Welcome to Australia's only Vintage Radio and Television discussion forums. You are not logged in. Please log in below, apply for an account or retrieve your password.
Australian Vintage Radio Forums
  Home  ·  About Us  ·  Discussion Forums  ·  Glossary  ·  Outside Links  ·  Policies  ·  Services Directory  ·  Safety Warnings  ·  Tutorials

Tech Talk

Forum home - Go back to Tech talk

 PALEC VCT-3 Valve Tester Schematic and Rework
« Back · 1 · Next »
 Return to top of page · Post #: 1 · Written at 1:04:29 PM on 7 May 2023.
Comalco's Gravatar
 Location: Emerald, VIC
 Member since 7 May 2023
 Member #: 2558
 Postcount: 9

Hello Folks,
I have been trying to find a schematic for a PALEC VCT-3 Valve Tester.
I have tried the web, RadioMuseum, etc - and I have found one for a VCT-2, but it's quite different to the VCT-3. I have recently acquired a VCT-3 and in using it for a while I have decided to rework it to add a few useful extra features - including some additional connectors to measure heater current, Merit current, etc.
I note the Wanted forum is still locked, so hoping someone may spot this email and have access to the VCT-3 schematic - otherwise I will go through it and trace it out manually......


 
 Return to top of page · Post #: 2 · Written at 3:10:29 PM on 7 May 2023.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

Mine is 1938 Paton and there are variants. This one has a 6V vibrator PSU in addition to mains. Some show half of a 6X5 as the rectifier mine has 1V. I would love to choke the genius who wired it up with some black but everything else is purple.

There was a plug in group of sockets that mounted in the lid for other tubes. That appeared during the war, made by a different company.

I actually have an original book which has a circuit, plus scanned versions and have serviced at least four.

Watch the meter movement, there are screws in mine, under the bracket holding it in. As mine clearly had a lot of mobile work one damaged the meter by falling out & shorting.

There is a resistor with a note on it saying it was specifically selected for its value. Read: Some bunny got to sift through a bucket of duds, picking out the ones of the right value.

I will send Brad a photo of it

Marc


 
 Return to top of page · Post #: 3 · Written at 5:56:58 PM on 7 May 2023.
Comalco's Gravatar
 Location: Emerald, VIC
 Member since 7 May 2023
 Member #: 2558
 Postcount: 9

Thanks.
I think yours may be an earlier model than my VCT-3
The VCT-3 model I have doesnt have a vibrator PSU or a rectifier valve.
By the look of the build, type of wire insulation, etc, I would say its from the early 50s.
I would also say its been worked on at some time as the wiring loom lacing has been done in new-looking plastic spaghetti tubing.
I have a schematic of a VCT-2,and mine is very different.....

I have a pretty thorough look on the web and the schematic of this model is proving elusive.
There are photos and mentions of it in a number of places, but no hint of a schematic yet.


 
 Return to top of page · Post #: 4 · Written at 9:11:34 PM on 7 May 2023.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

I have sent a circuit to Brad. The vibrator PSU was an extra and was for rural use on the more common at the time 6V car batteries or the common at the time 12V one with exposed over wall connections. I would believe I have a photo of mine an another I repaired.

Where mine had a V1 and a four pin vibrator unit, everything was different in the second one. It had a completely different chassis layout and a "ferrocart" vibrator. The major advantage being, unlike mine which has UX4 sockets it had an octal socket and a six pin socket. That means that the Vibrator unit & tube cannot be interchanged, nor were they likely to fall out.

I did say there were variants, even the tube sockets varied between the two. 862 is the military variant.

If it has no tube rectifier it may be an ET4.

https://www.radiomuseum.org/r/paton_paton_valve_tester_et4a.html

Paton VCT Valve Tester
Paton VCT Valve Tester


 
 Return to top of page · Post #: 5 · Written at 12:56:23 AM on 8 May 2023.
Comalco's Gravatar
 Location: Emerald, VIC
 Member since 7 May 2023
 Member #: 2558
 Postcount: 9

There is an actual photo of this VCT-3 model on radiomuseum;
https://www.radiomuseum.org/r/paton_palec_valve_tester_vct_3.html

The circuit in my unit uses some of the elements of the ET4,schematic on the page you have linked (like the signal switching bank of lever switches, but there are considerably more components (wirewound resistors etc) mounted on and between the switches' tags.

There would also appear to be some clip-in style battery holders (for non-AC operation), with what appear to be two battery-supplied rails from the holders (LT and HT?). I don't think these clip 'battery' holders are for a vibrator PSU, although perhaps they are and I am just not familiar with the physical style of module that may click into these holders? There are holders for two almost "D Cell" size batteries (in series), and a third socket which looks like it would almost hold two "C Cells" end to end in it. This makes no sense considering likely LT and HT requirements in the design. I think I am just going to have to start tracing out the circuit with a multimeter. With all the switches and components it will be a bit of a slow task......

