my diy arcam fmj 32 amp mod

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After two months of hard work finish the project ARCAM amplifier FMJ 32

It started amp burn by faulty diode that burned power transistor and some components
This project encountered any problem is possible,
DC FOSET
Overload
Plus

But the end
Successful
I changed the amp about 70 components

Electrolyte capacitors all recipients to RUBYCON-ZLK

film capacitors replaced

VISHAY 1837MKP

VISHAY 1813MKT

LCR CAPACITOR

10000UF filter capacitors of BHC
Replaced by capacitors of MUNDORF 15000UF

All the SMD resistors main tracks were replaced with the SMD resistors of
VISHAY DALE Thin film resistor 0.1% TCR 25PPM°C
(I replaced approximately 40 SMD 1206 resistors )

And the thru hole CF resistors
cange to film resistors ( bootstrap and output )
VISHAY DALE 2W - 0.1%
VISHAY BC 2W
- 5% .1%

Variable Resistors 100 OHM of the bios
Resistors were replaced with 25 turns resistor of

BOURNS - 3296W-1-101LF - TRIMMER, 25 TURN 100R


all the 4003 diode replaced to
diode of

VISHAY SEMICONDUCTOR - VS-ETX0806FP-M3 - DIODE, HFAST RECT, 600V, 8A, TO220FP


4 power transistors
SAP15P
SAP15N

replaced

and Some burn fmmt497 transistor Also replaced
and burn bas 16w diode Also replaced

I learned so much from this project
As Middle Ages
I found out that notebook and pencil subtle uses circuit analysis
After BIOS calibration the amp works perfectly and sounds a hundred times better as before
😀
 

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Nice work Dazzz!!

Could you please provide some comments to your photographs? Which are before and after? Can you also give an impression of the differences you noticed after your repair/modification?

Regards,
Edwin
The first image is before
If you pay attention you will see power transistor SAP15N burn

The most significant improvement is the dynamic
Musical instruments such as the piano sounds much better especially in the lower octaves .
Musical instruments such as acoustic guitar subtleties of Slade are delivered perfectly .

The DC voltage on the speakers output is very low 1 to 3 milli volts

Amp currently connected to another DIY project of my
DENON DVD 3910
And speakers B&W 804
And I am very pleased with the result

Finish the last six months 3 large projects
DENON DVD 3910
DENON DVD 2900
AMP ARCAM FMJ-32
 
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more photo
 

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I changed the amp ARCAM FMJ 32
24 SMD resistors
Per channel
Two resistors 100 OHM
Line tension transmitted to
CURRENT MIRROR Two resistors in each circuit 100 OHM CURRENT MIRROR

(Per channel Total 6 SMD resistors of -
VISHAY THIN FILM - PHP01206E1000BST3 - RESISTOR THIN FILM, 100 OHM, 0.1%, 1206

Two resistors at the exit from the PRE DRIVE
Per channel
I changed two resistors
33 OHM



TE CONNECTIVITY / HOLSWORTHY - RP73D2B33R2BTG - RESISTOR, 1206, 33R2 0.1% 15PPM

150 OHM
VISHAY THIN FILM - PAT1206E1500BST5 - RESISTOR, 1206, 150R, 0.1%

and

Every channel I changed the two resistors
22 OHM
In OP AMP
No inverter circuit
Amplification of 2
22 OHM 22 OHM divided
+ 1

Equal amplification 2


TE CONNECTIVITY / HOLSWORTHY - RP73D2B22R1BTG - RESISTOR, 1206, 22R1 0.1% 15PPM



Total 24 resistors



Now the problem I do not know how the hell I got the in the left channel DC voltage on the Speaker outputs

The tension starts from 40 millivolts
And increases gradually up to 200 millivolts
And even more


I checked all the soldering I checked there shorts
What could be the reason of the DC voltage in the left channel off the speaker
output ???????


( Correctly BIOS voltage on both channels .the
And the right channel to the DC voltage
Correctly 2
millivolts )
 

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After Work
At the end I solved the problem of the DC OFFSET
Now the amp stable even after an hour of work without a signal
The DC OFFSET about 13 millivolts
Another thing that has improved Halafta film capacitors RIFA
470NF film makers of VISHAY V730P
They were very helpful stabilize the voltage

