Marantz 1122DC Restoration
- Thread starter MBuras
- Start date
MBuras
Restoration is an Addiction
Undocumented e-caps across the AC/DC switch on the back panel. I didn't notice these before I did my original order. A pair of 1uf 50v bi-polar Elna's across the terminals. Closest thing I had laying around was some big Panasonic polypropylene's. I know it's overkill but they were handy. And the lead spacing actually worked out pretty well. 
MBuras
Restoration is an Addiction
P400 Phono & Amp Selector Board
This is pretty much the only board on the left side of the transformer when looking at the unit from the front. Tons of slack on the attached wires to freely move it around. Not like those crazy packed 22xx units.
Here is the before pic with the angle bracket removed. That huge local filter cap (the axial) was mounted to the bracket I removed. Imagine a cap being so big they couldn't even fit it on the planned space on the board. Ha!
As I dug into this board you'll notice they used a ridiculous amount of everyones favorite glue on those low leakage caps to the right. I can only assume to keep them bent over but they're tiny caps and not really going anywhere. Hmmmm....
Those 2 ceramic discs on the right side are undocumented. No position numbers. Looks like they were added at the factory but you usually see them on the underside. Not the last mystery with this unit.
And here's the finished board. Well, almost finished. Guess which cap I forgot to order? Yep. The biggest one there. That 160v/470uf local filter. Doh!!! Luckily I was placing an order for another receiver and tagged it on. Will get a new pic up when it arrives and gets installed.
And a pic of the missing local filter cap installed.
And here are the details. None of the original parts were failing or damaged. Replacement was a personal choice. The only real change in spec was the RIAA low leakage caps (documented below). I also thought the cataloging of the board could help future techs looking for details on this unit.
C401/402 - 50v/2.2uf input filter low leakage e-caps were replaced with WIMA MKS2 series polyester films of the same value. Used these instead of my favorite Panasonics due to space constraints.
C403/404 - 50v/20pf ceramics [error in manual says 10pf] and were replaced with Kemet 5% C0G ceramics of the same value with slightly higher voltage.
C405/406 - 16v/100uf low leakage e-caps. Thanks to @Leestereo I know these are the DC cutoff caps for the RIAA feedback and best served with a bipolar cap. The manual said 16v/33uf but I ended up with Nichicon ES series 16v/47uf (the big greenies in the picture above).
C409/410 - 10v/47uf electrolytics. I ended up going with Elna Silmic II 16v/47uf caps here but in the future noted the need for Nichicon UPW series or similar with better ESR ratings.
C411/412 - 50v/10pf ceramics [error in manual says 20pf] and were replaced with Kemet 5% C0G ceramics of the same value with slightly higher voltage.
C413/414 - 50v/3.3uf low leakage electrolytics. These were replaced with WIMA MKS2 series polyester films of the same value.
C415/416 - 50v/4.7uf low leakage electrolytics. These were replaced with WIMA MKS2 series polyester films of the same value.
C417/418 - 50v/100pf ceramics were replaced with Kemet 5% C0G ceramics of the same value with slightly higher voltage.
C423/424 - 50v/5600pf films were replaced with Kemet PHE426 series polypropylene films of the same value.
C425/426 - 50v/100pf ceramics were replaced with Kemet 5% C0G ceramics of the same value with slightly higher voltage.
C427 - 100v/470uf axial electrolytic. This was the big local filter mounted up off the board. No reason for that mounting other than space but newer caps are much smaller and the one I have coming in will fit on the board. It's a Nichicon UPW series 100v/470uf electrolytic cap. Also note in the before picture that the board marking for positive is incorrect.I'll mount the new cap in reverse of the board markings when it arrives. This seems to be an issue across many boards for Marantz.
Q401/402/403/404 - 2SC2240 to-92 transistors were replaced with Fairchild KSC1845FTA's. Same pinout. Gain matched.
Q405/406 - 2SC1775 to-92 transistors were replaced with Fairchild KSC1845FTA's. Same pinout. Gain matched.
R436 - 2.7K/0.5W resistor was replaced with the same value KOA Speer 5% carbon film resistor.
