Electronic Development Corp E100E Pictures and Specs - Page 1
Forum section: electronics / testgear

author: idpromnut
author_rank: Unknown
timestamp: January 02, 2014, 07:01:12 pm
content: This jumped onto my bench the other day... Merrrry Christmas!This is an EDC Millivolt Standard, two ranges (10V with 0.1mV resolution, and 100mV x with 1uV resolution). The closest "manual" that I could find was for the E100RC (which is what looks like a newer revision of the same model from EDC, and I believe Krohn-Hite bought EDC at some point). I have done some quick testing against my HP 3748a, and it looks like it is within ~1.9uV on the 10V range.One thing that I am wondering about (and I couldn't find any obvious information online) is the tube-like component on the top right of the board. Anyone have any ideas what it is?I will probably trace out the board schematic at some point, but a few of these components are rather alien to meAnyhow, enjoy!Chris

author: david77
author_rank: Frequent Contributor
timestamp: January 02, 2014, 07:15:50 pm
content: I'd say the tube-like thing is a relay. Might be some special kind of relay, maybe one with mercury wetted contacts? I seem to remember they used to be made in this shape.Edit:Nice to see those German made axial caps in there, the golden axial ones on the left should be ERO caps, the blue ones might be as well - the shape fits but I've never seen them with blue heatshrink. In my experience they last a long long time.

author: Unknown
author_rank: Unknown
timestamp: January 02, 2014, 07:18:35 pm
content: Quote from: idpromnut on January 02, 2014, 07:01:12 pmGoing on the basis it has a schematic if a relay on top I'm going to guess.... relay.

author: idpromnut
author_rank: Unknown
timestamp: January 02, 2014, 07:43:50 pm
content: Quote from: Lurch on January 02, 2014, 07:18:35 pmHmm, I didn't think about it, but yes, it does look like the schematic for a relay. And it buzzes (but more like a transformer buzz) when on.

author: Bored@Work
author_rank: Super Contributor
timestamp: January 02, 2014, 09:21:16 pm
content: It is not just any relay, it is a chopper relay, typically used to build a chopper amplifier. A choper amplifier is an old technique to work with very low voltage DC signals, by chopping the signal, i.e. converting it into low voltage AC, and then using an AC amplifier to amplify the signal.Edit: Oh, and it buzzes like a transformer, because it is likely driven with 50 Hz/60 Hz AC from the secondary of the power transformer.

author: Vgkid
author_rank: Super Contributor
timestamp: January 02, 2014, 10:03:22 pm
content: Bored is correct In identifying the airpax chopper relay. Can you post some pics of the switches/ divider resistors.Did you buy this one on ebay, if so I was the other watcher.

author: SeanB
author_rank: Super Contributor
timestamp: January 02, 2014, 10:18:05 pm
content: I will also point out that most of the capacitors in that unit are wet tantalum types. Check the ESR on them and if they have a rubber seal then sadly you will need to replace them as they do tend to dry out from evaporation through the seals. If they have a glass frit seal ( white and soldered to the outer case) then they will still be fine. I replaced many hundreds of those rubber sealed units over the years as they died.

author: Vgkid
author_rank: Super Contributor
timestamp: January 02, 2014, 10:33:18 pm
content: Sean, for most applications would it be acceptable to replace the wet tantalums with electro caps?

author: idpromnut
author_rank: Unknown
timestamp: January 02, 2014, 11:29:58 pm
content: Quote from: Vgkid on January 02, 2014, 10:03:22 pmWill do in a bit (after the kiddo is in bed). And yes, I did buy it on ebay. It looked like an item that was "discovered in an attic" by the seller

author: Vgkid
author_rank: Super Contributor
timestamp: January 02, 2014, 11:57:27 pm
content: You beat me to the bid, I did find out from the bidder that it seems to have worked correctly.(I asked about the ready light, which is used to check on the offsets) It is rather interesting that your unit uses a mech chopper, the schematic I have uses a op37 for that.

author: idpromnut
author_rank: Unknown
timestamp: January 03, 2014, 12:48:08 am
content: Hmm, would you be able to/mind posting the schematic here? And yes, I had to make an offer twice, the seller was sick during the first offer period. I was actually really lucky that they countered (they could have said to hell with this dude) I will see if I can easily pull the board out and get some hi-res photos of the component and trace sides.

author: Vgkid
author_rank: Super Contributor
timestamp: January 03, 2014, 01:38:12 am
content: Here you go, I got it from Krohn Hite.http://www.filedropper.com/e100servicemanual

author: idpromnut
author_rank: Unknown
timestamp: January 03, 2014, 04:13:07 am
content: Some more pictures of the insides.

author: SeanB
author_rank: Super Contributor
timestamp: January 03, 2014, 08:28:23 am
content: Yes you can replace the wet tantalum with modern electrolytics. Just up the voltage rating to double and use the same capacitance low ESR units.Replace C6, C10, C16, C23 with 1000uF 63v unitsC1, C4, C15, C17, C21 with 10uF 63VC5, C25 100uF 63VYou probably will only get them in radial mount, so form the leads to fit the axial layout and sleeve the ends with thin sleeving.Please get a TO66 heatsink for that toasty transistor in the middle of the board, I think you can still get top mounting TO66 heat spreaders, otherwise get a TO220 version of the transistor and a PCB mount U heatsink which will be a bolt in replacement. The later versions seem to use a TIP48 in that location.