ADDED: Also, as best I can tell, my unit does not have all of the switch positions as the VCT circuit on RadioMuseum does - with the capacitor test switch positions missing, and mine has 3 Merit positions (1, 2 and 3) whereas the RadioMuseum schematic only has one Merit switch position..

ADDED: After some time comparing what's online to my unit, it seems the VCT-3 is a heavily modified variant of the VCT-2 schematic on RadioMuseum, with only 8 test sockets - not the 9 shown on the VCT-2 schematic. The switches are very different in my unit, with a six position function switch covering Multimeter, Line, Shorts, and Merits 1, 2 and 3. Ohms ranges are selected by the filament voltage switches. In summary, the VCT-3 is a modified VCT-2, with the different switch configurations being the major difference. The VCT-2 also shows 2 batteries, which explains the clip sockets in my VCT-3 and my earlier comments re batteries - and them only being for multimeter functions by the looks of it..

I hope to trace out a schematic of my VCT-3 and post it soon.


 
 Return to top of page · Post #: 6 · Written at 9:35:48 AM on 8 May 2023.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

I think we are getting closer to establishing what that actually is. Mine I suspect is first generation VCT_V. It has no chassis like the newer versions. The fact that mine has no panel ID and the later ones did, should make things a lot clearer.

These are emission type testers and I doubt that the circuit varies a lot.

You may need a cotton reel tube or similar for batteries. VCT-V uses three "D" cells for the ohms range, as it also incorporates a multimeter, voltmeter, mA low ohms, capacity, HV & 25V electrolytic cap reformer and leakage tester for HV Non polarised caps.

Cap leakage tester is brilliantly simple (literally). A NP cap should not pass DC. So, with the neon in series with the cap. The neon should blink & extinguish. The brilliance of the glow if it doesn't, indicates how bad the cap is and you replace it.

If that has caps they will have likely failed. I seem to end up replacing caps in old meters like AVO 7x, Peak 200H, and others around that era. plus other test equipment.


 
 Return to top of page · Post #: 7 · Written at 9:38:51 AM on 8 May 2023.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

It may be less confusing if you separate and draw heaters, and each function separately? A lot of automobile workshop manuals are doing that.


 
 Return to top of page · Post #: 8 · Written at 10:51:36 AM on 9 May 2023.
Tinkera123's Gravatar
 Location: Melbourne, VIC
 Member since 5 October 2009
 Member #: 555
 Postcount: 465

Hi Comalco et al,

I can't help with the circuit diagram as my Palec is a VCT-V without the Vibrator ... a different animal to your VCT-3. I went down the same path trying to find a circuit diagram ... and have a few of the earlier circuit variants ... but not an exact match ... not unusual in any industry.

As luck would have it, I was given a more modern Valve Tester soon after and have used that ever since. So my VCT-V will be up for sale whenever (if???) the For Sale site is re-opened.

Good luck tracing out the circuit ... my approach is to use the closest circuit that I can find and use a lot of 'White Out" or some other editing technique ... Smile

Cheers,
Ian


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
Cheers, Ian

 
 Return to top of page · Post #: 9 · Written at 9:49:46 PM on 9 May 2023.
Brad's avatar
 Administrator
 Location: Naremburn, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 7342

Photos uploaded to Post 4.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 10 · Written at 8:18:08 PM on 16 May 2023.
Comalco's Gravatar
 Location: Emerald, VIC
 Member since 7 May 2023
 Member #: 2558
 Postcount: 9

Many thanks Brad, but the VCT-3 model appears different.
There have been quiet a few sold on eBay and other sites, but still no sign of a schematic for this model.
I have determined that it remains a stormy night's activity to trace it out by hand Sad


 
 Return to top of page · Post #: 11 · Written at 8:50:29 PM on 16 May 2023.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5303

I have a copy of the original add for mine. In its case, it clearly states that the vibrator PSU was an extra, but you could buy it with it factory fitted. Do note when searching; It is a Valve and Circuit Tester.

It may, or may not have: But mine was intact; A flying lead with a six pin plug (UX) which I was not wrapt in. It did not appeal to my idea of intrinsically safe. The mains lead coupled to that plug & both the plug and socket have metal caps.

I added an IEC socket as the alternative, leaving the 6V on the original plug. Vibrator section has been refitted and works.

Marc


 
 Return to top of page · Post #: 12 · Written at 12:29:42 PM on 23 May 2023.
Comalco's Gravatar
 Location: Emerald, VIC
 Member since 7 May 2023
 Member #: 2558
 Postcount: 9

Thanks Marcc,
Alas, your picture and schematic are quite different to to the VCT-3.
Fundamentally different in switches, configuration and layout.
Switch functionality is all different too.
The VCT-3 also has 7pin and 9pin miniature sockets in its array.

The search continues.............


 
« Back · 1 · Next »
 You need to be a member to post comments on this forum.

Sign In

Username:
Password:
 Keep me logged in.
Do not tick box on a computer with public access.