Test Equipment Anonymous (TEA) group therapy thread

[bitseeker]

Item one - Tektronix 7603. £50. Seems to be working perfectly as promised! Timebase knob is cracked but complete and repairable.

Wow, four channels and on-screen displays.

Holy shitballs, a real live unicorn. No battery leakage and like new inside



Considering these are both penciled in with construction dates of 1961, this is a miracle:

Really nice catches bd. Congrats.

[mnementh]

I think I am insanely lucky there. Literally everything is spotless. That has never happened before. 

Mmmm.... tasty. Those look like they came from a radio museum.  Thanks for sharing!


mnem
*Father-son couch-potato time*

[6PTsocket]

I love the smell of burning selinium in the morning

Certainly would not want to be in the same room as them if they let go without a gas mask thats a fact.

Sent from my SM-G900V using Tapatalk

[bd139]

And the smell of the hospital in the evening

@factory: nice one with the curve tracer. I’m going to get my hands on one of them one day

Also liking Griefkit as that’s what you get a lot of the time. Really Heathkit stuff is mostly pretty good. It’s usually just enough parts to do the job, very close to minimalism with some clever tricks and the performance is good enough.  In some cases like the VTVMs it’s better than some of the commercial items. Certainly good enough for amateur or repair shop use. The grief usually comes in when it was assembled by a drunken monkey or being modified by the owner or left in a shed for 30 years.

Random question here. I rarely restore tube kit and anything else is purely a functional repair however the signal generator is too good for that. But I still need to replace the filter caps and selenium rectifier in it before I even consider powering it up.

So the question is: as part of the restoration is it safe to leave a disconnected electrolytic in the chassis or do I need to gut it first and remove the electrolyte?

The rectifier replacement will require addition of a new tag strip where the old selenium death block was and I will stick the replacement capacitors under the chassis on that.

Edit: also if anyone in UK wants any tag strips FOC let me know. I just bought a metric shit ton of them.

[med6753]

Random question here. I rarely restore tube kit and anything else is purely a functional repair however the signal generator is too good for that. But I still need to replace the filter caps and selenium rectifier in it before I even consider powering it up.

So the question is: as part of the restoration is it safe to leave a disconnected electrolytic in the chassis or do I need to gut it first and remove the electrolyte?

If you're talking the up right metal cans they don't usually physically leak. They just dry out. So it's generally safe to leave them in place.

[bd139]

Cool that’s good then. I will leave i situ then. I don’t get people who restuff the things. No vents ?!?!?  Kaboom!

[med6753]

Cool that’s good then. I will leave i situ then. I don’t get people who restuff the things. No vents ?!?!?  Kaboom!

They do that to keep the "original factory appearance". I think it's a waste of time and yes.....kaboom.

[bd139]

Ok so selenium rectifier out, new tag strip in, clip out old cap and leave it, reroute everything to new caps on new tag strip and done 

Have to say the guy who built this did a dead good job. Even used silver bearing solder for everything. Acknowledgement of his quality and care is noted. Well done sir.

[med6753]

The other thing is you may be able to dispense with the dropping resistor in the B+ after converting from the selenium rectifier to the sillycon diode. Yes, the B+ will be higher but unless you're exceeding the maximum ratings on the tubes it really won't matter much. Although some of the bias voltages may be out of whack. I would try it without the dropping resistor and if things align and cal properly leave it as is. 

[bd139]

Cool thanks for info. It already has 47 ohms and 2.2k in line with the B+ using an RC pi filter so I suspect it’ll be not too terribly off. That 2.2k is a hefty drop. The thing runs down at 160v usually which is pretty low for HT.

Plan is to swap the selenium rectifier out for a 1n4007.

When I do the Heathkit VTVM I will add dropping resistor. I bought a lot of two watt carbon film resistors yesterday for this purpose ranging from 1k down to 22 ohms.

I am going to fix the Heathkit VTVM first then use that only to fix the signal generator

There’s a guy in the US who will ship a full set of replacement probe kits for these for about £22 delivered here which I think is worth spending on this unit as well.

[med6753]

Don't bother with the VTVM's. Their B+ is even less critical. When I converted my Father's Heath V-5 VTVM to diode the B+ jumped to 80 volts without a dropping resistor. The manual specified that the B+ should be 60 - 80 volts so I left it.   

[bd139]

Good to know. It’s not particularly dritical due to the differential amp design which is cool. I’m  mainly worried about the 160v cap I am sticking in that I have lying around exploding 

[med6753]

Just measure the B+ after the conversion. I doubt it will be anywhere near 100 volts. So that cap should be OK.

Yep, the DC probe. The 1 MEG isolating resistor in the probe assembly. I built this one myself because the original was lost.

[bd139]

Cool will do that. Thanks for info.

Just been dragged out shopping to Westfield on a bank holiday Monday no less so no more playing around for me for a bit 

Probe looks good 

[mnementh]

I love the smell of burning selinium in the morning

Certainly would not want to be in the same room as them if they let go without a gas mask thats a fact.

Sent from my SM-G900V using Tapatalk

There is something seriously wrong with you.  You belong here. 


mnem

[mnementh]

In Other News...

Wife and kids are gone to their first day back at school; summer is officially over. Home alone with nothing but my thoughts and Paul Simon on the boom box...


mnem

[Cerebus]

I can't see your pictures because you're using facebook to distribute them and facebook is blackholed here. Might I suggest that you use a more trustworthy host. Your choice, but I suspect that I'm not the only person who's decided (long ago in my case, the zone file date suggests since Nov 2013) that allowing packets from any facebook property onto my network was a "bad thing^TM". No doubt someone will be along to ridicule me for that, but I'm happy to suffer that for the pleasure of knowing that I've got one of the smallest footprints in facebook's data silos possible.