I know 1% metal films are the gold standard but I used them once and perceive some harshness in sound so I'm gun shy. The 5% carbon films are really good quality, much smaller than comparable components from the 1970's, and have the same color coding bands for easy identification.
That's it. Again, I'll post a new picture when that filter cap gets in. Oh, and for anyone following that might follow this later just be aware the big 4.7uf WIMA on the front left corner had to be tilted slightly to accommodate the selector shaft coupler. Not a huge deal but worth noting.
This is pretty much the only board on the left side of the transformer when looking at the unit from the front. Tons of slack on the attached wires to freely move it around. Not like those crazy packed 22xx units.
Here is the before pic with the angle bracket removed. That huge local filter cap (the axial) was mounted to the bracket I removed. Imagine a cap being so big they couldn't even fit it on the planned space on the board. Ha!
As I dug into this board you'll notice they used a ridiculous amount of everyones favorite glue on those low leakage caps to the right. I can only assume to keep them bent over but they're tiny caps and not really going anywhere. Hmmmm....
Those 2 ceramic discs on the right side are undocumented. No position numbers. Looks like they were added at the factory but you usually see them on the underside. Not the last mystery with this unit.
And here's the finished board. Well, almost finished. Guess which cap I forgot to order? Yep. The biggest one there. That 160v/470uf local filter. Doh!!! Luckily I was placing an order for another receiver and tagged it on. Will get a new pic up when it arrives and gets installed.
And a pic of the missing local filter cap installed.
And here are the details. None of the original parts were failing or damaged. Replacement was a personal choice. The only real change in spec was the RIAA low leakage caps (documented below). I also thought the cataloging of the board could help future techs looking for details on this unit.
C401/402 - 50v/2.2uf input filter low leakage e-caps were replaced with WIMA MKS2 series polyester films of the same value. Used these instead of my favorite Panasonics due to space constraints.
C403/404 - 50v/20pf ceramics [error in manual says 10pf] and were replaced with Kemet 5% C0G ceramics of the same value with slightly higher voltage.
C405/406 - 16v/100uf low leakage e-caps. Thanks to @Leestereo I know these are the DC cutoff caps for the RIAA feedback and best served with a bipolar cap. The manual said 16v/33uf but I ended up with Nichicon ES series 16v/47uf (the big greenies in the picture above).
C409/410 - 10v/47uf electrolytics. I ended up going with Elna Silmic II 16v/47uf caps here but in the future noted the need for Nichicon UPW series or similar with better ESR ratings.
C411/412 - 50v/10pf ceramics [error in manual says 20pf] and were replaced with Kemet 5% C0G ceramics of the same value with slightly higher voltage.
C413/414 - 50v/3.3uf low leakage electrolytics. These were replaced with WIMA MKS2 series polyester films of the same value.
C415/416 - 50v/4.7uf low leakage electrolytics. These were replaced with WIMA MKS2 series polyester films of the same value.
C417/418 - 50v/100pf ceramics were replaced with Kemet 5% C0G ceramics of the same value with slightly higher voltage.
C423/424 - 50v/5600pf films were replaced with Kemet PHE426 series polypropylene films of the same value.
C425/426 - 50v/100pf ceramics were replaced with Kemet 5% C0G ceramics of the same value with slightly higher voltage.
C427 - 100v/470uf axial electrolytic. This was the big local filter mounted up off the board. No reason for that mounting other than space but newer caps are much smaller and the one I have coming in will fit on the board. It's a Nichicon UPW series 100v/470uf electrolytic cap. Also note in the before picture that the board marking for positive is incorrect.I'll mount the new cap in reverse of the board markings when it arrives. This seems to be an issue across many boards for Marantz.
Q401/402/403/404 - 2SC2240 to-92 transistors were replaced with Fairchild KSC1845FTA's. Same pinout. Gain matched.
Q405/406 - 2SC1775 to-92 transistors were replaced with Fairchild KSC1845FTA's. Same pinout. Gain matched.
R436 - 2.7K/0.5W resistor was replaced with the same value KOA Speer 5% carbon film resistor.
I know 1% metal films are the gold standard but I used them once and perceive some harshness in sound so I'm gun shy. The 5% carbon films are really good quality, much smaller than comparable components from the 1970's, and have the same color coding bands for easy identification.
