10 Sep
2014
10 Sep
'14
1:21 a.m.
On Fri, 5 Sep 2014, drlegendre . wrote:
Check your filter caps anyway, even the small ones. The one I have is
newer than yours, so if it is an age factor, the caps in yours may have
issues as well. It could also be that the trainer I have here has a lot
more hours on it. They certainly didn't use high quality caps in the one I
have. The replacements I obtained will probably outlast the trainer
itself.
On Thu, Sep 4, 2014 at 8:42 PM, Tothwolf <tothwolf
at concentric.net> wrote:
I don't know about the model you have, but it was possible to buy fully
assembled units for the later models (at a much higher cost of course).
I don't know which model you have, but that
trainer was made by RSR
Electronics. Do you have any photos of the boards inside the trainer?
Ah.. RSR Electronics. Excellent, now at least I have a manufacturer's
name to work with.
I have a similar but slightly newer RSR
Electronics trainer in my
active repair pile right now. As you suspected, these were commonly
sold as kits and were often poorly assembled. The one I have will need
to be completely resoldered, and all the toggle switches will be
replaced (the assembler melted them when soldering and several don't
work at all).
It sounds like my kit was in slightly more capable hands than yours. In
fact, it looks as if some of the boards may have been factory built..
though there were several bad joints here & there. I did have to replace
several switches, two in the 'logic' array and one of the pulsers. The
unit didn't see a lot of use, so as in your case, it was most likely a
matter of damage during assembly. One switch was actually working fine, but had a very
odd feel to it..
there was a secondary 'click' in there, sort of like the feel of a
disconnector resetting inside the trigger group of an autoloading rifle,
when you release the trigger after a shot. Turns out that one side of
the switch body was broke clean off, and it was held (very) loosely in
place with black tape.. and it was a part that actually held one of the
fixed contacts! How in the heck that was continuing to work is a
question above my pay grade, lol.
At least two of the toggle switches in this one felt weird too. They take
a lot of extra force to switch. I'm sure I'd just find displaced contacts
in them if I were to disassemble them. The originals are very cheap import
parts anyway and the replacements I got are of much better quality. I've
also decided to replace the lighted rocker power switch too, but I just
can't decide if I should use a red or green switch (I have both in my
spare parts bins).
It also has
failed/popped filter caps in its DC power supply and a
cooked pc board (melted black goo) where the TO-220 transistor is
mounted to the board that the rotary switches are also soldered to. I
found an inexpensive Aavid TO-220 heatsink that fits the board layout
and silkscreen perfectly that I plan to install. One major gripe I have
with the design is a lack of a Molex connector for the power
transformer which made removing the main board extremely difficult (I
finally snipped the wires off at the board). The board was clearly
designed for a header, but like the TO-220 heatsink, they were being
cheap and left that out of the kit. I've already sourced a
header/connector though and will be fixing that when I redo the rest of
it. If you decide to replace the electrolytics in one of these, be
aware of the lone bipolar/non-polarized cap used in the function
generator circuit. If your boards are the same as those in the trainer
I have here, I have a repair parts list that also includes all of the
electrolytics.
Again, mine hadn't suffered the same ugly fate as yours.. in fact, I
don't even recall if I rebuilt the PSU or not. It may have just
checked-out OK on the scope. Same for the generator / clock section - I
didn't have to mess with it, at least not so far. I'll have to look at
the issue you mention wrt the lack of plug-header on the power
transformer, but they did use cables & header connectors to link the
various boards & modules together, so maybe I got lucky in that
department. When I find the time, I'll take some photos of the
innards and post them
to my shell. Don't suppose you've come across any schematics or other
docs for these RSR devices? Any sense if they were supplied - as I'd
guessed - as part of a tech school or correspondence course?
I have the assembly manuals and schematics for the model I have, but it
looks like it is very different from yours. They did include assembly
manuals and schematics with these trainers. Maybe RSR Electronics can
supply you with a copy of the assembly manuals for the model you have? At
the very least, hopefully they can tell you which model that is. These
trainers seem to be specified in some college electronics courses, but I
assume a student would have to purchase it themselves.