Test Equipment Anonymous (TEA) group therapy thread

[bd139]

Done before it was even open. Joy to the disorganised nature of groups of old men (no offence intended here - you lot are more organised). The grey man principle works at hamfest, in and out like the SAS

Passed on a huge amount of kit. Prices were quite frankly ridiculous. Not even eBay on a good day as a seller prices. 

Managed to snag a working Tek 2235 for £25 though. And that was it. Felt like I should bail after that. Lots of evil eyes on the way out with that one 

[TERRA Operative]

I just recently got myself a mild horror show of a HP 5340A Frequency Counter..
https://www.eevblog.com/forum/repair/hp-5340a-frequency-counter-resurrection/

Good ol' nixie version with some missing parts etc.
Does anyone have any spare parts or parts machines I can pick over? If I manage to get this thing working, its good for 10Hz to 18GHz.
To start with I need the rear voltage selector switch, the front Resolution switch assembly and the metal can for the 'Dir. Count Amp.'

[TERRA Operative]

Managed to snag a working Tek 2235 for £25 though. And that was it. Felt like I should bail after that. Lots of evil eyes on the way out with that one 

They are a nice unit, mine seems to work really well since I restored it.
Check out my video I made on restoring mine (shameless plug), I figured out all the cross references to current parts, the list is in the description.

https://www.eevblog.com/forum/repair/tektronix-2235-upgrades/

[Specmaster]

Well done that grey man, what excuse did you give them that you had to get in early? Did you tell them that you had to back quick before SWMBO got home from her late shift?

There's a form of magnetic pull towards scopes for you and I, can't put my finger on the reason why we both tend to end up with one on the bench so often, although I've resisted well recently, due to the fact that my lab is already full of other shit that needs clearing out first I think.

[Specmaster]

Managed to snag a working Tek 2235 for £25 though. And that was it. Felt like I should bail after that. Lots of evil eyes on the way out with that one 

They are a nice unit, mine seems to work really well since I restored it.
Check out my video I made on restoring mine (shameless plug), I figured out all the cross references to current parts, the list is in the description.

That multi turn pot is indeed a standard fitment on that 2235 scope.

[TERRA Operative]

That multi turn pot is indeed a standard fitment on that 2235 scope.

Yeah, I realised later on. I think I mentioned it in passing near the end of the video.

I'd never seen it on a scope before, we usually retrofitted them to machinery for the fine control.

[tggzzz]

One NiCd is well past its sell-by date and the battery voltage with power applied only totals 4.3VDC - not even 4VDC when running on batteries alone, which trips the LO BATT indication.  I'm pretty sure this is not helping the meter's accuracy at all.  I know I shouldn't power it up with the batteries out, so I'm pondering my options for additional testing.

It may be simplest to just replace the NiCd cells, depending on size, capacity and whether or not they are tagged. Much to my amazement, that turned out to be the case for my TDR.

Another alternative might be NiMH, but be careful with both the charging current (NiMH needs <C/20) and claimed capacity.

Not sure that is the case now. Decent nicd cells have a price premium since 2016. Not sure when you did your TDR.

I would find a way of regulating the output of the transformer myself. LT do some very low drop out regulators for not much. Pd will be quite low.

Two months ago:

• one TDR I simply replaced the broken transformer and broken battery with an 90-250Vac->12Vdc brick, and ignored the (destroyed) battery compartment. That is now mains only
• the other TDR I inserted new tagged NiCd cells and soldered the tags together.  A new 1300mAh cell costs £1.60. That works like new, except I wouldn't operate it underwater

[bd139]

Managed to snag a working Tek 2235 for £25 though. And that was it. Felt like I should bail after that. Lots of evil eyes on the way out with that one 

They are a nice unit, mine seems to work really well since I restored it.
Check out my video I made on restoring mine (shameless plug), I figured out all the cross references to current parts, the list is in the description.

https://www.eevblog.com/forum/repair/tektronix-2235-upgrades/

Thanks for this. Will watch this afternoon 

Have just got it home and it works almost perfectly. The power supply is a bit noisy as expected but attenuators are healthy and triggers perfectly. Intensity is a bit low but this looks like the power supply is struggling a bit. I will refurb this unit and see where I get.

@tggzzz: where did you get your tagged cells from? Admittedly I only looked at RS and CPC for them.

[bd139]

Argh it’s got a Schaffner filter in it and then a filter board with two RIFAs! 

