~MP'E5X

MODEL

BULLETIN NO.

DATE 4/84

VPR-2A/2B 60935 SHEET 1 OF 5 AS-8404-23

POWER REGULATOR PROTECTION IMPROVEMENT

I. APPLICABILITY

This modification is applicable to all VPR-2A/2B's.

II. PURPOSE

To prevent catastrophic damage to the regulator assembly in case of -6/-l2V rectifier failure.

Ili. DISCUSSION

Two additional fuses are added to the heat sink assembly, which will protect the regulator PWA from severe damage if the rectifier bridge and its associated components fail.

IV. PARTS REQUIRED

Ampex Part Number Description Quantity

070-054 Fuse, Fast blow, H)A 2

103-054 Fuse, Holder 2

473-326 Screws, Pan Head 2

473-327 Screws, /'-'lach., Pan Hd. 2 4-40 x 1/2 x Rec.

501-169 Hasher, r lat ,4 2

611-549 Hire, AWG-18 2 Ft.

169-859 Contact, Pin 18-16 AWG 2

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BULLETIN NO 60935 SHEET 2 OF 5 DATE 4 /84 AS - 8 4 0 4 - 2 3

POHER REGULATOR PROTECTION H1PROVEt-1ENT

IV. PARTS REQUIRED-continued

Ports required for this update may be purchased t_hrough Ampex. Installation assistance can be obtained through your local Ampex regional office at current Ampex Field Engineering rates.

V. PROCEDURE

1. Remove the back cover from the machine and the power supply regulntor and heat sink assembly.

2. Remove the regulator Ph/A from the heat sink assembly.

3. Viewing the heat sink assembly with the fin's uway from you, remove the small metal bracket on the right hand side of the heat sink.

NOTE

On power supply assemblies equipped wi th tho crowbar kit, this bracket has (2) fuses mounted on it. Fuse must be removed first before the bracket can be removec1 from the heat sink assembly.

4. Using a 3/16 drill bit, drill a hole as shown in Figure 1.

DISTIlIC BOLES- EB- - -IIIIICIt BOU) till IUCUT TO IlEAT SIIIIl

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FIGURE 1

) . 25"

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I I3EB­1

HEAT SINK ASS'i . REAR VIEW (FINS FARSIDE)

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).4"

~ 2. 5" ).4" ·

I 1, •

AMPEX o~po,,~rIO:S DP/IS ION

fiELD :~~:;;'AIHG EHGIHEEH BULLetl MODEL VPR-2A/2B

BULLETIN NO. 60935 SHEET 3 OF 5 DATE 4/84 AS-8404-23

POWER R~~ULATOR PROTECTION IMPROVEMENT

V. PROCEDURE-continued

5. On hea t sink assembly equipped with the crowbar kit, drill 3 holes as shown in Figure 2. Use a drill size 43 for holes 1 & 2 and drill size 31, .1200 Dia. for hole 3.

G. Using a 4/40 tap size, tap holes on 1 and 2.

6.1"+ REF.

FIGURE 2

NOTE

On power supply assemblies not equipped with the crowbar kit, drill and tap holes 1 and 2 only.

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FIISLI~seftING ISNG 11N ,---------------------,sULLIS VPR- 2A/ 2BMODEL

BULLETIN NO 60935 SHEET 4 OF 5 DATE 4/84 AS-8404-23

POWER REGULATOR PROTECTION IMPROVEMENT

V. PROCEDURE-continued

7. On heat sin]. ~5umblies equipped with the crowbQr kit, move the tie lug next to transistor Q003 and install it in the new hole designated Number 3.

8. Mount the bracket back on heat sink assembly and ins­tall the fuse holder, Part Number 130-054 using a screw, Part Number 473-327 in hole designated Number 1. Mount the holder in parallel with (Y), reference Qxis ­(refer to Figure 2).

9. Mount the second fuse holder in position designated by hole 2, using a screw, Part Number 473-327, perpendicu­lar to (Y), reference Qxis - (refer to Figure 2).

10. Remove the wire connecting J~, Pin 19 to regulator j3 Pins 23, AI~.

11. Remove the "'/ire conl1,~cting J2, Pin 23 to regulator J3 Pins 24, BB.

12. Using 18 AWG wire, Part Number 611-549, connect the fuse holdeLs instQlled in step 8 as follows:

A. Connect terminal lug (A) of fuse (1) to J2 Pin 19 and terminal (B) of fuse to Pin regulator J3 Pin 23, l\A.

NOTE

Use the Pin (169-859) on J2.

B. Connect terminal lug (A) of fuse (2) to J2 Pin 23 and terminal lug (B) of fuse to regulator J3 Pins 24, BB. Refer to Figure J.

C. Install the 2 fuses, Part Number 070-054, ln the new fuse holders.

- - - - -- -

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O~"TION OIVIS ION AMPEX pt." CORP '1sTE"S

FIIS~~i~fliHG !~LLS1IH MODE L VPR-2/2B Pu BULLETIN NO. 60935 SHEET 5 OF 5

DATE 4/84 AS-8404-23

rmn::r< l<I:':GULATu{, P HU'l'L:C '1' 1 ON HiP ROVU1E N'l'

V. PROCEUU~E - continu~J

1j. l~ (..:illsti:lll t.hc r C(j UL d t or P~ i A on t he h '~ut sin;': i;J,SS Clilb ly

i-in,] r-einst;1l1 both asscmb li t= s in mdchinc .

, - ­ -

REF. b},M[£4_, BBJ3 - - ~ -T

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,,---'­. ­ TERMINAL LUG (A)!­19

I I FUSE (1)

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I J2 1 i HEAT sua< ASSY.

BRACKET

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I", ~~ ~I~ I, ~r: [iF·

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l.I.

FUSE (2) 1--" ~

~f- ITERMINAL LUG (A)I......­ .o..B

FIGURE 3