Marantz 1070 & Marantz 3600 Rebuilds

Marantz 1070 Integrated Amplifier 

Hier ist ein quick write up on a fairly rare integrated, e Marantz 1070! very similar design characterists of the 1030/1060 variants and the final quality step before the 1090 productions.   Ein unique feature on the 1070 short of rarity is the horizontally mounted filter caps under the chassis versus veritcle orientation via clamps on top. Looking  at the chassis space I am not sure why this was chosen, the 1070 does utilize two 10,000 microfarad capacitors for filtering vs the typical two 6800 + or 4700(X2)+ 6800 combination. Another neat little feature is the use of a stepped logarithmic controls for the tone, makes dialing it a pleasure. 

Power Supply P800

The 1070 uses a very simple regulated switching design working off a difference of 40 und 50V rails on the 120VAC version. All the electrolytics were replaced with high temp (105C) long life Panasonic FC's and the common cathode rectifier replaced with adjoined UF4005 to a TO-220 package. 

Phono P400

The phono section is very similar to other 10#0 variants like the 1060. They avoided the use of the 2sc458 transistor here so thats not an issue on these. All electrolytic here were replaced with low impedance, high reliability audio grade PW and KA Nichicons. Noted the original films were left in place as these are typically signature oriented in this design, the ECW PP's just sounded a tad different.

Tone/Preamplifier PE01

All the electrolytic here were replaced with audio grade Elna Silmic II's and Elna BP Cerafines along with Nichicon KA's, the coupling films at CE01/02 were replaced with high quality polypropylene Solen MKP's with astounding results! This particular PCB is sehr easy to open and work on, especially if you remove the tone shielding for optimal work space. 

Driver (single topography)

Again, like the 1060 the 1070 uses a single PCB  Push-Pull topography. Like above the electrolytic were replaced with low impedance high reliability Nichicon PW's and audio grade KA's. Both sets of differentials replaced with matched Hfe KSA992's and glass pack diodes at H705/706 with 4148 diodes in series. The 1070 uses an oddball Omron, which in this case was pulled and contacts cleaned.  The 1070 uses those robust plastic cases potentiometers I prefer so they remained. As pictured its best to remove the heatsink entirely to open-book the P700 PCB, thats a great time to add new MICAs and thermal compound anyhow.  

Audio Adjustments 

Bias

punkten J714 und J716 beim R733 für  10mV

punkten J715 und J717 beim R734 für  10mV

DC

punkten J723 und Boden beim R711 für 0<

punkten J724 und Boden beim R712 für 0<

Regulated PS

 punkten J810 und J811(Boden)  beim R807 für 40Vdc

New hardware and final adjustments and this one impressive little integrated…dare I say maybe even acoustically better than the 1060? hard to judge.

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Marantz 3600 PreAmplifiier 

I also wanted to share some simple photos of a Marantz 3600 preamplifier the customer has paired to it above. The 3600 was mated to the following; Marantz 140, 250 und 510 variants. Produced from 75-79 it has a very simple topography with a plethora of attenuation options, musically very well rounded. 

Heres a few shots of the 3600 we had in with the 1070. One major issue id like to lend is to quality of PCB and tracing. This equipment is old, and the tracing, especially on these bleu PCBs is very delicate. This particular unit required a few hours just to repair the damage performed by someone unfamiliar with proper soldering techniques, fast and moderate heat is the key on these, any significant heat or movement in the component WILL lift the trace and cause eyelet damage.

**PS Id save the below graphic, was a PITA to generate a full diagram from four pages of scans**

All the lytics here were replaced with audio grade PW's  and Elna Silmic II's, the two initial filtering caps were replaced with high temp (105C) long life Pansonic FC's (470 microfarad) along with BC axials. Films were replaced with WIMA (stacked white films)  and Panasonic ECW polypropylenes.  I also want to recommend paying very close attention to the PCB assembly as it uses pin connectors for the PCB communication, these can be easily bent. 

Aker's Marantz 2245 Receiver

Marantz 2245 

UPDATE 11/30/2015

Here is the 2245 back at the customers home, he has installed a new Black Faceplate, the attention to detail on these plates is amazing!

With all the press these are getting lately I wanted to go over a Marantz 2245 receiver that came in from an Audiokarma member. The 2245 was the little brother price quid for the 2270, sharing a very similar driver design (difference in rails and drive power basically) and a very similar pre-amplifier topography.  Built from 71-76' their fairly common units but built extremely well, besides the bias modification thats needed on many serials.

Power Supply P800

Per my usual all the electrolytic here were replaced with Panasonic FR/FC high temp (105C) long life capacitors and all general diodes updated to UF. Common cath/anode to220 packaged rectifiers are omitted from this design but because this particular unit is a European version it includes an extra fusing assemblage. The PCB is a tight fit in this section so cleaning the caustic glue is a major PITA on this model, it took several soakings and still had to chip away. The relay was removed and contact  operations tested and cleaned. 