That's it. Again, I'll post a new picture when that filter cap gets in. Oh, and for anyone following that might follow this later just be aware the big 4.7uf WIMA on the front left corner had to be tilted slightly to accommodate the selector shaft coupler. Not a huge deal but worth noting.
Last edited:
MBuras
Restoration is an Addiction
PS00 Speaker Switch Board
Really not much to this one. In fact the 4 big resistors were in great shape but as usual, while I'm in there might as well freshen things up.
And here's the finished board. Almost hard to tell it's been worked on. The newer metal oxide resistors haven't changed much in size like the carbon films and capacitors.
RS01/02 - 330 ohm/2 watt metal oxide resistors were replaced with KOA Speer 5% metal oxide resistors with the exact same specs.
RS03/04 - 150 ohm/1 watt metal oxide resistors were replaced with KOA Speer 5% metal oxide resistors with the exact same specs.
Really not much to this one. In fact the 4 big resistors were in great shape but as usual, while I'm in there might as well freshen things up.
And here's the finished board. Almost hard to tell it's been worked on. The newer metal oxide resistors haven't changed much in size like the carbon films and capacitors.
RS01/02 - 330 ohm/2 watt metal oxide resistors were replaced with KOA Speer 5% metal oxide resistors with the exact same specs.
RS03/04 - 150 ohm/1 watt metal oxide resistors were replaced with KOA Speer 5% metal oxide resistors with the exact same specs.
MBuras
Restoration is an Addiction
P850 Power Supply Board
This board has fairly free access but can be mildly fiddly because there are so many wires attached. I didn't mind but you might want to disconnect more than me.
Here's the before. This board took the brunt of the dust and dirt inside the case. And plenty more of our favorite indestructible glue.
This board deals with some higher voltages that your standard 22xx Marantz receiver so you'll quickly notice that meaty stock gray cap toward the front of the board. Interesting that the rectifier is also mounted on the power board as well as the inbound filters. Usually those are hidden somewhere else in the chassis.
Here are the finished photos. Everything was cleaned and replaced with fresh new components.
And here are the details. None of the original parts were failing or damaged, well maybe some of the caps were looking a little overworked. Replacement was a personal choice. The only real changes were in the uf and voltage on some of the caps in order to provide better ripple and esr numbers. I also thought the cataloging of the board could help future techs looking for details on this unit.
C851/852 - primary filter caps - 50v/10,000uf electrolytic caps were replaced with Cornell Dubiller 383LX series 63v/15000uf electrolytics. These would normally not be my first choice but requirements for width and lead spacing meant this was literally the only series available from Mouser or DigiKey. And neither of them listed the actual lead spacing or size so I had to dive into the data sheets. Definitely my most challenging cap search yet!
C853 - 160v/220uf electrolytic snap in capacitor replaced with Nichicon LGU series snap in electrolytic rated at 160v/680uf giving a substantially better numbers in esr and ripple for this position.
C854 - 25v/100uf electrolytic cap replaced with Nichicon UPW series rated at 50v/220uf.
C856 - 100v/10uf electrolytic cap replaced with Nichicon UPW series rated at 100v/22uf.
C857 - 16v/47uf electrolytic cap replaced with Nichicon UPW series rated at 35v/47uf.
C858 - 16v/220uf electrolytic cap replaced with Nichicon UPW series rated at 35v/220uf.
C859 - 50v/22uf electrolytic cap replaced with Nichicon UPW series rated at 50v/47uf.
C860 - 100v/100uf electrolytic cap [not documented in service manual!] replaced with Nichicon UPW series rated at 100v/220uf.
C861 - 50v/22uf electrolytic cap replaced with Nichicon UPW series rated at 50v/47uf.
C863 - 160v/10uf electrolytic cap [board not marked with C number/placed over diode markings] replaced with Nichicon UPW series rated at 160v/10uf.
L851 - MS4U 24v relay replaced with Omron MY4-02DC24. This is the same relay as used in some of the later 22xxB receivers. Clip the last row of 4 leads as well as 2 of the inner leads up front. Make sure it looks the same as the one you're replacing.
