New to me Gralab 300 Timer just stopped

[Bill Burk]

The inverters work fine!

 

[ic-racer]

You need model 7-171-250R.

 

[AgX]

But it looks completely different.

And I am sure there is no shortage in the UK, or the EU, of used switching and non-switching lab-clocks that would just do the job, if that would be the issue.

 

[Chan Tran]

Your 'adapter looks like a mechanical converter from UK to US plug. What you need is a UK to US 220 to 110 voltage converter; otherwise you'll hit the US timer with 220V and destroy it. I'm just wondering why itdidn'tblow right away?

Even if the adapter convert to 120V the timer would run slow because it's designed for 60Hz. The timer has a synchroous motor and the speed is locked to the frequency of the power. And yes the adapter killed the timer.

 

[ic-racer]

But it looks completely different.

And I am sure there is no shortage in the UK, or the EU, of used switching and non-switching lab-clocks that would just do the job, if that would be the issue.

Yes, for some reason I could not find a black one for 220V in the catalog.

 

[bdial]

I have a white-face Gralab 300, I like it better than the black ones. Easier to see in the safelight gloom.

For the OP, if you have a service center in the UK you might be able to get the guts of a 220v/50 Hz model swapped into yours. Though that probably wouldn't be cheaper than finding a complete one that's 220.

 

[Chan Tran]

I have a white-face Gralab 300, I like it better than the black ones. Easier to see in the safelight gloom.

For the OP, if you have a service center in the UK you might be able to get the guts of a 220v/50 Hz model swapped into yours. Though that probably wouldn't be cheaper than finding a complete one that's 220.

I think it's cheaper to use the newer digital timer.

 

[Richard Lee]

The gadgets that do what you need won’t run an enlarger but you could run a safelight… a 220 volt ac 50 hz to 12 volt dc… connected to a 12volt dc to 110 volt ac 60 hz converter

Like this. The cheapest ones could run the clockworks. But this one for example has max 20 watts which isn’t enough to run an enlarger. I use the GraLab timer to time developing, fixing and washing so I don’t use the sockets.

Bill,

I've recently found myself in a similar situation to the OP, and am interested to learn more about your solution to the UK power/frequency conversion problem.

My concern is that the inverter you recommended has a maximum power rating of 20 watts, while the timer (if I'm reading the specs correctly, below); churns out 600 watts:

I understand the OP intended the timer to be used solely for timing tray processes (as I do), and therefore will not be connnected to an enlarger, however, I'm unclear as to how an inverter with a 20 watt threshold is able to handle a 600 watt appliance, or how you calculated the level of 'draw'? Many thanks,


Richard

Time Range	1sec-59mins/59secs.
Maximum Wattage (Load)	600w
Maximum Resistive Load	1200w
Number of Outlets	Two
Audible Options	Buzzer automatically signals end of cycle
Memory	None
Display	Large numerals, visible in dark
Auto Reset	No
Foot Switch	No
Voltage	120V/60Hz (Available in 220v/50Hz)
Dimensions	7.5 x 7.5 x 2.5" (191 x 191 x 63.5 mm)
Weight	Not available

 

[Niglyn]

Bill,

I've recently found myself in a similar situation to the OP, and am interested to learn more about your solution to the UK power/frequency conversion problem.

My concern is that the inverter you recommended has a maximum power rating of 20 watts, while the timer (if I'm reading the specs correctly, below); churns out 600 watts:

I understand the OP intended the timer to be used solely for timing tray processes (as I do), and therefore will not be connnected to an enlarger, however, I'm unclear as to how an inverter with a 20 watt threshold is able to handle a 600 watt appliance, or how you calculated the level of 'draw'? Many thanks,


Richard

Time Range	1sec-59mins/59secs.
Maximum Wattage (Load)	600w
Maximum Resistive Load	1200w
Number of Outlets	Two
Audible Options	Buzzer automatically signals end of cycle
Memory	None
Display	Large numerals, visible in dark
Auto Reset	No
Foot Switch	No
Voltage	120V/60Hz (Available in 220v/50Hz)
Dimensions	7.5 x 7.5 x 2.5" (191 x 191 x 63.5 mm)
Weight	Not available

Older stuff would have had a transformer, rather than a modern switch mode power supply. (assuming it does not run directly on mains power)

Depending on what the kit is, it maybe very easy to swap the power supply.

If it uses a synchronous motor, then this would need changing.

Where in the UK are you?

 

[Richard Lee]

Depending on what the kit is, it maybe very easy to swap the power supply.

If it uses a synchronous motor, then this would need changing.

Where in the UK are you?

Hi,

I did consider that option until the timer arrived from the US, and I discovered the case is rivetted together. More hassle than I care to take on.

I currently live in Cumbria.

Richard

 

[Niglyn]

There are loads of cheap inverters. A quick look on AliExpress finds them.
I doubt a timer, even driving relays would pull more that 1A @120V
I X V =W. so 1Amp is only 120 watts.

12V input, to give 120W output is 120/12 = 10A. This of course is excluding conversion loss.
So a mighty 12 power supply is needed.

https://vi.aliexpress.com/item/1005006151682263.html?spm=a2g0o.detail.1000023.6.4a5fn47mn47mUR&gatewayAdapt=glo2vnm

 

[Niglyn]

Can't find a schematic.
The 600W is the maximum current the relay contacts can handle, not the current used by the timer itself, which will be teeny.

The OP never did post a picture of the innards.

Removing the rivets is easy, use a metal drill bit smaller that the diameter of the rivet & it should just drill out. Use a small drill & work up. To put it back together, use self tapping screws.

 

[Niglyn]

Have found a tube of the timer with the back removed.
It is just a synchronous motor.
Again turning to aliexpress, they have loads of cheap motors. Would need to know what rpm the old motor is & see if the shaft is the same diameter.


Link to my photography projects, developing timer, shutter tester etc.

billbill100 - Overview

billbill100 has 8 repositories available. Follow their code on GitHub.

github.com

 

[Richard Lee]

There are loads of cheap inverters. A quick look on AliExpress finds them.
I doubt a timer, even driving relays would pull more that 1A @120V
I X V =W. so 1Amp is only 120 watts.

12V input, to give 120W output is 120/12 = 10A. This of course is excluding conversion loss.
So a mighty 12 power supply is needed.

https://vi.aliexpress.com/item/1005006151682263.html?spm=a2g0o.detail.1000023.6.4a5fn47mn47mUR&gatewayAdapt=glo2vnm

Interesting and informative replies for which I am sincerely grateful.

PM sent for minor clarification. Thank you.


Richard

 

[Niglyn]

I'm so intrigued by these timers now, I'm happy to look any anybody's dead timer & see if I can source a suitable replacement motor.

I need need to see the actual timer, so would need to be posted to me.

Will return it, of course, either fixed or not.

Postage at owners cost.