UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Test Gear and Workshop Equipment

Notices

Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

Closed Thread
 
Thread Tools
Old 30th Oct 2017, 12:53 am   #1
MotorBikeLes
Nonode
 
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 2,346
Default TEK 212 Oscilloscope.

Split from this thread:-

http://www.vintage-radio.net/forum/s...d.php?t=140839


I have a little TEK 212 (?) with a 2" approx Sony CRT. Its internal rechargeable cells are long gone, so I use it off a 12v wall wart or a small external battery pack. Quite useful for jobs out in the 'bike workshop, but looking at the spec of this Chinese device, its analogue functions pretty well mirror the Tek unit. It could go in a little box with either a few AA's, a PP9 or better still, and old tapped 9v grid bias battery.
The only drawback is it being a SINGLE channel device. It has got to be worth a tenner. I may buy one.
Les.
MotorBikeLes is offline  
Old 30th Oct 2017, 7:46 am   #2
RogerEvans
Hexode
 
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 378
Default Re: Oscilloscope Kit from China

A slightly off-topic reply to MotorBikeLes - I have one of the little Tek 212s and it is quite cheap and easy to replace the battery pack with 10 x 2/3AA NiMnH cells with solder tags (and a little foam padding). I had poor results after soldering directly to non-tagged cells. They last at least a couple of hours and it leaves the scope completely isolated and relatively safe for working on the live side of inverter power supplies, and it has two channels!

Roger
RogerEvans is online now  
Old 30th Oct 2017, 11:58 pm   #3
MotorBikeLes
Nonode
 
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 2,346
Default Re: Oscilloscope Kit from China

Roger, thanks. I will have looked previously, but just looked again, but at £4:80 each, rather expensive. Now if anybody knows of these, or just plain NiCad at a price I can afford, then I am all ears.
Cheers, Les.
MotorBikeLes is offline  
Old 31st Oct 2017, 3:49 am   #4
mark_in_manc
Octode
 
Join Date: Nov 2011
Location: Manchester, UK.
Posts: 1,872
Default Re: Oscilloscope Kit from China

Les -

I've been breaking open dead laptop batteries and re-using the 4v Li-Ion cells inside, without any of the clever gubbins. I've apparently been charging them wrongly (I've used a small constant current, I thought to be safe) and they still work fine for my purposes (instrument supplies, a stand-alone 10W speaker-amplifier, etc etc). I work in a university and keep an eye out at the battery recycling bucket. Perhaps you could get lucky at a laptop / phone shop.

On-topic, I like this little scope - I had to wait until I was well in my 20s before someone threw a huge, ancient, valve, single-beam solartron in my direction. I can see it would be really handy for vehicle stuff, for which I hang onto an old Scopex single-beam which is more-or-less portable.
mark_in_manc is offline  
Old 31st Oct 2017, 10:23 pm   #5
MotorBikeLes
Nonode
 
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 2,346
Default Re: Oscilloscope Kit from China

Mark, am a bit cautious about using Lions.There is (we are told) dangers if wrongly handled. A few years ago I changed the cells in a laptop battery using good ones from another unwanted one. Success. Then I tried to do the same for a Lenovo laptop. I fitted the batteries and tried a few charge/discharge cycles to establish if the power was good or almost "past it". I had read about maximum and minimum voltages, so I monitored carefully and satisfied myself they were very good. Then I installed in the laptop, but they would neither charge nor discharge. It seems the Lenovo batteries are "extra" intelligent, decided I had gone below their chosen voltage, and simply locked the thing up. Effectively dead.
More recently I used a GPS for the first time, four years after I bought it. The battery was dead, so I found one from a previous phone, same size. The GPS had its controller built into the battery, whereas the phone used one in the phone itself, so I transferred it from dead battery to that from the phone. Success. Only a couple of weeks ago, I replaced the single cell battery of an Android tablet, so I dug out the controller from that. Maybe if I get a three of the controllers, I could connect them to three Lion cells and connect them in series and pop those in the 212? Not sure how I would do that, maybe need some diodes to separate them so each controller looks after its own cell without any interaction. Ideas anybody? I have plenty of laptop cells, just need two more controllers and some assurance of a safe job.
Les
MotorBikeLes is offline  
Old 31st Oct 2017, 10:37 pm   #6
mhennessy
Dekatron
 
Join Date: Jul 2007
Location: Evesham, Worcestershire, UK.
Posts: 4,241
Default Re: Oscilloscope Kit from China

The problem come from trying to recharge them quickly. If you provide them with a gentle supply of current and allow them to charge over many hours, then they should be pretty well behaved. In practice, it's a question of picking one of the many dedicated charger ICs and letting that take the strain. For example:

http://uk.farnell.com/microchip/mcp7...t23/dp/1834890

That one was chosen completely at random - there's hundreds out there. Many use SMT, so for hobby use we might need to pick up an SMT to DIL adaptor PCB. Alternatively, you can get these already assembled - for example:

https://www.ebay.co.uk/p/5v-Mini-USB...-BU/2157618352

Again, chosen at random - just to give an example of what's out there...
mhennessy is offline  
Old 31st Oct 2017, 10:53 pm   #7
ex seismic
Heptode
 
Join Date: Sep 2009
Location: Tonbridge, Kent, UK.
Posts: 685
Default Re: Oscilloscope Kit from China

MotorbikeLes, Look in the usual place for protection boards. You can get them very cheaply for any number of cells. They include charging facilities as well as protection.

