HP5334B Universal Counter

G

George S.

Veteran and General Yakker
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So my father gave me this recently, hadn't been used for years. I brought it up slow with the DBT and Variac. Looked good. Went to work testing it with a 2 kHz 250 mV frequency from my cheap Koolertron signal generator/counter. The HP frequency read out was way low, so was reading the manual a second time when the HP sizzled, popped, and smoked. Found a shorted cap in the High Voltage section. Bummer!!!
Pulling it apart now to determine the damage and see if a recap may save it.
 

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Thinking I got very lucky, the board looks perfect on both sides. Now to remove the shorted cap and find out exactly what it is. Good thing HP has excellent documentation. Just told my father I smoked his counter. He admitted it's been years since used. Found a 1980 manufacture date sticker on the back. Not a bad run to failure!
 

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After research, this appears to be a common well known issue, the infamous RIFA exploding capacitors. Common problem. It's rated a safety capacitor as it's connected directly to the mains. Guess the plastic case cracks, it absorbs moisture, boom.
 

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Mine sizzled, I watched my dog's ears go up vertical as he got up off the floor where he was laying. Then it popped with a LOUD bang, he ran out of the room! Smoke then poured out of the unit. Here's a good page and video of this well known problem. My father also gave me a Boonton FM/AM signal generator. I'll be opening it up and looking for these RIFA caps and other issues before powering it up with the DBT and Variac.
https://pjhenley.com/2020/03/19/not-today-rifa-cap/
 
Mark L. Thanks, it took some reading yesterday to learn what the X2 designation on the 0.1 uF and Y on the 2200 pF meant. Two of each in the unit. Going to do some more reading and learn more about Safety Capacitors. I had no idea these were such a specialized item. Can't go wrong with CDE products.
 
They are part of the conducted EMI suppression filter to pass FCC requirements for conducted and radiated emissions. Otherwise not functional.
 
Thanks Joe, was wondering about that, got a lot of RFI filter results when researching this. Makes sense. Very cool how the X caps are supposed to short closed to blow the fuse, and Y caps are supposed to short open to keep the chassis from being a shock hazard. I had no idea.
In this case the X cap shorted and didn't blow the fuse. For my education I need to ohm that blown cap and make sure the proper fuse is in the unit. Yeah I know, should have checked for proper fuse before hooking it up to the DBT and Variac.
I'll get back to it this weekend.
 
Well, the X2 cap shorting did blow the fuse as designed, excellent. Got exact replacement caps from Digikey as they are readily available. They're now made by Kemet and have the RIFA logo and all appropriate markings on them. The new Y caps are now marked Y2.
It's up and running, seems to be working. So many options on this thing, I'll have to refer to the manual every time I use it.
Going to let it set here and run most of day, play with it some, then finish reassembly.
 

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Also got the Boonton 102D up and running today. Thinking this technology precedes the HP by a decade or more
It had a note written inside it about a repair in 1978. Opened it up to inspect it before power. Has 3 metal can Mallory caps in the power supply. Noticed electrolyte stain on the board, so pulled all three caps and tested them with the DER-EE DE-5000 meter. What a great meter! I constructed the optional Kelvin clamps for the meter and it calibrates perfectly. I tested at 120 Hz for uF and ESR. All three tested good. No sign of leakage on the caps themselves, so it must have at least one replaced cap.
Going to let it sit here and idle overnight and do a basic alignment on it tomorrow. Looks easy and straight forward.
 

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laatsch55 said:
Quite a few decimal points there..
Click to expand...
Yup, and I don't have a female N to BNC adapter handy to test it's output. I'll dig in the garage tomorrow and might find one. If not I'll put in Monoprice order, need a few extra cables anyway.
 

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Found a adapter. Going to take me a good while to learn how this all works.
 

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They survived the night powered on just fine and a basic power supply voltage check on the Boonton shows it's within spec. Don't know how much I'll use them in the future, but at least they're saved from the land fill.
Starting work on the PL5000 tuner now. Moderate rebuild, caps, IEC socket, LED lamps.
 

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George S. said:
Also got the Boonton 102D up and running today. Thinking this technology precedes the HP by a decade or more
It had a note written inside it about a repair in 1978. Opened it up to inspect it before power. Has 3 metal can Mallory caps in the power supply. Noticed electrolyte stain on the board, so pulled all three caps and tested them with the DER-EE DE-5000 meter. What a great meter! I constructed the optional Kelvin clamps for the meter and it calibrates perfectly. I tested at 120 Hz for uF and ESR. All three tested good. No sign of leakage on the caps themselves, so it must have at least one replaced cap.
Going to let it sit here and idle overnight and do a basic alignment on it tomorrow. Looks easy and straight forward.
Click to expand...
The DE-5000 is a great portable LCR meter. Side by side with my bench unit, it comes up with the same results. Measures large cap values that the bench unit will not.
 
Joe, good to hear that, gives me confidence the meter reads correct as I have nothing to compare it to.
 
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