Checking Tektronix PCB's with a Huntron Tracker 2000 SUCCESS! (+Recapping)

[Smoky]

I just wanted to comment on the use of a Huntron Tracker 2000.

I repaired a front panel board out of a Tektronix TDS420 oscilloscope two years ago. It needed new capacitors and the traces needed to be repaired due to the leaking electrolyte. I didn't test it since it was just practice. Since then, I came across another front panel board that worked perfectly after just replacing the caps. Both boards share the same part number and revision number:





Last year, a retiree gave me his old test equipment which included a Huntron Tracker 2000. Tonight, I broke out the Huntron and read the manual relating to "comparing."

I set both front panel boards up and connected the common lead to the (-) leg of the same capacitor on each board. I set the Huntron to alternate channels A & B, set the range to Med 1, and frequency to to 2000:





I was absolutely blown away as to how well it worked!

The Huntron probe tips are like needles. If you touch something it feels like it stuck to it!

I quickly touched and compared every component and pass-through on both sides of the boards.

You can adjust the speed of how fast the scope alternates plus select one channel to quickly touch several points that look like grounds or if they were all capacitors, etc.

Since most Tektronix oscilloscopes of that era don't have schematics, this tool is a dream come true to quickly check your repairs by comparing your work to a good board.

Here's a couple things that I noticed. If you touch an LED, it fires it! If you touch a terminal of a buzzer, it sets it off! I was able to compare the difference of the "tone" from the buzzers on each board!





I read in the manual, that when checking IC's, the signatures may be slightly different if they are from different manufacturers or lots. Here is an example of pin "5" of a TL074BC from each board (both are in the same location). Unless you guys think otherwise and feel that these should look identical? This also could be due to having the "range" set too low?


     


Anyway, what an awesome tool, and especially when used to repair these Tek scopes!

I'm finishing up on an attenuator board which I'll compare with a good one before I spend the time to install it

[Chris56000]

Hi!

The usefulness of these devices is reflected in the prices they go for – I've seen seller's wanting precious short of £1K for smashed examples of one's with the case & CRT in fragments!!

I use one every day at work provided by my employer and the CRT in it has just about had it!!

I ended up having to buy one of the Chinese TR–210 thingys, because the prices of Huntrons have skyrocketed thro' the roof!

However, it is normal for there to be slight variations from component to component – you're testing them with a.c., and the internal capacitances and impedances, particularly with semiconductors, will vary from device to device!

However I can state for definite that these Huntrons' will show up a part or an IC pin that is most definitely short or open circuit, but beware, DON'T use them across the gate/source pins of MOSFETs – I speak from personal experience!

Also if you've Schottky or fast recovery rectifier diodes to test, up–end them from the PCB if they're not surface–mount, and test them on the "High" setting!

Chris Williams

[Smoky]

Thanks for the info and the warning Chris.

Just for an experiment, I went back to pin "5" on that TL074BC. This time, I set the range to "Med 2" and frequency to "400." It came out to an angled ellipse shape.





And just like you said, as long as you get a similar signature, you're good. No need to go through all of the ranges. Even though you can set the Huntron to "auto" if you want to and it'll scan through all of the ranges for you. Just hold the probe on the terminal

As for the CRT, my screen looks sharp and has plenty of life in it but, maybe, NewScope will come out with an LCD upgrade kit!

[Chris56000]

Hi!

There are ex-USSR rectangular CRTs (8L01 & similar) that can be fitted to these Huntrons with a little bit of adjustment and perhaps a mod. to the mountings, but any rectangular CRT with the same corner-to-corner dimensions at the front will be suitable as long as it doesn't require a high-voltage PDA anode supply!

Russian CRTs often come supplied with a base and a (Cyrillic!) data-sheet packed in with them but there are English Translations available - the Huntron has vertical & horizontal internal gain adjustments for trace height & length!

There are Manuals with circuit & Maintainence Information on kO4BB etc., if you need the Huntron circuits!

Chris Williams

[Smoky]

I went to Huntron's website and read that they're taking in older Trackers and Probers as trade-ins and giving the customer $500 off the purchase of a new 2800!

I don't see the prices for these going down much on Ebay, even if they're broken!

A new 2800 w/o trade-in is over $4,000.

By the way, here are the specs to the Huntron 2000 from one of the brochures:





I'm reading the manual to find out what the "pulse generator" is used for too.

