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{{Oscilloscope Sidebar | |||
|manufacturer=Tektronix | |||
image=Tek-7904-front.jpg | | |series=7000-series scopes | ||
caption=Tektronix 7904 (with [[7A19]], [[7A11]], [[7D11]], [[7B85]]) | | |model=7904 | ||
introduced=1971 | | |designers=Val Garuts;Thor Hallen;John McCormick;Les Larson;Bill DeVey;Bill Peek;Hans Springer;Joe Burger;Joel Swanno;Ken Hawken | ||
discontinued= | |image=Tek-7904-front.jpg | ||
summary=500 MHz non-storage mainframe| | |caption=Tektronix 7904 (with [[7A19]], [[7A11]], [[7D11]], [[7B85]]) | ||
manuals= | |introduced=1971 | ||
* [ | |discontinued=1984 | ||
* [ | |summary=500 MHz non-storage mainframe | ||
* [ | |manuals= | ||
* [ | '''7904''' | ||
* [ | * [[Media:070-1399-00.pdf|Tektronix 7904 Operators Manual]] | ||
* [[Media:070-2390-00.pdf|Tektronix 7904 Instruction Manual with PSU Schematics]] SN B260000+ (OCR) | |||
* [[Media:070-2390-02.pdf|Tektronix 7904 Instruction Manual with complete schematics]] Below SNB260000 (Needs OCR) | |||
* [[Media:Servicing the Tek 7904 Power Supply.pdf|Servicing the 7904 High-Efficiency Power Supply]] | |||
* [[Media:Tektronix - 7904 - Horizontal Amplifier B010100 - B079999.pdf|Horizontal Amplifier SN B010100 - B079999]] | |||
<small> | |||
'''Modifications''' | |||
* [https://hakanh.com/dl/docs/kitinstructions/050-0650-00.pdf 050-0650-00 (1980) Vertical amplifier IC replacement] | |||
* [https://hakanh.com/dl/docs/kitinstructions/050-0651-01.pdf 050-0651-01 (1975) Vertical output IC replacement (155-0065-00)] | |||
* [https://hakanh.com/dl/docs/kitinstructions/050-0706-01.pdf 050-0706-01 (1980) Vertical output IC replacement (155-0065-00)] | |||
* [https://hakanh.com/dl/docs/kitinstructions/050-0729-06.pdf 050-0729-06 (1980) A Trigger selector circuit board replacement] | |||
* [https://hakanh.com/dl/docs/kitinstructions/050-0730-06.pdf 050-0730-06 (1980) B Trigger selector circuit board replacement] | |||
* [https://hakanh.com/dl/docs/kitinstructions/050-0763-03.pdf 050-0763-03 (1981) Vertical interface circuit board replacement] | |||
* [https://hakanh.com/dl/docs/kitinstructions/050-1014-00.pdf 050-1014-00 (1980) Vertical output IC replacement] ([[155-0064-00]]) | |||
* [https://hakanh.com/dl/docs/kitinstructions/050-1723-01.pdf 050-1723-01 (1983) P31 CRT replacement] | |||
* [https://hakanh.com/dl/docs/custommods/7904mod721K.pdf Custom Mod 721K (1972) Single shot readout and/or grat illumination] | |||
</small> | |||
}} | }} | ||
The '''Tektronix 7904''' is a 500 MHz, non-storage 7000-series oscilloscope mainframe with four bays. | The '''Tektronix 7904''' is a 500 MHz, non-storage 7000-series oscilloscope mainframe with four bays. | ||
It accepts two [[7000-series_plug-ins#Vertical plug-ins|7000-series vertical plug-ins]] and two [[7000-series_plug-ins#Horizontal plug-ins|7000-series horizontal plug-ins]]. | |||
There is also a rack-mount version, the [[R7903]], albeit with only one horizontal bay. | |||
Performance is largely determined by the plug-ins. | The 7904 was introduced in late 1971/early 1972 (Note 1). In 1984, it was replaced by the redesigned [[7904A]]. | ||
Performance is largely determined by the plug-ins. | |||
The [[7A19]] vertical amplifier and [[7B92]] time base were introduced along with the 7904 to match the 500 MHz system bandwidth. | |||
Design Staff of 7904 Project (from July 1971 Tekscope): | |||
