Denon PMA 925R Service Manual

Page 1

D E N O N Hi-Fi Integrated Scereo Amplifier

SERVICE MANUAL
MODEL PMA-QEEFI/725Fl

INTEGRATED STEREO AMPLIFIER A

Pink-9253

PMA-725R

CONTENTS
OPERATING INSTRUCTIONS ................................................................. 2-7
REMOVAL OF EACH SECTION . .
FUNCTION OF NEW CIRCUIT .......
METHOD OF ADJUSTMENTS .....
BLOCK AND LEVEL DIAGRAM . .
SEMICONDUCTORS ........
PRINTED WIRING BOARD ,
NOTE FOR PARTS LIST ............
PARTS LIST OF P.W.B, ASSV
PMA-925R ..............
PMA-725R ....................
EXPLODED VIEW OF CHASSIS AND CABINET. PARTS LIST OF EXPLODED VIEW .
PMA-925R .... . . . .......
PMA-725R ......
WIRING DIAGRAM ......
SCHEMATIC DIAGRAM I I
PMA-925R ............ . .
PMA-725R ......................................................................... 33,34

NIPPON COLUMBIA CO.. LTD.

Page 2

CAUTION

RISK OF ELECTRIC SHOCK
DO NOT OPEN

CAUTION: TO REDUCE THE RISK OF ELECTRIC
SHOCK DO NOT REMOVE COVER (0R BACK]. NO
USER SERVICEABLE PARTS INSIDE. REFER SERVIC-
ING T0 QUALIFIED SERVICE PERSONNEL.

The lightning llash wilh arrowhead symbol. within an equilateral mangle. is in-
lended lo slerl The user To the presence 01 uninsulaled dangerous volloge
wrlhln The ploducl's enclosure That may be cl suIIlclem magnilude loconslllule
a rlsk oI sleclric shock lo persons,

The exclamallon palm wirhin an equilateral mangle is intended to alert the user
To ille presence cl importanl operanng and malnlerlance lserwcmg) lnslrucllons
in lhe lllererure accompanying lhe applrence
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE
THIS APPLIANCE T0 RAIN OR MOISTURE.

. rah us A. a. CANADA MODEL ONLV

O POUR LE MODELE CANADIEN uumuEMEm

CAUTION ATTENTION

To PREVENT ELECTRlC SHOCK DO NOT USE rl-lls TF0.
LAllleol PLUG WITH AN EXIENSlON CORD RECEPTACLE
on OTHER DUTLEV UNLESS THE BLADES CAN BE rum IN:
SERVED To PREVENT BLADE EXPOSURE

mu: PREVENIR LE5 canes ELECTRIGUES NE PAS uTlLls
ER CET'TE FICHE POLARISEE AVEC UN PROLONGATEUR
UNE PRISE DE COURANT ou UNE AUTRE SofiTlE DE cou»
RANT. SAUF SI LES LAMES PFUVENT ETRE INSE REES A
FOND SANS EN lAlssEa AUCDNE PARTrE A DECOWERT

u DECLARATION or coNrolTMlTv
w-uurnreryreelen :Merlswlyw ly TharTrltnroduclnronulhAmmlm PNlAvSle/YZERluwnrmmlsacclzullarlrllalasmlmcnlormlywllnlm rule.-
rhc slMlruds
mason, Ehssozo 91535554 and ENsilsis-zl
UBEREINSTIMMUNGSEIKLARUNG
w" .rhsren "hm unsuruVIr-lllwmllu .9 ma no: realm Vm-Halmluelslar! n PMAe-szsh/ rash. and damn dim Eruuurw emu ueh rowan Snfi
oalos .nupheh.
mason Enasnm (NMSS 2 Md 9605554
DECLARATION DE CONFORMITE
NW5 dtzlarms suf have we lesnwamllle aim nuusre-l Alum-humid we sashr 715R quml 5: Talu- enr. Munich nu (datum. on sunruuls
mm
:usson. Ehssom, ENmsss-z el shwsss-s
' olclllAluzlonlr: nl conmhMlTA
duhunenlo can gland respmssornl he .r pronoun amvrlrlcalorl or pliismnli Plan-925mm»: .l uusl. eunsr. minnow s. m... . curJom-e nu-
sow-hr. normally.
Ehssma Ehssozo EthEr-I e Encussso
o bEcunAcléN DE ccmnnmmo
Dcclimmos one nlrulu unis. moons-ulcer w .r pruduzln human. ll Amplrlludel Malia/725R. .l mu .sr. mansion rue. rclormcra, es
wlurma can lo: snomehles asumnrfi
ENssnla. shssozu. zNwsss-z y 0483555»:
0 EENVORMIGHEIDSVERKLAIIING
w. mlunn uuslumo so am- wrammmdmnkmld an MI mom-Twain» on. mlunhp hulalllngh-III or MNIVEIEVKIIVMH1§R1725R in Mr
unsi-lwvl-rluls m. rl. volunrlu nolmen
meson, mama Eusossso .n ENwsss-J
o OVERENSSTAMMELSESINTYG ,
Nataled mlvsa: nelr pa roe! Mm... prod-Tin" ler'erlwky-lnlllm-g mush/725K villln an. lyg hurry-u: humour" mono. :uuaamnl
msnors. memo 9460555»? pen Ehsossm
o ctcwucilo a: cournnmlnme
Dsdnramus sou nessu exclusive rusoonruuiulm nus o procure prs Amymuuor Frmlpal PMAszah/Tzah no pool um oueluraclu corresponds. esla r n
millolmndelxw as sznrunrus «om
{Nafiflll (Mama. ENmESS-Ze mason

FOR U.S.A. MODEL ONLV

SAFETY INSTRUCTIONS

Read lnsTrucfions , All The salsly and operaTlng Inslluflr
llolls should be read beIore The appliance is dpersled

Rslarn lnslruclrcns - The salary and opersnng inslruc-
Irons Shnuld be relalnea (or Iulure rersrenca

Heed WarriIHDSrAIIWamlngs on lhe applianlre end rnlne
cpernlrng rhslruclrons should be adhered lc.

