Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

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Potatu
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Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#1 Post by Potatu » Mon Sep 05, 2016 12:03 pm

I have two BHTU microscopes and I'm trying to understand why the lamp intensity adjusters function differently between them, and whether one of these microscopes (microscope 2) may in fact be faulty.


Firstly, Microscope 1 which I think is working as it should do.
Lamp intensity smoothly intensifies as the slider is moved up to 7.

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Now Microscope 2. Light appears medium intensity when slider is at "position 0" and then quickly loses intensity as it is moved towards 7. Also note that the starting light is green rather than red on microscope 1.

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I am using the same halogen socket (LS20H-M2), same bulb, same power cable and same power source when I tested these two microscopes.

Any idea why they behave differently? Is one of them faulty?

I should probably mention if it's not already obvious that I am a beginner with using these microscopes.

Any info/insight would be greatly appreciated.

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lorez
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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#2 Post by lorez » Mon Sep 05, 2016 3:33 pm

Over the life of this model Olympus used a lot of different LED indicator boards and there were differences in the colors of the LEDs. The problem is probably a failing circuit board. Since the instrument is long out of production original replacement parts are no longer available, but there are aftermarket parts that work fine. An LED conversion is also something you may wish to consider.

lorez

Potatu
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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#3 Post by Potatu » Mon Sep 05, 2016 5:34 pm

Thanks for the reply.

So you believe microscope 2 to be faulty then? Possibly requiring a new circuit board?

The color of the LED indicator isn't an issue, I only mentioned it in case it was relevant to why the lamp adjuster was acting differently.

My next question would be where do I go for information on repairing it? Prices, parts.
I'd like it to get it working as intended.

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lorez
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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#4 Post by lorez » Mon Sep 05, 2016 6:12 pm

I don't know where you are located, so I can't offer any suggestions.

lorez

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c-krebs
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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#5 Post by c-krebs » Mon Sep 05, 2016 9:01 pm

I suspect lorez is correct, in that repair is needed. These folks were able to repair a faulty power supply on an Olympus BHS for me. It was under "guarantee" by the dealer, l so I don't know the cost involved (you might find it is too high to justify).

Rocky Mountain Microscope Corporation  
440 S Link Ln, Fort Collins, CO 80524
(970) 484-0307

BTW, any time you experience a problem like you describe it is always a good idea to swap out bulbs for a known "good one", and check the socket for any corrosion before considering repair or an LED conversion. It is surprising how often this is the problem (wishful thinking! ;) )

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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#6 Post by carlh6902 » Wed Sep 07, 2016 12:18 am

I recently repaired a BH2 with exactly that symptom. Had a bad transistor on the dimmer board (not the power pass transistor). Was an easy fix, part was easy to find.

The electronics of the BHT/U scopes is described in detail in an article I wrote a few years back. Google "bhtu electronics PDF" and you'll find it.

Carl
--- If you're in the Kansas City area and you need help with an Olympus BH-2 scope, PM me. I love to work on these things ---

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75RR
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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#7 Post by 75RR » Wed Sep 07, 2016 1:12 am

The electronics of the BHT/U scopes is described in detail in an article I wrote a few years back. Google "bhtu electronics PDF" and you'll find it.
Looked it up: very nice work!
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#8 Post by carlh6902 » Wed Sep 07, 2016 1:58 am

75RR wrote:
The electronics of the BHT/U scopes is described in detail in an article I wrote a few years back. Google "bhtu electronics PDF" and you'll find it.
Looked it up: very nice work!
Thanks. There are a few versions of the article out there. Be sure you've got the latest version.

Edit 4/14/2019: Replaced outdated link with a link to the master index, which always contains the most recent versions:

https://drive.google.com/open?id=0B7ckZ ... nFYVDJSRW8

Carl
Last edited by carlh6902 on Mon Apr 15, 2019 12:48 am, edited 2 times in total.
--- If you're in the Kansas City area and you need help with an Olympus BH-2 scope, PM me. I love to work on these things ---

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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#9 Post by carlh6902 » Wed Sep 07, 2016 2:05 am

lorez wrote:Over the life of this model Olympus used a lot of different LED indicator boards and there were differences in the colors of the LEDs. The problem is probably a failing circuit board. Since the instrument is long out of production original replacement parts are no longer available, but there are aftermarket parts that work fine. An LED conversion is also something you may wish to consider.

lorez
Parts are available for most all bhtu electrical repairs, just not through Olympus (unless you're very unlucky and the transformer is shot). People have shipped electrical bases to me for repair, and I've had good luck bringing these beasts back from the dead. It's a labor of love for me. They're my favorite scopes on planet earth.

