DIY Clip Lead Adapter (TL-21) for DE-5000 LCR?

[NT0Z]

Hi, gang,

I just opened my DE-5000 and turned it on. So far, so good. It came with the SMD tweezers, two "guard wires" with banana plugs, but no TL-21 clip lead module. I think I knew this when I bought it on sale 1-2 years ago from a seller in Japan.   I was delayed in the unboxing by flood recovery and two surgeries. Life happens when you're not test equipping.

Anyhoo, I'm wondering if I can make a clip lead adapter from coax (or shielded wire) and banana plugs until I find a TL-21 that's somewhat reasonably priced?

I see that the blade sockets and the banana plug sockets are connected. I assume that the guard socket would connect to the test clip shield cable and that each remaining plug socket would connect to its own gator clip? Or maybe each clip gets its own short length of shielded lead wire with shield to guard and test point to test clip?

I did measure a few caps by using the long guard plugs/clips with the test sockets, calibrating out the 3 pF or so lead capacitance from the long bundle of test wires. Seemed to work on anything but a 2 pF mica cap.

At present I'm not overly concerned with the many discussions of whether this meter suxx or not, etc. It's the tool I have, and at present, the tool I need to use.    I have a separate ESR meter and a separate low/high voltage cap leakage measuring device.

I am not a rocket surgeon with most test gear, but I'm working on it.

As always, your help is appreciated,

--NT0Z

[TomKatt]

There's a few threads on the TL-21 adapter here on the forums...

Have you seen this one?

[mawyatt]

Believe the banana sockets on the DE-5000 are a split type, meaning that each banana socket has two connections, not the usual one. Awhile back we looked for the split male banana plug but couldn't find any, and just ordered the TL-21 ~$20 and modified it for a use with external fixtures such as this one for SMD devices. Also got another TL-21 and modified it for the Kelvin Clip use, we just wired the Kelvin Clips directly into the TL-21.

BTW the DE-5000 we have has proven to be quite good, with excellent repeatability and agreement with our lab LCR Meters (IM3536 & TH2830) with a proper Open/Short Cal.

Also a note we tried to use a custom fixture we created for our lab meters to allow a DC bias to be introduced (valuable with hi-density ceramic caps and electrolytics), however the DE-5000 evidently requires a DC path for the Short Cal procedure and would not achieve Cal with the DC Bias custom fixture since this includes large Film series Capacitors in the Hcur and Hpot lines.

Best,

[TimFox]

I think the female banana connectors on the front panel of the DE-5000 are "normal" (not split).
They come after the female "blade" connectors that are split in order to interface with the two-sided PCB male connectors in the small box for the TL-21 and other leads.
When nothing is inserted, the two blades in the female contact each other across the gap to connect the bananas.
A similar idea is used in the "Digibridge" series, originated by General Radio and now sold by IET:  long slots allow Kelvin-wired component clips to slide and match the component length.
Like others here, I have taken a TL-21 and re-wired from the small box to other connector types, retaining the four-wire connections as required.

[mawyatt]

The female banana connectors on our DE-5000 are definitely "split" with two separate electrical "half-pipe" contacts on each side (you can see this by looking down the banana "barrel" on the DE-5000. There also are separate contacts on the PCB, two for each banana. The "blade" connectors would require separation with a blank insert to use the 4-wire setup with the split contact banana connectors, so we just modified the TL-21s as mentioned.

Best,

[NT0Z]

Interesting.

I used the two long "guard wires" with their attached banana plugs to test a few small value caps. Those long wires, when arranged to minimize coupling, etc, passed the CAL routine.

Whether that means that my unit's jacks are split, I don't know.

Looks like I'll be buying a TL-21 sooner rather than later. They're now up to approx $40 delivered, and stocks are low.

How are those long guard wires used, anyway?

Thanks.

--NT0Z

[mawyatt]

If referencing the DE-5000 and using standard banana wires (cables), then the banana wire plugs will short out the 4 wire Kelvin capability in the DE-5000 sockets (as well as having the blades sockets short out the Kelvin capability), so you won't have 4 wire Kelvin capability, just simple 2 wire capability.

If referring the the image we posted, these aren't "Guard Wires", they are coaxial leads, 4 of them. The center "wires" are Hcur, Hpot, Lpot and Lcur, each shield of the coaxial lead is analog ground which is also Guard on the DE-5000, thus a total of 4 wires. The ends of these coaxial leads are female BNC connectors with wire shields attached (soldered) to the BNC case.

The OEM supplied TL-21 Alligator clips actually have 3 wires in each line. One is for Force (current), one for Sense (potential), and a shield for analog ground (Guard) in each line. The 2 wires have the Force and Sense soldered at the end of the Alligator clip, the shield (Guard) is not connected to the clip and only connected inside the TL-21 case to analog ground which is also Guard.