Q852/853/854 - W06C diodes replaced with Fairchild UF4007 diodes.
Q855 - 1S1555 diode replaced with Fairchild 1N4148 diode.
Q856/857/858 - 2SC945 to-92 transistors replaced with Fairchild KSC2383YTA transistors. Same pinout.
Q859 - 2SC1913 to-220 transistor replaced with Fairchild KSC2073TU. Same pinout [very important here because of mounting to heatsink]
Q860 - 2SC1775 to-92 transistor replaced with Fairchild KSC1845FTA transistor. Same pinout.
Q861 - WZ-240 zener diode [actually mounted below the board and marked space] replaced with Fairchild 1N5252B zener diode.
Q862 - 1S1555 diode replaced with Fairchild 1N4148 diode.
Q863 - W06C diode replaced with Fairchild UF4007 diode.
R851 - 47 ohm/1 watt resistor [manual error says 100 ohm] replaced with KOA Speer metal oxide 5% resistor with same values.
R863/864 - 5.6K ohm/0.5 watt resistors replaced with KOA Speer carbon film 5% resistors with same values.
R866 - 5.6K ohm/1 watt resistor replaced with KOA Speer metal oxide 5% resistor with same values.
Next up is partial reassembly and power up testing. Assuming that goes well I'm on to the power amp board which has more parts than all of these others combined. It's massive but some of the modern parts I'm using will save space and hopefully provide better cooling. At least that's my justification.
This board has fairly free access but can be mildly fiddly because there are so many wires attached. I didn't mind but you might want to disconnect more than me.
Here's the before. This board took the brunt of the dust and dirt inside the case. And plenty more of our favorite indestructible glue.
This board deals with some higher voltages that your standard 22xx Marantz receiver so you'll quickly notice that meaty stock gray cap toward the front of the board. Interesting that the rectifier is also mounted on the power board as well as the inbound filters. Usually those are hidden somewhere else in the chassis.
Here are the finished photos. Everything was cleaned and replaced with fresh new components.
And here are the details. None of the original parts were failing or damaged, well maybe some of the caps were looking a little overworked. Replacement was a personal choice. The only real changes were in the uf and voltage on some of the caps in order to provide better ripple and esr numbers. I also thought the cataloging of the board could help future techs looking for details on this unit.
C851/852 - primary filter caps - 50v/10,000uf electrolytic caps were replaced with Cornell Dubiller 383LX series 63v/15000uf electrolytics. These would normally not be my first choice but requirements for width and lead spacing meant this was literally the only series available from Mouser or DigiKey. And neither of them listed the actual lead spacing or size so I had to dive into the data sheets. Definitely my most challenging cap search yet!
C853 - 160v/220uf electrolytic snap in capacitor replaced with Nichicon LGU series snap in electrolytic rated at 160v/680uf giving a substantially better numbers in esr and ripple for this position.
C854 - 25v/100uf electrolytic cap replaced with Nichicon UPW series rated at 50v/220uf.
C856 - 100v/10uf electrolytic cap replaced with Nichicon UPW series rated at 100v/22uf.
C857 - 16v/47uf electrolytic cap replaced with Nichicon UPW series rated at 35v/47uf.
C858 - 16v/220uf electrolytic cap replaced with Nichicon UPW series rated at 35v/220uf.
C859 - 50v/22uf electrolytic cap replaced with Nichicon UPW series rated at 50v/47uf.
C860 - 100v/100uf electrolytic cap [not documented in service manual!] replaced with Nichicon UPW series rated at 100v/220uf.
C861 - 50v/22uf electrolytic cap replaced with Nichicon UPW series rated at 50v/47uf.
C863 - 160v/10uf electrolytic cap [board not marked with C number/placed over diode markings] replaced with Nichicon UPW series rated at 160v/10uf.
L851 - MS4U 24v relay replaced with Omron MY4-02DC24. This is the same relay as used in some of the later 22xxB receivers. Clip the last row of 4 leads as well as 2 of the inner leads up front. Make sure it looks the same as the one you're replacing.
Q852/853/854 - W06C diodes replaced with Fairchild UF4007 diodes.
Q855 - 1S1555 diode replaced with Fairchild 1N4148 diode.
