HP-Service-Note-1750B-x 电路图.pdf

HP Archive This vintage Hewlett Packard document was preserved and distributed by vvwvv. h parc Please visit us on the web ! Scanned by on-line curator: Tony Gerbic * For FREE Distribution Only * RadioFans.CN 收音机爱 好者资料库 SERVICE NOTE APRIL 1965 MODEL 1750B DUAL TRACE AMPLIFIER Serials Below 435-00176 Increased Frequency Response Increasedhighfrequency response on the 5, 10, and 20 volt ranges can be obtained in the above instruments by changing the resistors indicated below: Modification Procedure Replace resistors R105 and R205 (0683-1005) with resistors R105 and R205 (0683-1805) 18 ohm 5% 1/4 watt. Recalibration of the 5, 10, and 20 volt ranges will be necessary. See Para- graphs 5-20 thru 5-26 of your Operating and Service Manual. Change the Replaceable Parts List and the schematic diagrams in your 1750B Operating and Service Manual to incorporate the above changes. 02524- 1 8 n rgoo Garden of the Gods Road, Colorado springs, coiomdo, U.S.A. re/. (303) 636-5iri Europe: 54 Route Des Acacias, Geneva, Switzerland, Cable: HEWPACKSA Tel. (022) 42.81.50 CRINTLD IN U.*.A. RadioFans.CN 收音机爱 好者资料库 I P SERVICE NOTE I750B- 2 i Printed in U.S.A I hp MODEL 1750B DUAL TRACE AMPLIFIER Serials Below 543-00616 Improved B Trigger Out Parts Kit 01750-69501 Improved B Trigger Out The following modification improves the dc stability of the B Trigger Out Amplifier. Over a period of time dc drift can cause the amplifier to go into saturation. Modification Procedure a. Replace R62 (390K) with 1 megohm resistor. The bandwidth of the Trigger Amplifier after this mod- ification is 5 cps to 2. 5 Mc. Formerly it was dc to 2. 5 Mc. b. Replace R63 (33 ohms) with 27 ohm resistor. c. Replace R64 (300 ohms) with 150 ohm resistor. Components Included in Kit 01750- 69501 Ref. Desig. Qty R62 1 R63 1 R64 1 R60 1 R59 1 c55 1 1 R: R: R: R: R: C: 1 megohm, 1/8w, 27 ohms, 1/4w, 150 ohms, 1/8w, 7. 5k ohms, 1/8w, 511 ohms, 1/8w, 50f, 25vdcw 1% 5% 1% 1% 1% d. Remove CR51 (diode) and install R60 (7.5K ohm resistor). e. Connect a 511 ohm resistor (R59)between the Figure 1. f. Connect a 50 i!f capacitor (C55) between the base of Q11 and ground. See Figure 1. g. Make the dc level adjustment (R65) as indicated in Section V of your hp Model 1750B Operating and Service Manual. h. Change the Schematic Diagram and Replaceable Parts List in your hp Model 1750B Operating and hp Part No. 0698-3129 base of Q11 and Pin 8 of V1 (cathode). See 0683-2705 0757- 0284 07 57- 0440 07 57 - 04 16 01 80- 0058 Service Note 1750B-2 Service Manual to incorporate the above changes. p- * I* 11/65-8 7900 Garden of the Gods Road, Colorado Springs, Colorado, U.S. A. re/. (303) 636-5777 F-3 Europe: 54 Route Des Acacias, Geneva, Switzerland, Cable:”HEWPACKSA” Tel. (022) 42.87.50 RadioFans.CN 收音机爱 好者资料库 i S E E HEWLETT 1-PACKARD u I hp MODEL 1750B DUAL TRACE AMPLIFIER Serials Beginning with 516-00426 Selected Transistor Replacement for Optimum Pulse Response Transistors $103 and Q104 are selected at the factory for optimum pulse response, The 2N709 (hp Part No. 1854-0009) is faster than the 2N2708 (1854-0005). The faster transistor improves the rise time but causesexcessive overshoot in some of the above instruments. If Q103 or Q104 is replaced, install the same transistor type as selected at the fac- tory. The transistor type number is on the top of the transistor. Recalibration is not necessary after replacement of the above components. Change the Schematic Diagram and Replaceable Parts List in your hp Model 1750B Operating and Service Manual to indicate the proper transistor type and part number. 02548-1 10/65-8 1 1900 Qarden of the Qods Road, Colomdo Spdngs, Colorado, U. S. A. Tol. (808) 836-6111 0 Europe: 54 Route Des Acacias, Qeneva, Sw/tzerland, Cable: uHEWPACKSAu Tel. (On) 42.81.bb hp MODEL 1750B DUAL TRACE AMPLIFIER Serial Prefixes Below 516- Improved DC Balance Parts Kit #01750-69502 300k 5% 1/2w 2.5M Variable Re si s t or Service Note The following modification improves the DC balance of the above instruments by addinga base current adjust- ment. Formerly there was only one balance adjust- ment andno provisionfora vernier balance was made. After modification, the base currentwill be adjustable for no trace shift as the vernier is rotated. This modification includes the addition of two variable resistors and replacement of two fixed resistors. R131, R231 0686-3045 R129, R239 2100-1543 175OB-4 Components Included in Kit #01750-69502 Quantity I Description I Ref Desig I hp Part No. I 2 2 1 6. Trim the leads of the 300k resistors as follows: a. At one end make the lead 1/8 long. b. At other end make the lead 3/8 long and bend a right angle in it at its mid point. 7. Solder the bent end of the resistors to the bent lead of the variable resistor. 8. Insert the combination such that the 300k resis- tor (short end) goes in the hole nearest the tube. The remaining variable resistor lead goes in other hole, and the fourth lead of the variable resistor goes into the hole drilled in the PC board. Do this for both combinations. 9. Solder the 300k resistors and variable resistors in place. Adiu stm ent Procedure Modification Procedure 1. Remove R131 and R231. 2. Remove the right hand lead from both of the vari- able resistors as viewed from the lead side with the three contacts toward the top. The fourth lead is not e 1 ec t ricall y connected. 3. Bendup the center leads of both variable resis- tors at their center such that they point in opposite directions. Be careful not to bend too sharply and break them off. Do not bend at the point at which the right angle bend is already there. 4. Insert the third lead in the hole left by removing R131, located farthest away from the tube. Make an arc with the fourth lead. Drill a small hole at a point on this arc that does not touch the print on the circuit board. 5. Repeat step 4 for the other variable resistor around corresponding hole left by R231. Channel A Short the junction of R123, CR101 to pin 3 of V101. Adjust R129 until there is no movement of the trace with rotation of the VERNIER. Remove the short and reset the trace with the DC BAL to the same position on the screen as when the short was in place. Channel B R223, CR201, and pin 3 of V201A Use R229 for adjustment. Repeat asin Channel A using the junction of Insert the above adjustmentprocedure in Section V of your hp Model 1750B Operating and Service Manual in place of the dc balance procedure. Change the schematic diagram and Replaceable Parts List as indicated in Table 1. 02 560- 1 Printed in U.S.A. 1 1 /6 5- 8 7900 Garden of the Gods RoadI Colorado Springs, Colorado, U.S.A. Tel. (303) 636-5717 Europe: 54 Rout8 Des Acacias, G8n8Va1 Switzer/and, cable: HEwPAcKsA 781. (022) 42.81.50 I