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Old 12th April 2013, 04:52 PM   #1
luke2fr is offline luke2fr  France
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Default Marantz PM68 tweak

Hi everyone,

Those last week I've followed Ray's advice and started to read the CD53-57-63-67 to mod my cdp.
I'm putting my CD57 mod on hold for a little time. It sounds great (well a lot better than it used to), and I want to get used to it before modding it more. Got many CDs to listen and discover again. So far, most of the time, I'm quiet amazed.

I've started to read my amp's service manual ( you can get it here Free - Envoyez vos documents ) and I'd like to ask you a few (or many) questions about it.


Input section:
From what I understand, DC blocking caps aren't the best thing.
If DC coming out of my CD57 si low enough (how low is low enough as one would write ? ), would it be a good idea to remove them (CD input is my only concern for the moment) ?
Which one are the DC blocking caps ? On page 10, the schematic show many caps on the input. Are they 2601 and 2602 or 2613+3601 and 2614+3602 or all that ?


Power section :
I was thinking about addind a 250VAC/20mm. varistor (100-4357 @ farnell) directly on mains pins of IEC socket or on mains terminals on the PCB, but since I've read Brent's PM66ki tweek thread, I believe it's not really a good idea. What's you point on that ?

Can I swap the multiple 1N4003G diodes (6210 6211 6212 6213 6214 6215 6216) for schottky ? I've only found those one (1431066) at farnell which seems to have the good caracteristics, but they are 3 pins instead of two. (http://www.onsemi.com/pub_link/Colla...MBR40250-D.PDF)

Since the amp is 13 year old now, changing all the caps would be a good move (also, in the other section) ? Should I keep the same capacities ? According to the schematics, do you think some should be upgraded ?
So far I've only checked the two biggest ones as it seems most improvement can be achieved with them. Original are 12000uf 63V. They are "for audio elna" ones. I didn't find them on farnell. They are (D x h ) 40mm x 70mm. But a height of 100mm would fit. How about 1166570 or 9348140 or 9347941 ? I also found some Mundorf M-Lytic AG 63V 22000F and 15000F on a french website. Which one would be a good choice ? Having read Brent's PM66ki thread, I wonder if 22000F really is ok, or if I should stick to 15000F (in rush issues seems to have occured to some). Any advice on this ?
I guess decoupling them would be a good idea too, am i right ? But what should I use for that ? I tried to guess from what has been done on the cdp, but I don't get the rule behind the choices made. Ray advised me "an MKT that's anywhere between 2.2 and 4.7uF"


tone and volume section :
About the opamps used there. Looks like they are not the best ones possible njm2068. May I change them for ad8620 ? Or is that a bad idea if other component around them aren't changed too ? I've also read LM4562 could be a good swap too, any opinion one this ?

Last question
I've read (yes, still the same thread) in Brent's PM66ki thread bypassing the tone and tape thing would help. Kimber 4TC is often mentionned for that : where can I find such cable ? Is there a good known alternative ?


That's all for now
Thanks for reading, and in advance for all you answers.
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Old 1st May 2013, 08:48 PM   #2
luke2fr is offline luke2fr  France
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some reading but not as much answers as hoped.

Anyway, I've changed the NJM2114D on the volume board for a LM4562.
I've also ordered the Mundorf M-Lytic AG 63V 22000F caps.

Today, I've spent some time making this list


------
POWER
------
--------------------
page 13 & 26 in pdf
--------------------

part# | original value | new value | comment
6205 | GBU6D | please advise what ref if schottky can be used here
2205 | 12000F 63V | 22000F 63V | + bypass? what to use ? same cap but 4700F ?
2206 | 12000F 63V | 22000F 63V | + bypass? what to use ? same cap but 4700F ?



