Hi:
In preparing some Christmas lights I found a dead string. The light set
contains a selectable flash sequencer to allow 6 different flashing
patterns. The flash sequencer contains an IC that is stamped: RH 606,
thats it. Any pointers on a replacement?

Also, it contains 4 transistors that drive each of the colored strings
within the entire string. The transistors are marked: HFH 1225.
Several google and IC specific sites yielded no useful information.
Any help in finding replacements is appreciated.

I can probably use any generic switching transistor once I determine if
they are PNP or NPN. (just havent had time to check the existing
transistors, although I know that one is dead)

Thanks
John

"John Hudak" wrote in message
...
Hi:
In preparing some Christmas lights I found a dead string. The light set
contains a selectable flash sequencer to allow 6 different flashing
patterns. The flash sequencer contains an IC that is stamped: RH 606,
thats it. Any pointers on a replacement?

Also, it contains 4 transistors that drive each of the colored strings
within the entire string. The transistors are marked: HFH 1225. Several
google and IC specific sites yielded no useful information.
Any help in finding replacements is appreciated.

I can probably use any generic switching transistor once I determine if
they are PNP or NPN. (just havent had time to check the existing
transistors, although I know that one is dead)


Are these the usual tree-type incandescent light sets? If so, they're likely
to be small triacs or thyristors, not transistors, so a transistor type test
is no good. Are they in TO-92 cases by any chance? Every multi-sequence
Christmas light set I've seen uses a dedicated IC for the flash sequencer,
(probably not possible to get a replacement except from manufacturer) which
turns 4 triacs/thyristors on or off to switch the AC to the lights.

All you need to do is measure the current each light group uses, and select
a triac/thyristor with a suitable current handling, allowing a comfortable
safety margin. Some lights are directly mains voltage so you'll need to
select a suitable replacement with that in mind. (ie for 220V use a 400V or
better, for 120V use a 200V or better).Others use something like a 24V AC
transformer, and just about any triac will handle that, you just need to
worry about the current handling.

Another thing to consider is the gate sensitivity. If the IC drives them
directly without a buffer it's likely they are the 'sensitive gate' variety.
If you use a non-sensitive gate variety it won't work and could damage the
IC.

Dave

see below...

Dave D wrote:
"John Hudak" wrote in message
...

Hi:
In preparing some Christmas lights I found a dead string. The light set
contains a selectable flash sequencer to allow 6 different flashing
patterns. The flash sequencer contains an IC that is stamped: RH 606,
thats it. Any pointers on a replacement?

Also, it contains 4 transistors that drive each of the colored strings
within the entire string. The transistors are marked: HFH 1225. Several
google and IC specific sites yielded no useful information.
Any help in finding replacements is appreciated.

I can probably use any generic switching transistor once I determine if
they are PNP or NPN. (just havent had time to check the existing
transistors, although I know that one is dead)



Are these the usual tree-type incandescent light sets? If so, they're likely
yes

to be small triacs or thyristors, not transistors, so a transistor type test
Yes, your right...I should have known better...
is no good. Are they in TO-92 cases by any chance? Every multi-sequence
yes to-92

Christmas light set I've seen uses a dedicated IC for the flash sequencer,
(probably not possible to get a replacement except from manufacturer) which
turns 4 triacs/thyristors on or off to switch the AC to the lights.
I figured as much...the lightset was in a GE box, but, it was made by
GOKW in China...I *really* wish we would not off-shore all this
stuff....but that is another rant...

All you need to do is measure the current each light group uses, and select
a triac/thyristor with a suitable current handling, allowing a comfortable
safety margin. Some lights are directly mains voltage so you'll need to
select a suitable replacement with that in mind. (ie for 220V use a 400V or
better, for 120V use a 200V or better).Others use something like a 24V AC
transformer, and just about any triac will handle that, you just need to
worry about the current handling.

Yes, that is direct enough to do...I would like to scope the thing but
first I better draw a ckt dwg. The input side is a diode bridge
directly across 120 VAC, one filter cap and then dropping resistors to
the IC..as cheap and dirty as it can get.....and not even a
fuse....since I realized this, I may just pitch them...too
dangerous..I've seen too many semiconductors become wires, then fuses...

Another thing to consider is the gate sensitivity. If the IC drives them
directly without a buffer it's likely they are the 'sensitive gate' variety.
Yes the IC drives it directly.....I agree with you...Thanks for waking
me up.....
If you use a non-sensitive gate variety it won't work and could damage the
IC.

Dave