Q856/857/858 - 2SC945 to-92 transistors replaced with Fairchild KSC2383YTA transistors. Same pinout.
Q859 - 2SC1913 to-220 transistor replaced with Fairchild KSC2073TU. Same pinout [very important here because of mounting to heatsink]
Q860 - 2SC1775 to-92 transistor replaced with Fairchild KSC1845FTA transistor. Same pinout.
Q861 - WZ-240 zener diode [actually mounted below the board and marked space] replaced with Fairchild 1N5252B zener diode.
Q862 - 1S1555 diode replaced with Fairchild 1N4148 diode.
Q863 - W06C diode replaced with Fairchild UF4007 diode.
R851 - 47 ohm/1 watt resistor [manual error says 100 ohm] replaced with KOA Speer metal oxide 5% resistor with same values.
R863/864 - 5.6K ohm/0.5 watt resistors replaced with KOA Speer carbon film 5% resistors with same values.
R866 - 5.6K ohm/1 watt resistor replaced with KOA Speer metal oxide 5% resistor with same values.
Next up is partial reassembly and power up testing. Assuming that goes well I'm on to the power amp board which has more parts than all of these others combined. It's massive but some of the modern parts I'm using will save space and hopefully provide better cooling. At least that's my justification.
MBuras
Restoration is an Addiction
P700 Power Amp
Last board. And the most grueling just from the number of components on the board. But all are relatively easy access.
Before picture.
Here you can see down in between the board and the heatsink. Specifically there are 4 biasing diodes tucked into the heatsink (1 left, 1 right, and 2 in the middle) that you need to pull out with a tweezers before the board will flip forward.
And here is what you get once the board is flipped forward. Another smaller board where all 8 output transistors are mounted. Well their leads at least.
And then once you desolder all 24 leads you can finally pull the amp board away from the heatsink.
I was pretty anxious to get this project over with so the rest will be word heavy as I just plain forgot to document most of it. Sorry.
All the outputs were pulled form the heatsink as well as the brackets. The other side of the heatsink was covered with years of smoke & dust so it got a bath in hot dishwater for a few hours and then air dried outside all day. Worked very well to clean it up with little effort.
All output transistors were cleaned with 91% ipa, new thermal grease applied and remounted with original mica. I usually like to change out the mica but wasn't expecting these interesting "batwing" transistors and their rectangle mica. Might have to stock some of those moving forward.
Below is the board as I documented it. A few question marks still remain and I'll note those. None of these parts had to be replaced nor would I suggest you do it. Simply posted here to catalog this particular Marantz unit should someone need the info at a future date.
C701/702 - 50v/100pf C0G ceramics [manual error notes them as film]. Even though these were already C0G ceramics I replaced them with the same because modern replacements are about 1/10 the size. EDIT: 4/2021 - these may be 10pf in your amp. Check before replacing.
C703/704 - 50v/1600pf films were replaced with the same value in the Nichicon QYX series of polyester films.
C705/706 - 50v/0.047 films were replaced with the same value in the WIMA MKP2 series of polypropylene films.
C707/708 - 35v/22uf electrolytic capacitors were replaced with similar value Nichicon UPW series.
C709/710 - 500v/50pf ceramics were replaced with the same value Kemet 5% C0G ceramics.
C711/712/713/714 - 100v/0.1uf films were replaced with the same value WIMA MKP2 polypropylene films.
C715/716 - 35v/22uf electrolytic capacitors [manual error notes 100v] were replaced with similar value Nichicon UPW series.
C717/718 - ??v/300pf ceramics [manual error says film & doesn't note voltage] were replaced with 100v/300pf Kemet 5% C0G ceramics.
C719/720 - ??v/270pf ceramics [manual error says film & doesn't note voltage] were replaced with 100v/270pf Kemet 5% C0G ceramics. Also note these are actually mounted on the board where R757/R758 should be.
C721/722 - 50v/0.047 films were replaced with the same value WIMA MKP2 polypropylene films.
C723/724 - 50v/10uf electrolytic capacitors were replaced with similar value Nichicon UPW series.
C725/726/727/728/729/730 - 100v/0.1uf films were replaced with same value WIMA MKP2 polypropylene films.