<blockquote>[[Val Garuts]] was project manager and developed the large signal amplifier circuit used in the horizontal and Z-axis amplifiers. [[Thor Hallen]] did the [[7A19]] plug-in and the vertical amplifier, and [[John McCormick]] the horizontal. The trigger and time base ([[7B92]] plug-in) were done by [[Les Larson]] and [[Bill DeVey]]. [[Bill Peek]] worked on the Z-axis amplifier and auto-focus, with [[Hans Springer]] doing the mainframe interface and channel switching. [[Joe Burger]]'s work on the power supply, coupled with [[Joel Swanno]]’s efforts in mechanical design, reduced the weight to only 30 pounds. [[Ken Hawken]] did the fine job on the CRT. </blockquote> | |||
{{BeginSpecs}} | {{BeginSpecs}} | ||
{{Spec | Bandwidth | 500 MHz }} | {{Spec | Bandwidth | 500 MHz (with [[7A19]] or [[7A29]] amplifier) }} | ||
{{Spec | Fastest calibrated sweep | 500 ps/Div (with [[7B92A]], other time bases "uncalibrated for first 60 ns") }} | {{Spec | Fastest calibrated sweep | 500 ps/Div (with [[7B92A]], other time bases "uncalibrated for first 60 ns") }} | ||
{{Spec | | {{Spec | Outputs | Vertical Signal Out (25 mV/Div into 50 Ω, 0.5 V/Div into 1 MΩ); +Sawtooth; +Gate; camera power; probe power }} | ||
{{Spec | Inputs | Z Axis (15 V<sub>p-p</sub>) }} | |||
{{Spec | | {{Spec | CRT | | ||
* Standard: (8×10 Div @ 1 cm), P31 (green) [[154-0644-05]] or P11 (blue) [[154-0644-09]], acceleration voltage 24 kV (+21 / –3 kV) | |||
{{Spec | CRT | |||
* Standard: (8×10 Div @ 1 cm), P31 (green) [[154-0644-05]] or P11 (blue) [[154-0644-09]] | |||
* Option 4, high writing speed: (8×10 Div @ 0.5 cm) , P31 (green) [[154-0661-05]] or P11 (blue) [[154-0661-09]] | * Option 4, high writing speed: (8×10 Div @ 0.5 cm) , P31 (green) [[154-0661-05]] or P11 (blue) [[154-0661-09]] | ||
}} | }} | ||
{{ | {{Spec | Calibrator | DC, square wave (1 kHz or ½ B Sweep gate), 4 mV to 40 V in decade steps (2/20/200/400 mV into 50 Ω); 40 mA current loop }} | ||
{{Spec | Power | 90−132 V or 180−264 V, 48−440 Hz, 190 W max. }} | |||
{{Spec | Weight | 13.5 kg (30 lbs) }} | |||
{{Spec | Dimensions | 34.2 cm × 30.5 cm × 69.5 cm (13.5 in x 12.0 in x 23.8 in) H×W×L }} | |||
{{Spec|Options| | |||
* Opt.1: deletes read out system | |||
* Opt.2: X-Y delay compensation network | * Opt.2: X-Y delay compensation network | ||
* Opt.3: Extra EMI shielding | * Opt.3: Extra EMI shielding | ||
* Opt.4: Maximum-brightness CRT with reduced area | * Opt.4: Maximum-brightness CRT with reduced area | ||
* Opt.78: P11 phosphor | * Opt.78: P11 phosphor | ||
}} | |||
{{EndSpecs}} | |||
==Links== | |||
* [https://lazyelectrons.wordpress.com/2018/11/24/tektronix-7904-oscilloscope-power-supply-repair/ 7904 Repair with Video] | |||
* [http://amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_mainframe/7904.htm Tek 7904] @ amplifier.cd | |||
* [https://www.circuitsathome.com/measurements/repairing-front-panel-buttons-of-tektronix-7904-oscilloscope Repairing front panel buttons of Tektronix 7904 oscilloscope] | |||
{{Documents|Link=7904}} | |||
{{PatentLinks|7904}} | |||
==Operation== | ==Operation== | ||
The 7904 has many modes of operation. | |||
One mode is called "Independent-Pairs Display" in the manual, where the input to the left vertical plug-in is displayed using the B horizontal time-base plug-in, | |||
and the input to the right vertical plug-in is displayed using the A horizontal time-base plug-in. | |||
This resembles the trace-slaving "ALT" mode that is produced by an [[1A4]] in a [[547]]. Many other modes are available. | |||
It is possible to put vertical plug-ins in the horizontal slots for X-Y operation. | |||