-------------------
CONTROL CIRCUIT II
-------------------
--------------------------------------------
Volume circuit board / page 23 & 28 in pdf
--------------------------------------------

2653 | 100pF 50V | PANASONIC - ECHU1H101GX5 - CONDENSATEUR 0805 0.1NF 50V Farnell 9695125
2654 | 100pF 50V | PANASONIC - ECHU1H101GX5 - CONDENSATEUR 0805 0.1NF 50V Farnell 9695125
2657 | 22pf 50V | LCR COMPONENTS - FSC 160V 22PF+/-1PF - CONDENSATEUR 22PF +/-1PF 160V OR MURATA - GRM1555C1H220JA01D - CONDENSATEUR CMS 22PF Farnell 9519971 or 2218849
2658 | 22pf 50V | LCR COMPONENTS - FSC 160V 22PF+/-1PF - CONDENSATEUR 22PF +/-1PF 160V OR MURATA - GRM1555C1H220JA01D - CONDENSATEUR CMS 22PF Farnell 9519971 or 2218849
2659 | 2.2nF Y5R | ?? what does Y5R mean ? Can i use the same as 2669 and 2670 ?
2660 | 2.2nF Y5R | ?? what does Y5R mean ? Can i use the same as 2669 and 2670 ?
2661 | 22F 25V | RUBYCON - 25ZLG22MEFC5X7 - CONDENSATEUR 25V 22 UF Farnell 1281815
2662 | 22F 25V | RUBYCON - 25ZLG22MEFC5X7 - CONDENSATEUR 25V 22 UF Farnell 1281815
2663 | 4.7nF 50V |PANASONIC - ECHU1H472GX5 - CONDENSATEUR 1206 4.7NF 50V Farnell 9695320
2664 | 4.7nf 50V | PANASONIC - ECHU1H472GX5 - CONDENSATEUR 1206 4.7NF 50V Farnell 9695320
2669 | 2.2F 50V | PANASONIC - EEUFC1H2R2 - CAPACITOR, RADIAL, 50V, 2.2UF Farnell 1848456
2670 | 2.2F 50V | PANASONIC - EEUFC1H2R2 - CAPACITOR, RADIAL, 50V, 2.2UF Farnell 1848456

those 2 are for the AOP reserve
2665 | 220F 25V | RUBYCON - 25ZLG220MEFC8X11.5 - CONDENSATEUR 25V 220 UF + 100n PPS farnell 1281814 + 185-5059
2666 | 220F 25V | RUBYCON - 25ZLG220MEFC8X11.5 - CONDENSATEUR 25V 220 UF + 100n pps farnell 1281814 + 185-5059

those 3 for the motor
2667 | 4.7F 63V | NICHICON - UPW1J4R7MDD1TD - CAPACITOR ALUM ELEC, 4.7UF, 63V, 20%, RADIAL Farnell 1899885
2668 | 4.7F 63V | NICHICON - UPW1J4R7MDD1TD - CAPACITOR ALUM ELEC, 4.7UF, 63V, 20%, RADIAL Farnell 1899885
2671 | 10nF 50V | MKT ? which ref ? or PANASONIC - ECHU1H103GX5 - CONDENSATEUR 1206 10NF 50V or WIMA - MKS2C021001A00JSSD - CONDENSATEUR 5% 0.01UF 63V farnell 9695362 or 1890129

7654 | NJM2114D | LM4562NA | already changed
7655 | NJM2114D | LM4562NA | already changed

-----------------------------------------
Tone circuit board / page 22 & 28 in pdf
-----------------------------------------

for the regs on tone board
2201 | 10nF 50V | MKT ? which ref ? or PANASONIC - ECHU1H103GX5 - CONDENSATEUR 1206 10NF 50V or WIMA - MKS2C021001A00JSSD - CONDENSATEUR 5% 0.01UF 63V farnell 9695362 or 1890129
2202 | 10nF 50V | MKT ? which ref ? or PANASONIC - ECHU1H103GX5 - CONDENSATEUR 1206 10NF 50V or WIMA - MKS2C021001A00JSSD - CONDENSATEUR 5% 0.01UF 63V farnell 9695362 or 1890129
2203 | 470F 35V | PANASONIC - EEUFC1V471 - CAPACITOR, RADIAL, 35V, 470UF ( OR RUBYCON - 35ZLH470MEFC10X16 - CONDENSATEUR 470UF 35V ) farnell 1848452 (or 8126755)
2204 | 2200F 35V | RUBYCON - 35ZLH2200MEFC16X25 - CONDENSATEUR 2200UF 35V OR PANASONIC - EEUFC1V222 - CONDENSATEUR 2200UF 35V farnell 8126704 or 9692347
2205 | 220F 25V | RUBYCON - 25ZLG220MEFC8X11.5 - CONDENSATEUR 25V 220 UF + 100n PPS Farnell 1281814 + 185-5059
2206 | 220F 25V | RUBYCON - 25ZLG220MEFC8X11.5 - CONDENSATEUR 25V 220 UF + 100n PPS Farnell 1281814 + 185-5059
2209 | 470F 35V | PANASONIC - EEUFC1V471 - CAPACITOR, RADIAL, 35V, 470UF ( OR RUBYCON - 35ZLH470MEFC10X16 - CONDENSATEUR 470UF 35V ) farnell 1848452 (or 8126755)

