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{{Oscilloscope Sidebar |
{{Oscilloscope Sidebar |manufacturer=Tektronix |designers= |
title=Tektronix 434 |
series=400-series scopes |
model=434 |
summary=24 MHz analog storage scope |
summary=24 MHz analog storage scope |
image=434 Tek 4.jpg |
image=434 Tek 4.jpg |
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* [[Media:070-1915-00.pdf|Tektronix 434 Manual sn 500,000and up (complete, PDF, OCR, bad-OCR)]]
* [[Media:070-1915-00.pdf|Tektronix 434 Manual sn 500,000and up (complete, PDF, OCR, bad-OCR)]]
* [[Media:070-1131-00.pdf|Tektronix Maual sn below 500,000 (complete, PDF, OCR)]]
* [[Media:070-1131-00.pdf|Tektronix Maunal sn below 500,000 (complete, PDF, OCR)]]
* [[Media:Tek 432 and 434 fcp april 1972.pdf]]
* [[Media:Tek 432 and 434 fcp april 1972.pdf|Tektronix 432 and 434 Factory Calibration Procedure, April 1972 (PDF, needs OCR)]]
}}
}}
The '''Tektronix 434''' is an analog [[CRT storage scope]] with two independent storage areas on the screen.  
The '''Tektronix 434''' is an analog [[CRT storage scope]] with two independent storage areas on the screen.  
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==Links==
==Links==
* Ken Matheson, ''Servicing the 432/434 Oscilloscopes''. In [[Media:Tekscope 1972 V4 N5 Sep 1972.pdf|Tekscope Vol. 4 No. 5, 1972]]
* Ken Matheson, ''Servicing the 432/434 Oscilloscopes''. In [[Media:Tekscope 1972 V4 N5 Sep 1972.pdf|Tekscope Vol. 4 No. 5, 1972]]
* [[050-0674-00|Handle Replacement Modification Kit]]


==Pictures==
==Pictures==
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Tek 434 front up.jpg
Tek 434 front up.jpg
</gallery>
</gallery>
{{Custom ICs|434}}


[[Category:400 series scopes]]
[[Category:400 series scopes]]
[[Category:Analog storage scopes]]
[[Category:Analog storage scopes]]

Revision as of 02:55, 22 November 2021

Manuals – Specifications – Links – Pictures

The Tektronix 434 is an analog CRT storage scope with two independent storage areas on the screen.

It has a bandwidth of 24 MHz and uses a tunnel diode in its trigger circuit. The storage is done in the CRT itself, by trapping charge on a special fine grid of isolated pads behind the phosphor where the electron beam is then blocked or released.

There is a chopped two channel system and the fastest sweep time is 20 ns/div. An option for a tube with higher sensitivity at high writing speeds was available (OPT. 01).

Key Specifications

  • please add

Internals

The signal passes through rotary cam-operated input attenuators, then passes through an input amplifier that is on a separate small board. The input amplifier contains a JFET source-follower buffer that uses a 2N5911A (Tektronix part number 151-1032-00) biased with a drain current of 12.5 mA and Vgs of -0.26 V. The input amplifier has unity gain, high input impedance, and an output impedance of about 120 Ω. The input amplifier drives a Tek-made differential amplifier chip, part number 155-0050-01.

The original instrument design utilized an all-discrete switching power supply, making this an incredibly light portable scope. Unfortunately, this power supply was extremely difficult to troubleshoot when it went belly-up. At serial number B500000 and later, the design of the supply was simplified to use the same basic circuitry as found in the 7704A using a Tek-manufactured controller chip.

Repair Issues

In general, the 434 is a nice-looking, easy-to-use oscilloscope. However, the 434 was probably one of the worst mechanical scope designs to come out of Beaverton engineering. This was the model that caused bench technicians to think that the factory should send all new mechanical engineers out into the field to work at a Service Center for a year to get an idea of good and bad mechanical designs.