It is even possible to put a horizontal plug-in in one of the vertical slots to produce a raster scan. | |||
A special plug-in, the [[7A21N]], provides direct access to the deflection plates up to 1 GHz at an uncalibrated sensitivity of 4 V/Div. | |||
This plugin requires modifications to the mainframe to bypass the Y output amplifier (thus disabling readout and the other vertical plugin bay). | |||
A | A rear-panel [[7904 remote control connector| remote control connector]] has connections for single-sweep ready lamps, a reset button, and readout control. | ||
==Internals== | ==Internals== | ||
The 7904 uses a switch-mode power supply and has no fan. | The 7904 uses a switch-mode power supply and has no fan. The signal path is completely differential and the internal signal wiring is 50 Ω coax. | ||
[[ | The Y delay line in the 7904 has a delay of 65 ns, which is too short for some older time bases such as [[7B53]] to display the trigger event. | ||
The CRT ([[154-0644-05]]) has [[distributed vertical deflection plates]]. | |||
[[Thor Hallen]] designed the main vertical amplifier and the [[7A19]] plugin (Note 1). | |||
It used bridged T coils and the "[[ft doubler|f<sub>t</sub> doubler]]" circuit patented by [[Carl Battjes]] to achieve its bandwidth. | |||
The | The 7904 makes extensive use of custom integrated circuits and hybrid circuits, inter alia, the [[155-0064-00]] 470-ps output amplifier, | ||
[[155-0022-00]] analog multiplexer for channel switching, [[155-0059-00]] HF amplifier, | |||
[[155-0095-01]] and [[155-0095-03]] differential HF amplifiers, and [[155-0067-02]] SMPS controller. | |||
Early 7904 have issues with horizontal aberrations for sweep rates of 1 ns/Div or faster. After discovery of the issue modification kits that replace the horizontal amplifier were offered. For more information see the table below and the [[Media:Tek 067-0657-00 with schematics.pdf|manual]] of the [[067-0657-00|067-0657-00 Normalized Ramp Generator]] that was used to investigate and rectify this issue. | |||
{| class="wikitable" | |||
|- | |||
! Serial Number | |||
! A9 Horizontal Amp. | |||
! Issue | |||
! Modification Kit | |||
|- | |||
|B010000-B081987 | |||
||670-1632-00 | |||
|Fully calibrated sweeps for rates of 1 ns/Div or faster requires a dedicated [[7B92]] (non A!) and the two units to be calibrated as a system. | |||
|050-0636-01 | |||
|- | |||
|B081988-B219999 | |||
||670-1632-01 | |||
|Can be calibrated to either work with magnifier timebases ([[7B70]],[[7B80]]), or alternatively non-magnifying time bases ([[7B92A]]), but not both. | |||
|040-0791-00 | |||
|- | |||
|B220000 and above | |||
|670-1632-02/03 | |||
|None - fully compatible with all timebases and all sweep rates. | |||
|− | |||
|} | |||
==Prices== | ==Prices== | ||
Line 67: | Line 128: | ||
! 1976 | ! 1976 | ||
! 1980 | ! 1980 | ||
|- | |- | ||
! Model | ! Model | ||
Line 75: | Line 134: | ||
|align=center| 7904 | |align=center| 7904 | ||
|align=center| 7904 | |align=center| 7904 | ||
|- | |- | ||
!rowspan=2| Mainframe only | !rowspan=2| Mainframe only | ||
Line 83: | Line 140: | ||
|align=right| $4,100 | |align=right| $4,100 | ||
|align=right| $6,265 | |align=right| $6,265 | ||
|- | |- | ||
! | ! In 2024 Dollars | ||
|align=right| $ | |align=right| $21,800 | ||
|align=right| $ | |align=right| $22,600 | ||
|align=right| $23,900 | |||
|align=right| $23, | |||
|- | |- | ||
!rowspan=2| Mainframe with [[7A19]],<br />7A19 Opt. 04, [[7B92]] | !rowspan=2| Mainframe with [[7A19]],<br />7A19 Opt. 04, [[7B92]] | ||
