#2090

Episode 2090
magic smoke escaped
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[@JRJJ5077]

The logo is Matsushita now known as Panasonic

[@TomSherwood-z5l]

Matsu sure did that time.

[@ebrombaugh]

A similar thing happened on an old HP frequency counter I have - blown main fuse caused by shorted power filter cap. It escaped with no collateral damage but the shorted cap is an old bolt-in style Sprague that costs ~$40 to source. I'm planning to replace it with a PCB mount type that's much less expensive.

[@analog_guy]

The shorted cap problem can sometimes be avoided on old equipment that hasn't been turned on in some time by using a variac to bring up the ac voltage slowly. This procedure gives the capacitors time to re-form the dielectric barriers.

[@TheElectronicDilettante]

Here’s a trick for photographing objects that aren’t easily accessible or easily focused on. Works well for small bore inspection too….. Kinda weird but works…. WiFi based, Ear wax removal cameras available on Amazon for like $10-12. They’re great for inspecting firearm barrel and 3d printer nozzles, small electronic parts under small electronics parts A Tip of the day, in lieu of “Chip of the Day”. Happy Holidays to ImsaiGuy, -Gal, -Dog, -Fam and ImsaiGuy Subscribers

[@glasslinger]

You might check the mains fuse to see if someone put a larger value in. I replaced the whole power supply in my unit. That damn cabinet was over two feet deep! I shortened it to about 18 inches by using a torroid transformer running at over 20 KHZ. It was a bench hog!

[@kenchilton]

A lot of this older equipment has capacitors with older technology. You can replace them with newer ones with higher voltage ratings and get higher longevity while keeping the ESR and all else the same. The working voltages are often much different across electrolytic, and ripple can kill a cap fast, so cap selection is not always that trivial. Too often people will ignore the ESR for bridge-connected caps and end up stressing the diodes and transformer in older gear - maybe not 1980s old, but 1960s for sure. Some diodes are actively self-limiting, others only limit the current permanently on the first try. I recently repaired an “antique” radio where the entire bridge and PS filter part of the PCB had actually caught fire because the owner did something wrong during the repair. The etch fusing is a blessing compared to components breathing fire. It reminded me of my FA work at a former job where they brought me a box of ziplock bags that contained black gravel that used to be a circuit board. The damage to the adjacent boards in the system started me down a path that concluded that the fire started from a cap. One 6.3V cap on a 5V rail killed a $1 million machine and ruined a company’s business for a day. Give it margin.

[@TomSherwood-z5l]

My Fluke RF signal gen. developed a tendency to not turn on, occasionally. Looking at AC into the transformer and nothing out, I discovered the XFMR has a built in thermal switch. But this is a cold start. I thought it was the issue with a winding continuity check. Anyway for awhile if it quit I would rap the transformer can and it would come back to life. Last time it would not power on, it turned out to be one of those plastic pin connectors like on yours. I think I cleaned up the intermittent that I located by nudging it, and so far it has been working all the time.

[@albrowne1035]

A Thor Copper and rawhide mallet on your bench. That's serious percussive maintenance!!!!!!

[@IMSAIGuy]

kzbin.info/www/bejne/pYGcpaCcrbSXb5Isi=XZUohdFuzKJ8jsaO

[@albrowne1035]

@@IMSAIGuy I've never seen any other make other than the Thor mallets. They also make Nylon faced mallets with screw in heads and they come in various sizes and hardness's. I have a 20mm 3/4" with 2 different hardness heads and a bigger one with harder heads as well as a Cu/hide No1 as well. Covered on all sides. Thanks for all the videos. & also licenced radio amateur since 1980

[@henrikstenlund5385]

The typical problem with older PS's are electrolytic caps becoming either dead or shorted. Shorting may cause blowing up of other parts. I have met this problem often with older instruments. The lifetime of electrolytics is about 5000 hours

[@KeritechElectronics]

Is the original IBM magic smoke refill canister compatible with HP equipment, or do you have to do any modifications? Ha. The old 4-pin layout was pretty common here in Europe for multi-section caps. If single section, the remaining pins were just for mechanical support.

[@TomSherwood-z5l]

I think IBM uses digital smoke but the power supply would use analog smoke refills.

[@Janktzoni]

It's the same type of smoke but for the canister to fit you need an adapter from imperial to metric.

[@mikesradiorepair]

Well that sucks. No smoked ham for you for Christmas, just smoked circuit traces. :-( The capacitor logo is Panasonic Matsushita.

[@ivolol]

Might need to dremel some of the burn away so it's not conductive

[@zebo-the-fat]

I thought all the smoke mines had been closed down and most of the smoke in stock is well past it's puff by date!

[@mr1enrollment]

Mine did this also: with all those fuses there is still a Cap that shorts and is not fused,... When the cap shorts - it blows the traces off the PCB where the transformer wires enter the PCB at the rectifiers. dumb. Exactly the same.

[@MrBtcruiser]

That's what happens when you replace the 1A fast-blow main fuse with a 30 A slow-blow - the trace becomes the next fuse - LOL - JK... I had a large 250 VDC electrolytic capacitor short on a switching power supply for a vector scope once - first time I've seen one of those short out.

[@greengrayradio1394]

HP made good equipment (contrary to Wavetek ;) )!

[@ivanpopovic9503]

I have HP4274A and 4275A. 4275 had some problems with memory but it turned out to be the contacts from the board to main board. But 4274 gives me bad hadache. Its ADC has some problems that I can not debug still, and criminally bad scanned and absolutely confusing service manual is of little or no help. 😢 When it is working it is a great instrument thou. P.S. If someone have some higher quality pdf service manual for 4274A, please help!

[@MAGA-Brad]

Omg this video is tooooo short...