Workshop tools

[bbjunkie]

In the last week or so I've got very interested in this forum, smps and tv repair. I've decided to take it a step further and get myself some tools for the job, as a licensed radio amateur I have spent the last while making solder smoke from building kits, but this is expensive and im getting bored with it. TV repair seems more challenging and nowhere near as expensive (except for the tools!)

I have ordered a basic ESR meter, and am considering building a LOPT/fbt tester. I already own a 100mhz analogue oscilloscope which hopefully may help diagnosing some faults in the future.

The only thing I think I haven't that would be a requirement is an isolation transformer so I can use the 'scope - i'm having difficulty finding a source for one here in the UK. Prefer due to price to buy a used one.

Any suggestions on where I could locate one?

Thanks

Jim

[PlainBill]

Re: Workshop tools

In the last week or so I've got very interested in this forum, smps and tv repair. I've decided to take it a step further and get myself some tools for the job, as a licensed radio amateur I have spent the last while making solder smoke from building kits, but this is expensive and im getting bored with it. TV repair seems more challenging and nowhere near as expensive (except for the tools!)

I have ordered a basic ESR meter, and am considering building a LOPT/fbt tester. I already own a 100mhz analogue oscilloscope which hopefully may help diagnosing some faults in the future.

The only thing I think I haven't that would be a requirement is an isolation transformer so I can use the 'scope - i'm having difficulty finding a source for one here in the UK. Prefer due to price to buy a used one.

Any suggestions on where I could locate one?

Thanks

Jim

An isolation transformer is not strictly necessary unless you are working on the hot section of a power supply, but is always a good idea. We always hate to loose experienced techs.

Try eBay. I suggest you try to get one one rated for at least 500VA, 1KVA is better.

PlainBill

[popeye]

Re: Workshop tools

at last someone with some common sence the first thing you learn at a City And Guilds Coarse is safety first an isolating transformer is a must I found out a phew years ago when someone working in our workshop disconnected the isolater I did not know and while working on a TV after I had repaired it I forgot to switch power off while putting the chassis into the TV well all of a sudden I was twitching about like mad by luck the chassis snapped intwo and saved me I had burns every were. any way as the board saved my life I repair it again like new.So SAFETY FIRST GUY'S..

merry chritmas

[tom66]

Re: Workshop tools

I have a 15A variac, 500VA isolation transformer, two oscilloscopes (one 20 MHz w/ 400V inputs, another 100 MHz digitising), a multimeter, a power supply, an ESR meter, various screw drivers, and soldering gear... and I still don't have enough!

[PCBONEZ]

Re: Workshop tools

Something I've thought about but never actually looked into.
Old UPS units with dead batteries sell pretty cheap sometimes. [Even up to 1500 VA.]
Wouldn't they use a good sized Isolation Transformer?
.

[tom66]

Re: Workshop tools

Something I've thought about but never actually looked into.
Old UPS units with dead batteries sell pretty cheap sometimes. [Even up to 1500 VA.]
Wouldn't they use a good sized Isolation Transformer?
.

Yes but probably designed for 12/24V - 115V/230V, not 1:1.

[PCBONEZ]

Re: Workshop tools

Typically they have an unfiltered feed-through which I imagine is also through the transformer [if it's an Isolation device] so what I'd expect to see is 115V or 230V AC at the xfmr OP and an SMPS tapped off of it.
[Like I said I've never looked. I've never broken one..]
.
What I'm not sure about is if they actually use an ISO-Xfmr.
Seems like they should.
.

[PlainBill]

Re: Workshop tools

Typically they have an unfiltered feed-through which I imagine is also through the transformer [if it's an Isolation device] so what I'd expect to see is 115V or 230V AC at the xfmr OP and an SMPS tapped off of it.
[Like I said I've never looked. I've never broken one..]
.
What I'm not sure about is if they actually use an ISO-Xfmr.
Seems like they should.
.

I don't thing that they do. The electronics may be isolated, but I'd think that the neutral and ground pins were always connected together.

PlainBill

[ecking767]

Re: Workshop tools

The only thing I think I haven't that would be a requirement is an isolation transformer so I can use the 'scope - i'm having difficulty finding a source for one here in the UK. Prefer due to price to buy a used one.

Any suggestions on where I could locate one?

Thanks

Jim

I don't know if there is any electronic recycling places in the U.K., I found one in some old medical equipment that was being recycle. I brought the isolation transformer,got it home, tested it and it work great.

[tom66]

Re: Workshop tools

The only thing I think I haven't that would be a requirement is an isolation transformer so I can use the 'scope - i'm having difficulty finding a source for one here in the UK. Prefer due to price to buy a used one.

Any suggestions on where I could locate one?

Look for surplus stores near you. I found a test equipment store less than 5 miles from me, and they sold me one for £30.

[bbjunkie]

Re: Workshop tools

I have a couple of 1500VA UPS units here, I assume a simple continuity check between input neutral and output neutral and same for live would indicate if it was isolated? (when they are unplugged from the mains)

Then I began wondering to myself, would the UPS electronics have any effect on this, would it need to be powered at the mains input to check for isolation?

tom66 - I have no such stores here, does your local store do mail order? Perhaps I could order one from them if the UPS idea doesn't work out.

[tom66]

Re: Workshop tools

tom66 - I have no such stores here, does your local store do mail order? Perhaps I could order one from them if the UPS idea doesn't work out.

Yea, they do mail order. http://www.stewart-of-reading.co.uk/

[dumpystig]

Re: Workshop tools

eBay...

[Krankshaft]

Re: Workshop tools

Something I've thought about but never actually looked into.
Old UPS units with dead batteries sell pretty cheap sometimes. [Even up to 1500 VA.]
Wouldn't they use a good sized Isolation Transformer?
.

If you're talking about the AC over voltage clipping function most UPS units have yes that is a result of transformer action. But is the output isolated or is it an un isolated tapped primary winding like an auto transformer?

Schematics for these units are hard to come by and so I've never looked at one close enough.

[bbjunkie]

Re: Workshop tools

eBay...

Tried there, nothing coming up at the moment.

Will check the UPS tonight, or in the next few days.

Jim

[bbjunkie]

Re: Workshop tools

Didn't have time to check the UPS tonight, the Atlas ESR-70 arrived along with some caps so I got some proper work done.

Very impressed with the meter, measured the 4 new 1000uf 35v caps had esr ranging from 0.0 to 0.04 ohms. I have a feeling it will save a LOT of head scratching in the future