Protection Diode

[Irv Finkleman VE6BP]

I am restoring a Kenwood TS-930S. It took what appears to have
been a near lighning strike. The mains fuse and a regulator were
blown. At the coax input to the unit there was a blown diode -- a Diac
I believe. It appears to be a protection diode and is connected
between the coax input and ground. The Diac was shorted and the
result was very low receiver sensitivity. After removing
it, the receiver worked fine. On the schematic it is listed as D67 and
the listing shows it (somewhat blurred) as D5A-44??. Between the
parts list and the schematic I am unable to
tell just what it is. Does anyone know of a good protection
diode that I can use as a substitute?

The unit is now working fine and cleaned up beautifully I just
want to replace the darned Diac to complete the restoration.

Thanks in advance for any assistance.

Irv VE6BP

[highlandham]

On 23/05/15 09:42, Jeff wrote:

> Have a look for back to back transorbs from companies like Vishay and
> Semitron, particularly the one designed for EMP suppression.
>
> Jeff
====================
Suggest you also have a look at a range of Schottky diodes
Assume your receiver would not have to accept a signal over S9 +60 dB
which is -13dBm or 50 mV (over 50 0hms)

Frank , GM0CSZ / KN6WH in IO87AT

[John S]

Here is a link to the service manual if you don't have one. Courtesy of
N6WK.

<http://www.n6wk.com/kenwood/TS930_service-Updated-Correct%20Bias%20info.pdf>

[Irv Finkleman VE6BP]

Thanks John -- had it already but appreciate your assist.
I have all the N6WK stuff and it's really handy.

Irv

[Irv Finkleman VE6BP]

Thanks to those who replied and tried to help.
I am not all that knowledgeable in this area, and was sort of
hoping someone might have been able to provide me with a
diode number, or an equivalent such as NTE-xxx.
I did look up Tranzorb and Transient Voltage Suppressors,
and did a little reading on EMP Suppression and Schottky
Diodes, but it becomes mindboggling to my aged mind and
limited technical knowledge what to go for. The TS-920S
manual was just as blurred in the diagram where I earlier
tried to get the part number.

The rig will run without the device, but this will be the
first time I have restored something, or nearly restored,
and the psychological effect of knowing that I did not
find the required part will be on my conscience every time
I fire it up my 'incomplete' restoration! :-)

My search will continue! My next move will be to contact N6WK
if he's still around and see what I can find out.

Irv VE6BP

[Irv Finkleman VE6BP]

I should have checked first -- QRZ.COM has him listed
as a Silent Key. I've got to give him credit though --
he left a good legacy of material on the TS-930 which
I found invaluable. Thanks Wallace! I trust you are
having a good time in Ham Heaven.

Irv VE6BP

[nm...@wt.net]

I had a friend that had one of those back in the 80's when it was
still fairly fresh.. Dang good radios when they are working right.
Never had one myself.. Only Kenwood I have right now is a TS-830S
and VFO-230 I've had for many years. It's got a good receiver with the
CW filter and VBT, which I think the TS-930 also had if I remember right.

I've had and overhauled a few TS-520's, but ditched the last of those
when I got the TS-830, it being the high end of the old hybrid Kenwoods.

The VFO-230 is S/S with five memories. Doesn't drift at all, like the
VFO in the radio can with temp changes. Made the 830 feel like a 930 as
far as stability.

[Jerry Stuckle]

Irv,

This may be a stupid question, but did you try checking with Kenwood?
Their service center might be able to help you.