What would you suggest? I really am asking, i use facebook for it being free and more or less permanent but i am open to suggestions.

I'd go with BD139 and say upload them as attachments to posts. All other considerations aside, it helps preserve the integrity of the forum, we had a lot of threads get broken when, overnight, Photobucket changed their 3rd party linking policy and hundreds of images that the forum linked to became unavailable.

[iainwhite]

Just remember the limits for forum images/attachments:
maximum individual image size 1000KB,
maximum total size per post 2000KB

I usually downsize images to lower-quality jpegs so I can fit several in.
 

[Cerebus]

In Other News...

Wife and kids are gone to their first day back at school; summer is officially over. Home alone with nothing but my thoughts and Paul Simon on the boom box...


mnem

Another week to go here before the roads congest from 3:15PM to 4:30PM weekdays with idiots who were too cheap to buy the 'optional extra' indicator lights for their scarily large SUVs.

[mnementh]

You mean these?


mnem

[Specmaster]

Cool thanks for info. It already has 47 ohms and 2.2k in line with the B+ using an RC pi filter so I suspect it’ll be not too terribly off. That 2.2k is a hefty drop. The thing runs down at 160v usually which is pretty low for HT.

Plan is to swap the selenium rectifier out for a 1n4007.

When I do the Heathkit VTVM I will add dropping resistor. I bought a lot of two watt carbon film resistors yesterday for this purpose ranging from 1k down to 22 ohms.

I am going to fix the Heathkit VTVM first then use that only to fix the signal generator

There’s a guy in the US who will ship a full set of replacement probe kits for these for about £22 delivered here which I think is worth spending on this unit as well.

Don't forget that when you fit that 3 core cable to earth the VTVM, that it uses the chassis as a common connection in 12 incidents that you'll need to address, also of course in its current configuration that one side of the AC probes is also connected to chassis so its possible for the entire case to be live. As part of that addressing the chassis problem I also did away with the 1.5 cell and used a 6v to 1.5v dc to dc converter so there is no chance of forgetting the battery and risk it leaking in the future.

I'm just about to order up high voltage 4mm banana sockets that will also accept shrouded plugs to fit in mine and horror of horrors, I had forgotten to replace my Selenium rectifier (diode)  so ordering suitable diode as well.

[Specmaster]

Just remember the limits for forum images/attachments:
maximum individual image size 1000KB,
maximum total size per post 2000KB

I usually downsize images to lower-quality jpegs so I can fit several in.
 

The problem with sending photos as attachments is that in order to meet the file size requirements, quality has to suffer and sometimes, that quality matters so that there is no real alternative to using hosting sites then.

Yes, I agree that if the site closes or changes their policies that the links may not anymore but I see no suitable alternative because the bandwidth and huge storage problems that would accompany attachments of high quality would no doubt be cost prohibitive for the forum to sustain. 

[GreyWoolfe]

In Other News...

Wife and kids are gone to their first day back at school; summer is officially over. Home alone with nothing but my thoughts and Paul Simon on the boom box...


mnem

Not a thing wrong with listening Paul Simon.

[neo]

Just remember the limits for forum images/attachments:
maximum individual image size 1000KB,
maximum total size per post 2000KB

I usually downsize images to lower-quality jpegs so I can fit several in.
 

The problem with sending photos as attachments is that in order to meet the file size requirements, quality has to suffer and sometimes, that quality matters so that there is no real alternative to using hosting sites then.

Yes, I agree that if the site closes or changes their policies that the links may not anymore but I see no suitable alternative because the bandwidth and huge storage problems that would accompany attachments of high quality would no doubt be cost prohibitive for the forum to sustain. 

Yes, that is exactly the problem. I want a picture of my tube tester in all its beauty not a tiny thumbnail. Of course compromises must be made, or do they? I've went back through all of my hamfest pictures and replaced the links with imgur and uploaded a lower res back up. Best of both worlds,  .

[bd139]

Cool thanks for info. It already has 47 ohms and 2.2k in line with the B+ using an RC pi filter so I suspect it’ll be not too terribly off. That 2.2k is a hefty drop. The thing runs down at 160v usually which is pretty low for HT.

Plan is to swap the selenium rectifier out for a 1n4007.

When I do the Heathkit VTVM I will add dropping resistor. I bought a lot of two watt carbon film resistors yesterday for this purpose ranging from 1k down to 22 ohms.

I am going to fix the Heathkit VTVM first then use that only to fix the signal generator

There’s a guy in the US who will ship a full set of replacement probe kits for these for about £22 delivered here which I think is worth spending on this unit as well.

Don't forget that when you fit that 3 core cable to earth the VTVM, that it uses the chassis as a common connection in 12 incidents that you'll need to address, also of course in its current configuration that one side of the AC probes is also connected to chassis so its possible for the entire case to be live. As part of that addressing the chassis problem I also did away with the 1.5 cell and used a 6v to 1.5v dc to dc converter so there is no chance of forgetting the battery and risk it leaking in the future.

I'm just about to order up high voltage 4mm banana sockets that will also accept shrouded plugs to fit in mine and horror of horrors, I had forgotten to replace my Selenium rectifier (diode)  so ordering suitable diode as well.

Yes I’m wondering what I should do. I’m on the fence as to whether I should keep it original and museum piece or make it 100% safe and use it as a lab instrument. A working VTVM is actually pretty damn useful as both my Brymen and Keysight meters are pretty RF sensitive and jump all over the place. Not so with a VTVM. But that means either heavily modifying it to make it floating or keeping it grounded. If it’s grounded you can measure non ground referenced circuits which is a pain however.

Hmm.