Advance Instruments TC2 counter information?

[Dekatron]

Hi,

Does anyone have any information on the Advance Instruments TC2 Timer Counter, like a schematic or a manual?

[ronbryan]

Martin

I have a manual for an Advance TC1, which is a UK made version of a Den-Haag design. It has the same 1MHz counting range and front panel controls as the TC2, so it might be similar internally, although the display drivers would be different. The TC1 has an analogue meter counter display.

The TC1 uses multiple decade dividers (OC44s and OA70 diodes) counting in in two out of five code, with the cards soldered directly to a mother board. It has a crystal oven oscillator (1Mhz I think) as the reference. What is inside the TC2? Any similarities so far?

Ron

[Dekatron]

Ron,

Yes, there are lots if similarities, I've not had a chance to see what's beneath all the dirt, it is very greasy and dirty inside but it seems to be a lot like yours except for the display type used.

Any chance that you can email me a scan of your manual?

/Martin

[ronbryan]

Martin

I do not have the manual scanned at the moment, so it might take a while, but I will do it as soon as I can. The drawings are all fold-out sheets.

I made a mistake with the name of the original designers of the Advance TC1 - it was Van Der Heem, (a 9908-03) not Den Haag.

Ron

[Dekatron]

Ron,

Excellent, thanks for helping me!

Mins starts and shows zeroes and the decimal point moves when the switches are turned but nothing else works, the input and buttons doesn't do anything else at all.

I'm not sure how to clean it as it is very dirty inside, looks like I'll have to shower it with isopropyl alcohol or something similar to even see what's inside. Something greasy has been falling down through the ventilation on top and bonded with the dust.

I'll try to see if the crystal oscillator is running as I guess that everything runs from that clock signal and without it it is probably dead.

/Martin

[karesz*]

Hi Martin,
If it does nothing in position "Check"_I think XTAL/Oscillator is possibly a problem_do have it eventually external Ref-in?
Karl

[Dekatron]

Karl,

Nothing happens in position CHECK, just a single zero.

If I hook up a wire with a switch from the ground connection to the reset input I can get it to either reset or to display any random number.

I also had a look at the components and there are some suspect electrolytic capacitors, one dangling as it is just soldered on two pins from a trim potentiometer. The voltages are a bit high too, it says -24V and +10V on a solder strip but they are -36V and +14V so I guess that I'll have to check the power supply first to make sure that the capacitors are good and that the output voltages after the regulators are good too, there are some trimmers for adjustment but I need to fond where to measure those voltages.

Now I'll just have to find a way to reach those capacitors, I have to disassemble a lot of pieces to get to them as they are right in the middle of everything.

I've included a few photos.

[karesz*]

Martin,
than is possibly a problem to find in your gate-circuit, but I agree w y; for beginn is a must to have correct working PSU. I would separate it from rest of electronics and test with some loads! What about tantalums too? Btw, nice compact unit(or too...).
Regards - Karl

[Dekatron]

It turns out that the counter is quite servicable! I spotted a few rivets when I had the first look but then I found two screws when looking at the photos and with those out of the way the counter could be opened as the rivets were in fact two hinges! The there were four screws to remove the power supply. I found that the mains wiring had been stuck between a heat sink and and the power switch so I'll replace those wires as the cover has been compromised partly.

What is nice is the rack of spare lamps on the front!

I removed the plastic front as it is sadly coming apart from old age. I'll see if I can rebuild the parts that are falling apart with some other plastic glue.

[Dekatron]

I replaced all of the large smoothing capacitors in the power supply, now the voltages are closer to what is printed, +12V (+10V) and +29V (+24V) but there are still a few small electrolytic capacitors in the power supply to replace. There are two regulated voltages that should be -6.8V and -17.5V but i can only adjust those to -6V and -16.5V so I guess that I have to replace the rest of the small electrolytic capacitors to get the power supply to work properly.

There are also a whole bunch of small electrolytic capacitors on all of the counter and logic boards which all look very dry and cracked in the rubber seals so I'll replace those too, but now I have to order axial types as I am out of those, only have radial types left.

Nothing except the voltages changed after I had replaced the large smoothing capacitors. I even tried to replace the crystal without any change (haven't had time to check the oscillator with my scope).

[Dekatron]

I ordered a bunch of axial capacitors yesterday and hope they arrive this week so I can finish replacing them.

I also did some more checks today and found that it has been repaired a few times before, a few of the metal can transistors have been replaced with modern TO92 types (couldn't see the text on them though so I don't know which types), otherwise it looks like nothing else has been replaced.