--
==================
Remove the "x" from my email address
Jerry, AI0K
jstu...@attglobal.net
==================

[Irv Finkleman VE6BP]

I've restored a couple of TS520s in the past, and have a
TS-820 which I plan to restore (The previous owner diddled
the alignment to death, otherwise it's in pretty clean condition),
but I'll give it to some young ham who is just getting started.
It's a nice rig -- I ran one for a few years way back when. I
never had a TS-830 but always admired them, and almost bought
one at a flea market this spring. I also had the VFO and the
Antenna tuner for the 820. I've always liked the Kenwood
equipment -- it was well built and very serviceable although
one of the TS-520s frustrated me for a long time till I finally
got it running. The TS-930 is is a beautiful rig with all the
bells and whistles built in. I also have the SM-220 monitor
scope. Ah for the good old rigs -- most of today stuff is tough to
service although I have an FT-817ND and
a FT-857D which were easy to fix -- both just had burned
traces on the boards, but I find them unwieldly to operate with
all the menus and such.
I'll save the 857 because I want to try running it
under computer control which may take a lot of the headaches
of settings away from the knobs and put them on a
PC screen control instead. Time will tell.
So many projects, and so little time!!!

Irv VE6BP

[Irv Finkleman VE6BP]

Thanks Jerry - I already did but have not yet received a reply.
It's been about two weeks already! Maybe I'll resubmit as I have a
confirmation number from them.

Irv VE6BP

[John S]

Have you looked up the diode in the service manual? Does it have a
designator on the schematic or board?

[John S]

Disregard. I just looked back and saw that you already posted it as D67.
Sorry. I'll continue searching.

[John S]

On 5/23/2015 11:23 AM, Irv Finkleman VE6BP wrote:

Irv-

The service manual says D67 is an LT8001P. I have found neither a source
nor a readable data sheet for such a device.

Actually, the service manual says that D56,67,120,222,225,245 are all
LT8001P. Does that square with what you see?

John (N1JLS)

[Irv Finkleman VE6BP]

John S wrote:

>
> The service manual says D67 is an LT8001P. I have found neither a
> source nor a readable data sheet for such a device.
>
> Actually, the service manual says that D56,67,120,222,225,245 are all
> LT8001P. Does that square with what you see?
>
> John (N1JLS)

I haven't found any connection through LT8001P. The Kenwood manuals
are often sadly lacking when it comes to parts designations and
part numbers!

Next time I get to the parts wholesalers, I have a small shopping
list and when its long enough I make a trip, I'll see if they have
any cross reference. Thanks!

Irv VE6BP

[FBMBoomer]

Irv,

I too restore radios in general. Mostly antique AM radios and short
wave radios. I have also restored several transceivers. I would not
really worry about the problem you have. I would however put in some
back to back fast diodes. After doing that I would not need to worry
about using the rig. I would consider that problem "fixed".

I too know what you mean about fussing over something not being quite
right. I restore radios for customers. I will not do it unless I am
allowed to do a good job. That means I will not work on say a 1948
Philco and just repair it. I will also replace at least the electrolytic
capacitors so that it keep running a while. All my customers agree with
me on this. You just need to explain it to them.

BTW, I am retired and do not do this for a profit. I just love doing it.
I only try to cover my advertising costs.

I am pretty good at diagnosing an electronic problem. Perfected that
skill at Raytheon in the 70s. I am finally getting better at restringing
dial cords. A necessary skill for this work. You need to use actual dial
string cord to do this properly.

[Irv Finkleman VE6BP]

FBMBoomer wrote:

>
> I am pretty good at diagnosing an electronic problem. Perfected that
> skill at Raytheon in the 70s. I am finally getting better at
> restringing dial cords. A necessary skill for this work. You need to
> use actual dial string cord to do this properly.

Ah yes -- The dial cords! I got my training in the Navy, and after I
got out I did 13 years as a Journeyman tech with Sony. It didn't much
matter if you could diagnose and fix, but if you couldn't string a
dial cord you weren't as top notch as you'd like to be. From the
time I was about 11 years old I used to haunt all the radio stores
for trade-ins -- I took them apart down to the last component, even
unrolling paper capacitors just to see what was inside. I began
building and fixing when I was about 14 -- mostly tube replacements
(I had a great collection of old tubes from the junk stuff), and
then onto crystal sets and eventually ham radio. Then I moved to
surpluc conversion, and on to restoring rigs. It's been a lifetime
of fun for me. It was a revelation once I learned that you adjusted
the coil slug on the low end, and the trimmer cap on the high end. And
even now, once in a while, I can string a dial
cord on the first try. True -- the secret was getting hold of the
proper cord. Fun. Fun, Fun.