(Reducing the DC circuit consists of an amplifier Server LT072 .
The circuit DC SERVO running as a inverter .
The DC voltage rises . Output in the OP AMP becomes negative
it raises the Current Negative Supply foot .
circuit consists of resistor 1 MEGA OHM
And Film Capacitor 470NF
)

the BIOS
voltage is Stable 16 millivolts
During the calibration i passed back forward
Between Measuring Voltage DC OFFSET to measure voltages BIOS
A few more measurements and then I'll turn it to the speakers
AIUJFJjLEaFejDwMFPgDB6skt9YYKOAAQDBMSlS9GiMMVAogX+iUUoMiBgIhJ2zUEvjmQp9ArRJdaTSIDw8ZIEgMzENkhIINC4KQ2jKFwg2Bf2R1IhAmDiUBBzh5MWShjqdRHdwsmQVMj6UnBgboAqTFFBgyAwMgSjVkhYs2EvAEWCiQA5IeVeTsyJImypGFEKwo+BAiVpkMri7tyoGrkDBblUQ4qYCFSiYzGhDcKSFJDA1fvEw0OKBDgKgCNWawWABLSqgip5o8wICGAIABmwDQQqVplR1hilTsmcPkzCMuRmBMSuDj0EBBv+CwgcSgRYJFkbp8oivwhZ8IE6DMA10YEAA7
 

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part II
on the
pre-amplifier of arcam FMJ 32


start I changed about 30 SMD resistors to
THIN FILM 0.1 % TCR 25PPM
of
VISHAY THIN FILM - PNM
and
PANASONIC - ERA

Diodes in the Diode Bridge
Replaced to diodes of HEXFRED .

in the LM317 regulator circuit resistors
And the filtering capacitor 470UF
Replaced to the Panasonic capacitor AD
its ESR 120 Mohn
Compatible with the permitted range to prevent the LM317T Oscillat.
Resistors have been replaced in the digital volume circuit .
Rail resistors replaced in the power supply 15 volts .
Resistors have been replaced inthe CD input.
(i Improved one input better I plug the 2900 player )
in Short 40 components were replaced

I replaced 5 capacitors
Capacitors to mundorf suprim

3 Unitsof
MUNDORF SUPRIM 0.47UF 600V

1 input filter power output of the pre amp
And
2 cap for the pre amp digital volume .
and
2 Units of
MUNDORF SUPRIM 0.1uf 1400v

digital volume circuit 🙂


Next Upgrade
Probably will
Regulator LM317
Will be replaced with LM1085
 

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Herculean task ..Good on you.
However that unit is imo A Classic example of total overkill.
Most ALL the features Arcam lists for it are, again imo Inane.
It has more circuitry than a Server Motherboard.
WHY? just to amplify some music inputs?
Clearly, form following function is a dead concept there.
More than likely Marketer driven features, obviously nothing to do with improving the sounds.
Shame .. Arcam used to be a decent midmarket brand.
 
Herculean task ..Good on you.
However that unit is imo A Classic example of total overkill.
Most ALL the features Arcam lists for it are, again imo Inane.
It has more circuitry than a Server Motherboard.
WHY? just to amplify some music inputs?
Clearly, form following function is a dead concept there.
More than likely Marketer driven features, obviously nothing to do with improving the sounds.
Shame .. Arcam used to be a decent midmarket brand.

The ARCAM sounds amazing after all the improvements
the Amp ARCAM FMJ 32
is the stereo system amplifier in my bedroom.

the Amp of my main stereo system
is
B.M.C
AUDIO CS2
That costs 9000 $
with B&W 804 Speakers
 

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Hi Dazzz,
You made me curious. And I have an almost unused ARCAM FMJ32. Like you, was my first audio with Triangle Naia. Is forgotten somewhere in original box, in a while I even thought to take it out on sale! Sound a little disappointed after I heard other amps even diy amps. If you say you have got good results after upgrade, maybe one day I'll get myself to improve my Arcam. I am convinced that this amplifier can much more!
Continued success!
 
Hi Dazzz,
You made me curious. And I have an almost unused ARCAM FMJ32. Like you, was my first audio with Triangle Naia. Is forgotten somewhere in original box, in a while I even thought to take it out on sale! Sound a little disappointed after I heard other amps even diy amps. If you say you have got good results after upgrade, maybe one day I'll get myself to improve my Arcam. I am convinced that this amplifier can much more!
Continued success!
After upgrades it sounds awesome 😉
Most importantly if you are upgrading
start capacitor in the power supply
10000UF
I switched to MUNDORF 15000UF
this Give
what was missing in the low frequency
More or less wrote here
Everything that the change.