Bang goes 20 quid

[TERRA Operative]

Yeah.
The Schaffner filter seems to only have ceramic caps inside, but those Rifa's have gotta go!

[bd139]

Indeed - don’t want to risk it with the schaffner. Have had one blow on me once. New one is only £6. Pricing up bits now. Looks to be around £25. Happy with that. Hopefully it’ll be more reliable than my 465 and 475 are

[med6753]

I think that a 3D printer could be on the horizon for that space and the Pontiac moving right to the next parking spot.

I can tell you that the planned renovation does NOT include a 3D printer. But it was an interesting thought. 

[med6753]

Done before it was even open. Joy to the disorganised nature of groups of old men (no offence intended here - you lot are more organised). The grey man principle works at hamfest, in and out like the SAS

Passed on a huge amount of kit. Prices were quite frankly ridiculous. Not even eBay on a good day as a seller prices. 

Managed to snag a working Tek 2235 for £25 though. And that was it. Felt like I should bail after that. Lots of evil eyes on the way out with that one 

That's because those grey beard Hams are flap jaws and never know when to shut up. Listening to some of them on the air is a loooooong key down repeating their life story. Put them all in the same room eyeballing each other and nothing gets accomplished. 

A  semi-working Tek 2235 for $32 USD? You suck!    How do you manage that?? 

[med6753]

Indeed - don’t want to risk it with the schaffner. Have had one blow on me once. New one is only £6. Pricing up bits now. Looks to be around £25. Happy with that. Hopefully it’ll be more reliable than my 465 and 475 are

Damnit, don't jinx all the hard work I put into my 465B. Since it's overhaul it has been 100% reliable. Now watch, I'll pull power on and it will go BAM. 

[bd139]

Done before it was even open. Joy to the disorganised nature of groups of old men (no offence intended here - you lot are more organised). The grey man principle works at hamfest, in and out like the SAS

Passed on a huge amount of kit. Prices were quite frankly ridiculous. Not even eBay on a good day as a seller prices. 

Managed to snag a working Tek 2235 for £25 though. And that was it. Felt like I should bail after that. Lots of evil eyes on the way out with that one 

That's because those grey beard Hams are flap jaws and never know when to shut up. Listening to some of them on the air is a loooooong key down repeating their life story. Put them all in the same room eyeballing each other and nothing gets accomplished. 

Indeed. I think they though I was part of the staff 

A  semi-working Tek 2235 for $32 USD? You suck!    How do you manage that?? 

That was the advertised price (!). I decided to leg it off with it quick before he changed his mind.  I've seen them go for £150 here!

Damnit, don't jinx all the hard work I put into my 465B. Since it's overhaul it has been 100% reliable. Now watch, I'll pull power on and it will go BAM. 

Mine are both just dicks. Yours is probably fine. Actually I really need to debug my 475A. That's the most likely to work scope out of the two. It just has a lazy timebase. Starts off fine and slowly drops off and goes to sleep. Works fine in X-Y mode so trigger / timebase needs sorting.

Ordered replacement capacitors and mains filter. I actually had a big chunk of the capacitors lying around. £20.30 spent. Nearly as much as the scope!

[bd139]

Before I forget, some porns:

Outsides (pretty damn good condition!):



Insides with PSU cover removed (you can smell the telequipment engineers designed this):

[TERRA Operative]

I only paid about $40 for mine, seems we both got lucky.

Your PSU section looks like a different revision to mine, the caps and stuff are in slightly different positions.
Also, be sure to replace the resistors for the focus circuit, near the black pot with the long black/grey rod to the front panel, they are a common failure point on these units.

[Specmaster]

BD, looking very good, nice and clean inside but where is your fan=?

[bd139]

I only paid about $40 for mine, seems we both got lucky.

Your PSU section looks like a different revision to mine, the caps and stuff are in slightly different positions.
Also, be sure to replace the resistors for the focus circuit, near the black pot with the long black/grey rod to the front panel, they are a common failure point on these units.

Yeah I noticed that it was different to yours from your video. Mine doesn't have a fan as well and appears never to have had one.

I shall indeed replace the HV resistors. I already actually have the correct ones in stock (Vishay VR series) for that from rebuilding the HT in a Telequipment D83 (this thing's ancestor in theory).