author: bingo600
author_rank: Super Contributor
timestamp: January 03, 2014, 07:25:53 pm
content: I have an EDC E100C , and my board is quite different.I have got the Caig DeoxIT , but still haven't gotten around to clean the switchesI have attached some picts of my unit.I wonder if i have any of those fynny tantals also .....I was thinking about replacing all the elco's.But i was wondering why there was a 400v cap in there (the orange on pic : xsP4010154.jpg)/Bingo

author: SArepairman
author_rank: Frequent Contributor
timestamp: January 03, 2014, 07:50:15 pm
content: those mechanical choppers are very interesting I recall reading a EEvblog post about how in the 1960's someone worked on a chopper amplifier accurate to the nanovolt.

author: SeanB
author_rank: Super Contributor
timestamp: January 03, 2014, 08:00:16 pm
content: Only tantalum units are those 2 in silver cans above the MJE340. The 400V ERO capacitor is there to AC couple the circuit to the case. The other electrolytics are from the early 1970's, best to replace them all.

author: bingo600
author_rank: Super Contributor
timestamp: January 03, 2014, 08:25:15 pm
content: Quote from: SeanB on January 03, 2014, 08:00:16 pmThanx SeanI'll open the box , and make an elco replacement list.The 100v cap on the last pic is that a film or an elco , it's got a black stripe ?/Bingo

author: SeanB
author_rank: Super Contributor
timestamp: January 03, 2014, 09:15:10 pm
content: ERO capacitors are all metallised polyester units. If you want to replace it use another metallised polypropylene, the green ones from EPCOS IIRC are very good. The outer cases do craze after time, but it really only has a problem in hot humid environments, though you might replace them with the same capacitance same voltage units. Note where the black band goes though, as it indicates the outer foil winding, and should go in the same orientation with the new one, generally the foil outer is used as a noise shield for the inner layer to reduce radiated or induced noise.

author: idpromnut
author_rank: Unknown
timestamp: January 04, 2014, 02:51:49 am
content: So if I understand correctly, all the elco's that are wrapped in plastic should be replaced? There are few metal canned elcos, I assume I should check those and replace if needed as well?

author: Vgkid
author_rank: Super Contributor
timestamp: January 04, 2014, 04:41:42 am
content: Bingo's unit is very interesting, a Philbrick chopper opamp.

author: SeanB
author_rank: Super Contributor
timestamp: January 04, 2014, 05:39:25 am
content: Metal cans with a white glass seal are not always electrolytic capacitors, they can be high stability film units. Basically anything with a rubber end plug is due for replacement.

author: bingo600
author_rank: Super Contributor
timestamp: January 04, 2014, 08:50:58 am
content: Does anyone know what the 3-pin plug on the backside could be ?It's connected via that black DAVEN thingy.I don't think the uV range (switch on the front) is functioning on my unit , meaning the uV range is just "dancing around" no matter the wheel selection. Measured with my HP 3457A.Could that 3-pin plug be another output for the uV range ?The schematic is for an E100-RC , not a E100C like mine./Bingo

author: bingo600
author_rank: Super Contributor
timestamp: January 04, 2014, 08:54:05 am
content: @idpromnutI hope it's ok that i am posting in your thread , our units need the "same cure".Else let me know , and i'll open a new one for the EDC E100C/Bingo

author: Vgkid
author_rank: Super Contributor
timestamp: January 04, 2014, 11:53:13 am
content: It looks like a male 3 pin xlr connector, can you get more light on it?

author: idpromnut
author_rank: Unknown
timestamp: January 04, 2014, 12:24:14 pm
content: @bingo600:No worries, even if it's a different model, tis the same piece of kit

author: idpromnut
author_rank: Unknown
timestamp: January 04, 2014, 09:51:40 pm
content: So I have started prep and pulling out those elcos; I have another pic of the board "unmolested", and a few pics of the various types of elcos that I have to replace. Could someone help me identify the one that just has the marking 100/35? Is that 100uF @ 35V?I will continue to post pics of the fixing up of this unit as I go along. Also, I have found a source for the top-mount TO-66 heatsinks, just have to see if I can get it from the US without getting pooched at the borderCheers!Chris

author: SeanB
author_rank: Super Contributor
timestamp: January 05, 2014, 09:22:56 am
content: Yes, 100uF 35V.

author: idpromnut
author_rank: Unknown
timestamp: January 05, 2014, 07:29:51 pm
content: Quote from: SeanB on January 03, 2014, 08:28:23 amIf this was intended for the unit that I have, why the difference in component values from what is in the E100? I can understand the voltage rating, but shouldn't I stick as close as I can to the capacitance values?Thanks!

author: bingo600
author_rank: Super Contributor
timestamp: January 05, 2014, 07:46:58 pm
content: Quote from: idpromnut on January 05, 2014, 07:29:51 pmI'd think Sean based those values on the E100-RC schematic , witch doesn't match our boards 100%.I'd go for the same values as you have taken out , but maybe listen to Sean on the higher voltage advice./Bingo

author: SeanB
author_rank: Super Contributor
timestamp: January 05, 2014, 07:56:24 pm
content: Generally with power supply decoupling caps you can always go up to the next value with very low chance of bad side effects. I just consolidated some values that were low and close together so as to reduce the getting of many values. Higher voltage as well, as they will still be smaller than original, but the voltage derating will improve life. Modern units are a lot better than the originals size wise, generally they will fit.

author: idpromnut
author_rank: Unknown
timestamp: January 05, 2014, 09:50:49 pm
content: Ah, ok. I was thinking about your comment a bit more, and was slowly coming to this conclusion as well. I will do a quick check to make sure that all the elco's I need to replace are decoupling (they should be) in my board revision. And yes, I think it would be wise to consolidate some of those values; they are freaking expensive in some combinationsCheersChris

author: idpromnut
author_rank: Unknown
timestamp: January 09, 2014, 03:31:47 am
content: Quick update; all the elco's that SeanB suggested have been replaced and retested and there doesn't seem to be any appreciative degradation in the performance, so