Carl
--- If you're in the Kansas City area and you need help with an Olympus BH-2 scope, PM me. I love to work on these things ---

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75RR
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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#10 Post by 75RR » Wed Sep 07, 2016 2:12 am

There are two versions of the article out there. Be sure you've got revision 2.
Do now, thanks!
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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#11 Post by carlh6902 » Sat Feb 18, 2017 5:23 am

To keep this thread current, here is a link to a recent significant update to this document.

Edit 4/14/2019: Replaced outdated link with a link to the master index, which always contains the most recent versions:

https://drive.google.com/open?id=0B7ckZ ... nFYVDJSRW8


Carl
Last edited by carlh6902 on Mon Apr 15, 2019 12:49 am, edited 2 times in total.
--- If you're in the Kansas City area and you need help with an Olympus BH-2 scope, PM me. I love to work on these things ---

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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#12 Post by carlh6902 » Sat Feb 18, 2017 5:25 am

Here is a recent update to this document.

Edit 4/14/2019: Replaced outdated link with a link to the master index, which always contains the most recent versions:

https://drive.google.com/open?id=0B7ckZ ... nFYVDJSRW8


Carl
Last edited by carlh6902 on Mon Apr 15, 2019 12:50 am, edited 1 time in total.
--- If you're in the Kansas City area and you need help with an Olympus BH-2 scope, PM me. I love to work on these things ---

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75RR
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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#13 Post by 75RR » Sat Feb 18, 2017 6:06 am

Thanks for the update. Have added the link to the Resources (online, books etc.) section to improve access to it.

viewtopic.php?f=15&p=42184&sid=9de31fa6 ... 968#p42184
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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#14 Post by carlh6902 » Mon Jan 07, 2019 5:32 am

I have released another significant update to this document. It now includes a comprehensive troubleshooting section, complete with flowcharts. It went from 22 to 34 pages.

Carl

Edit 4/14/2019: Replaced outdated link with a link to the master index, which always contains the most recent versions:

https://drive.google.com/open?id=0B7ckZ ... nFYVDJSRW8
Last edited by carlh6902 on Mon Apr 15, 2019 12:51 am, edited 1 time in total.
--- If you're in the Kansas City area and you need help with an Olympus BH-2 scope, PM me. I love to work on these things ---

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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#15 Post by PeteM » Mon Jan 07, 2019 6:00 am

Thank you, Carl.

One of our fellow travelers, interested in buying a microscope, recently said something to the effect that there are several great scopes (Nikon, Olympus, etc.) -- but your efforts kind of put the BH2 over the top as a great, reasonably affordable, . . . and maintainable scope.

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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#16 Post by MichaelG. » Mon Jan 07, 2019 9:36 am

carlh6902 wrote:I have released another significant update to this document. It now includes a comprehensive troubleshooting section, complete with flowcharts. It went from 22 to 34 pages.

Carl

https://drive.google.com/open?id=1AxTHU ... AyNVcLv6EG
Thanks Carl ... I have just downloaded that ^^^
I don't [yet?] have a BH2, but something so thoroughly written is worth having for wider reference.

Very nicely done !!

MichaelG.
Too many 'projects'

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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#17 Post by Tom Jones » Mon Jan 07, 2019 3:33 pm

Before you get too carried away, you might try squirting contact cleaner on the slider (through the slider opening) and then moving the knob back and forth the full range several times. Dirt on the slider can make contact intermittent at best. I've resurrected several this way.

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Re: Olympus BH-2 Question. Lamp intensity adjuster. Faulty?

#18 Post by ROLLER BOLT » Tue Jan 08, 2019 4:50 am

If you are using an incandescent bulb and you have a rheostat type slider it may need cleaning with an electronics spray cleaner, from Home Depot.
I found that these Chinese microscope LED lights are stepping not linear, and some have color shift
as the intensity changes.

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