Just realised I seem to have collected 6 Tek heritage at least scopes again now 

1x Tek 465 100MHz (working but vertical attenuators dicky)
1x Tek 475A+DM44 250MHz (working but timebase dicky)
1x Tek TDS210 60MHz (fully working)
1x Tek 2235 100MHz (fully working but power supply needs refurb)
1x Tek/Telequipment D83 50MHz (fully working but intensity control iffy )
1x Tek/Telequipment D83 50MHz (totally deceased parts mule)

I had a 7603 until recently as well (yes I got rid of it - not enough room here).

BD, looking very good, nice and clean inside but where is your fan=?

Looks like mine didn't come with one or ever have one.

[Specmaster]

Looks like mine didn't come with one or ever have one.

Even better news then or is it? It all depends on whether yours is a newer or older model than TERRA operatives example. I#m guessing that it is newer. What about those bastard tands, ripping them out as matter of course?

[bd139]

That is good news. I can’t stand fans!

Very few tants in this. I think I counted 4 and they were the tubular ones which are usually ok.

Edit: meant to mention this yesterday ... have designed a compacy fully discrete dual rail bench power supply with static current limit. Will kick out +/- 2-15V at around 100mA.  This was after giving up on making the scope ball thing single rail. Dual rail is so much easier. Just add enclosure, inlet, binding posts, switches, toroidal transformer and job done. Why discrete? Cheap, reliable, easy to repair, standard parts. Line rejection is around 30dB. Load rejection is +/-5mV across entire load line. Also no output capacitor is required for this meaning no current dump problems into the load. If you must add one, stick them across the binding posts.



I'll put the gerbers up somewhere if i didn't screw them up when they come back from JLCPCB

[tggzzz]

Just realised I seem to have collected 6 Tek heritage at least scopes again now 

1x Tek 465 100MHz (working but vertical attenuators dicky)
1x Tek 475A+DM44 250MHz (working but timebase dicky)
1x Tek TDS210 60MHz (fully working)
1x Tek 2235 100MHz (fully working but power supply needs refurb)
1x Tek/Telequipment D83 50MHz (fully working but intensity control iffy )
1x Tek/Telequipment D83 50MHz (totally deceased parts mule)

I had a 7603 until recently as well (yes I got rid of it - not enough room here).

My Tek collection is:
1*485, my main scope
1*485, a mule
1*465, a mule
1*465B, nearing the front of the queue
1*475+dm44, working
1*2445B, working
2*2465, working
1*492, working
4*1502, working
plus pulse generator and time-mark generator.

(And an HP1740 and LeCroy 400MHz something, and a few fag packets)

Hence I refuse to consider 7k mainframes. And while I'd like the Fluke 5200 that could be collected, it is 24kg/53lb and a mere 6.5digit.

[TERRA Operative]

That is good news. I can’t stand fans!

Very few tants in this. I think I counted 4 and they were the tubular ones which are usually ok.

You'll find two dipped tantalums next to the blue pots on that top board for the front panel. I replaced them with new ones with double the voltage rating (25V to 50V IIRC)

[med6753]

I had a 7603 until recently as well (yes I got rid of it - not enough room here).

You mean to tell me after making me drool all over myself and be green with envy with that spectacular spectrum analyzer plug-in you turned around and got rid of it?!  You sir, are cruel!   

And my Tek collection is a little more modest:

2465 - working
2465DMS - working
465B/DM44 - working
OS245 (7603N) - working
465/DM44 - parts mule.

[bd139]

That is good news. I can’t stand fans!

Very few tants in this. I think I counted 4 and they were the tubular ones which are usually ok.

You'll find two dipped tantalums next to the blue pots on that top board for the front panel. I replaced them with new ones with double the voltage rating (25V to 50V IIRC)

Thanks - will swap them. Didn’t see them.

I had a 7603 until recently as well (yes I got rid of it - not enough room here).

You mean to tell me after making me drool all over myself and be green with envy with that spectacular spectrum analyzer plug-in you turned around and got rid of it?!  You sir, are cruel!   

Yes unfortunately. Due to the size of it and the lack of size of my house, it turned out to be wedged under the desk most of the time at risk of damage. Also it caused a little contention in the household as my bench is in the living space. I am currently trying to stockpile some cash to buy a new much more compact SA so other things will be going soon too. About half way there now.

Plan is to keep the 475A and the TDS210 as they are diametric opposites and both have extreme utility.

Most of the gear you see me with is passing through generating cash to pay for the nicer and newer bits. My net expenditure on electronics is currently zero you see which is something I want to maintain when I have no income in the future.