Irv VE6BP

[Irv Finkleman VE6BP]

FBMBoomer wrote:

>
> I am pretty good at diagnosing an electronic problem. Perfected that
> skill at Raytheon in the 70s. I am finally getting better at
> restringing dial cords. A necessary skill for this work. You need to
> use actual dial string cord to do this properly.

Ah yes -- The dial cords! I got my training in the Navy, and after I
got out I did 13 years as a Journeyman tech with Sony. It didn't much
matter if you could diagnose and fix, but if you couldn't string a
dial cord you weren't as top notch as you'd like to be. From the
time I was about 11 years old I used to haunt all the radio stores

for trade-ins they didn't want to bother fixing -- I took them apart
down to the last component, evenunrolling paper capacitors just to see

what was inside. I began building and fixing when I was about 14 --
mostly tube replacements (I had a great collection of old tubes from
the junk stuff), and then onto crystal sets and eventually ham radio.

Then I moved to surplus conversion, and on to restoring rigs. It's

been a lifetime of fun for me. It was a revelation once I learned
that you adjusted the coil slug on the low end, and the trimmer cap on
the high end. And even now, once in a while, I can string a dial cord
on the first try. True -- the secret was getting hold of the proper

cord, and then tying the right knots. Fun. Fun, Fun.

Irv VE6BP

[FBMBoomer]

Irv,
We share such a similar background. My first novice rig was a Knight Kit
Space Spanner for a regenerative receiver and spark gap transmitter
tuned approximately for 40 meters. It was what I could afford after
mowing lawns when I was 11.

I bought an aircraft surplus set when I got my general license and
converted it to 75 meters. I made a high voltage power supply with a
pair of mercury vapour rectifiers. Those were the old days. I loved them.

I quit doing repair work in 1980 because I saw the handwriting on the
wall. People were just going to replace radios rather then get them
repaired. I studied electrical engineering and went to work as a design
engineer. That was never as satisfying or as fun as working on radars,
radios, and sonar. Going out on ships and subs was such fun.

But I had a family and needed to make better money. Life can be like
that. You can't always get what you want, but if your try......."Stones"

[Irv Finkleman VE6BP]

Irv Finkleman VE6BP wrote:
> I am restoring a Kenwood TS-930S.
>

> Irv VE6BP

Now it's Murphy's Law. I got everything put together nicely and
tested the unit -- all fine....

...and then, MURPHY STRIKES AGAIN!...

The motor on the PA Cooling heat sink failed -- and it's no longer
available. I've replaced it with a small brushless motor/fan combo,
and it all fit nicely and runs fine. So much for full restoration!
I guess that with some of the parts no longer avaiable, a total
restoration is out of the question. In any event, I now have a
great rig fully operational -- till something else goes (hopefully
not for a long time).

Irv VE6BP

[George Cornelius]

In article <Qp%dx.98503$Dd3....@fx23.iad>, Irv Finkleman VE6BP <fin...@shaw.ca> writes:
> Irv Finkleman VE6BP wrote:
>> I am restoring a Kenwood TS-930S.
>>
>> Irv VE6BP
>
> Now it's Murphy's Law. I got everything put together nicely and
> tested the unit -- all fine....
>
> ...and then, MURPHY STRIKES AGAIN!...
>
> The motor on the PA Cooling heat sink failed -- and it's no longer
> available.

Find somebody who can rewind it.

Brushes can be repaired too.

Bearings - well, depends.

Or, if you're lucky, someone will have a nonfunctional unit on
eBay you can get for a song. Or, if you can fix it, put the non-
original part in whichever one you don't want to keep and sell it
on eBay.

> I've replaced it with a small brushless motor/fan combo,
> and it all fit nicely and runs fine. So much for full restoration!
> I guess that with some of the parts no longer avaiable, a total
> restoration is out of the question. In any event, I now have a
> great rig fully operational -- till something else goes (hopefully
> not for a long time).

George