Best,

[NT0Z]

Okay! Now I'm getting somewhere!

So, while I'm waiting to buy a TL-21, I want to make a TL-21-like adapter for my DE 5000. If I understand correctly, I can make a 2-wire rig by using three standard banana plugs and some short lengths of mini coax (I have teflon stuff on hand).

Each clip line will be made from coax, the lower shield ends of which will be connected to the guard socket/plug. The center lead of each coax run will connect to a clip (and a plug). The clip end of the shield will be unconnected and insulated from the clip itself.

In theory this provides a pair of shielded clip leads that should make the test useful for measuring C (not ESR).

Is that right?

Thanks,

--NT0Z

[mawyatt]

That should work for 2 wire measurements.

Best,

[NT0Z]

T-H-A-N-K  Y-O-U

Yes, I was shouting.

--NT0Z

[mawyatt]

You are quite welcome!!

The little OEM TL-21 with Gator Clips works quite well indeed, it was as good as the modified TL-21 with proper Kelvin Clips added. We almost never used the DIY Kelvin modded TL-21 version and removed the Kelvin clips and added the BNC connectors shown in the above image for use with various SMD fixtures, which have seen much more use!!

Best,

[TimFox]

The female banana connectors on our DE-5000 are definitely "split" with two separate electrical "half-pipe" contacts on each side (you can see this by looking down the banana "barrel" on the DE-5000. There also are separate contacts on the PCB, two for each banana. The "blade" connectors would require separation with a blank insert to use the 4-wire setup with the split contact banana connectors, so we just modified the TL-21s as mentioned.

Best,

My mistake:  I had never seen "split banana jacks" before, but they would be required not to short out the two blades.
That only takes "4-wire connections" up to the jacks, and any banana plug connections would be "2-wire" thereafter, since "split banana plugs" are not practicable.
I had thought that with nothing connected to the blades, they would short out vertically and that the banana jacks were only connected to the "lower" blades.
The TL-21 boxes have plastic dummy banana plugs that are only there for mechanical support.
For making ones own fixtures, modifying a TL-21 box for its blades is the way to go.
Inserting a leaded part with thin wire leads works with the Digibridge split blades, but is probably mechanically unwise for the DE-5000.

[mawyatt]

The female banana connectors on our DE-5000 are definitely "split" with two separate electrical "half-pipe" contacts on each side (you can see this by looking down the banana "barrel" on the DE-5000. There also are separate contacts on the PCB, two for each banana. The "blade" connectors would require separation with a blank insert to use the 4-wire setup with the split contact banana connectors, so we just modified the TL-21s as mentioned.

Best,

My mistake:  I had never seen "split banana jacks" before, but they would be required not to short out the two blades.
That only takes "4-wire connections" up to the jacks, and any banana plug connections would be "2-wire" thereafter, since "split banana plugs" are not practicable.
I had thought that with nothing connected to the blades, they would short out vertically and that the banana jacks were only connected to the "lower" blades.
The TL-21 boxes have plastic dummy banana plugs that are only there for mechanical support.
For making ones own fixtures, modifying a TL-21 box for its blades is the way to go.
Inserting a leaded part with thin wire leads works with the Digibridge split blades, but is probably mechanically unwise for the DE-5000.

Even tho the manual shows using the blades for direct insertion of leaded components, I agree as this could damage the internal blades and/or if one jams long leads they could do damage to the internal PCB. We've done it a couple times carefully but now since we've got one of the modded DL-21 with BNCs we can use the standard fixtures for bench Lab LCR meters instead, like these shown. With these fixtures and the SMA fixture shown earlier, the DE-5000 qualifies as an entry level bench type LCR meter IMO. We get excellent repeatability, for example within 0.01pF repeatability with a quality Venkel 0603 COG 4.7pF, and same for agreement with our Lab Grade Hioki IM3536 or Tonghui TH2830 LCR meters, the DE-5000 is that good with a proper fixture and Open/Short Cal.

Best,

[TimFox]

Grayhill used to make a useful component test adapter with two standard banana plugs on 3/4 inch centers connected laterally to two component lead clips on 1-3/4 inch centers.
I found two of these adapters on eBay, and they are very useful for quick sorting of leaded components on devices with two banana jacks.
(Capacitors on the DE-5000 and resistors on normal DMMs.)
They still make the component lead clips, but their catalog does not show the assembly.
See p/n 02-1 and 02-0 on this datasheet:  https://www.grayhill.com/documents/Test-Clips-Datasheet