R
Robert Baer
Guest
tm wrote:
Yes, it is possible that there may be one or two degraded
'lytics..even the old wet electrolytics lasted 20 years at best and even
then many could be recovered by adding electrolyte.
On old tube equipment, powering them up with a variac at zero and s l
o w l y raising the line voltage to full will allow most of degraded
'lytics to re-form and perform adequately at worst.
be found."Robert Baer" <robertbaer@localnet.com> wrote in message
news:n4lNs.128399$Id.39557@newsfe24.iad...
tm wrote:
"rickman" <gnuarm@gmail.com> wrote in message
news:ke1n0i$97l$1@dont-email.me...
I bought this thing some 10 years ago used and it has worked ok,
mainly as an audio generator. I fired it up the other day and the
upper ranges seem to output a funky sine wave now. The 10 kHz and 100
kHz ranges output a distorted waveform that does a direction reversal
a little bit after going negative of the midpoint. It almost looks
like a rectified sine wave, but the waveform is more than half a
cycle. I don't see any issues on the other waveforms.
I can play with the range switch and find that turning it slowly can
have an impact on the point of the waveform where the reversal occurs.
But it doesn't really feel like a switch problem. I would disassemble
the switch to see if there are mechanical issues, but it is one of
those multi-gang wafer switches with components mounted directly on it
and each gang is soldered to the board, a real nightmare to remove.
This thing was made to never break, not to be repaired.
I don't have any info on it. The circuit board has some dozens of
transistors, a couple of what are likely op amps (metal cans) and well
over a hundred passives. I don't know where to begin trying to fix
it... other than connectors and switches are the primary point of
failure. But even removing and reseating boards looks like a bear in
this thing.
Any suggestions on ways to repair this?
I saw the other thread on new units and had looked at some of the
little $8 boards on eBay. Funny that there isn't much in between the
$8 boards and the $400 boxes. I would have thought this is something
that could be done very inexpensively these days. I would use a PC
audio output but my signal is outside the 20 kHz upper limit of audio
outputs.
Maybe I'll add a simple sig-gen to the prototype circuit I'm building.
Lots more than $8 of effort, but I'll know what I'm getting.
Rick
Service manual here:
http://www.home.agilent.com/agilent/techSupport.jspx?searchT=3310b&id=3310B:epsgro&pageMode=OV&pid=3310B:epsg
As always, check the power supplies first.
Then RTFM
NOTE: The OP _only_ complained about the sine output, and mostly at
higher frequencies; definitely not PS oriented; prob is in one of the
DFG chains.
So you would not recommend first checking the power supplies on a 40+
year piece of test equipment before doing any follow-up trouble
shooting? Even when it is a well known fact that electrolytic capacitors
that old are often found degraded.
Oh well, whatever.
I did NOT say that; i mentioned where the problem was most likely to
Yes, it is possible that there may be one or two degraded
'lytics..even the old wet electrolytics lasted 20 years at best and even
then many could be recovered by adding electrolyte.
On old tube equipment, powering them up with a variac at zero and s l
o w l y raising the line voltage to full will allow most of degraded
'lytics to re-form and perform adequately at worst.