Advance Timer/counter TC18

[Hermit6345]

I have one of these. It's quite old and is full of TTL chips in sockets. Already found a DM74176N device faulty, but probably more faults as well. It seems to be a fairly uncomplicated counter, good up to about 500 MHz, with two inputs. Does anyone have a schematic for this counter? I can't find anything on the web and nothing much in the Forum archives. It sort of works but the decimal point seems to be missing and it's a bit unstable on the longer gate times. A copy of the schematic would be handy so that I could check it out with a scope. TIA

Ian

[Chaparal]

Hi Ian,

Can you post a front picture ?

The Advance counter series are running under diff names/manufacturers,
(for example Ballentine, Gould)

Peter

[Glos_Joe]

Advance TC18 is 50 Mhz with TC18A being specified at 80MHz though my experience is that TC18s will do 80MHz plus at TTL type levels. I do have a manual though it's hard copy and I'll need to dig it out over the weekend to scan the circuit. Major problem with these is that due to their age the nixie drivers 7441/74141s tend to go leaky so that you get multiple digits showing. If you get this the nixies are usually OK and you can just swap out the driver if you can find a replacement part. Last time I looked I could only find Soviet era Russian clones.

JoeD

[Glos_Joe]

Whoops! Just went to look for the manual and I've actually got the TC17 so ignore my last message. In my defence I have to say it's a year or two since I last used the unit.

JoeD

[Hermit6345]

Thanks Peter and Joe. I will post a picture of the item ASAP. It's a bit scruffy looking but should be possible to repair it with a bit of help from a schematic or whatever is available. My model uses a type of display comprised of small dots rather than the true nixie tubes. At least most of the ICs are socketed which could be a good or a bad thing I guess.

cheers


Ian

[Hermit6345]

Here are a couple of pictures. Sorry about the focus but I hope that it will give some idea as to what it looks like.

[WME_bill]

Advance counter TC18. It would help a lot if your photo was in focus. The reason for suggesting a photo was that often Advance produced several variants of the basic unit with different model numbers. With a clear photo, it is possible to identify an alternative model which may have more or fewer features, but will give you the basic circuit.
I have manuals for nearly a dozen Advance Counters/Timer Counters, some with nixie, some with dot matrix in neon or semiconductor, and one may suit your purpose. Can you also list the IC types used, as that will also give a clue to alternatives.
I am a bit surprised when you suggest your machine operates to 500 Mhz. Or is that a typo. I cannot tell from the photo is there is a second or third uhf input socket. There will presumably be a pre-scalar, and some ECL, as TTL is hopelessly too slow at that speed.
Or is Glos_Joe correct, at 50Mhz. what he says sounds much good sense to me. Maybe we should wait until he manages to scan his manual. wme_bill

[Hermit6345]

Thanks for responding Bill. I have taken three photos which should be more in focus. In my defence I have Parkinson's which makes focus a bit hit and miss. Hopefully these will be better.

There are two inputs to the counter, marked as will be seen from the photos. I only quoted what was written so not a typo. In the photo of the inside the separate miniature coax can be seen going to the mother board amidst a whole host of components. There is a Plessey SP635D on a ceramic package which might be an ECL pre-scalar. I have not researched that chip yet.

The display is an led dot type display as far as I can tell. Behind the display are six TTL ICs. From the left these are 7473 x1 74176 x3 and 74LS112 x 2. Other ICs are a 7400 just in front of the Plessey chip (The white one) Next to the power transformer is an MC10116. Adjacent to the 1MHz xtal is an MC1035P. Behind a large cap just behind and to the LH side of the mother board is a 7474 and adjacent to the rear panel are three ICs one unmarked, then a 7400 and finally a 74LS112. In addition there is a chip under the screening in the front end, looks like a TTL package but I don't have its type number. That about sums it all up.

I am interested to know if there should be a decimal point appearing because without one it makes the display most confusing. One decimal point on the decimal part of the Hz display appears, but no others.