Line 98: | Line 151: | ||
|align=right| $7,765 | |align=right| $7,765 | ||
|align=right| $12,015 | |align=right| $12,015 | ||
|- | |- | ||
! | ! In 2024 Dollars | ||
|align=right| $ | |align=right| $41,300 | ||
|align=right| $ | |align=right| $42,900 | ||
|align=right| $ | |align=right| $45,800 | ||
|} | |} | ||
==Notes== | ==Notes== | ||
# See [[7A11]] and [[John Addis]], ''Good Engineering and Fast Vertical Amplifiers'', in Jim Williams (Ed.), ''Analog Circuit Design: Art, Science and Personalities'' (1991), p.114, and [ | # See [[7A11]] and [[John Addis]], ''Good Engineering and Fast Vertical Amplifiers'', in [[Jim Williams]] (Ed.), ''Analog Circuit Design: Art, Science and Personalities'' (1991), p.114, and [[Media:Tektronix_New_Products_March_1972.pdf|Tektronix New Products 1972]] brochure. | ||
==Pictures== | ==Pictures== | ||
<gallery> | <gallery> | ||
Tek-7904-front.jpg | 7904 (non-A) front | |||
Tek 7904 rear.jpg | 7904 rear | |||
7904-left.jpg | Left side. Left top: Vertical amplifier; left bottom: switch-mode power supply; right center: delay line; right bottom: plug-in bays | |||
7904-right.jpg | Right side. Top left: calibrator; bottom left: plug-in bays; top center: [[7000 series readout system|readout board]]; top right: Z amplifier | |||
7904-right-front.jpg | Right side detail. Left: calibrator; right: readout. | |||
7904 interface 1.jpg|Plug-in backplane board front (left trigger selector piggyback board removed) | |||
Tek7904-trig-selector.jpg | B Trigger selector piggyback board (A6) | |||
Tek7904-vertical-interface.jpg | Vertical interface piggyback board (A7). The two [[155-0095-03]] amplifiers (large metal cans) are used to select the signal from one vertical plug-in bay, and drive the delay line. | |||
7904 interface 2.jpg|Plug-in backplane board rear | |||
Tek7904-backplane-bottom.jpg | Backplane board sandwich seen from below | |||
7904-x-amp.jpg | Horizontal (X) amplifier board (late >B220000) | |||
7904-y-amp.jpg | Vertical (Y) amplifier board | |||
7904-z-amp.jpg | Z amplifier board | |||
7904-controls.jpg | front-panel controls | |||
7904_block.gif|7904 block diagram | |||
Tek7904-7a19-7b92a-1010mhz-hfsync.jpg | A 7B92A (B098xxx) displaying a 1.01 GHz sine in HF Sync mode ([[7904]] mainframe, [[7A19]] amplifier). | |||
</gallery> | |||
====Power Supply==== | ====Power Supply==== | ||
<gallery> | <gallery> | ||
7904-psu-internal.jpg | 7904 switchmode power supply, covers removed | |||
7904-psu-right.jpg | View from right (as seen from front of instrument) | |||
7904-psu-primary.jpg | Primary side circuit board | |||
7904-psu-primary-caps.jpg | Primary side capacitors | |||
7904-psu-transformer.jpg | Detail view of transformer from the side | |||
Tek_7904_SMPS-xformer.jpeg| Switching transformer | |||
7904-psu-rectifier.jpg | Secondary side rectifier board | |||
7904-psu-regulator.jpg | Secondary side post-regulator | |||
Tek_7904_SMPS-HV-Block.jpeg| HV block, multiplier | |||
</gallery> | </gallery> | ||
==Parts== | |||
{{Parts|7904}} | |||
{{Custom ICs|7000 series readout system}} | |||
[[Category:7000 series non-storage mainframes]] | [[Category:7000 series non-storage mainframes]] |
Latest revision as of 05:37, 26 September 2024
The Tektronix 7904 is a 500 MHz, non-storage 7000-series oscilloscope mainframe with four bays. It accepts two 7000-series vertical plug-ins and two 7000-series horizontal plug-ins. There is also a rack-mount version, the R7903, albeit with only one horizontal bay.
