TA4650 SONY
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@ ~ | v, Sen" EB : Service Bulletin No. 49 SONY CORPORATION OF AMERICA | Model: TA- 4650, -5650 Technical Publications Department ——— ui i i i. . 47-47 Van Dam Street, Long sland City, New York 11104 Subject: V-FET Replacement Date: August 16, 1976 The TA-4650 uses two V-FETs (25J18 and 2SK60) and the TA-5650 uses four V-FETs, in each channel of its power amplifier. Both the 2S8J18 and 2SK60 are divided into six ranks (-53 to -58) according to their Vsgo (gate-source voltage) and Vp (cut-off voltage). It is necessary to use the same rank V-FETs in the same channel. The rank is indicated on each V-FET as shown. If the correct rank is not available, replace with a complete set of another rank. SONY 2SK60 AS6 rank It should be noted that only the ranks from -54 to -57 are usable in the TA-4650/5650.
= = SONY. nl SONY CORPORATION OF AMERICA | Model: Leer “bgp. =8650 Technical Publications Department a ia ‘47-47 Van Dam Street, Long Island City, New York 11101 Subject: V-FET Replacement Date: August 15, 1977 Refer also to Hi-Fi Service Bulletins No. 41, 49, and 51. Perform the following procedure if V-FET failure is suspected. To avoid damage to a replacement V-FET, do not replace without first making this check. Py 1. Turn off the power and remove the suspect V-FET. 2. Check resistance readings of this V-FET using a VOM set to the X1Q range. See illustration below. S VOM set to X19 range. S to G-----~~ Same as a diode D 6 s Dto G_i_____ Same as a diode 2SJ18, 2SK60 If readings appear normal, the V-FET is probably okay, and other circuit components should be checked. @ 3. If readings are not normal, turn on the power with the V-FET still out of the circuit. Set the VOM to the 50 VDC range @ (or as close as possible) and connect the leads to the V-FET conductor patterns on the board as follows: = TF 28J18 VOM (+) VOM (-) | 2SK60 VOM (-) | VOM (+) 4. Set the de bias adjust resistor (see below) on the Power Amp Board for maximum reading. TA-4650, -5650 = RT-301 (RT-351) TA-8650, TAN-8550 ~ RT-701 (RT-751) TAN-S550 ~ RT-501 (RT-601) 5. Turn off the power and install the replacement V-FET. Reapply power and reset the de bias according to the service manual for the respective model.
i SCHEMATIC DIAGRAM — Power Amplifier Section — — USA (new type), E, AEP model — 504 25C 326K O307 - BCSAGA aso" ZeAB40 O31 28418 ~ 901 5 301 ISISS5 9305 28C634.A 0309, 25463915) 0312 26x60 i 4 Le Sava Pech een her he 54 eae, 0301 asae7e pala vo-12% ™ 031 1670 305,306 IT22A pai | Seton? ea on 14 VO-I22m 0302 V-I721M O06 Fern peat i a, ha RS. TY ET
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tH) omg | 8? > | : ' G e384 Woo SE t cos iia Peon 9.00 ied R364 0353 1Si5S5 nt —— i \\ ' 0354 2SC926A Q356 25A678 0354 ISI555 036: 355 IT22A 138) 25510 CLARE nah WANSISTOR PROTECTION 0359 23A638@) DSSS ITER Oe er | 357 25¢9264 9360 25C1679 0356 ITZZA 0362, 25x60 : ee : Note: All resistance values fre in ohms. k= 1,000, Mi ‘All enpacitance valuedare in uF except as indicatd Eh munancine ,
