Troller dual power pack

[peteski]

There was a photo of the front of the throttle with the lights on (on the first page of the thread).  Was that your throttle or some photo from the Internet?

[mmagliaro]

You are absolutely sure you had the meter set on AC volts?

0.1v across the output terminals from that transformer sounds like the transformer is dead.

Check your meter on a known, good, AC source.  Do you have some other power pack that has accessory terminals
on the back?   You should read 16V AC on those (or thereabouts).  If your meter still shows 0.1v, then I'd start suspecting
your meter.

As Peteski alluded... if that photo you posted earlier, showing the pilot light on, was YOUR troller, than the power
switch is probably good.   

[peteski]

The 41 ohm DC resistance of the primary transformer winding seems to be reasonable (for a working transformer).

[Rich_S]

The 41 ohm DC resistance of the primary transformer winding seems to be reasonable (for a working transformer).

Pete, The pictures with the 41 ohm resistance are my photos, not SD75i's photos. I was using the pictures to show SD75i how to check the on / off switch and the primary side of the step down transformer.  As mmagliaro allured to, another check of the power pack is checking the AC Accessories terminals for voltage.

[Rich_S]

Here is a photo of mmagliaro idea.

[peteski]

Pete, The pictures with the 41 ohm resistance are my photos, not SD75i's photos. I was using the pictures to show SD75i how to check the on / off switch and the primary side of the step down transformer.  As mmagliaro allured to, another check of the power pack is checking the AC Accessories terminals for voltage.

  to myself!  Nice Fluke BTW! 

[mmagliaro]

Checking the accessory terminals on the Troller to see if the transformer is okay is a good idea.
But what I was really after was for the OP to put his meter on something *else* other than the troller and confirm
that the meter is working.  I want to make sure that 0.1 volt reading isn't a fluke 

(oh boy... that didn't hit me until I typed
it, but I'm leaving it there now!)

[Carolina Northern]

Remember - it's a Fluke if it works, at least that's what we always said in the field.

I'm kind of out of touch, so I can't post very much. There are many knowledgeable electronics people on here, so I didn't feel I was leaving him hanging.

The points that are being tested are one leg of each of the two taps off the transformer. They should be VERY close to each other.

The transformer is double wound to allow isolation between the two throttles - remember common rail was popular when these were built.

The original statement that he had good voltage at both the AC and DC accessory ports kind of eliminates the transformer as the problem.

Don

[peteski]

The original statement that he had good voltage at both the AC and DC accessory ports kind of eliminates the transformer as the problem.

Don

I revisited the entire thread and nowhere it was stated that those voltages were ok on the defective unit.  Maybe, like me, you were confused by Rich_S's instructional posts (with photos).  But I did ask whether the earlier photo of the unit's faceplate with the lights illuminated was of the defective unit or some random photo off the Internet.

[mmagliaro]

....

Remember - it's a Fluke if it works, at least that's what we always said in the field.

The points that are being tested are one leg of each of the two taps off the transformer. They should be VERY close to each other.

The transformer is double wound to allow isolation between the two throttles - remember common rail was popular when these were built.

...

Don

Oh!  That transformer has two secondaries???   Oh boy.  Then yes, there shouldn't be 16v across those two output tabs
in my picture.  The 0.1v is probably correct.

Okay, in that case try measuring between each of those terminals and GROUND (the metal case would probably be fine).
There should be some decent voltage there from each of those terminals.
But like you say, the transformer is very very unlikely to be the culprit here.

I still think we want to get some kind of accurate assessment on those thermal overload glass capsules (I assume that's what they
are.  It's a little hard to tell in the pictures).  If the ohm readings on those were wildly varying then yes, disconnect one lead of each one and measure the resistance across it.

A little perusal on Trollers turned up a lot of on-line posts about the main power transistor failing.  So if the capsules check out,
and there is AC voltage from that transformer, and there is still absolutely nothing coming from the DC output of the throttle,
I would probably look there next.
I don't see it in the photos.  Must be hidden under that board.

[sd75i]

DC access and AC

[sd75i]

Measurement item 1

[sd75i]

Other test  on then off

[peteski]

What you show in the photos seem to confirm that the transformer (or at least some part of it) is working.  Just to confirm, are any of the lights on the faceplate illuminated?

If there are separate low-voltage windings on the transformer for each of the throttle circuits then those windings should be fully independent.  So you should not get any voltage readings either between each winding's terminals or between the terminals and ground/chassis.

If there are 2 windings then the reason you don't see any voltage between the 2 terminals with yellow wires might be because each terminal belongs to the separate windings. and maybe the other terminals of those windings are on the other side of the transformer.  But since I'm not familiar with this throttle, this is only a speculation.

[sd75i]

  Tried to get closer