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TWANG

never say die

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Here we go.. testing an OT out of the amp first.. I'll use a 7K V2 OT. since I have two.

 

If it checks out, then I'll reflow the solder joints here and there..

and see you in a bit.

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well that was total BS.

bulb wont light even if connected directly to 6V lantern battery.. yes it lights the lantern.. or a 9V battery I have in my compressor pedal.

????????

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let me add first, I've never tried testing a transformer this way before.

 

hmm I seem to remember the field has to collapse on the transformer, try a darkened room, and rapidly attach and detach the battery to see if you can get any type of faint glow

 

 

My first guess wasn't the transformers with this amps problems

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ok.. turn off shop lights.. watch for quick flash.. and connect/disconnect/connect a few times..?

I'll give it a shot.

 

yeah.. I had about six first guesses.. they were all me! *G*

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I think you've read the instructions like I have

 

This is one thing that jumped out at me when just reading the article again.

 

Keep in mind there are a few sneaky things that can invalidate your test. If there is a load on any winding, those loads will eat the inductive kickback and the neon will not light up.

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but the bulb should light connected straight to the battery, shouldn't it?

that's all I've tried.

If 6 or 9V wont light it up.. I couldn't see how connecting it to the OT would make any difference.

so I didn't hook up the OT at all.

 

As far as loads go.. I'll have the OT disconnected entirely.. that should be the way.

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but the bulb should light connected straight to the battery' date=' shouldn't it?

that's all I've tried.

If 6 or 9V wont light it up.. I couldn't see how connecting it to the OT would make any difference.

so I didn't hook up the OT at all.

 

As far as loads go.. I'll have the OT disconnected entirely.. that should be the way.

 

[/quote']

 

No! For the last time... Neon bulbs only, I repeat, ONLY light up with AC. Batteries are DC. Big difference. Touch a battery to the neon bulb and you get nothing for the reason stated above. Batteries are DC! But touch the battey to a transformer, and for a millisecond, the transformer's resistance to a change in current will cause the neon bulb to think it has AC and will flash. That's due to the electrical nature of the transformer, not the battery, and that's why this test works... IF, and only if, you read and follow the instructions exactly.

 

Gil...

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check this out then

I test the 6V batt. with tongue. yep got some juice. had the light on first, but I like doin' that. *S*

 

hook the batt. to the yellow and white wires.

test the brown and black and the orange and red..

lights off.. connect disc. connect.. nothing.

take off lamp.

go to remove the batt. and got a shock..

pulled my hand back quick.. hurt more than the tongue test.

 

also saw a spark.

 

so. retested.

this time batt. to brn/blk and lamp to or/rd.

nothing glowing.

but, more carefully, no shock, but, still saw a spark.

 

so what the hell???????

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In case you didn't get that.. the batt. sparks when connected disconnected.. and if you happen to be touching both wires, it's a fairly big jolt.

but, the lamp will not come on.

everything on alligator clips, which I'm going to go insulate with shrink tube right now.

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same deal on second OT.

spark when conn/disc but no glow.

 

I'll go do another, but.. the ones I tested should have been fine.

It seems to me this bulb is not the right one.

 

brn and blk conn. to batt.. or/rd to bulb.. zip.

 

I'm holding the bulb while I connect the last leg. so.. I should see it.. dark room.. right under my nose..

a millisecond is awfully quick, but it should work as well for me as anyone.

 

on to the third OT!

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Right. A spark, but no neon light up means what? You're not getting a momentary AC out of that transformer, only DC. Which means one of two things... either you're still not following the instructions; or you are, and the OT is toasted with shorted windings. Shorted windings won't create that momentary AC your neon is looking for.

 

Be sure to verify your methodology and your results! Try the same simple test on a transformer that you know works. If you should "see the light" in neon with a good OT, you'll know you're doing the test right.

 

Gil...

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hold that thought.

Here's what I found.

you can't do this by disc. the wires to the bulb.

you can only get it to spark if you disc and recon the batt wires..

all three OTs tested fine this way.

 

Now.. correct me if I'm wrong, but I found.. black and brown to the batt.. red and orange to the lamp

spark with a batt wire and you can see the bulb flash.

 

is that enough or do I have to reverse this procedure or anything like that? seems unlikely.

 

but yep.. messing with the bulb wires did nothing.. only the batt wires.

 

so.. I've done three OT's and now I'll go ahead and disconnect the one in the amp.. but, since one of these OT's was IN the amp before this..

and I took it out since there was some question as to whether or not I'd hurt it.. and since I went all over that amp before I risked another

PT.. I really think the OT is fine. and the problem is somewhere else.

 

each time I tried this test.. I used the lamp bulbs.. until this time.. made the difference. Might want to note that for the FAQ!

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you disconnected the bulb from the transformer? :-

 

also from what I understand only do 1 winding at a time. that means bulb on both org and then both red; I don't think you're supposed to tie them together.

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yeah. I was checking the thing.

here's what happened.. did it the right way.. got no flash.

later found out that in order to get that flash messing with the bulb wires wont do it. you have to mess with the battery wires.

but.. since it didn't work. I tried connecting the bulb straight to the battery.

it's been some days since we talked about this and I guess I forgot it wont work that way.

 

now. all the OT's work.

 

battery has two wires. connect to brown and black..

bulb has two wires. connect to orange and red..

bulb flashes when you connect disconnect and connect either battery wire.

 

I didn't tie any wires together. I took 'winding' to mean any pair, blk/brn or red/orange

I haven't done anything with the yellow and white wires

should I?

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Seems logical to assume it'd work on any transformer. When checking the OT, using the 16 ohm tap and ground should give you access to the entire secondary winding from end to end. Sometimes OT's have multiple secondaries, but I suspect the VJr OT's don't. They'd be bigger if they did. The Hammond 125xSE series don't, according to the spec sheet. They're just one long winding of wire from ground to 16 ohms, with taps along that winding for 4 and 8ohm outputs.

 

On a PT, you'd definitely want to check all the windings.

 

Gil...

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Well I'm glad you got it working, did you have the whole instructions or just the diagram or neither?

 

when we open the DC loop, the voltage on all windings will increase until something conducts current. If all of the windings are open (as they should be), the NE-2 lamp will break over and flash when the voltage across it hits 75-90V.

 

DC loop means battery connection.

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OK I getcha.. I'll do it.

I think I'll rig up the gator clips and make a little stand for the lamp.

 

I've got this little switch in my junk drawer.. press for on, release and it goes off.. so I can hook the battery up to that, run leads to the tranformer being tested, and the lamp will be mounted next to the switch.

 

Now I can test the things right.

the instructions weren't very clear.. but I think I get it thanks to you guys.

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