Phono P700

The 2245 uses the same phono PCB design as the Marantz 2230, which is noted for its incredible phono stage.  Typically the films here would be replaced but in this case the original fat brown films known in Marantz were populated and left.  Original tantalums were replaced with 22 microfarad  Elna Silmics and C713 follows the upgrade from 100UF to 220UF. When working on these phono stages one needs to updated the original failure prone 458 transistors as in this case to a matched Hfe pair of 1845 transistors, also noted glass pack diodes were replaced with 41418 and H409 with two 4148 in series. 

Tone/ Preamplifier P400

The major difference in the 45 vs the 30 pre-amplifier is the use of a 1uf film at R418/419 vs omitted on the 2245, all microfarad values remain the same along with topography.  On this version I populated with all audio grade Nichicon KA and Elna Silmic II's, the coupling c414/415 was originally a mylar upgrade to a polypropylene .22 microfarad film capacitor. 

Drivers P750

This section takes the longest on the 2245 rebuild. Due to serials variations their are some noted modifications and upgrades that should be performed to ensure stabile, reliable operations. 

The biggest point is that most 2245 use an oddball transistor at H760 (circle body TO), this BJT's is fairly unreliable and lends itself to many biasing issues on the 2245 and 2270, if your experiencing biasing issues I recommend attacking this modification. The recommended replacement that works is 2SD669 transistor but this typically only available as NOS, I recommend MJE243 or KSC3503.  Though the ECB pinout is different than the original so leads are recommend and using the existing heat-sink mount. 

H760 acts as a output coupled thermal regulator compensating for thermal variances at H001/2 & H003/4. From an Aker's experiment he (excuser) noted that the driver stages (H758/759) current bias stability  is affected by thermal variations far more than H001/H002 thermal variations and thus elects bias runaway. He discusses compensating with a lower Vbe at the drivers and reducing source voltage  in comparison, to create a constant bias along with isolating thermal governance at  H001/02. Very interesting topics discussed and I recommend reading all the comments. 

I also recommend on the 2245/70 adding a protective device against excessive on/off voltage peaks in case of a catastrophic failure, add a 4004IN diode across the output (TO-3's) H001/2 & H003/4 according to the following; 

Audio Adjustments

Regulated PS P800

-J802 und Boden beim R809 für 35vdc

Bias P750

-punkten +J754 und -J760 beim R763 für 10mV

H001/03 PNP SJ2514 - Cathode zu Emitter und Anode zu Collector w/ 1N4004

H002/04 NPN SJ2513- Kathode zu Collector und Anode zu Emitter w/ 1N4004

Differential pairs at 701/702 were updated with matched Hfe 992's (2SA640) along with the electrolytics here replaced with audio grade Elna Silmic II's and the very large paper film replaced with a high quality Panasonic ECW polypropylene film capacitor. The original mylar film at C763 was also upgrade to a high grade Solen MKP polypropylene film capacitor New Micas and compound applied as well. 

As the right driver stage is pulled I always recommend replacing the filter at this time for more accessibility. The coupling capacitors were replaced with 10,000 microfarad Nichicon Fine Gold capacitors (40mm) which are a perfect drop-in replacement.  I also like to complete the new power switch (7a Eg1018) and Vishay X1Y2 safety cap at this time to complete hardware along with new LED compliment in the main and meters. 

RF Stages

The final boards attacked consists of the RF stages MPX/FM and AM. After the left drive is pulled I like to complete these stages as you have the most work room. The P300/P150 assemblies are stacked, I recommend pulling all the mounting hardware so you can open book the RF PCB modules.  \/

Depopulated capacitors...shit load

Bitte, notiz beim C183 polarity error!

For all RF stages I use  high reliability, low impedance Nichicon PW capacitors. 

Short of the inherent bias flaw the 2245 is an incredibly nice sounding Marantz, very similar IMHO to the 2230 (compare again pre-amp stages) with a solid construction. 

Aker's Marantz 2240 Restoration

Marantz 2240 Receiver 

I thought a write up on this unit would be fun because theirs not a whole lot out there on the 2240, its a fairly limited production series manufactured in 1974 and you don't come across em' often like say the 2245 which is coming on the next posts, the 2240B appears to be available. The 2240 shares a similar phono stage to many of the lower wattage 22XX's series Marantz.

Power Supply P800

One nice little detail on this PCB is unlike the darker/maroon colored PCB's this seems to have a slicker surface and removing caustic glue is much easier! The relay was removed and contacts cleaned along with all new Panasonic FR/FC high temp (105C) long life capacitors which are ideal for switching/regulated power supplies. Also updated were the common cathode TO-220's @ H808/811. We'll be coming back to this board for regulated PS adjustments and DC offset adjustments after the coils. I am currently investigating the updating of the H801/802/803 BJT array used as a voltage regulator for maybe a LM packaged regulation, more to follow on this later….

