Kearsarge 401 Timer Issues

Just thought I would reach out and see if anyone has any experience with this.

I have a newly donated Kearsarge 401 enlarger timer. It seems to partially function but the "ones" digit selector seems to be having problems. While the "Tens" and "Tenths" rotary knobs correctly display digits, the "ones" knob, when rotated thru positions 0-9, display digits in this order: 2-3-2-3-2-3-6-7-6-7 -- only these digits never a 1, 4, 5, 8 or 9. When I activate the timer the "ones" digit LED display counts continuously through the digits 2, 3, 6, 7 and the timer does not properly turn off. It seems to go into an endless loop with the "ones" digit counting thru those four numerals.

I've done a goodly amount of cleaning and sprayed a bit of contact cleaner into the mechanism, but to no avail. All the wiring is connected and the interior of the timer seems pretty clean with no visible damage.

Anyone have experience with these timers or such an issue?

Many thanks, Joe

Do you get the right times, even though the display is off?

If it is only the display, then things should work as:

2-3-2-3-2-3-6-7-6-7 Display
0-1-2-3-4-5-6-7-8-9 Time

NIcholas, thanks for the reply. I don't think I quite understand what you are asking, which likely demonstrates some lack of knowledge of this timer on my part. Is it helpful to tell you that whether the switch is positioned to "Focus" or "Timer" it exhibits the same behavior?

Such timers were usually based on a combination of 7400-series (or conceptually similar) IC's, in particular decade counters. Sometimes, a single gate on one of these IC's can fail; it sounds like something along those lines has happened on your timer. Might also be degradation of PCB traces due to fouling (esp. with acids).

See if you can find someone who has a working knowledge of electronics. Devices like these can usually be repaired provided someone is willing to take the time to track down the issue. HAM radio enthusiasts are a crowd you might want to check out. They sometimes enjoy a puzzle like this one.

I think it would have the counter, the display driver and then the display. If the timing is correct then I would say the counter is OK. The pattern doesn't seem to indicate bad segments so I would say the problem is in the display driver.

Chan Tran said:

If the timing is correct

Click to expand...

Yeah, but since the counting apparently gets stuck in an endless loop, I think the counter array itself is at fault.

Joe Edwards said:

NIcholas, thanks for the reply. I don't think I quite understand what you are asking, which likely demonstrates some lack of knowledge of this timer on my part. Is it helpful to tell you that whether the switch is positioned to "Focus" or "Timer" it exhibits the same behavior?

Click to expand...

As you turn the 'ones' knob does the exposure time(*) advance correctly - 1 second/2 seconds/3 seconds - or do the times match the display.

The reason for asking is to try to isolate the problem to the switch or the circuitry.

Did you take the panels off the timer and spritz the contact cleaner into the ones/seconds rotary switch innards?

* Time/Focus in the Time position; hit the Start button.

I did take it apart and spray the internals (including the seconds mechanism) with contact cleaner. Its probably going to get some more...

This is getting pretty interesting. I am using a lamp to simulate an enlarger, plugged into the 500 watt timer outlet.

When the timer is plugged into an outlet and timer power OFF, (and the lamp turned on) the lamp flashes at a 1 Hz rate. This occurs when the Time/Focus lever is in either position (when the timer power switch is selected to OFF). If I then turn on the timer power and select the Focus mode, the lamp is properly turned on and stays on. If I select Time rather than Focus, it begins flashing again at 1 Hz. If I take the seconds knob off zero, and then depress the START button, with the lever at the Time position, the lamp turns on continuously, but does not turn off (as the seconds digits go thru their seemingly endless loop).

It seems it is currently a little outside my primitive electrical engineering skills!

Joe Edwards said:

When the timer is plugged into an outlet and timer power OFF, (and the lamp turned on) the lamp flashes at a 1 Hz rate. This occurs when the Time/Focus lever is in either position (when the timer power switch is selected to OFF). If I then turn on the timer power and select the Focus mode, the lamp is properly turned on and stays on. If I select Time rather than Focus, it begins flashing again at 1 Hz. If I take the seconds knob off zero, and then depress the START button, with the lever at the Time position, the lamp turns on continuously, but does not turn off (as the seconds digits go thru their seemingly endless loop).

Click to expand...

Ah, all is clear now. Your timer is possessed by demons.

I have no idea what is wrong with it.

You wouldn't happen to have a picture of the innards?

I have the Kearsarge 301 timers, three of them since the mid-eighties. These never gave me any problems. Can you send a picture of the front and the rear of the timer? I would like to understand the differences between the 301 and the 401.

If I understand correctly, your problem is only when using 1 seconds dial? You do not get 1 up to 9 in that order, right? On my 301 there's a switch to simply turn on the lamp in the enlarger, to install the negative. Are you turning that switch off before starting the exposure? This is important.

The 1 second dial is the most used dial because we always use it. I hardly ever use the one tenth dial. I do use the tens dial, often in combination with the one second dial.

Given that your problem happens with the one seconds dial, this may suggest the problem results from this dial's mechanism having worn out. Between the dials, does turning the seconds dial feel the same as turning the others? I am very careful when using these timers, they look like new still. But I have seen some that looked like some of my beat-up cars.

I would also suggest to find someone who knows how to test the electronics.

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Sorry, I understood better your later posts: it is essential the lever on the bottom left of the front is turned off while you start any exposure. This switch is for installing the negative only. Not for any exposure.

In case the problem remains and you get help, do tell that you may have made that error.

Can we post video in here? I think a video of what the timer is doing would be helpful.

Thanks, guys. Photos coming...having a hard time getting uploaded at the proper size. The timer is actually in a bit better shape than it appears in the stark light I took the images -- not that it can't use a bit more cleaning up.

*Yes, the issue seems to be limited to the Ones dial, in that I do not get 1-9 in that order.
*The switch to turn on the lamp for negative installation is labeled Focus on this unit. That switch is flipped to the Timer position to start the exposure (as I understand it).
*The Ones dial feels good, as do the others. None of them seem to have any rounded detents, slipping or anything like that.
*As Hilo noted I'm about to the point of finding a curious electronics repair person. That said, I did notice last night upon closer inspection, that the power cord (leading from the 500W enlarger outlet to the relay) has been spliced in the past, and covered w/electrical tape. Not the worst splice I've ever seen, but not the best. I will properly splice that wire.
*I don't think the splice is my problem though as whether a lamp is plugged into the enlarger outlet or not, the timer exhibits the same erratic behavior.
*I'll get a video uploaded, but I must splice that one wire properly before I plug it in again. (!)

Can anyone crack the code on uploading images? Even at 700KB I'm being told "The uploaded file is too large," while it appears the max size is 2 mb.

Resize your photos down to a jpeg, quality 80, with the longest dimension no longer than 1000 pixels.
That works reliably.
You can squeeze in some that are a bit bigger - particularly if black and white - but that size works and displays well.
For videos, you need to have them somewhere else like YouTube or any of the other compatible places, and post a link using the media function.