motor
2207 | 470F 35V | PANASONIC - EEUFC1V471 - CAPACITOR, RADIAL, 35V, 470UF ( OR RUBYCON - 35ZLH470MEFC10X16 - CONDENSATEUR 470UF 35V ) farnell 1848452 (or 8126755)
2210 | 470F 35V | PANASONIC - EEUFC1V471 - CAPACITOR, RADIAL, 35V, 470UF ( OR RUBYCON - 35ZLH470MEFC10X16 - CONDENSATEUR 470UF 35V ) farnell 1848452 (or 8126755)
2208 | 220F 63V | RUBYCON - 63ZL220MEFC10X23 - CONDENSATEUR 63V 220 UF Farnell 1281839

6201 | 1N4003G | VISHAY FORMERLY I.R. - VS-11DQ10 - DIODE SCHOTTKY 1.1A 100V Farnell 364472
6202 | 1N4003G | VISHAY FORMERLY I.R. - VS-11DQ10 - DIODE SCHOTTKY 1.1A 100V Farnell 364472
6203 | 1N4003G | VISHAY FORMERLY I.R. - VS-11DQ10 - DIODE SCHOTTKY 1.1A 100V Farnell 364472
6204 | 1N4003G | VISHAY FORMERLY I.R. - VS-11DQ10 - DIODE SCHOTTKY 1.1A 100V Farnell 364472

7201 | L7915CV | Raygulators ?
7202 | MCT7815CT | Raygulators ?



To deactivate treble & bass & balance control
EITHER THAT (easy option)
1)
signal input
2501 | 22u 50V | REMOVE
2502 | 22u 50V | REMOVE
signal output
3526 | 220R | REMOVE
3525 | 220R | REMOVE
2520 | 4.7n | REMOVE
2519 | 4.7n | REMOVE

OR THAT (best option)
2)
add 4 coax (what ref ?) from volume board near 1652 get RG R L LG and go to RG R L LG near 1251 on main board. Then remove 1506 which is now useless.


AND in both cases but ONLY IF one of the above as been done
3)
to isolate +/-15V from treble & bass control aop
3514 | 47R | REMOVE
3513 | 47R | REMOVE
to isolate +/-15V from balance control aop
3524 | 47R | REMOVE
3523 | 47R | REMOVE

Last edited by luke2fr; 1st May 2013 at 08:57 PM.
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Old 1st May 2013, 09:26 PM   #3
McGyver is offline McGyver  Poland
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Can't read such long list of numbers. No need to replace everything.

I've modded several PM68's with good result.
Don't use schottky to replace GBU6D. Use 6-8A ultrafast diodes, soft recovery type recommended. No need of any heatsink, unless your amp is PM78.
If you use good ultrafast soft recoverys it's impact on sound will be very significant (more dynamic, more speed on bass).

Click the image to open in full size.
Most of effort needs a "volume" board. An opamp needs to be replaced, it's wise to solder a socket and try several different ones (LM6172 is fine, but sometimes it oscillates, safe choice will be OP275 or OPA2132, 2134). 2,2uF lytic Elna Cerafine replace by same value finest quality foil cap, Mundorf EVO alu oil will be excellent. 22uF Elna Cerafine replace by same value finest guality foil capacitor, and again Mundorf Evo aluminium oil will be excellent.