090 15555 Oe ~~ 7 ~ TERMINAL . med) L TM! ee ; @® I ® basalt ven) i © b A Met te bat A home © ‘ee EO 6 ; oe oP ow oe E al J ; a DIO Fee aS ay Te TE G @ ss F oar En [oe wig) QO . ' © * aod, a0 tpl Nes "98 foe [Tole ascalron % Joe02 . po rt eam Wes Gorse Usa MODEL ome eed east 8 | (easel [ceaoe aon ra | (Fr © ict Toma " g401|asce34 _ mo] owe He Qe a eT Baar OE | EE wear (e (2| (el ce i Se | om, ie ie Te Nee fest ie a ow oe wie — a BY once ate 4 L K) ' . i i ' i KK, = Vie Yd il i eens 1 m pa et NS eas. [| tress | |) ote \\ zesyey | | te) OL wo | Sy dt \\ ; “ | DaIO, aN 108-2 oy, | 404,406 2sc634a 3 1 i i 6 250834A ala 151855 ©) ! ! : von see | q405, 407,408 25A678 (town ree sep ove ae t iS | Jee ae oe:
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fp ohms. k= 1,000, M= 1,000. Ea H lin ué except as indicated with p, je dod gj t . ' ph Ee J | with 2. VOM which has an input bi Becton ‘pit. No signal in. at - je noted because of normal pro moe: B- — 22 —
4EMATIC OIAGRAM — Preamplifier Section — oe A \\- ost 2 sane a ° se OF = PD fe esa rat AY aac cae ai i ae or 22... + 2@-—p WM He se] [tel MGT SE4]} (SPS Tho fg ‘Tuner an B ® 2 led 4 [a ‘so rtd [ms an | [| = ‘ q or ates «OP TTT — Sosy fee wove] CK) rT pososy 9 BH lvoe [NE i H™ waa th) [ite] ose |" (8 Lid Gait DT fost tear saa” leg" tell Icowecton TAL © fod O ©) akan cs pL |e LF) QA | GO OAD | [nay are | — Ce gel #] -——- > th ake eis ata) e baal salt on Bal anne ane Sse os ira i oo 1 er aete2 mO—F a i Ta dettelers sad a oo ie a i ae eed "a wll t-2 OF 1 i ee LI, acre Sl x, oO & aS 0 ttt Joy | #254 68 UK 1 . ). —— 1—t+-+ as jw | ike oy b9 © Af teedy teahy 43 reer wee eey eee: 2 ® ie D) o Za So sae soe D sre! a ~ Oe - 7 - - = nc TO (PHONO 21 89--TOME (CANCEL 4 SNire convcoumce) stone rute or) i
Woe 4 cae. —on a jorre OFF OFF = 0% wono— STEREO 28enne 89-1 soon = 2schn OFF-=ON OFF ON ; \\ * Toa _ aH P| Jean iy [se | C [| ae [plaza zsnes0 oalrseasa spe? & | 4 meee, | || Pees Lh fae Se 2 fee he | hel BB al] [oe || Test ‘ in onl Bg I ane watt ay t dee! a Ea] Ie EA te le mS) is tat FS ae] (Kav e We att] K) 2 WL Ua 00 \\ Pa ay i 2. A 28 feo coor | ) au a: en) i HP weil | Wes cc Q) (syd 1%) dealt) tad cee i} wx pha owe 6 mot m8 Ee B L Frc a BST | caott cu 1 Ez 0 i. Y riot fad a a Se SS ae eas 4 rl art aoe [face wesc | | ate ' ae | a” a = r ees | K) es = oa cer lf ee, ka 55, q 1 2 oo, | le | [hale 1 TL iS eo | Be Ee os H oat Ke) na} &) | ' ie presi CK wt ||} eaes Sys wee wasion HEB bel] ise || rte t OR 286: ase el | 289 bead AT ets HEE O82 ZPKSS, | | Pe eSSea CaP See] i es ee aes TLL ee asa 254705 i ~ ness (a roe mae a }W05 ar pe itance values are in wF except Ff Sees oot Ait canara fe Sromon ruree ort which means HF. se Seriboareeren terns All voltages are de measured with a VO! inpatance of 20K onma/velt. No sant » Voltage variations may be noted bec eRe duction tolerances. os és =
Note: Turn POWER on and allow about three minutes for warm-up: 2-4. POWER SUPPLY VOLTAGE ADJUSTMENT See Fig. 2-1 and 2-2. | Bi. of a a * e 2 & | TEES 8 volume contro!) ae Lr a eee dng ie ceiaaaias | ce Adjust RT401 for aie ? ‘eo. 2, Ga. 20V reading on the MTL OPAMP ces wih no sen an er eee iepob 1 SRD. Pa ii TATU rie a nad de voltmeter Fig. 2-1. ie To ground of amp (TA-4650) ve Soy La at QNRUTANILI (LU) Bg : LH ul Ly : i eT) Fig, 2-2. | ~4-