There is a facility on the rear panel for a hi stab 1MHz input via a slide switch.

Fingers crossed that one of the ccts you have will be similar if not exactly the same as my model.

Ian

[Hermit6345]

Still looking for a schematic for this counter, or one similar. Can anyone help?

Ian

[WME_bill]

Advance TC18.
I have looked through my stock of Advance counter manuals, but nothing comes particularly close. Clearly the ECL chip MC10116 and the Plessey prescalar SP635 are related to the 500 Mhz input, which will be divided down and then fed to the 10Mhz section.
The manual for the TC20 shows 10Mhz, to Sperry/Beckman 7 segment LED display. But driven by transistors and a DM8880 decoder. The other ICs are CMOS, not TTL. The TC21 looks very similar. The circuit diagram is poor copy, but I will try to scan it for you. I don't hold out much hope it will be any help.
The earlier TC17 is 80Mhz, with ECL at the input stages and the rest TTL driving neon nixie indicators.
TC14 & TC15 are 250Mhz with ECL input stages, some TTL and mainly DTL. Display 5870 neon nixie tubes. A very sophisticated design indeed.
None of these would be any help to you at all.
I thought you had found someone with a manual. Perhaps a polite prod reminding him of your need would work. I also would quite like a copy to complete my records!
I have some data upon the Plessey SP8xxx family of dividers, but nothing upon the SP635 series. wme_bill

[Leon Crampin]

Bill, I have a TC21 (working) and would appreciate a copy of the circuit if you could post it.

Leon.

[backinuk]

Dear All,
I have read through this thread with interest, and noticed that there has not been a lot of response to the request for the TC18 schematic or service manual.
Is this because there simply is not any out there? Or was something passed on the quiet?

I was loaned this really old bit of test kit(Avanced Instruments - Timer Counter TC18) to help with a project iI am building.
I am getting close to the stage where I need to use it, so had a play with it
I was getting some funny readings from it. So had a look inside and had to clean up the pins on about 5 of what I think are IC's as they were very sooty looking.
Once I cleaned them up and tried the 1MHz test signal out it gave me a 001.000 read out
I went on to try using a Freq Gen with it but It does not register anything for any length of time
i.e. it will show say 101.000 for a few secs then shift to 300.000 and so on
This happens on which ever time base/freq iI select.

It would be nice to be able to get it working properly can anyone help with a schematic or service manual please?

Many thanks

[WME_bill]

Ian "Hermit6345". TC18.
Advance Timer counter TC20-TC21. These are both very similar models, and could be similar to the TC18, but without the UHF prescaler.
You have not commented upon the IC and display used in the TC18, and how they compare with those I quoted for the TC20-21, so I cannot guess if the TC20-21 would be helpful to you.
It therefore remains with you to advance the discussion.
Leon Crampin has asked for the circuit etc of the TC21. It is too large to post on the Forum. I am sending him a PM. wme.bill m0wpn

[jimmc101]

SP635 doesn't ring any bells with me, I thought all the Plessey high speed dividers were given SP8nnn numbers. Maybe later it was renumbered to comply with this format.

The SP8635 is a 600MHz divide by 10 with TTL compatible outputs which could well be the one.

Unlike the more common SP8680 (11C90) this one was designed for Vee -5.2v, Vcc 0v and open collector outputs to interface with TTL on +5v (vs Vee 0v and Vcc +5v shared with TTL).

Jim

[Humber888]

I thought that Telford Electronics might have a service manual for this counter but checked in passing and they do not.

Mike

[Hermit6345]

Thanks for the input all. The TTL is all socketed so was easy to shift devices of the same type around. All told two devices had defective ccts. The counter was working pretty well after replacing those devices. it seemed that a handbook/schematic was not going to be easy to get and the I desperately needed the room so decided to dispose of it along with many other items of test equipment. Thanks again to all those that gave their input. This thread can be closed.


Ian