Vintage Lighting fixin vintage EDI SCRimmer modules

[goatiemon]

so l got all the problem modules
a dimmer pack and control board
to santa cruz

and after abunch of comparative testing and trial and error

it appears that
mod "a" has a bad coupler
mod"b" has a bad op amp and bad opto couplers
mod "C" has a bad op amp too

(no failed caps, no bad scr's)

so l'm wondering about sourcing replacements
it appears that l cant get the original chips ay where
and recommendations on quality replacements/crosses

and JD thanks so very much for all the help

goat

 

[mrb]

so l got all the problem modules
a dimmer pack and control board
to santa cruz

and after abunch of comparative testing and trial and error

it appears that
mod "a" has a bad coupler
mod"b" has a bad op amp and bad opto couplers
mod "C" has a bad op amp too

(no failed caps, no bad scr's)

so l'm wondering about sourcing replacements
it appears that l cant get the original chips ay where
and recommendations on quality replacements/crosses

and JD thanks so very much for all the help

goat

the op amp crosses to NTE987 which is a LM324 that you should be able to get anywhere.

the optocoupler is a H11C6 which is discontinued / obsolete. I believe I have a tube of them, i have to check. There is also a guy selling them on ebay for a couple bucks. It crosses to NTE3046 so thats an option too.

if you go to the trouble of replacing the chips, i would install IC sockets.

 

[goatiemon]

ic sockets have been installed
made the trouble shooting so much easier
(l had only one known good set of chips)

mrb if you have some of those h11c6 chips l'd be interested
in having some as spares
(l'm running one of the nte chips right now though and it seems fine)

l spoke too soon about the scrs though

l have one module with at least one bad scr on channel 2
any advice on trouble shooting scrs?

the channel in question is on @ 50% no matter what
though with control it will adjust up to 100%

still on with the transistor removed (as JD recommended as a first trouble shooting step) so either optocoupler or scr...

witha known good optocoupler swapped in still same problem

so l'm prety sure it is an scr, and it seems to me the one of them still works

l found a source for them in florida
but l'd rather not buy 2 if l only need one

but l cant figure out how to test them

(in attempting to late last night l seem to have burned up the thermostat on the heat sink cuz it thinks the module is over heating all the time -- so l need to find a source for one of those as well)

so, how does one test the scrs?
(any one know a better source)

thanks again
goat

 

[JD]

SCR should read open from the large terminal to the stud in both directions. Small terminal (gate) should read like a diode. SCR's usually blow shorted leaving the dimmer on 100%, but they can blow in a way that they end up working like a diode, thus the 50% Still, unusual to go that way.

Thermostat on these (from memory) is "normally open" which is not as common as the "normally closed" ones, so be careful when buying. Double check that by reading a good one on another module. Remember, there are two of them and a cheap little switch, all wired in parallel, so make sure it is not the "test" push switch.

Should have the temperature stamped on it somewhere, they are available from Mouser. ( Mouser Electronics - Electronic Component Distributor )


On the H11C6 - If you can get them anywhere, great. If not, I have used the MOC3010 photo triac instead. It is not a direct replacement. Pin 1,2, and 3 are fine, but the output is between pins 4 and 6, not 4 and 5, as it is a triac and not an scr, polarity does not matter. There is no need for the gate support circuit that is attached to pin 6 on the H11C6. This simpler circuit on the 3010 is I think why the H11C6 was discontinued.

HC11C6:
http://www.datasheetcatalog.org/datasheet/vishay/83610.pdf

MOC3010:
MOC3010M Fairchild Semiconductor Triac & SCR Output Optocouplers

 

[goatiemon]

muchas gracias

l'm confused though (away from the modules/scrs too)

seemed to me that the scrs only had 2 terminals
(that is 2 spots wires attached)
(l dont know what the "stud" is l guess)

good to know about the 3010
too

goat

 

[n1ist]

The stud is the threaded part that passes through the heatsink.
/mike