5 Sep
2014
5 Sep
'14
8:17 a.m.
On Thu, Sep 4, 2014 at 8:42 PM, Tothwolf <tothwolf at concentric.net> wrote:
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 slight 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.
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?