Gralab 500 series Timer (Blown Up - but there is a good news ending!)

RJ- · Jul 13, 2022

Well I did it...

After 20 years of printing happily using a 110volt step down transformer for a darkroom Gralab 545 timer, I found the instruction manual and became curious when I read that it has a switching 220volt power supply (not stated on the timer).

Plugged the Gralab directly into the mains using a UK -USA plug adapter and within 5 seconds, a loud bang! The smell of smoke and the RCD electrical safety tripped.

So the instruction manual was wrong for the USA model I use.

Has anyone any experience with repairing Gralab timers - Is there a safety fuse which protects the circuit inside the timer?

Going by the burning smell and dead on powering up on the 110volt step down transformer, I'm guessing I fried the circuit letting down my guard and bypassing the safety transformer to save just a little bit of space.

Any other comparable 220volt models with the brilliant Red LED and aural countdowns like this fantastic timer? I have a RH designs F stop timer which isn't as lucid reading as this amazing Gralab!

Kind regards
RJ

Sirius Glass · Jul 13, 2022

Just out of curiosity just were is the location '42' that uses 220 volts? I could not find it with any mapping website.

mshchem · Jul 13, 2022

50 or 60 Hz? I am curious.

mshchem · Jul 13, 2022

Power rating is on the label on back of timer. There's more than one version of the timer. One for 110 one for 220

MattKing · Jul 13, 2022

Sirius Glass said:
Just out of curiosity just were is the location '42' that uses 220 volts? I could not find it with any mapping website.

That is their number of messages, not their location.
Although The Hitchhiker's Guide to the Galaxy comes to mind.

koraks · Jul 13, 2022

RJ- said:
within 5 seconds, a loud bang

That doesn't bode well for a fuse being the problem. If I were to take a guess, this model would probably have a linear power supply and the power transformer on yours is likely blown now. Replace it and you'll likely find additional components are also blown because they had to run on double voltage, which likely exceeded the limits on some of the logic IC's.

Nice hobby project for the electronically-inclined. Of course, for those people it's also fairly straightforward to DIY something based on an Arduino c.s.

Sorry, not of much help...

Sirius Glass · Jul 13, 2022

MattKing said:
That is their number of messages, not their location.
Although The Hitchhiker's Guide to the Galaxy comes to mind.

ic-racer · Jul 13, 2022

Most switching power supplies are OK being fed from a transformer.
Where devices can run into trouble is powering one switching power supply with another switching power supply. Not all switching power supplies produce nice sine waves, yet most of them require a nice sine wave input.

RJ- · Jul 13, 2022

Sirius Glass said:
Just out of curiosity just were is the location '42' that uses 220 volts? I could not find it with any mapping website.

Hi - Oh sorry. Just noticed my location in the United Kingdom seems to have disappeared!

Yes - using 220Volt 50/60Hertz voltage here. Back when I was a photography student, I was very influenced by the superior American Gralabs which were really well designed - big bright red bold LEDs and picked it up in the USA knowing of the voltage challenges to step down from 220volt to 110volt....

Can't believe I've blown it (literally!) still

RJ- · Jul 13, 2022

mshchem said:
Power rating is on the label on back of timer. There's more than one version of the timer. One for 110 one for 220

Hi - yes it states 110volt only.
However the instructions states 220v 50/60Hz!! It came with it so I thought ... perhaps after 20 years of being cautious and using a stepdown transformer, this was my error.

This probably happened due to using a Fender Vibro Champ 1960s valve amplifier which stated 110volt power supply only on the back. I only used it with a step down transformer until my friend who gave it to me, told me it was definitely 220volt 50/60Hz and had been used in his church for some 50 years before the pandemic. Sure enough - it worked and still works on 220Volt 50/60Hz.

I thought this might have been the case with the Gralab 545 timer....! Boy how wrong!

RJ- · Jul 13, 2022

koraks said:
That doesn't bode well for a fuse being the problem. ...

Hi - thanks for chipping in and confirming. I guess I just have resign it since the smell and loud bang suggests toast!
Back to using the manual Durst Compulux timer. It's alright being a manual battery powered compact unit although the Gralab ....they don't make them like they used to!

RJ- · Jul 13, 2022

ic-racer said:
Most switching power supplies are OK being fed from a transformer.
Where devices can run into trouble is powering one switching power supply with another switching power supply. Not all switching power supplies produce nice sine waves, yet most of them require a nice sine wave input.

I know now

Thank you - I should have tested it rather than put it to the test. Is there a safe way to test if a timer unit to see if it is switchable, without blowing it up?

Kind regards
RJ

mshchem · Jul 13, 2022

I would open the timer up and see if there is any hope.
I bought a new lawn mower last week, my old one a 15 year old riding mower quit on me. As I dismounted I discovered it was on fire. It was a jumble of electrical, something to do with electric start, ignition switch, 12 V storage battery. Definitely electrical fire as I found melted wires.
I put a hose to it, but it extinguished itself, still there was a couple gallons of gasoline in the tank. Yikes!