First of all, the 434 design departed from the proven 4-40 steel PCB mounting screws. Instead, it uses 3-48 brass screws in a design that requires a screw-holding driver to get the fasteners in place. Brass screws are non-magnetic and getting them started in some of the more obscure places on the vertical preamp board is extremely difficult. Since these scopes are of an age that one can make modifications without incurring the wrath of Tektronix technicians, it is suggested that these brass screws be replaced with steel 3-48 screws, preferably ones with captive washers like the original brass screws. Most dedicated Tektronix fans and ex-technicians do not like changing any circuit design from the original, but some mechanical changes such as this are for everyone's benefit and don't affect operation of the oscilloscope in the least. In fact, if the circuit boards are removed, the original 3-48 threaded holes in the castings can be drilled out and retapped for 4-40 screws.

If the V/DIV knob skirt lamps go out, the vertical preamp board must be removed to replace them. This is a process involving the removal of a lot of the aforementioned brass 3-48 screws, the removal of some connectors, the unsoldering of a lot of wires and the removal of knobs and shafts all over that area of the front panel. Remember, it is always better to leave those red VAR V/DIV knobs on their shafts and instead remove knob and shaft as a unit by loosening it from the coupler on the potentiometer itself. Since these oscilloscopes are considered obsolete, the suggestion is to replace ALL of the vertical knob skirt lamps with light emitting diodes, choosing either white or yellow LEDs. These lamps already have small-value current limiting resistors on the circuit board that are in series, so replacing these resistors with the appropriate value to limit LED current is an easy process. Be careful that you select an appropriate power rating for the resistors. It is suggested that current be limited so that the panel lighting is sufficient for bright room lighting, but not so bright as to make it difficult to read the numbers on the knob skirts.

The 434 uses only two plug-in attenuators (both ×10) in each channel, and most V/DIV switching involves gain switching of the preamp. The 434 often cannot meet vertical gain specifications and some very low-value 5% tolerance resistors must be replaced to correct this. These resistors are not located in an easy-to-access area of the board and once the defective resistors are identified, the board will need to be removed to allow replacement of the resistors without board damage.

Another common problem involves the mounting hardware for the back casting. Nearly every 434 that was received in Tektronix Service Centers had to have these mounting screws tightened. There is one located under the cover for the line cord and fuse. If that screw comes completely out, it is held captive inside that small space, and causes a lot of damage to the open mains connections on the fuse holder. This is a job for a #2 Pozidriv screwdriver and a LOT of muscle torque. Don't use a Phillips driver for this because it will "cam out" of the screw head with the torque that you must apply, causing screw head damage. Regardless of how much torque you apply, you won't strip the extruded aluminum rails or break the large 10-32 screws. Tighten all of these casting-mounting screws by hand as tight as you possibly can. Of course, do not use high-torque pneumatic or electric tools for this job. Especially don't use the electric impact drivers that are so popular now in the construction industry. The hardware DOES have its mechanical limitations.

Links

Pictures


Custom ICs used in the 434

Page Model Part nos Description Designers Used in
155-0028-00 M018 155-0028-00 155-0028-01 155-0042-00 155-0042-01 155-0042-02 155-0042-03 Miller integrator and delay pickoff Joe Burger 5030 R5030 5031 R5031 1401 1401A 1480 1481 1482 1485 26G1 26G2 26G3 314 335 432 434 4701 5B10N 5B12N 5B31 5B40 5B42 5S14N 7B52 7B53A 7B53N 7L12 7L13 7L14 7L18 7S14 AN/USM-281C RG501 Telequipment D63 Telequipment DM63
155-0050-01 M065 155-0050-00 155-0050-01 differential vertical preamplifier Bert tenKate 432 434
155-0051-00 155-0051-00 155-0051-00 Z-axis and HV regulator 432 434
155-0067-02 M091B 155-0067-00 155-0067-02 155-0067-03 SMPS controller Joe Burger Gene Andrews 7704A 7834 7844 7854 7904 R7903 7904 7904A 7934 R7912 7912AD 7912HB 7934 7104 R7103 308 434 485 690 P7001