There is a pair of 47uF lytics in signal path on input at the power amp board, it is essential to replace them by good quality foil capacitors. And again Mundorf Evo alu oil is my recommendation.
One can replace also a bunch of capacitors and diodes in diverse places, but IMHO it's impact on sound is marginal and no use to doing it.
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Old 1st May 2013, 09:50 PM   #4
luke2fr is offline luke2fr  France
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Thanks for you answer !

Quote:
Originally Posted by McGyver View Post
Can't read such long list of numbers. No need to replace everything.
I thought, as the amp is old, most lytics would need to be change. Well, those in the signal path or in the power section.

Quote:
I've modded several PM68's with good result.
Don't use schottky to replace GBU6D. Use 6-8A ultrafast diodes, soft recovery type recommended. No need of any heatsink, unless your amp is PM78.
If you use good ultrafast soft recoverys it's impact on sound will be very significant (more dynamic, more speed on bass).
I have a stock PM68.
I'm a newbie here, could you please give me a ref (at farnell at best, or anywhere else) for those diodes ?

Quote:
Most of effort needs a "volume" board. An opamp needs to be replaced, it's wise to solder a socket and try several different ones (LM6172 is fine, but sometimes it oscillates, safe choice will be OP275 or OPA2132, 2134). 2,2uF lytic Elna Cerafine replace by same value finest quality foil cap, Mundorf EVO alu oil will be excellent. 22uF Elna Cerafine replace by same value finest guality foil capacitor, and again Mundorf Evo aluminium oil will be excellent.
I already put a socket on my volume board, and fitted a LM4562 as TI gladly sent me some free samples

Are the Mundorf Evo alu oil those ones Mundorf Mcap Evo Oil - Audiophonics - Cbles, Amplificateurs et Accessoires DIY ? If so, is there a version < 450V : they are quite big !

are the 2.2F 2669 & 2670 ?
are the 22F 2661 & 2662 ?

Quote:
There is a pair of 47uF lytics in signal path on input at the power amp board, it is essential to replace them by good quality foil capacitors. And again Mundorf Evo alu oil is my recommendation.
One can replace also a bunch of capacitors and diodes in diverse places, but IMHO it's impact on sound is marginal and no use to doing it.
Are those 2251 and 2252 on the main circuit (page 19 of the pdf or 23 in the real manual) ?

PS: there's a link to the pdf in my first post.
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Old 1st May 2013, 09:57 PM   #5
McGyver is offline McGyver  Poland
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Now I'm on vacation in the mountainside, and no my papers here. When I get home I'll check my papers and write something more. Hate to read manuals in PDF.

The amp is not so very old, and you may leave alone most of lytics in power supply.
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Old 6th May 2013, 05:46 PM   #6
luke2fr is offline luke2fr  France
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Got some....well.... a lot of advise from Ray, but I'm waiting for your next post McGyver !
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Old 6th May 2013, 05:52 PM   #7
McGyver is offline McGyver  Poland
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Still haven't found any papers. But I have some photos, will try to mark components to replace.
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Old 6th May 2013, 06:05 PM   #8
luke2fr is offline luke2fr  France
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If you can tell me what ref are the diode you use to replace the GBU6D, I'll be able to wait for the rest a bit longer
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Old 6th May 2013, 11:04 PM   #9
McGyver is offline McGyver  Poland
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Quote:
Originally Posted by luke2fr View Post
If you can tell me what ref are the diode you use to replace the GBU6D, I'll be able to wait for the rest a bit longer
GBU6D is the Gretz bridge, you can not replace it by single diode. You need four diodes to make Gretz bridge. It can be HFA08PB60 for example.
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Old 7th May 2013, 12:36 AM   #10
luke2fr is offline luke2fr  France
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Thanks.
Unfortunately, RS seems to be the only one to sell them in europe, and they don't sell to particular, only professional :/ Got to find a way to place an order with them, they have some toroidal tx too i'd like to get from them. Or if anyone as some for sale or can help me order there as a middle man, contact me please !
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