I’m looking for a replacement bulb (5V) for the HP 59303A digital to analog converter in the front panel. I decided to use the LED and a resistor of 360 ohms. The result looks very good.
The difference between an LED on the left and an original bulb in the middle.
I have an HP 9872B plotter in my collection that is in very bad condition. There is a short circuit in the power supply somewhere. The foil on the paper surface has come off. I noticed that the HP 9872B plotter has a card slot. Does anyone know what it is for?
I think I’ve found the reason for the fuse blowing. Perhaps a short-circuited diode. With the variable transformer I already have 2 A at a few volts. I found a diode with a short circuit. Maybe I have a suitable one in my spare parts store.
I swapped a few filters. I didn’t have the right values but I improvised.
YES!!! Successfully repaired! Three of four diodes replaced. The HB 9872B plotter has come back to life!
The missing HP logo was replaced with an original one. Everything was cleaned and the HP 9872B plotter was ready.
The HP 8481B power sensor can measure 1mW to 25W without an offset on the HP 438A power meter and can do so up to 18 GHz. The attenuator is part of the power sensor system. I will carry out a few tests.
The HP 9872C is one of the most beautiful plotters HP has ever developed. Repair first… I’m trying to replace the foil cable that broke with a new one.
Repair successfully completed
Demonstration of a 1981 HP 9872C pen plotter drawing a Columbia space shuttle. The plotter is controlled by an HP 85B computer.
Troubleshooting the HP 5334A Universal Counter. The internal highly stable crystal oscillator drifts after 2h. Monitor all voltages on the power supply. Definitely a thermal problem. The drift disappears through a brief cooling and then returns a short time later.
The problem was the C8 capacity. This must be removed after installing option 010.
