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 :)

Aker's Marantz 2265B Receiver

Marantz 2265B Receiver 

Id like to showcase this rebuild. I was extremely happy with how it turned out, cosmetic and performance wise I was just blown away. both hi and low level stages are crystal clear yet pronounced for each input. I really like the high level stage for line level devices such as my MicroMega CDP. I was lucky enough to have a Thorens TD160 to audition this with as well :)

This is an Audiokarma members unit, Arrived in quite dirty shape with oil smudges all over the faceplate and finger mares. Also noted was the unit was stuck in protection with a host of driver issues.  In this case the 3rd stage drivers and final output devices were shorted along with the bias array resistors. All new outputs were ordered for this overhaul.

Power Supply P800

The power supply is a little different here than in per-say the 50-70 22XX series. I would suggest attacking this board as one replaces the filter capacitors and removal of the driver stage, this allows you to contort the board in a open-book fashion. A new MY4 Relay was installed with OS cover, this particular relay is easy to replace in this supply as the tracing is easily accessible. All the lytics here were replaced with my standard high temp, long life rated Panasonic FR/FC capacitors. 

Also updated were the common Anode/Cathode devices. MicroSemi manufactures an extremely reliable 20A/200V Ultra-Fast TO-220P packaged rectifier to replace the originals. Its important, while your in here to remove the caustic glue used to support the larger lytics.

Driver (Single Topography) P700

Normally I'm not a big fan of the single topography PCB's like used in the 2265B driver stage, though in this case the layout is very symmetric and clean with totally separated rails and return, they way it should be done, if done, unlike per say the 2252B which houses the PS and Driver  stage all on ein PCB.

All the lytics here were replaced with audio grade Elna's and low impedance, high reliability Nichicon PW's. Differential pair transistors were updated to Hfe matched 992 BJT's and all general and rectification diodes updated to UF applications or general 4148 type. Also updated were glass pack diodes to 4148's soldered in series All new outputs and MICA were installed, reliable modern outputs cross referenced to MJ21193/94G devices.

The damage consisted of a shorted resistor at R772, the final stage Q759, Q757 was shorted along with outputs in that bank. 243G MJ' were replaced in the final stage along with 2690ays for the the Q757. 

New 35mm 10,000 microfarad CDE capacitors were installed these have been my best find since Panasonic THA's became less available. When the driver board is removed is convenient. They also share a common ground strap like many of the higher rated 22XX's do. I like to add the new EG1018 7A power switch and a Vishay X1Y2 safety capacitor after the filters to finish up on hardware. 

Phono P400

The phono here shares the same PCB as the switching control assembly as is in many later 22XX series Marantz, I prefer the stand alone PCB. Though they did get away from the faulty 458 transistors like the earlier models. All lytics here were replaced with low impedance, high reliability Nichicon PW's. I recommend reflowing the control connections at this time as they appear to suffer excessive torque from the switch when in use. Remember when replacing to save the leg dressings as a few lytics need to be contorted to allow for the shaft of the selector switch.

Pre-Amplfier/Tone PE01

I like these assemblies, not as easy to access as say the 2325 with that molex. All the lytics here were replaced with again Nichicon PW's and audio grade KA's by Nichicon, along with bypass polypropylene WIMA and coupling MKP polypropylenes. This is the perfect time to clean and treat phenolic based potentiometers as well. 

RF Stages

I really like how the main FM stage is accessible under the chassis, which makes recapping this section easier than most units as they typically sandwich these boards. In any RF stage, AM or FM I like to use the PW's again. Low impedance and very reliable they are perfect suitable here. 

I was very happy with how clean the faceplate and knobs turned out on this unit, Overall I'm quite blown away with the 2265B, after the overhaul it really sounds amazing, clear and precise are the two words that come to mind.