Power supply woes

[75RR]

Don't know why this is suddenly happening ... anyone know? Any solutions?

[MichaelG.]

Does that PSU have a Variac [or similar] under the knob ?
... If so, the wiper brush may be worn, or the track may dirty.

MichaelG.

https://uk.rs-online.com/web/c/power-su ... s/variacs/

[Hobbyst46]

Sorry for not being able to provide specific info.

Ancient capacitors often deteriorate with age. Oldish cloth-style wire insulation could fail as well.
My Carl Zeiss power supply (for the 6V 15W tungsten lamp) was repaired for free by an electronics technician, but after a while failed again.

Modern good-quality variable power supplies, although not cheap, are much more reliable.
Example (regretfully beyond my budget) is Delta Elektronika model ES300 (0-30VDC, 0-10A, 300W max) or ES015-10 (0-15VDC, 0-10A, 150W max). Lightweight, quiet, stable and reliable bench instrument (long-term user experience, no personal affiliation of any kind).

[75RR]

Thanks MichaelG. and Hobbyst46

Well, wiped the track and the brush with Isopropyl alcohol (does it need a firmer hand?) - plugged back in into another wall socket - same result.

Could a brown out be causing this?

[BramHuntingNematodes]

try some 320 grit sandpaper then isopropyl

edit on the other hand it looks really clean. What's the brush look like?

[Charles]

From the video it appears your regulator is loosing contact and then re-establishing. It could be the roller or wiring? You can open it up by first removing the power knob and then the four screws on the side. Unplug it first, of course. Then you will see a copper platform with an arm with roller which rolls across the copper platform as you increase/decrease the power knob. Insure the roller contacts the copper platform properly and you can also clean the path on the copper platform.

[Charles]

Okay, I was late posting. I see you got it open and tried cleaning. I use an eraser along the track and then wipe with alcohol. Also make sure all the wiring is secure.

[75RR]

Thanks for all the replies

Will recheck all connections are secure.

I imagine ideally mark on track should be removed, will try with an eraser, failing that I dug out some 600 sandpaper (also happen to have 320) and will try with that.

Apply to brush as well?

[Charles]

Yes, clean the roller/brush as well.

[MicroBob]

Hi Glen,
do I see a broken solder joint here?

Bob

[75RR]

Hi Glen,
do I see a broken solder joint here?

Bob

Well spotted! Yes I did. Turned out it was cracked but still connected. Soldered it anyway. Does not look as neat now :( I am going to have to learn to solder!

Double checked all the connections - all solid.

Tried the eraser trick to clean the track - worked very well. Still no luck.

Then I had a light bulb moment ... literally! Bulb was on its last legs.

Power supply now (again) solid as a rock!!!

Many thanks to all, especially Charles - who was the previous (very careful owner) :)


Feel sad about the demise of the bulb, had had it for several years - being always careful to keep below the rated voltage.

That was until I started trying to obtain COL + Pol with the 63x

Will use a LED for that next time!
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[Wes]

Hi Glen,
do I see a broken solder joint here?

Bob

Well spotted! Yes I did. Turned out it was cracked but still connected. Soldered it anyway. Does not look as neat now I am going to have to learn to solder!

Double checked all the connections - all solid.

Tried the eraser trick to clean the track - worked very well. Still no luck.

Then I had a light bulb moment ... literally! Bulb was on its last legs.

Power supply now (again) solid as a rock!!!

Many thanks to all, especially Charles - who was the previous (very careful owner)


Feel sad about the demise of the bulb, had had it for several years - being always careful to keep below the rated voltage.

That was until I started trying to obtain COL + Pol with the 63x

Will use a LED for that next time!
.
.
.
.

They still sell these bulbs, I bought a couple a few months ago.

[75RR]

They still sell these bulbs, I bought a couple a few months ago.

Can you remember what you paid? I had two spare, now I only have one!

Since we are on the subject of illumination, anyone have a broken Zeiss 100w halogen lamphouse?

I ask because I have a Zeiss 100w halogen lamphouse that is perfectly fine apart from the fact that it is missing the focusing lens. Shame not to be able to get it going.

This is what the lens looks like ...

.

[Wes]

https://www.proflamps.com/uk/en/Product ... 302843057/

The most I've paid for a bulb, ever.

Hopefully you can get the lens for the 100W lamp, its ideal for DIC at high magnifications.

[75RR]

I remember they used to be around $8, which I thought excessive even then!

[MicroBob]

The bulb filament can be a very attractive object for observation under (improvised) incident lighting - so no complete loss.

[75RR]

Every cloud has a tungsten lining ;)

[MichaelG.]

I remember they used to be around $8, which I thought excessive even then!

I was amazed to see that bulb has an ordinary bayonet mount, not a tricky prefocus flange.

MichaelG.