The 7904 was introduced in late 1971/early 1972 (Note 1). In 1984, it was replaced by the redesigned 7904A.
Performance is largely determined by the plug-ins. The 7A19 vertical amplifier and 7B92 time base were introduced along with the 7904 to match the 500 MHz system bandwidth.
Design Staff of 7904 Project (from July 1971 Tekscope):
Val Garuts was project manager and developed the large signal amplifier circuit used in the horizontal and Z-axis amplifiers. Thor Hallen did the 7A19 plug-in and the vertical amplifier, and John McCormick the horizontal. The trigger and time base (7B92 plug-in) were done by Les Larson and Bill DeVey. Bill Peek worked on the Z-axis amplifier and auto-focus, with Hans Springer doing the mainframe interface and channel switching. Joe Burger's work on the power supply, coupled with Joel Swanno’s efforts in mechanical design, reduced the weight to only 30 pounds. Ken Hawken did the fine job on the CRT.
Key Specifications
Bandwidth | 500 MHz (with 7A19 or 7A29 amplifier) |
---|---|
Fastest calibrated sweep | 500 ps/Div (with 7B92A, other time bases "uncalibrated for first 60 ns") |
Outputs | Vertical Signal Out (25 mV/Div into 50 Ω, 0.5 V/Div into 1 MΩ); +Sawtooth; +Gate; camera power; probe power |
Inputs | Z Axis (15 Vp-p) |
CRT |
|
Calibrator | DC, square wave (1 kHz or ½ B Sweep gate), 4 mV to 40 V in decade steps (2/20/200/400 mV into 50 Ω); 40 mA current loop |
Power | 90−132 V or 180−264 V, 48−440 Hz, 190 W max. |
Weight | 13.5 kg (30 lbs) |
Dimensions | 34.2 cm × 30.5 cm × 69.5 cm (13.5 in x 12.0 in x 23.8 in) H×W×L |
Options |
|
Links
- 7904 Repair with Video
- Tek 7904 @ amplifier.cd
- Repairing front panel buttons of Tektronix 7904 oscilloscope
Documents Referencing 7904
Document | Class | Title | Authors | Year | Links |
---|---|---|---|---|---|
Tekscope 1971 V3 N4 Jul 1971.pdf | Article | A Subnanosecond Realtime Oscilloscope | Val Garuts • Thor Hallen | 1971 | 7904 • 154-0644-00 • 7A19 • Ft doubler • 7B92 |
7000 series brochure March 1973.pdf | Brochure | 7000 series brochure, March 1973 | 1973 | 7A11 • 7A12 • 7A13 • 7A14 • 7A15A • 7A16A • 7A17 • 7A18 • 7A19 • 7A21N • 7A22 • 7B50 • 7B53A • 7B70 • 7B71 • 7B92 • 7CT1N • 7D11 • 7D13 • 7D14 • 7D15 • 7M11 • 7L12 • 7S11 • 7S12 • 7T11 • 7704A • R7704 • 7904 • R7903 • 7603 • R7603 • 7403N • R7403N • 7313 • R7313 • 7613 • R7613 • 7623 • R7623 • P7001 | |
Tekscope 1974 V6 N3.pdf | Article | Servicing the 7904 high-efficiency power supply | 1974 | 7904 |
Patents that may apply to 7904
Page | Title | Inventors | Filing date | Grant date | Links |
---|---|---|---|---|---|
Patent US 3453403A | Power selection device | Eldon Hoffman | 1966-08-18 | 1969-07-01 | 115 • 140 • 141 • 141A • 144 • 145 • 146 • 147 • 148 • 149 • 149A • 230 • 284 • 286 • 453 • 454 • 491 • 520A • 521A • 522 • 545B • 547 • 556 • 561B • 564B • 568 • 576 • 611 • 647A • 2101 • 2601 • 5030 • R5030 • 5031 • R5031 • 7503 • 7504 • 7704 • 7704A • 7904 • R7903 |
Operation
The 7904 has many modes of operation. One mode is called "Independent-Pairs Display" in the manual, where the input to the left vertical plug-in is displayed using the B horizontal time-base plug-in, and the input to the right vertical plug-in is displayed using the A horizontal time-base plug-in. This resembles the trace-slaving "ALT" mode that is produced by an 1A4 in a 547. Many other modes are available. It is possible to put vertical plug-ins in the horizontal slots for X-Y operation. It is even possible to put a horizontal plug-in in one of the vertical slots to produce a raster scan.
