4 channel lamp controller?

[Ronnie Dent]

Wondered if anyone could help me out? I have this 80's lamp controller it has 4 channels running 32 60volt lamps, it's mains fed, the lamps are staying on and not chasing as they should? Adjusting the pot does nothing I assume it's to alter the speed?

If not able to see the 2 chips at the top are 4011B and 4081B

The 3 further down are 4011B 4017B 4001B

I'm thinking one of the chips are bad, bit worried about probing anything as it's 240v!

THanks Ronnie

Ronnie Dent2021-09-19 09:48:17

 

[Ronnie Dent]

Trying to get to the fault on this! I wrongly read the last digit on some of the chips as "8" when it was "B" so have updated that above.

So the 4017B is a decade counter so assume that does the flashing? Now I'm getting pulsing on it's enable but nothing on the outputs? To me that would look bad? but there may be much more to it, then all the lamps are on, if that was bad would they not be off?

The 2x 4011B left top and bottom seem to be regulators possibly 5v logic?

And then the 4001B some kind of buffer?

Any pointers would be great, I don't want to replace anything that's not needed!

Thanks Ronnie

 

[Martinmurphy30]

4011 is a nand gate array, 4001 is a nor gate array, none of the chips are anything to do with voltage. The 2 large resistors on the board will be lowering the voltage to the chips. Basically the logic is doing the timing and the 4 what I presume are jfets or transistors are turning the lamps on and off, I would be looking at the switching part before replacing anything.

 

[Ronnie Dent]

4011 is a nand gate array, 4001 is a nor gate array, none of the chips are anything to do with voltage. The 2 large resistors on the board will be lowering the voltage to the chips. Basically the logic is doing the timing and the 4 what I presume are jfets or transistors are turning the lamps on and off, I would be looking at the switching part before replacing anything.

Hi Martin, thanks for your reply, when you say switching part do you mean the 4 TIC206 transistors? there are also 4 smaller 2N3704 transistors. I think the smaller one's switch the bigger one's on to then light the strings of 4? Could all 4 transitors be stuck closed? Each lamp is 60v so must be in series to handle the 240v feed?

Thanks Ronnie

 

[Martinmurphy30]

Yes, the 4 smaller transistors will be switched by the logic, then they will switch the 4 large jfets/transistors to switch on the lights.....this is I complete guess though just looking at the pictures!

 

[Ronnie Dent]

Thanks Martin it looks like the input to the transistor is low (not pulsing) the output is high, this is with my logic probe tapped on to 7vdc across the large capacitor.

Thanks Ronnie

 

[Martinmurphy30]

Looks like the 4 small transistors are driven by the 4081, I'd pull and test the transistors first because they are the easiest to de-solder, then if they are ok focus on the 4081.

 

[Ronnie Dent]

Looks like the 4 small transistors are driven by the 4081, I'd pull and test the transistors first because they are the easiest to de-solder, then if they are ok focus on the 4081.

Thanks Martin they are 2N3704 I crossed checked them for BCX38C I might just swap them put see what happens

 

[Ronnie Dent]

Pulled the 4 transistors and they read as good in my cheap component tester, not sure to put them back or replace with the BCX38C's?

I guess I could check the 4081's inputs to see what happens?

Thanks Ronnie

 

[Martinmurphy30]

With the small transistors removed do the lamps go out? That would be a simple way of testing the larger transistors.

 

[Ronnie Dent]

Good point Martin cheers, all lights off with the transistors removed, should I order a 4081 or could I probe it to see anything off?

Thanks Ronnie

 

[Martinmurphy30]

Good, that proves the big transistors are working, you could probe it but we already know the outputs are whatever state lights on is, IE high or low. Best to de-solder and test it out of circuit. The cd40** series isn't expensive, I'd be tempted to just replace the whole lot of them and socket the board while I was at it. But it's entirely up to you mate!

 

[Ronnie Dent]

Good, that proves the big transistors are working, you could probe it but we already know the outputs are whatever state lights on is, IE high or low. Best to de-solder and test it out of circuit. The cd40** series isn't expensive, I'd be tempted to just replace the whole lot of them and socket the board while I was at it. But it's entirely up to you mate!

Cheers Martin, I think your right, I will just order them all, I also have another one to test but waiting on 1 of the big transistors for that one. I will report back when I get it all done.

Many thanks for taking your time up with this

Cheers Ronnie

 

[Martinmurphy30]

Your very welcome Ronnie and I'd be interested in hearing how you get on, stay safe mate!

 

[Ronnie Dent]

UPDATE!

I replaced the decade counter as the new one's came this morning, and hey presto we have running lights! One down one to go!

Once I get it all back together I will do a short video and report on the number two controller, again thanks for your help Martin.

Cheers Ronnie

 

[Martinmurphy30]

Glad you got it working, always nice seeing things be saved and reused! Good luck with number 2!

 

[Ronnie Dent]

Here she is!

http://www.youtube.com/watch?v=xT-XJrT4Mjw

 

[Martinmurphy30]

Looks great Ronnie! Wouldn't be the same with the lights on constant!

 

[Ronnie Dent]

It's been a while! But just got round 2 this other controller it's not in such goood condition but I should have all the parts to restore it.

I made a start it looks much better than it did! Some ropey resistors changed it was a task figuring out what they were!

I must have removed the smoothing cap years ago and have forgot it’s value🤬