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My milling machine Optimum BF20 Vario electronics has problems

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dcosta04/06/2016 00:20:11
486 forum posts
206 photos

Dear All,

A few days ago my milling machine Optimum BF20 Vario started making a pulsing noise similar to interrupt for a moment normal noise after pulsing, then normal, and so on ... At the same time the built-in lamp that receives power from the same source shimmered.
Thinking the cause was the speed driver board I bought a new one and today I installed it.
When I start the milling machine, being very close to the electronic boards, I hear a very low noise that reminds me eggs to be fried and, moreover, the pulsing behavior remains.
Apparently the electronic board speed control is not to blame.

In the documentation of the milling machine, Optimum (the distributor) calls the power board "relay board".
I identify in it a transformer but I am not able to identify any other components.
In the board I can read can read the following: 608BD / 230V 0710300050 P / b ROHS 05/25/2007

Searching the web I didn't found any reference to a plate with those sayings.
I did further research with other criteria but was not successful.

Will someone, among the distinguished participants in the forum, can give me some clue or guide?

I can, if one wants, add some photo of the two electronic boards but, as both are in a position that makes it impossible for a decent photograph, I can show photographs of sections of each electronic board.

Thanks in advance
Dias Costa

mark smith 2004/06/2016 09:39:05
671 forum posts
331 photos

Hi Cant really help as electronics are not my area but BD 608 is a transistor i think.


Tim Stevens05/06/2016 21:10:25
1259 forum posts

I had a similar (but not identical) problem, which was traced to the variable resistor which is the 'speed knob'. It had the resistance marked on so finding a new one was easy and cheap. Worth a try?


dcosta07/06/2016 16:40:03
486 forum posts
206 photos

Dear all,


When testing the new electronic board again, I realized that the noise was coming from the main button on/off of the milling machine.
A further examination using a mirror showed me that two of the switch terminals showed signs of being badly burned.
Before ordering from the Optimum
distributor in Portugal, I have searched for the switcher on the WWW and I found it only somewhere in Romania and, apparently, they sell it only in quantity.
The written reference on the switch is as follows:

Its image is as follows:


Will someone, among the distinguished participants in the forum, can give me some clue or guide to where I can find it?

Thanks in adavance
Dias Costa

Edited By dcosta on 07/06/2016 16:52:31

Tim Stevens07/06/2016 17:31:34
1259 forum posts

First, I assume that you are skilled in electrical work of this nature. If not, you need help from a proper professional or you might electrocute yourself or someone else.

I think your switch is the item S1.3 in the Optimum parts list. It contains a relay which allows the switch to hold itself on when electric power is applied, and which lets go (turns off) as soon as the supply is stopped. This can be by pressing the red button, or by any other fault in the supply, or you turning it off at the plug.

And it seems likely that there is a problem somewhere in which the relay does not hold firm - perhaps because
a) the on switch (the green button) has dirty contacts, or
b) because of a poor contact somewhere else in the supply.

If the problem is b) you will not cure the fault with a new switch only - you need to be sure that the other switches (including in the supply system) are in good condition.

The switch you show is very similar to the switches used in 'no-volt-release' switches common (in GB) on most workshop machines. I have one in front of me now, not exactly the same as the knobs are level and not sloping. But my guess is that the working parts are what you need.

If you look at e-bay you can try this address: **LINK**

Or just try 'no volt release' and look for a switch which matches yours as nearly as possible.

Make a careful note of which wire is connected to which tab, and check that any new switch has a similar wiring diagram to be sure of getting it right.

I hope this helps and that you can understand it all.

Regards, Tim

Neil Wyatt07/06/2016 17:39:56
18133 forum posts
713 photos
77 articles

This happened to me once, but the switch was a larger unit and easily opened up, I cleaned the contacts and it's been good for years.


dcosta19/06/2016 23:50:05
486 forum posts
206 photos

Dear all,

After I bought an electronic board for motor speed control, as has already written, it is that I realized that the main switch showed signs of being severely burned. One of the terminals moved freely.
Having not found on the web a supplier, I decided to buy the button on the distributor in Portugal.
About 30,00after (price for the button) to milling machine BF20 Vario is working apparently well.
Now I have a spare speed controller electronic card which cost me 95,00€.

I thank all the support received.

Dias Costa

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