Gordon
ex seismic is offline  
Old 1st Nov 2017, 8:39 am   #8
RogerEvans
Hexode
 
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 378
Default Re: Oscilloscope Kit from China

Les,

I just looked on the standard auction site for 2/3 AA NiMnH cells. 12 for £4.98 from a seller in Hong Kong, with solder tabs. They look very similar to the ones I bought, also from the Far East , and you only need 10.

Roger

Roger
RogerEvans is online now  
Old 1st Nov 2017, 8:52 am   #9
MrBungle
Dekatron
 
MrBungle's Avatar
 
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
Default Re: Oscilloscope Kit from China

Watch out for the cheap ones from the Far East. Check the cell voltages when they arrive. A lot of them are old cells that are recycled with new shrink wrap.
MrBungle is offline  
Old 1st Nov 2017, 9:55 pm   #10
MotorBikeLes
Nonode
 
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 2,346
Default Tek 212 battery replacement.

I am creating a fresh thread from an off topic section of a thread about a £10 modern Chinese scope.
I have a Tek 212'scope, a small 2-1/2" CRT type, dual trace but only 200KHz bandwidth. Anyway, the batteries gave out maybe 30 years ago, and were more expensive than the value of the scope.
It was suggested I fit a lithium ion battery. Maybe not that simple, but it seems there are a few alternatives. Time to evaluate.
Les.
MotorBikeLes is offline  
Old 1st Nov 2017, 10:24 pm   #11
RogerEvans
Hexode
 
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 378
Default Re: Oscilloscope Kit from China

Agreed, I have had some rubbish when buying 'high capacity' AA from China. These 2/3 AA with tags are ok on the statistics of having bought two packs of 12 a few months apart. The second batch went into a TDR that also won't work without a battery or mods to the 110 volt only mains supply.

They appear to be unused, the tags look as new, and they are marked as 700mAh which is rather modest. Goodness knows if you will get the same stock next time round.

Roger
RogerEvans is online now  
Old 1st Nov 2017, 10:26 pm   #12
MrBungle
Dekatron
 
MrBungle's Avatar
 
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
Default Re: Tek 212 battery replacement.

Is this any help? Goes into the refurbishment of a unit from the same line:

https://youtu.be/nLWVTFj_Yik
MrBungle is offline  
Old 2nd Nov 2017, 1:05 am   #13
Argus25
No Longer a Member
 
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: Tek 212 battery replacement.

Les,
I have done this for the 222ps which I'm pretty sure has the same battery pack.

The method has been highly successful. I can't paste the link but if you google search replacing the battery pack in the 222ps scope you should find the article , or hunt around for it on the worldphaco.com website where it is listed. I'm sure also it has been mentioned on another thread.

There were some concerns about paralleling some cells, but provided certain rules (noted in the article) are followed, it doesn't give any trouble at all, I've proved this with a number of different battery assemblies over the years. Also when replacing the pack, it's best to use the full volume of space available, than wasting some, so as to have the max possible capacity.

Also in the case of these scopes the charge rate is relatively low, so it doesn't matter about having a specific charging protocol for cell types, just that the overall replacement cell pack has a very similar voltage to the original.

The scopes I think were meant to plugged all the time when they were not being used for portable-mobile test applications and mains power wasn't convenient or there.

I've been using my 222ps now for some years and the battery pack has lasted longer than any lead gel cell type in other equipment in my workshop. I think it has worked out to be superior to the original one Tek supplied by all reports.
Argus25 is offline  
Old 2nd Nov 2017, 9:06 am   #14
RogerEvans
Hexode
 
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 378
Default Re: Tek 212 battery replacement.

The Tek 222ps uses two 4V 'lead acid' gel cells and has a charge controller The 212 was originally ten NiCd cells in series in two groups of five with a permanently connected constant current trickle charge with no regulation or timer. The On/Off switch switches in a second dropping capacitor in parallel with the permanently on trickle charge but the smoothing and regulation is provided by the battery pack.

