws for marshalls of the wild west.
The big new PDF thing removes all the old PDF information from you
'puter and if you go back and reinstall old version you can read or print.
Other than the issues I outlined in the last five paragraphs,
I have no problems putting the 2230 editable doc together
and sending it around. For those of you without prior military
backgrounds find someone you can talk to in person and
they could probably tell you what is meant. For those of
you with service backgrounds, you'll figure it out.
I have a can do attitude, PM me with stuff to be added into
the 2230 service manual you'd like to see, read, and have
access to.
All the best,
PS - Everyman, don't mind me, I'm naturally a PITA.
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Hi Steve
where did you get that schematic from - it is a lot of work to rebuid them in simulators
I discovered MICROCAP 12 - great tool.
Robin
Steven Tate
CEO Flat Forehead Soc.
It’s in the AK Database as 2230 Hi-Res Schematic.
http://akdatabase.com/AKview/albums/userpics/10007/Marantz 2230 Schematic HiRes ALL.pdf
I have found one small error. H553 is labeled H563..
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