Beseler Enlarger Timer - How to Calibrate?

[mikecnichols]

Repair is going to cost more than the timer is worth.

The first point of failure is the switch contacts. Try spritzing some 'contact cleaner' into all the the switches and then exercising them - although not ideal, WD-40 can be used in a pinch.

The second point of failure are the electrolytic condensers - especially for equipment made in the early '90s. Often wholesale replacement of the electrolytics will restore a bit of broken electronics. Replacements are available through Digikey.

Thanks for the tips, that's what I was gonna ask the shop. This timer I'm sure is from the 60s.

 

[mklw1954]

Thanks everyone for your help. To complete this thread I can confirm the following:

R10 adjusts the 1x time (clockwise increases time)
R7 adjusts 10x time (clockwise increases time)
R20 adjusts audio beep increments (clockwise increases time in between the beeps)

You have to be careful, but I am quite satisfied with the accuracy. I just used a phillips head screwdriver for adjustments.

Again, gotta love Apug.

I was glad to find thread this as this timer was included as part of an enlarger deal a couple of years ago and I finally decided to check it out as a backup timer. It needed adjustment and I only had to adjust R7 for the 10x (slight clockwise turn to increase the time) as the 1x and beep increment were fine. I used a small flat-head screwdriver, not a Philips head, on mine. Works great now.

I also had an Omega CT20 which was way off but, unlike the Beseler, there's nothing to adjust when you open it up and I discarded it.

 

[faberryman]

Curious what prompted you to check the timer with a stopwatch?

 

[mklw1954]

I have used my better Beseler Digi-Timer (#8187), that checks exactly with a watch or stopwatch, for many years and have made many prints using it. I wanted this other timer to be exact as well in the event I ever need it, so I can use the same exposure times (which I record for each print) if I go back to printing from those old negatives.

These timers can be off, sometimes by a lot. For example, the Omega CT20 I mentioned previously, and discarded because it couldn't be adjusted, ran for 52 seconds when set to 40 seconds.

 

[darkroommike]

I understand your point, but yes, I suppose it is. I want to be able to record times and be able to use any timer in the future and get it right.

That assumes that your enlarger lamp hasn't aged, you haven't changed your paper or developer, or that the maker of your paper and developer didn't change it or discontinue it. As others have posted, I need a consistent time, not an accurate one.

 

[paul ron]

using an ocilascope is the best n probably teh only real way to get it accurate. Those 555 chips in that circuit put out duty cycles of square waves. the width of the waves as well as its frquency can be adjusted. the square wave must be equal length on n off as well as proper amplitude in ordder to be accurate. What part of the wave are you adjusting?.... its not visable without a scope so doing it by the clock is a rough estimation... perhaps accurate enough..

oh but does one adjustment effect the other? x1 vs x10 vs audio?

 

[mklw1954]

Keep in mind I am not using the Audible/Repeating timer and didn't look into its accuracy and adjustment based on getting different printing results. I use a Digi-timer, which I hope will last a long time but wanted to have the Audible/Repeating unit as a backup, since I got it in an enlarger deal, in the event the Digi-timer ever dies.

Consistent but inaccurate times from a timer are fine as long as you always use that timer. But things don't last forever, thus the desire to have another timer that is accurate so you can use your old print times.

I didn't get too technical, e.g., using an oscilloscope; I observed the 1x and 10x times at a bunch of settings, and observed the beep intervals, against a digital timer, stopwatch and my Digi-timer; saw that only the 10x was off (e.g., by 3 seconds over 20 seconds, 6 seconds over 40 seconds); adjusted the 10x; and repeated the test. The 10x adjustment didn't affect the 1x and beep intervals. So, is it totally accurate? Likely not, but accurate and consistent based on simple observations against a digital timer, stopwatch, and the Digi-timer which could all themselves be off (but they agreed). So the practical result is that the timer is no longer off by the amounts I mentioned above, which I think were significant. If it's still a fraction of a second off because of my simple method, I will be able to use it with the print times developed using my Digi-timer.

 

[paul ron]

consistency is more important. and since you got it closer, it will be fine im sure.

the scope would be great but not many people have them these days although.... now heres an idea.... find a frequancy counter app? or hook up a mike to your computer n use a recording program like they use for shutter testers?

the beeps change with the adjustments or are independant?

 

[StephenT]

I have the same timer and adjusted it in the same manner. However, it then began having trouble with repeatability. It's on my list to replace the electrolytics. The other fixed caps and fixed resistors might be OK.