Phono P400

Again, we've seen this topography on many of the Marantz receivers, their are a few components to notate, such as the failure and noise prone 2SC458 BJT's, which are replaced with Hfe matched 1845 transistors. Also updated is the glass pack diode and H409 to two 4148 diodes in series as you can see from the photo. Electrolytics were replaced with Elna Silmic II audio grades and a axial Nichicon TVX 220 microfarad capacitor along with quality ECW polypropylene at C414/415.

Tone/Pre-Amplifier PE01

I had some fun experimenting with different capacitor compliments in this stage and settled with audio grade Nichicon KA and Elna Silmics for electrolytics. Bi-Polar electrolytics were replaced with two ECW polypropylene 1microfarad film capacitors. The coupling stage CE01/2 were replaced with high quality audio grade Solen polypropylene capacitors as seen at the big black films.  This board has the tone potentiometers attached so now is the best time to clean and lubricate all the phenolic controls here.

  Errors evident on SM: Ce05/06 47/16 should be 4.7 & Ce21/22 33/50 should be 3.3

Drivers P700

Im always happy to see symmetric driver topographies on separate heatsinks and paths, its a sign up superior construction and quality.  The electrolytics were replaced with audio grade Nichicon KA's and low impedance high reliability Nichicon PW's. Differential pair transistors at 701/702 were replaced with Hfe matched 992fbu's transistors. Its important to update differentials pairs, they often elude to significant noise issues prevalent in the driver stage, along with help maintain stabile DC parameters

AUDIO ADJUSTMENTS

REGULATED PS P800

-J804 und Boden @ R806 für 35Vdc

BIAS P700

-Emitterwiderstand punkte J708 und J710 beim R719 für 10mV

DC @ POST RELAY P800 und P700

-Links J809 und Boden 0> 

-Recht J810 und Boden 0>

  New mica and thermal compound applied and that finished up this stage, I do like to note if your not replacing the bias/offset potentiometers make sure you clean them at this stage with a good de-oxit and lubricant such as D-5 faderlube.  I often leave these big white pots, I feel even the precision bourns available do not quite meet up to the robust solid design of these olders ones, if they track appropriately Id advise keeping them. 

The direct coupled filter capacitors were replaced with 40mm 10,000 microfarad Panasonic THA capacitors with new sign terminals for easy installation.  

RF und Hardware

Next we move onto the final RF stages which get all new low impedance high reliability Nichicon PW capacitors. New hardware and lighting  and cleaning up the final shielding which about wraps up this 2240. 

Marantz Model 30 - Upgraded Redux!

Marantz Model 30 Revisited and Upgraded 

I wanted to share about about a very special piece to me. I found this Model 30 a few years ago in just dire straights, boards were amiss and wires everywhere, the RCAs were damaged and catastrophic cascade failures from the driver to protection supply.  Below is a link to the original write up.

http://www.marantzhallo-fi.blogspot.com/2014/11/marantz-model-30-integrated-amplifier.html

 The unit has since regrettably changed hands, but alas found its way back to me for basic general maintenance and decided to run a little with it!

Polypropylene Film Capacitors

The biggest update was replacing the original plastic films with high quality polypropylene (PP) equivalents. I typically go for films if the microfarad value allows because of the superior characteristics of polypropylenes amongst other film dielectrics. PP's tend be more reliable and stable in comparison to response/operating parameters (Drivers) based upon notably lower dissipation factors (DF) and equivalent series resistance (ESR). Below is graph archived relating the above comments. Films have notable uses in tube topographies due to their more reliable higher voltage characteristics and coupling/bypass applications. 

All the remaining films and low value tantalums were replaced here with high quality Panasonic ECW and Solen MKP PP films, both driver/coupling and pre stages. 

Pre/Tone/Phone

Driver Assemblies

Another upgrade was to update the repaired output devices with matched OnSemi's MJ21195/96G TO-3's and new MICA and compound. Another item to note is a redo on the Bias protocols. Reviewing the service manual it utilizes an odd bias method of measuring the current draw and adjusting. A more reliable accurate method would be to measure at the emitter resistors and compensate. For a 120VAC line @ 130mA draw we need to adjusts R224 bias potentiometer for 26mV across one set of Emitters or 52Mv across both. Below are my bias notations for the Model 30. 

Model 30 Bias -Notation für 130mA @ 120 V AC =

Unter Verwendung eines DMM , legen Sie die Messleitungen über entweder R230 / R231 Emitterwiderstände und passt R224 Pelz 26mV > (EIN) 

oder (OR)

Unter Verwendung eines DMM , legen Sie die Messleitungen über weit Bein des R230 / 231 Emitterwiderstände und passt R224 Pelz 52mV > (Zwei)

I know this is an awfully big statement…but this has got to be the best Marantz I have heard yet. As I think the customer can attests to, at a mere rated 60W/ch this integrated plays at the top end. Very different than your typical Marantz sounds..think elegant :)