C731/732/733/734 - 63v/47uf electrolytic capacitors were replaced with similar value Nichicon UPW series.
CT01/02/03/04 - 50v/0.01uf films were replaced with same value Kemet MMK series polyester films.
CT09/10/11/12 - 16v/22uf low leakage electrolytic capacitors were replaced with similar value Nichicon UKL series.
Q703/704/705/706/707/708/715/716 - 2SC1775 to-92 transistors were replaced with Fairchild KSC1845FTA. Same pinout.
Q709/710/711/712/713/714/717/718/719/720 - 2SA872 to-92 transistors were replaced with Fairchild KSA992FBU. Same pinout.
Q721/722 - 2SA914 to-126 transistors were replaced with Fairchild KSA1381ESTU. Same pinout.
Q723/724 - 2SC1953 to-126 transistors were replaced with Fairchild KSC3503DSTU. Same pinout.
Q725/726 - 2SC1913 to-220 transistors were replaced with Fairchild KSC2073TU. Same pinout.
Q727/728 - 2SA913 to-220 transistors were replaced with Fairchild KSA940TU. Same pinout.
Q729/730/735/736 - 1S1555 diodes were replaced with Fairchild 1N4148.
Q737/738/739/740/753/754 - 1S2471 diodes were replaced with Fairchild 1N4148.
Q749/750/751/752 - W06B diodes were replaced with Fairchild UF4005.
QT01/02 - 2SC735 to-92 transistors were replaced with Fairchild 2N3904BU. Different pinout that originals.
QT03/04 - 2SA562 to-92 transistors were replaced with Fairchild KSA733CYTA. Same pinout.
QT05/06/07/08/09/10/11/12 - 1S1555 diodes were replaced with Fairchild 1N4148.
QT13/14/15/16 - 1S2471 diodes were replaced with Fairchild 1N4148.
R727/728 - 2.2K ohm/half watt oxide resistors [manual error notes quarter watt] replaced with same value KOA Speer 5% metal oxide.
R729/730 - 1.5K ohm/half watt oxide resistors [manual error notes quarter watt] replaced with same value KOA Speer 5% metal oxide.
R739/740 - 22K trimmers replaced with Bourns single turn trimmer [side slot] with a 25K value as 22K was not available.
R769/770 - 5.6K ohm/1 watt oxide resistors replaced with same value KOA Speer 5% metal oxide.
R779/780/781/782 - 24 ohm/half watt resistors not replaced at this time. Manual says half watt but these look closer to 1 watt. Would probably go with 1 watt to be safe or check circuit for dissipation needs.
R787/788/789/790/791/792/793/794 - 0.33 ohm/3 watt cement filled block emitter resistors. Replaced with same value Vishay 5% wire wound. Some worry about inductance with wire wound replacements but here's the thread that claims otherwise by at least one member I trust (I'm sure others are trustworthy as well I just don't know their posts as well) http://audiokarma.org/forums/index....-cement-resistor-as-emitter-resistors.644307/
R795/796 - 10 ohm/3 watt oxide resistors replaced with same value KOA Speer 5% metal oxide.
R797/798 - 2.2 ohm/2 watt oxide resistors replaced with same value KOA Speer 5% metal oxide.
RT05/06/07/08 - 3.3K ohm/half watt carbon resistors replaced with same value KOA Speer 5% carbon film.
RT09/10 - 4.3K ohm/half watt carbon resistors replaced with same value KOA Speer 5% carbon film.
And by the time I remembered to take a picture it was already back in the chassis.
Tested with DBT and found a glitch in the amp board. Had one of the small transistors turned around. Fixed that an everything fired up fine. Adjusted DC offset per specs. Very inconvenient test posts by the way.
Last board. And the most grueling just from the number of components on the board. But all are relatively easy access.
Before picture.
Here you can see down in between the board and the heatsink. Specifically there are 4 biasing diodes tucked into the heatsink (1 left, 1 right, and 2 in the middle) that you need to pull out with a tweezers before the board will flip forward.
And here is what you get once the board is flipped forward. Another smaller board where all 8 output transistors are mounted. Well their leads at least.
