Fluke 343 DC Calibrator disposition ideas? - Page 1
Forum section: electronics / repair

author: pete99
author_rank: Contributor
timestamp: November 17, 2018, 07:38:14 am
content: Hello, Not quite sure how to handle this situation, so I'll just throw it out there.A couple years ago I purchased a used, broke Fluke 343A DC Calibrator and put many hours repairing mechanical parts and replacing many electrical components. I replaced all capacitors and a few other parts. All parts were purchased from Mouser or DigiKey. It passed all of the test points and the 10v and 100v ranges were, I believe, in spec. However when I switched to the 1000 volt range, it would go into overload mode. I tested everything over and over and could not find the problem. I even paid a YouTube guy to assist in troubleshooting, but he got busy, bailed, and the problem remained. So I set it aside for a few months.On a side project, I decided to monitor the 15 vdc reference voltage, the output at 10v, and the internal temperature, over a period of 7 days or so just for kicks. However Murphy and me teaming up is a force not to be messed with. As luck would have it a 1 mm exposed area of an alligator clip (yeah, I know) ever so briefly made contact with the chassis and shorted out the 15 volt reference. I dicked around abit and didn't find anything obvious, so it remains in a sad state. Last straw.I have put way too much time in this, and it is time for it to leave this house and find someone more deserving. The case looks beautiful, like new, and I have many new spare parts to go with it. So I am willing to send it to someone that wants it. I am not interested in selling it on Ebay. And I rather not spend big bucks shipping it outside the lower 48 states unless someone wants to kick in some help with shipping costs (weighs about 25 U.S pounds).So I am open to suggestions as I respect youse guys greatly (and yes, even the beloved Dave Chicken Dinner How do ya do).Thanks for any ideas.Steve

author: DC1MC
author_rank: Super Contributor
timestamp: November 17, 2018, 08:12:06 am
content: If no US taker, I'll offer it asylum in Germany and take the payment of the cheapest shipping to Mannheim Germany you got with Parcel Monkey:https://www.parcelmonkey.com/PM for details please.Cheers,DC1MC

author: coromonadalix
author_rank: Super Contributor
timestamp: November 17, 2018, 02:05:15 pm
content: Sell to Canada ? usps for an 25 pound item is aroud 45 usd ?? how much do you want to sell it ?

author: pigrew
author_rank: Frequent Contributor
timestamp: November 18, 2018, 12:54:58 am
content: I'd be happy to receive it, but other than volt- nuttery, I don't have a great use for it. Except if the reference was dead, I expect that I can get it working again. I don't have any power supplies that go above 60V or so..I live in Indiana, the Crossroads of America, origin of our vice president, and home to Purdue University (where I am a student).Thanks for your consideration!

author: coromonadalix
author_rank: Super Contributor
timestamp: November 30, 2018, 11:06:59 pm
content: I was the lucky receiverWell i did manage to have some spare time sonner than anticipatedThanks to Pete 99Upon firsts checks, the first dial, is still wobly and shaky, the repaired stubs arent strong enough to keep it still ....The 15v main reference is dead, some transistors have blown, the smallest 2n3904 are damaged, the 2 main transistors C19 and C23 seems ok, all tested outside the board.I dont think the temperature compensated Q14 DH71005 diode/ transistor is damaged, the differentials transistors Q15 Q17 and zenners CR19 CR20 seems fine too.There is an tantalum capacitor who wansn't changed, c68 an 4.7 uf 50v, not shown on the schematic, it is conected to the TP1 test point and ground.There was a missing jumper for an bleeder resistor, for the C55 and C56 main high voltage capacitors, since the originals where 3 leads instead of the new 2 legged ones put by PeteNice to see an strange wire winding R24 resistor in a clear protection plastic for an precision 305 ohms resistorin the reference adjustment circuit.Thats all for now

author: coromonadalix
author_rank: Super Contributor
timestamp: December 03, 2018, 09:28:23 pm
content: I have now repaired the reference voltage circuit, 2x 2n3904 has been changed, even if 1 of them was ok.I'm now where Pete was i think, the control circuit in 1kv is going nuts, if i push manually the control relay (K1 ...k1a k1b), i can get more tha 100v on the outputs, but one power resistor R84 doesn't like this at all and i have only 1.86volts at c5, but should be around 10 voltsEdit december 11: it seems when you select the 1kv range, you have some current rush in it, it triggers the overload protection

author: coromonadalix
author_rank: Super Contributor
timestamp: December 11, 2018, 06:35:26 pm
content: I think there is 2 problems or one problem who affect 2 sections, the crowbar section and the current limitter, when selecting 1kv i have somekind of a surge who trip the current limitter ??Maybe the output capacitor has a low impedance ? But the output impedance is okay ??If i forcefully push the control relay, i can have more than 100v, tried 500v and up, but some power resistors get hot petty fast ??I will try to disable or bypass the current limitter and try to see where it goes ...The output seems noisy and jump a few mv`s once in a while ?Im debugging the 343 with an fluke 189, just bought an 34401A to be repaired on the casing parts, to go against it, and make some 343 calibrations when repaired ...