Follow Inslmcllons » All operaTlng and use lnslrucuons
should he lollcwed

Warer aha Morslurs - The appliance should nor be used
Heal wnlsr - lor example, near a baihlub. woshbowl.
lnlchen s k. laundry In!) in a wel hasemenl, or near a
swimming pool and lhe Ilke

Calls and srsnds , The appliance should he used only
wirh u can or sland lhor is recommended by me
manulaclllrer

An appliance and can

cDmDIrTaIIOn should he

moved wilh care

Quick slaps. exces-

SIVB IDICS, and UFVEVEI

surlaces may cause

me anpllancs and can -
mmhmallan Io overlurn _.,

Wall or ceiling Mourning - The appllance should be
rlountedroawallorcalling only esrecommenduduylhe
menulsclurer

VellTilallon , The appliance should be snualed so Ihax lls
localroh or pasmorl does nor .nlerlere wnh rls proper ven-
lrlenon For example we appliance should nol be sl-
luoled on a bed, solo, mg. or slmllar surluce rhal may
block The vemllallfln ope us, or, placed in a bullHn
rnsrallauon, such as a cooxcesc or column Ihal may rm.
peee The how or an lhrouoh lhe uenlrlenon openings

Hem - The appllahce should be snualsd away llom heal
sources such as radrolcrs. hear regslers, slouas. ororhsr
oppllances lrncludrno ampllllprsl lhal produce hear

Power Sources - The appliance should be connecled lo
a pawel supply only M me rype oescnoeo in The opera!»
Ing Inslrucllons or as marked on me appliance.

Grcundrng or Polarlullon _ Precaulmns should be Taken
so lhal The grounding or Dolallzallon means 0! an a»
plience is nor delealed

mun! .
mum ix mun «Wm
M m Mmm
meme-l (an:

:95 e

:ILJlir'm .ul
L. «creeps.»

when: pas
35}?! mm-

(AND null-s

r. . mlmm when can:

l1

7

20

Power-Card prolecricn - Power-supply cords should be
roured so mar rhey are nel Ilkalv lo he walked on or
pinched by llems placed upon or spainsl lhem. paying
panhulnr nuenuon rc cords al plugs. convenience recepr
mules. and lhe porhl where lhey exil lrern lhe appliance

Cloanlng - The Innllanca should be cleaned only as rec
ommendsd bv lhs manulauurel.

Power Lines - An ouldoor amenna should he localed
away lrom power llnes.

Outdoor Amenna Groundlhg - it an dulsrde memo is
Conneclud Ta The receiver, be sure The amunno syslem
is grounded so as Io provide some protection against
udllage surges and bulllwp slallc charges. Arllcle E l 0 or
(he Nalional Electrical Code, ANSI/NFPA 7i), prowdes ln-
Iolmalion wlTh regard lo proper grounding oI The masl
and supporllhg slruolure, grounding or (he Isa in wrru
[D an enrennsoischarge unil. '12 pl grounding conducr
lors, lanollon or anlenna-dlscherge unlL cannecucn lu
grounding slaclrodes. o'rld leqlliremehls for The groundr
mg eleclrodo See Figure A

Nonuse Periods-The power cord or lheappliance should

be unplugged lromlhe QuIleK when lell unused Iora long

period ol lime.

Objeclsnd Liquid Enlry-Care should be Taken so Thal labs

jacis do hm lull and liquids are nol spilled mm lhe enclc

sure lhrpuelr openings

Damage Requiring Service . The appliance should be

serviced by qualirrcd service personnel when.

n The War-supply cord or lhu plug has ceen dalm-
egs » r

a . colecls have lailen. or liquid has been spilled lnlo rhe
appliance: or

c The opulence has been exposed ID riln, or

o The appliance does ncl appear lo operale normslly or
exhlblls a marked change in performance. or

E The appliance has been dropped. or the enclosure
damaged.

Ssmclrlg-Tha use! should not suempr To Service The ap-
pliance beyond IhaT descnped :n TM ccerarlhp lnslrucV
uons All other serviculg should be rslerred lo qudlrlled
servrce personnel

- HEEL/HEEE'VWd -

Page 11

PMA-EESRHEER -

4. IC DESCRIPTION (uPCSOZ3CS-064)

Pin. No. Name Contents Pin, No. Name Contents
1 OPT I N CP 11 ZDI Control signal stabilizer input
2 OPTO 12 ZDO Control signal stabilizer output
10 3 N0 13 PH-l Psak hold input
20 4 N-l 14 PHO Peak hold output
1 5 15 EAEO Controller gain setting
6 16 EACO Control signal output
on II V E v_ 7 17 EA+l Reference voltage .
opro [E E] m B 18 EA-1 Comparator gain setting
no LT. 11] EH 9 19 EAO Comparator output
"4 E El w 10 + Power 20 V- - Power supply
er E E into
GND 5: El EAEO
m II If! PH-O
H IE El FH-l
PO [E E] mo
w E E zoi

5. CIRCUIT IN THE CONCRETE

OUTPU1 IRANSISTGY
It EMITIER RESISTOR

POWER alPPLV

+8

BIAS OONTRthERR

F'_-_ "l

a
E

E
a

LP. @
u. e

§

a
u

'__________ _
|_

l
|
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-B

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