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The HP 5015T Logic Troubleshooting Kit contains a 10525T Logic Probe and a 10526T Logic Pulser, complete with: 2 BNC to Croc Clip Adaptors for +5V dc power; and the original Operating & Service Manuals. The probe ground clips and 10528A Logic Clip are missing. This Kit cost $285 in 1980.

Troubleshooting Kit less the the Logic Clip
The HP 10525T Logic Probe indicates TTL/DTL logic states by means of an indicator lamp at the probe tip. This lamp has 3 states, off, half-on (dim), and full-on (bright). It is normally in the dim state and must be driven to off (logic 0 <+0.8V) or bright (logic 1 >+2.0V) by the logic levels at the probe tip. Tri-state or bad logic levels are indicated by the dim state. The lamp will flash for pulse trains >10Hz. The input impedance is similar to a low power TTL gate. The probe is powered by any external +5V suply. A useful feature is a pulse stretcher which provides the ability to detect short duration pulses and low repetition rate pulses that are difficult to observe on an Oscilloscope. Positive going pulses of >10ns will make the lamp flash on and negative going pulses will make the lamp flash off. The probe ground clip is essential for reliable operation with fast pulses, so I have made one up!

The HP 10526T Logic Pulser is a single-shot pulse generator to simulate TTL/DTL input signals. Pressing the small push-button on the pulser body generates a single low level (logic 0) pulse then a high level (logic 1) pulse of 0.3µs each with sufficient source and sink current to override the circuit, but without the possibility of damage. The pulser's output is tri-state so that circuit operation is unaffected until the push-button is pressed. In this way a logic gate can be tested by pulsing the gate's input while monitoring the gate's output with the Logic Probe.

January 2011

Carrying out the Performance Tests are a bit tricky!

The Logic Probe requires a 10µs +ve going and -ve going pulse to be generated with a 1s period, this is 1 in 108. I used my HP 8016A Word Generator and HP 3762A Data Generator for this as I don't have the 8004A specified.

Plastic Case
Initially I believed the Logic Pulser was not working as I couldn't see the 3.5µs pulse on the Oscilloscope. Eventually I realised why and used the storage function on the Tektronix 468 to display it. Fast single pulses are difficult to display and ironically that is one of the strengths of the Logic Probe! Also setting up the totalising count on my HP 5316A Universal Counter meant reading the Manual again.

Both the 10525T and 10526T are now tested, plus I now realise the benefits of using them for logic troubleshooting - a recommended set of test equipment.

July 2011

I have now bought the HP 10528A Logic Clip which clips onto 14 or 16 pin ICs, instantly displaying the states of up to 16 pins. Each of the clip's 16 LEDs independently follows level changes at its associated pin. The clip has its own gating logic for locating ground and Vcc pins and its buffered inputs reduce circuit loading.

The complete Troubleshooting Kit