And then once you desolder all 24 leads you can finally pull the amp board away from the heatsink.
I was pretty anxious to get this project over with so the rest will be word heavy as I just plain forgot to document most of it. Sorry.
All the outputs were pulled form the heatsink as well as the brackets. The other side of the heatsink was covered with years of smoke & dust so it got a bath in hot dishwater for a few hours and then air dried outside all day. Worked very well to clean it up with little effort.
All output transistors were cleaned with 91% ipa, new thermal grease applied and remounted with original mica. I usually like to change out the mica but wasn't expecting these interesting "batwing" transistors and their rectangle mica. Might have to stock some of those moving forward.
Below is the board as I documented it. A few question marks still remain and I'll note those. None of these parts had to be replaced nor would I suggest you do it. Simply posted here to catalog this particular Marantz unit should someone need the info at a future date.
C701/702 - 50v/100pf C0G ceramics [manual error notes them as film]. Even though these were already C0G ceramics I replaced them with the same because modern replacements are about 1/10 the size. EDIT: 4/2021 - these may be 10pf in your amp. Check before replacing.
C703/704 - 50v/1600pf films were replaced with the same value in the Nichicon QYX series of polyester films.
C705/706 - 50v/0.047 films were replaced with the same value in the WIMA MKP2 series of polypropylene films.
C707/708 - 35v/22uf electrolytic capacitors were replaced with similar value Nichicon UPW series.
C709/710 - 500v/50pf ceramics were replaced with the same value Kemet 5% C0G ceramics.
C711/712/713/714 - 100v/0.1uf films were replaced with the same value WIMA MKP2 polypropylene films.
C715/716 - 35v/22uf electrolytic capacitors [manual error notes 100v] were replaced with similar value Nichicon UPW series.
C717/718 - ??v/300pf ceramics [manual error says film & doesn't note voltage] were replaced with 100v/300pf Kemet 5% C0G ceramics.
C719/720 - ??v/270pf ceramics [manual error says film & doesn't note voltage] were replaced with 100v/270pf Kemet 5% C0G ceramics. Also note these are actually mounted on the board where R757/R758 should be.
C721/722 - 50v/0.047 films were replaced with the same value WIMA MKP2 polypropylene films.
C723/724 - 50v/10uf electrolytic capacitors were replaced with similar value Nichicon UPW series.
C725/726/727/728/729/730 - 100v/0.1uf films were replaced with same value WIMA MKP2 polypropylene films.
C731/732/733/734 - 63v/47uf electrolytic capacitors were replaced with similar value Nichicon UPW series.
CT01/02/03/04 - 50v/0.01uf films were replaced with same value Kemet MMK series polyester films.
CT09/10/11/12 - 16v/22uf low leakage electrolytic capacitors were replaced with similar value Nichicon UKL series.
Q703/704/705/706/707/708/715/716 - 2SC1775 to-92 transistors were replaced with Fairchild KSC1845FTA. Same pinout.
Q709/710/711/712/713/714/717/718/719/720 - 2SA872 to-92 transistors were replaced with Fairchild KSA992FBU. Same pinout.
Q721/722 - 2SA914 to-126 transistors were replaced with Fairchild KSA1381ESTU. Same pinout.
Q723/724 - 2SC1953 to-126 transistors were replaced with Fairchild KSC3503DSTU. Same pinout.
Q725/726 - 2SC1913 to-220 transistors were replaced with Fairchild KSC2073TU. Same pinout.
Q727/728 - 2SA913 to-220 transistors were replaced with Fairchild KSA940TU. Same pinout.
Q729/730/735/736 - 1S1555 diodes were replaced with Fairchild 1N4148.
Q737/738/739/740/753/754 - 1S2471 diodes were replaced with Fairchild 1N4148.
Q749/750/751/752 - W06B diodes were replaced with Fairchild UF4005.
QT01/02 - 2SC735 to-92 transistors were replaced with Fairchild 2N3904BU. Different pinout that originals.
QT03/04 - 2SA562 to-92 transistors were replaced with Fairchild KSA733CYTA. Same pinout.
QT05/06/07/08/09/10/11/12 - 1S1555 diodes were replaced with Fairchild 1N4148.