You can replace the originals with NiMnH and choose the cell capacity so that the trickle charge rate is still appropriate. I did that and it works fine, battery lfe is a few hours and charge is retained for months (ie whatever is the longest time it has been left in the cupboard!). Since mine was originally 110V only I still need a 110V auto transformer for the trickle charge. I opted to stay with that inconvenience, the alternative is to change the two dropper capacitors but then a UK mains plug would not have fitted in to the tiny stowage compartment for the mains lead and US style 2 pin plug.

There are reports of replacement with Li cells but then you need to provide suitable charge rate control and replace some of the internal power supply.

Roger
RogerEvans is online now  
Old 2nd Nov 2017, 10:40 am   #15
Argus25
No Longer a Member
 
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: Tek 212 battery replacement.

Les,
Interesting that the voltages were different between the 212 and 222 battery pack. But you can still use the same basic type of cells I used and wrapping that I used to make the right voltage battery pack.
Hugo.
Argus25 is offline  
Old 2nd Nov 2017, 11:04 am   #16
RogerEvans
Hexode
 
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 378
Default Re: Tek 212 battery replacement.

The 222s have a lot of digital circuitry and so draw large currents at 5V, the 212 and similar are all analogue (probably not the 213 since that has a DMM built-in). That must contribute to the choice of a lower voltage in the 222.

Roger
RogerEvans is online now  
Old 2nd Nov 2017, 9:25 pm   #17
MotorBikeLes
Nonode
 
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 2,346
Default Re: TEK 221 Oscilliscope.

I am now in a limbo mode.When I removed the two cell packs, I turned 4 dowels with main length of 52mm plus a pip at each end 3mm long and between 3 and 5mm diameter. The main body diameter was between 15 and 18mm. These four dowels replicated the two battery packs so that the scope's panels remained structurally rigid. I can't remember if there is a central long screw or bolt through the centre, or if the full volume of the two packs is available. Until I open it up again, I remain in limbo.
It seems I have two clear choices, and since I have quite a few good working ex laptop Lions, I am inclined to try to fit six of those inside, but the geometry may force me to choose to take the NiCad or NiMh route. My dowel length of 52mm above makes me wonder why I need 2/3AA, maybe standard AAs, but I probably would have fitted those years ago if suitable. Certainly it would seem that 4/5AAs would drop straight in, but I am sure the cost would be crazy compared with Roger's 12 for under a fiver!
I was unsure how to connect up Lions, but the various ones offered show it should be no problem, and I will find and look at Argus's stuff later.
As Roger says, originally set for 110v mains, but I took the change caps route for 240v 50Hz. This means changing both C210 and C212 to 2UFd at 400v DC.
PSU part circuit is appended.
Les.
Attached Thumbnails
Click image for larger version

Name:	PSU-part.jpg
Views:	130
Size:	60.4 KB
ID:	151728  
MotorBikeLes is offline  
Old 2nd Nov 2017, 10:29 pm   #18
RogerEvans
Hexode
 
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 378
Default Re: TEK 221 Oscilliscope.

There is space to fit 2 x 5 AA cells, the problem I had was attaching wires. I soldered wires successfully in terms of mechanical and electrical connections but the performance of the cells afterwards was abysmal. I tried this twice with different (cheap) cells and was tempted to blame the over heating, not even cheap cells could be that bad, but maybe Mr Bungle is right about re-packaging knackered cells. Anyway I then found the 2/3 AA with solder tags and they worked a treat.

Roger
RogerEvans is online now  
Old 2nd Nov 2017, 10:47 pm   #19
Argus25
No Longer a Member
 
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: TEK 221 Oscilliscope.

Les,
2 x5AA cells would be good and it's better as noted to use cells with tags, soldering to the non tag type sometimes degrades the seals .I see from the diagram there are fuses present. In any case when you make your new battery pack I would suggest, if there is room, putting fuses in series with it as part of the battery pack so if the external wires get shorted there is additional protection. If you look at my version I did it with a section of pcb and fuse clips in the top of the assembly.
One thing with all the types of batteries you are considering they have such a low internal resistance they will quickly burn up wires and vaporise insulation. Also if it's pvc wires that fumes are very toxic/corrosive. I used Teflon insulated wires too. Also the oddball sized plug was missing and I had to make it from scratch.

If you do look at my article you will see I managed to fit 14 AA cells in the space, but I don't know for sure if the battery compartments between the two scope types are identical, but I think they would be pretty close.

Last edited by Argus25; 2nd Nov 2017 at 10:54 pm.
Argus25 is offline  
Old 3rd Nov 2017, 12:16 pm   #20
MotorBikeLes
Nonode
 
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 2,346
Default Re: TEK 212 Oscilloscope.

Mods, I just spotted that I got the topic heading wrong. It is a TEK 212, NOT a 221 as written. Sorry, please change.
Les.
MotorBikeLes is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 11:32 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.