Today's Message Index:
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1. 11:03 PM - Re: Unusual Electric Problem (Stressmerchant)
2. 11:11 PM - Re: Re: Yak-List Digest: 1 Msgs - 12/14/25 (Mike Beresford)
Message 1
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| Subject: | Re: Unusual Electric Problem |
Thought I'd give an update.
A big thanks to two members who emailed me with some of their thoughts on potential
causes. My own (rough) understanding lead me to suspect a relay, which both
the emails also included on the list of possible causes. To illustrate the
relay position, the first pic is a snip from the wiring diagram that I have for
the Yak-52. The relay in question is labelled "36" in the sketch.
With the help of the M-14P team I sourced a replacement relay, which was fitted
today. It seems to have cured the problem. Holding thumbs that the problem stays
cured.
For reference, the relay is shown on the attached photo. The relay is located on
the right hand side of the firewall, on the cockpit side of the bulkhead. Access
is via the panel on the right hand side. Access requires removal of a cover
over the fuses and realys. The pic is taken looking forward.
You'll see that the relay (36) is directly next to another one (37). Relay 37 is,
according to my undertsanding, used for switching in external ground power.
I'm told that the relays are identical, and that I could have considered simply
swapping the two as a check. A quick check with a multimeter suggested that
relay 36 was fauly, so I didn't make extra work by doing a swap. But it would
have been an option, particularly because I have used external power once in
the 20 years I have owned the aircraft.
Other things I did check, with no problems noted:
- Master switch - continuity as expected when checking the three different switch
positions
- Battery voltage good.
Hope the info can help others encountering this rare problem. Given the age of
these aircraft, it would be interesting to know is there is a western raly (milspec,
etc) that is a viable replacement.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=516821#516821
Attachments:
http://forums.matronics.com//files/yak_relays_597.jpg
http://forums.matronics.com//files/yak_wiring_357.png
Message 2
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| Subject: | Re: Yak-List Digest: 1 Msgs - 12/14/25 |
Hi Justin
Quick feedback: Iended up replacing the relay (36 in the Yak wiring diagram
), which seems to have cured the problem. Rather a puzzle that it failed in
that way, but hopefully all will be good now.
Thanks for the input.
Happy New YearMike
On Wednesday, 17 December 2025 at 04:27:43 GMT+10, Justin Drafts <draft
sjust417@gmail.com> wrote:
Mike, any luck chasing the Yak's wiring gremlin?Hadn't seen any responses,
so I'll chime in w/ my hillbilly 2-cents worth.
My Nanchang was fraught with electrical issues years ago, and I wisely=C2
-decided to just get down to basics and refurb all the=C2-ground connec
tions=C2-(= Scotchbrite=C2-all terminals, alcohol clean, reinstall w/
a tiny dab of sealing"No-Ox Special-A" terminal paste).=C2- That helps a
lot.
My initial, "Capt.Obvious" thought is you've got a nasty short lurking... d
isconnecting=C2-the battery was the best thing you could have done, as we
ll as staging for troubleshooting.Since everything worked so well on previo
us flight, I'm guessing it's just in 1 spot, sovisually inspecting wire run
s from battery to the cockpit switch box can be a good first chore.Doesn't
take much at all to create a short in a Nanchang...
Pls keep us posted on progress...=C2- =C2-JustinN280NC, Seattle
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=C2- =C2- =C2-1. 01:42 AM - Unusual Electric Problem=C2- (Stressmer
chant)
________________________________=C2- Message 1=C2- ____________________
_________________
Time: 01:42:13 AM PST US
Subject: Yak-List: Unusual Electric Problem
From: "Stressmerchant" <mike_beresford@yahoo.co.uk>
I encountered an unusual electric problem with my Yak-52 today. I haven't y
et been
able to do any real trouble shooting, will only have time later in the week
.
The aircraft has recently been for maintenance. Performed well for post-mai
ntenance
test flight, and no issues on the short ferry flight home.
Took a work colleague flying today. No issues on flight, landed, shut down
normally.
Once I had pushed the aircraft back in the hangar, I went to put the canopy
cover over the aircraft - keeps dust off during the week. I noticed that a
light was on in the rear cockpit - the warning light that the master switch
in
the front cockpit was on. I looked, master switch was off - as were all oth
ers.
I then turned the master switch on and off, to see if that cured the proble
m.
Not only did it fail to cure the problem, no electrics came on at all when
the master switch was in the on poisition - except the rear cockpit light t
hat
remained illuminated. No electrics at all - no fuel tank bars, no gear ligh
ts,
nothing registering on the voltmeter.
I didn't have time to investiage fully, so I just disconnected the battery
and
left it at that. But I am puzzled by this. The aircraft had been flying fin
e,
no issues with anything electric, radios working, etc. But following the sh
utdown,
nothing appears to work - except a single rear cockpit light telling me tha
t
the master switch is on.
Any ideas on where to start looking? I'm thinking that my first port of cal
l wil
be a voltage check on the battery - although they are fairly new, it could
be
that one has died completely.
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