QT13/14/15/16 - 1S2471 diodes were replaced with Fairchild 1N4148.
R727/728 - 2.2K ohm/half watt oxide resistors [manual error notes quarter watt] replaced with same value KOA Speer 5% metal oxide.
R729/730 - 1.5K ohm/half watt oxide resistors [manual error notes quarter watt] replaced with same value KOA Speer 5% metal oxide.
R739/740 - 22K trimmers replaced with Bourns single turn trimmer [side slot] with a 25K value as 22K was not available.
R769/770 - 5.6K ohm/1 watt oxide resistors replaced with same value KOA Speer 5% metal oxide.
R779/780/781/782 - 24 ohm/half watt resistors not replaced at this time. Manual says half watt but these look closer to 1 watt. Would probably go with 1 watt to be safe or check circuit for dissipation needs.
R787/788/789/790/791/792/793/794 - 0.33 ohm/3 watt cement filled block emitter resistors. Replaced with same value Vishay 5% wire wound. Some worry about inductance with wire wound replacements but here's the thread that claims otherwise by at least one member I trust (I'm sure others are trustworthy as well I just don't know their posts as well) http://audiokarma.org/forums/index....-cement-resistor-as-emitter-resistors.644307/
R795/796 - 10 ohm/3 watt oxide resistors replaced with same value KOA Speer 5% metal oxide.
R797/798 - 2.2 ohm/2 watt oxide resistors replaced with same value KOA Speer 5% metal oxide.
RT05/06/07/08 - 3.3K ohm/half watt carbon resistors replaced with same value KOA Speer 5% carbon film.
RT09/10 - 4.3K ohm/half watt carbon resistors replaced with same value KOA Speer 5% carbon film.
And by the time I remembered to take a picture it was already back in the chassis.
Tested with DBT and found a glitch in the amp board. Had one of the small transistors turned around. Fixed that an everything fired up fine. Adjusted DC offset per specs. Very inconvenient test posts by the way.
Last edited:
Steven Tate
CEO Flat Forehead Soc.
Great job and great write-up, Mike! Very informative and a veritable transistor substitution manual. But the main thing it does is ratchet back my desire to refurbish an 1122DC - mainly because of those P700 boards.
I just made a recap of a 1122dc and I just realize the C715 and C716 are 35V 22uF and manual says 22uF 100V. I need to re-order 2 other 35V 22uF !!! The issue : distorsion on left channel. Half of the caps are blown (tested and are below the reading). I am sure it's a transistor but let see if recap will resolve the issue !
Bert 1100
Super Member
Using 100 volt rated caps instead of 35v might not be ideal, but it will not cause any problem at all. The distortion on left channel most likely does not come from this.
But yes I would change them for the 35v ones. Just don't expect it to solve your problem...
Good luck !
Hi !
I recaped the 1122DC (excluded the two filter caps) and replaced 12 transistors (model C1775, C735, A562 and A872A). All is fine now !!
Quick question, do I need to adjust the DC offset? The manual says J860 and J865 (or ground) but I don't know where is it. I will check that tomorrow.
Is there an easier to have a reading for the DC offset?
Thanks !
Guy
I recaped the 1122DC (excluded the two filter caps) and replaced 12 transistors (model C1775, C735, A562 and A872A). All is fine now !!
Quick question, do I need to adjust the DC offset? The manual says J860 and J865 (or ground) but I don't know where is it. I will check that tomorrow.
Is there an easier to have a reading for the DC offset?
Thanks !
Guy
I checked on the service manual for the 1122dc and I saw this :
Q717, Q718, Q719, Q720 needs 2SC872A.
On the post below, MBuras mentionned they are 2SA872A. Is there errors on the Service Manuel regarding these transistors?
I actually have KSA992FTA for my Marantz 140 but will fit to replace these 4 transistors (2 for the blown channel for now)
Thanks,
Guy
Q717, Q718, Q719, Q720 needs 2SC872A.
On the post below, MBuras mentionned they are 2SA872A. Is there errors on the Service Manuel regarding these transistors?
I actually have KSA992FTA for my Marantz 140 but will fit to replace these 4 transistors (2 for the blown channel for now)
Thanks,
Guy