A special plug-in, the 7A21N, provides direct access to the deflection plates up to 1 GHz at an uncalibrated sensitivity of 4 V/Div. This plugin requires modifications to the mainframe to bypass the Y output amplifier (thus disabling readout and the other vertical plugin bay).
A rear-panel remote control connector has connections for single-sweep ready lamps, a reset button, and readout control.
Internals
The 7904 uses a switch-mode power supply and has no fan. The signal path is completely differential and the internal signal wiring is 50 Ω coax.
The Y delay line in the 7904 has a delay of 65 ns, which is too short for some older time bases such as 7B53 to display the trigger event. The CRT (154-0644-05) has distributed vertical deflection plates.
Thor Hallen designed the main vertical amplifier and the 7A19 plugin (Note 1). It used bridged T coils and the "ft doubler" circuit patented by Carl Battjes to achieve its bandwidth.
The 7904 makes extensive use of custom integrated circuits and hybrid circuits, inter alia, the 155-0064-00 470-ps output amplifier, 155-0022-00 analog multiplexer for channel switching, 155-0059-00 HF amplifier, 155-0095-01 and 155-0095-03 differential HF amplifiers, and 155-0067-02 SMPS controller.
Early 7904 have issues with horizontal aberrations for sweep rates of 1 ns/Div or faster. After discovery of the issue modification kits that replace the horizontal amplifier were offered. For more information see the table below and the manual of the 067-0657-00 Normalized Ramp Generator that was used to investigate and rectify this issue.
Serial Number | A9 Horizontal Amp. | Issue | Modification Kit |
---|---|---|---|
B010000-B081987 | 670-1632-00 | Fully calibrated sweeps for rates of 1 ns/Div or faster requires a dedicated 7B92 (non A!) and the two units to be calibrated as a system. | 050-0636-01 |
B081988-B219999 | 670-1632-01 | Can be calibrated to either work with magnifier timebases (7B70,7B80), or alternatively non-magnifying time bases (7B92A), but not both. | 040-0791-00 |
B220000 and above | 670-1632-02/03 | None - fully compatible with all timebases and all sweep rates. | − |
Prices
Year | 1972 | 1976 | 1980 | |
---|---|---|---|---|
Model | 7904 | 7904 | 7904 | |
Mainframe only | Catalog price | $2,900 | $4,100 | $6,265 |
In 2024 Dollars | $21,800 | $22,600 | $23,900 | |
Mainframe with 7A19, 7A19 Opt. 04, 7B92 |
Catalog price | $5,500 | $7,765 | $12,015 |
In 2024 Dollars | $41,300 | $42,900 | $45,800 |
Notes
- See 7A11 and John Addis, Good Engineering and Fast Vertical Amplifiers, in Jim Williams (Ed.), Analog Circuit Design: Art, Science and Personalities (1991), p.114, and Tektronix New Products 1972 brochure.
Pictures
-
7904 (non-A) front
-
7904 rear
-
Left side. Left top: Vertical amplifier; left bottom: switch-mode power supply; right center: delay line; right bottom: plug-in bays
-
Right side. Top left: calibrator; bottom left: plug-in bays; top center: readout board; top right: Z amplifier
-
Right side detail. Left: calibrator; right: readout.
-
Plug-in backplane board front (left trigger selector piggyback board removed)
-
B Trigger selector piggyback board (A6)
-
Vertical interface piggyback board (A7). The two 155-0095-03 amplifiers (large metal cans) are used to select the signal from one vertical plug-in bay, and drive the delay line.
-
Plug-in backplane board rear
-
Backplane board sandwich seen from below
-
Horizontal (X) amplifier board (late >B220000)
-
Vertical (Y) amplifier board
-
Z amplifier board
-
front-panel controls
-
7904 block diagram
Power Supply
-
7904 switchmode power supply, covers removed
-
View from right (as seen from front of instrument)
-
Primary side circuit board
-
Primary side capacitors
-
Detail view of transformer from the side
-
Switching transformer
-
Secondary side rectifier board
-
Secondary side post-regulator
-
HV block, multiplier
Parts
Some Parts Used in the 7904