On their message board, I read that it is recommended to check the ESR of the 9 electrolytic capacitors within the Huntron Tracker 2000.

A few values are somewhat odd. Five of them are 1uf at 450V. So I opened up the case and located the capacitors. Here is one of the Marcon capacitors reading over 18 Ohms. One measured 21 Ohms. So out they went!





Here are a few photographs of the Tracker's chassis with the new Nichicon UPM 105c capacitors installed:





...and two Nichicon UHE 105c capacitors:














I also bought two new black banana/grabber ground leads by E-Z Hook. Boy, are they nice quality. Part number 601W-18BLK (Digi-Key# 461-1056-ND). They are the 18 AWG 5000v type. This will be the only brand I ever buy in the future!

[shakalnokturn]

I'm used to using the component tester on my Hameg scope in a similar way, on some components I even take reference pictures of known good curves. (I.e: The infamous Tek / Lecroy / Power Systems Inc. PSU hybrid module.)

What frequency does the Huntron test at?
If they are so handy and expensive it's surprising there are no CRO mod projects about.
Isn't it only a matter of having an adjustable AC source and setting X/Y gains automatically accordingly?

[Chris56000]

Hi!

Huntron 2000s have three test frequencies of 50/60, 400 and 2000Hz, whilst the Chinese "TR210s" are, 50/60, 200 and 2000Hz

Basically that's all that's involved, they consist of three oscillators of 50/60, 400 & 2000Hz feeding into a small low power a.f  power stage with a small transformer providing 30V RMS into a switched voltage divider network – there's no stabilization of the output voltage needed – in fact it has to be medium to high impedance to prevent excessive current flowing into the device being tested!

Maintainence Manuals with circuits and theory for the Huntron testers are readily available for free download from all the usual manual repositories!

The Chinese TR210s have all the facilities of the Huntron 2000s without a built in CRT – they need to be used with an external Oscilloscope, but for hobbyists who can't afford the skyrocketed prices of the Huntron, but can spare the room for an external Oscilloscope, they're an affordable solution!

Experience from other experimenters has shown that Digital Storage Scopes don't display well with these devices and also curve tracer designs, but it is feasible to build something like an 8L01 into a small project case with a switch–mode power supply module, a "Nixie Tube/Magic Eye" PSU module (can be bought in kit form), and a ready built cheap little eBay high–voltage dc–dc converter module, along with an "Oscilloscope Clock" display PCB.

The cost of this display would be about £25 for the CRT,  £10–15 for a case, £15 for a multi output PSU kit, £15 for the high voltage power supplies, and about £25 for the Oscilloscope Clock PCB and enough parts to complete the circuit, about £100 total.

All told, you're currently looking at about £275–£350 for the Chinese design with about another £100 to build a display, or less if you got a small used oscilloscope!

Chris Williams

[Smoky]

Back to the issue at hand, Why these two front panel boards pass their initial self-tests but one of the boards still had an odd issue!

These front panel boards come out of a TDS420 but this problem could probably arise in any model having the same symptom.

The symptom, the vertical scale knob would skip over a selection when the knob is turned.

Say you were at 100mV. Turn the knob down and it would go to 50mV, then to 20mV, then 10mV, then 5.00mV, then 2.00mV, and finally to 1.00mV. The same goes for the rest of the ranges. But in the case of the board under test, it would skip 20mV, 2.00mV, and so on as I turned the knob. All of the 2's.

So that's why I first turned to the Huntron to scan the boards. I touched every component and every pass-through on both sides of both boards. Everything matched. Hmm.

But what seemed to stare back at me were all of the black carbon pads. so I touched one of the pads with the Huntron probe and an LED would light up! So I went around the wheel of carbon pads of the vertical and horizontal knobs. I found one pad that wouldn't light up the LEDs but the other one on the other board would!!!

It turns out that there is a break in the trace that goes from the carbon pad to the pass-through!

Check out these pictures...











Can you see the corrosion on the trace...



 

And do you see where I put the red dot on the pictures above and below?...




The old SMD capacitor leaked and the electrolyte went through the hole and attacked the trace on the opposite side of the board!

I use leaded capacitors when I recap these boards since the pads are usually damaged.

Absolute "crazy-town" when attempting to fix this era of Tektronix oscilloscopes!

The front panel board functions properly now

Peace-out!

[m3vuv]

Im after a psu transformer for my huntron traker if anyone had one for spares,mine is open circuit on the primarys.