There is also a lot of surface corrosion on the metal can transistors, green looking crystal like corrosion so I guess it is from the copper in the material. Apart from making sure that it is stored dry I don't intend to do anything about the corrosion.

I'll replace all of the mains wires later as they are really poor in some places, not only where they have been squeezed between parts but also because the rubber has become loose and peels off.

There are a bunch of rubber standoffs, probably used both as isolation and vibration standoffs, that have started to crack, all are still in one piece but they will probably soon fall apart - any advice on how I can save them, any glue I can use or how to go about restoring them is appreciated!

[ronbryan]

Martin

I've scanned the Advance TC1 manual, but it is too large (23Mb) to post here. I have also scanned the block diagrams separately, in case there are any similarities with the TC2 basic design, and these are attached, along with a manual paragraph on self-check operation.

If you would still like the complete TC1 manual, please contact me by PM. I'm not sure how much use it would be now we know that the TC2 uses later technology.

Ron

[Nickthedentist]

Originally Posted by Dekatron

It turns out that the counter is quite servicable! I spotted a few rivets when I had the first look but then I found two screws when looking at the photos and with those out of the way the counter could be opened as the rivets were in fact two hinges! The there were four screws to remove the power supply. I found that the mains wiring had been stuck between a heat sink and and the power switch so I'll replace those wires as the cover has been compromised partly.

What is nice is the rack of spare lamps on the front!

That's beautiful

[Dekatron]

Thank you for the manual Ron, it will help a lot as many parts are identical, like the input/output stages and counters plus half of the power supply.

Replacing all electrolytic caps brought up half of the power supply to fully working condition, the other half is not working properly, but it gets really hot so it is is probably broken or loaded down from the rest of the circuits. It can only deliver some -16V and not -17.5V.

I'll remove power from the boards and only apply power to one board at a time to hopefully find which board(s) that load it too much.

/Martin

[Dekatron]

This turns out to be a time consuming restore if it will ever be finished.

I suddenly realised that I recognised the smell of what has been dripping through the instrument, mouse pee, I owned a few mice as a kid and I have also cleaned out a house from a mice infestation so I know that smell, it didn't come to my mind at first though.

This fluid has corroded most of the wiring as it has followed the outside of the wires and then flowed inside on the wires corroding the ends where they were soldered. I found more than ten wires that had been corroded right through. A mild tug on others made them break immediately. There are very little corrosion on other parts as most of the wires were protecting the circuit boards from this fluid, just a little surface corrosion on the metal can transistors but not much on the other components nor on the traces.

It will take a long time to cut each end of each wire and clean it as best as possible and the resolder it. I might remove most of the circuit boards and then drench the rest in my ultrasonic cleaner and let it sit there for a short moment cleaning all of the wiring, using only clean battery water.

De-soldering the circuits boards was easy but the other end that goes to the switches will almost be impossible so I might unscrew the switches from the front panel and put them in the ultrasonic cleaner too.

Cleaning the circuit boards will not be that hard but I'll leave the transistors as they are except for perhaps a very mild brush with IPO.

Any advise on how to get rid of mouse pee is welcome!

[Dekatron]

One big error found!

Almost all of the transistors on the "1.2.4.8 Translator" board had corroded pins making poor contact. It actually looks like this was a problem from the beginning when this counter was manufactured as there were a lot of dry joints on these pins. I found this out when I was trying to check these transistors in circuit as most read really high on the diode test on my Fluke 87V, some 1.5V. Re-soldering them all made the problem go away so now all seems good. No other components on this board had any dry joints.

Perhaps this was the main problem apart from broken and corroded wires as all other circuit boards look fine and this board is the one that drives the lamps and works as a binary to bcd converter. At least I hope so as I can't find anything else wrong with the other circuit boards.

Now I'll continue with the corroded wiring!

[Dekatron]

I got bored with the wiring so I started with the power supply.

After a lot of checking it turned out that there was one corroded common ground wire and two zener diodes that had corroded leads. I had forgotten to re-solder the zener diodes but when I removed them for checking and then re-soldered them the power supply started to work properly. The common ground wire only affected that the common ground was not connected to the screen of the transformer and to the mains ground, so it didn't affect the voltages.

The only thing that is not spot on now is that the +10V and -24V voltages are a bit high, they are some +17.5V and -38V, but those are unregulated voltages so they will be higher now that the mains voltage is 230V instead of 220V as stated on the transformer (2 * 110V windings) but I hope these unregulated voltages don't matter that much.

All of these corroded pins and wires really means that I will have to check every one of the soldered components.