RJ- · Jul 14, 2022

Wow mshchem ~ that really was a chariot on fire. I guess this is why public places have PAT tests unlike home dwellers and darkroom users!

I opened the Gralab - it smells of polymerised toast although it looks surprisingly non toast. The circuit board looks unmarked ...is it possible maybe the blown parts along the circuit spike surge not have destroyed it beyond repair..

mshchem · Jul 14, 2022

RJ- said:
Wow mshchem ~ that really was a chariot on fire. I guess this is why public places have PAT tests unlike home dwellers and darkroom users!

I opened the Gralab - it smells of polymerised toast although it looks surprisingly non toast. The circuit board looks unmarked ...is it possible maybe the blown parts along the circuit spike surge not have destroyed it beyond repair..

I would keep exploring. There's a good chance you find it repairable.

koraks · Jul 14, 2022

RJ- said:
The circuit board looks unmarked

That's says very little; if there's damage to it, which doesn't have to be, it would be on the top side.
Start by measuring the primary winding of the power transformer; if it's more than a few hundred Ohms you'll need a replacement. When that's settled, power up the unit and start measuring the various supply voltages to see if they make sense. It would help to either find a schematic on Google or otherwise trace it yourself.
If you don't know what the above means, try and find someone with electronics troubleshooting experience and bribe them with a case of their favorite beer.

mshchem · Jul 14, 2022

koraks said:
That's says very little; if there's damage to it, which doesn't have to be, it would be on the top side.
Start by measuring the primary winding of the power transformer; if it's more than a few hundred Ohms you'll need a replacement. When that's settled, power up the unit and start measuring the various supply voltages to see if they make sense. It would help to either find a schematic on Google or otherwise trace it yourself.
If you don't know what the above means, try and find someone with electronics troubleshooting experience and bribe them with a case of their favorite beer.

I'm Clueless about how the UK does electricity, in the USA, typical home has 2 x 110V main supply to the breaker box, and of course a grounded line. A proper polarized lamp cord in the US has a 110V line and a grounded wire (the bigger spade on the plug/outlet)
The 2 prong plug I'm familiar with for UK, what's up with that? Is one leg 220, how's does this work?

mshchem · Jul 14, 2022

Quick search shows neutral, line and earth. So the line should be at 240 V 50 Hz, neutral should be close to zero?

I see now that the 2 pin plugs are unusual, most are 3 pin, one of these being a grounded wire.

US is weird 60Hz etc.

Sirius Glass · Jul 14, 2022

mshchem said:
Quick search shows neutral, line and earth. So the line should be at 240 V 50 Hz, neutral should be close to zero?

I see now that the 2 pin plugs are unusual, most are 3 pin, one of these being a grounded wire.

US is weird 60Hz etc.

Just the US Standard. Some frequency had to be chosen.

Chan Tran · Jul 14, 2022

RJ- said:
Wow mshchem ~ that really was a chariot on fire. I guess this is why public places have PAT tests unlike home dwellers and darkroom users!

I opened the Gralab - it smells of polymerised toast although it looks surprisingly non toast. The circuit board looks unmarked ...is it possible maybe the blown parts along the circuit spike surge not have destroyed it beyond repair..

There is no visible damage. You need to find which component made the loud bang you heard.

koraks · Jul 14, 2022

mshchem said:
Is one leg 220, how's does this work?

230VAC, one phase, one neutral. Same as the rest of Europe, with the exception of the plugs which vary from place to place - sometimes subtly, sometimes fundamentally.

mshchem · Jul 14, 2022

Sirius Glass said:
Just the US Standard. Some frequency had to be chosen.

It was 50 Hz on the West Coast before the national grid. We will all be on DC someday.

Chan Tran · Jul 14, 2022

mshchem said:
It was 50 Hz on the West Coast before the national grid. We will all be on DC someday.

The US were on DC with Edison.

RJ- · Jul 14, 2022

Thanks guys!

The top side doesn't look any different from this side. Doesn't look like burnt toast!

In the UK, we draw 220 volt from the national grid. The potential gradient between the Live [220volt] + Earth = 220volt or so and the gradient between the Neutral and the Earth is about zero. Our 3 pin plugs have pins of equal sizes, larger than the US tiny pins (our plugs are usually larger with a fuse unit for protection unlike the US double insulated ones. Some units have a dummy Earth pin (no connection, just a pin to insert into the electricity socket) and rely on double insulation of the unit/appliance.

I guess the Gralab was double insulated - it's a completely plastic/hard body with no metal anywhere exposed to touch. Unlike RH Designs F stop timer - the chassis is metal!

So many things to fix ... good to know there might be hope to fix this!

Kind regards
RJ

jvo · Jul 14, 2022

RJ- said:
Thanks guys!
I guess the Gralab was double insulated - it's a completely plastic/hard body with no metal anywhere exposed to touch. Unlike RH Designs F stop timer - the chassis is metal!

So many things to fix ... good to know there might be hope to fix this!

Kind regards
RJ

ah, if i remember correctly, the rh designs timer (a wonderful machine), had a 220/110 switch!

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