Author Topic: HP3586A, B, C Selective Level Meters--Battery corrosion of A80 Power Supply PCB  (Read 666 times)

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Offline N2IXKTopic starter

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TL/DR: Just completed the prototyping and testing of a replacement power supply (A80) PCB for these instruments, and am making them available to the community. See my post in Buy/Sell/Wanted to purchase one.


Got hold of an HP 3586B selective level meter (frequency selective voltmeter) for a really cheap price because it was written off as beyond economic repair due to extensive damage to the power supply card due to the NiCd RAM backup battery leaking electrolyte all over the power supply regulator PCB.  the electrolyte also damaged the edge card connector on the motherboard, but fortunately caused no damage to the motherboard itself.  Apparently, the unit had previously been powered up before the corrosion damage was found, resulting in damage to the pass transistor (Q3) and OVP zener (CR20) on the +5V supply rail, which are mounted on a separate heatsink assembly. Replacing these, along with a front panel power switch damaged by someone installing a much too long screw to secure a rackmount bracket, and I now have a nicely working unit that passes all self tests. The A80 board itself suffered extensive damage, with many traces completely destroyed and component leads dissolved by the potassium hydroxide electrolyte. A complete board replacement was the best solution in my case, but people have repaired these in cases with less extensive damage. If you get one of these instruments, CHECK THE A80 BOARD FOR BATTERY LEAKAGE BEFORE POWER ON, and save potential damage to other components.

These are essentially highly sensitive LF/HF radio receivers with variable IF bandwidth and very finely calibrated signal strength meters. Originally intended for use in measuring multifrequency trunking systems for analog telco use, they are also handy instruments for general RF testing purposes.

"My favorite programming language is...SOLDER!"--Robert A. Pease
 


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