The customer said he smelled something burning a number of times when
trying to power the set on. He says he never saw any smoke. We tried it
when it came in but there was only the sound of a relay energizing and
then dropping out about one second later. I could not locate visually
or (with my nose) where anything seemed to have burned from. I checked
the HOT and the SCR and three diodes nearby it and found them all to be
good. I repaired the troublesome coil also. I can hear the little chirp
from the power supply when you first plug the set in which leads me to
suspect that the SMPS may be good. I have seen flybacks go bad in some
of these but I don't own a ringer so I can't be certain of that. Can
anyone offer a rule out or troubleshooting procedure or perhaps an
opinion based on the symptoms I've described? Thanks for any
assistance. Lenny Stein, Barlen Electronics

Normally when the lopt go in these sets that flak the h-output device also.
Check the case of the lopt to make sure there are not any little pin holes
with "juice" leaking out, indicating an internal failure, since the probable
odor. Have you checked the PCC circuits, thery have become a bit of a
nusiance also.
wrote in message
ups.com...
The customer said he smelled something burning a number of times when
trying to power the set on. He says he never saw any smoke. We tried it
when it came in but there was only the sound of a relay energizing and
then dropping out about one second later. I could not locate visually
or (with my nose) where anything seemed to have burned from. I checked
the HOT and the SCR and three diodes nearby it and found them all to be
good. I repaired the troublesome coil also. I can hear the little chirp
from the power supply when you first plug the set in which leads me to
suspect that the SMPS may be good. I have seen flybacks go bad in some
of these but I don't own a ringer so I can't be certain of that. Can
anyone offer a rule out or troubleshooting procedure or perhaps an
opinion based on the symptoms I've described? Thanks for any
assistance. Lenny Stein, Barlen Electronics

HOT plus IHVT plus plus.


Have fun

kip

wrote in message
ups.com...
The customer said he smelled something burning a number of times when
trying to power the set on. He says he never saw any smoke. We tried it
when it came in but there was only the sound of a relay energizing and
then dropping out about one second later. I could not locate visually
or (with my nose) where anything seemed to have burned from. I checked
the HOT and the SCR and three diodes nearby it and found them all to be
good. I repaired the troublesome coil also. I can hear the little chirp
from the power supply when you first plug the set in which leads me to
suspect that the SMPS may be good. I have seen flybacks go bad in some
of these but I don't own a ringer so I can't be certain of that. Can
anyone offer a rule out or troubleshooting procedure or perhaps an
opinion based on the symptoms I've described? Thanks for any
assistance. Lenny Stein, Barlen Electronics

I scoped the collector of the HOT while attempting power on. It peaked
at only around 600V and looked pretty bad. After replacing the
transformer the set worked fine. I again looked at the collector
waveform. It exceeded my graticule even with he X10 probe but I
estimated it to be around 1200Vpp with good symetry. Isn't it odd
though that the transistor was spared? BTW, just for my own edification
I did some comparison resistance readings (excluding of course the HV
winding), between the new and old transformers while they were both out
of circuit. There were some very minor descrepancies on two of the LV
secondaries in the order of tenths of an ohm but other than that noting
jumped out at me. Does anyone know exactly what fails in these things?
Thanks for all the help and advice. Lenny Stein, Barlen Electronics.