The most important power amplifier circuit
Be careful and always check voltage DC OFFSET
And voltage BIOS before you connect speakers.
( Because of that mistake I blew the amp twice....LOL )

Pre-amplifier circuit
The enhancements give it the precision at high frequencies 😉
 
Hello Dazzz,
I decided to make changes to my Arcam FMJ32 amplifier!
You have posted a list of parts that need replacing for preamp module, if you can do the same for amplifier module, only resistors value. I also want to put C209, C210 Mundorf 15.000 - 22.000uF/63V , if it allows height 70mm,bypassed with 1-2 uF PIO or Mundorf silver oil/gold. Instead of bridge rectifier BRGBU8D (BR200) I will make a bridge rectifier bridge with VISHAY SEMICONDUCTOR - VS-ETX0806FP-M3 - DIODE, HFAST RECT, 600V, 8A, TO220FP.
All 1N4003F I will replace with utrafast MUR120 or better. Instead of IC 201(L4940V5)- NewClassD +5V regulator, idem for Z301(LM317T).
On preamp module al Wima FKP2 replace with AMTRANS 470pf / 100VDC, AMCH Polypropylene Film Cap from PartsConnexion.
Course will primarily take into account changes made by you and your advice. Please explain to me once again about 33R resistors PRE DRIVER, R321, R323, R421, R423(22R)?
Give me a list please with 0,1% tolerance resistors.
Thank you in advance!
 
Hello Dazzz,
I decided to make changes to my Arcam FMJ32 amplifier!
You have posted a list of parts that need replacing for preamp module, if you can do the same for amplifier module, only resistors value. I also want to put C209, C210 Mundorf 15.000 - 22.000uF/63V , if it allows height 70mm,bypassed with 1-2 uF PIO or Mundorf silver oil/gold. Instead of bridge rectifier BRGBU8D (BR200) I will make a bridge rectifier bridge with VISHAY SEMICONDUCTOR - VS-ETX0806FP-M3 - DIODE, HFAST RECT, 600V, 8A, TO220FP.
All 1N4003F I will replace with utrafast MUR120 or better. Instead of IC 201(L4940V5)- NewClassD +5V regulator, idem for Z301(LM317T).
On preamp module al Wima FKP2 replace with AMTRANS 470pf / 100VDC, AMCH Polypropylene Film Cap from PartsConnexion.
Course will primarily take into account changes made by you and your advice. Please explain to me once again about 33R resistors PRE DRIVER, R321, R323, R421, R423(22R)?
Give me a list please with 0,1% tolerance resistors.
Thank you in advance!

This list of resistors I used in the project power amplifier circuit
( all part from farnell )
smd resistor list
TE CONNECTIVITY / HOLSWORTHY - RP73D2B22R1BTG - RESISTOR, 1206, 22R1 0.1% 15PPM

VISHAY THIN FILM - PAT1206E1500BST5 - RESISTOR, 1206, 150R, 0.1%

TE CONNECTIVITY / HOLSWORTHY - RP73D2B33R2BTG - RESISTOR, 1206, 33R2 0.1% 15PPM

VISHAY THIN FILM - PHP01206E1000BST3 - RESISTOR THIN FILM, 100 OHM, 0.1%, 1206

VISHAY DALE - TNPW12061K00BEEA - RESISTOR; THIN FILM; 1 KOHM; 250 MW; 0.1%; 1206 - RESISTOR, THIN FILM, 1 KOHM, 250 MW, 0.1%, 1206

VISHAY DALE - TNPW1206100RBEEA - RESISTOR; THIN FILM; 100 OHM; 250mW; 0.1% - RESISTOR, THIN FILM, 100 OHM, 250mW, 0.1%



VISHAY THIN FILM - PAT1206E1002BST5 - RESISTOR, 1206, 10K0, 0.1%

VISHAY DALE - TNPW1206100KBEEA - RESISTOR; THIN FILM; 100KOHM; 250mW; 0.1% - RESISTOR, THIN FILM, 100KOHM, 250mW, 0.1%



Through Hole resistor list
VISHAY DALE - CPF210R000BHE14 - RESISTOR; METAL FILM; 10 OHM; 2W; 0.1% - RESISTOR, METAL FILM, 10 OHM, 2W, 0.1%

VISHAY DALE - CPF2470R00FKE14 - RESISTOR METAL FILM; 470 OHM; 2W; 1% - RESISTOR METAL FILM, 470 OHM, 2W, 1%

VISHAY BC COMPONENTS - PR02000205608JR500 - RESISTOR; METAL FILM; 5.6 OHM; 2 W; 5% - RESISTOR, METAL FILM, 5.6 OHM, 2 W, 5%


VISHAY DALE - CMF60330R00FKEA - RESISTOR METAL FILM; 330 OHM; 1W; ¦1% - RESISTOR METAL FILM, 330 OHM, 1W, ¦1%

VISHAY DALE - CPF3100R00FKE14 - RESISTOR METAL FILM; 100 OHM; 3W; 1% - RESISTOR METAL FILM, 100 OHM, 3W, 1%
 
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