Unknown Zener Diode

[sachabinky]

While re-capping my Pearce Simpson Super Tomcat, i noticed something resembling a 1n914/1N4148 looking type of Diode soldered to the back of the board by someone during a past repair, due to either a lifted track or just being too crowded to get the old broken one out of it's holes.
It had the same type of orange glass body, but twice as fat.
It was located in the area of the LC7131 PLL chip , across pins 18 and 20, according to the circuit traces, and near a 2SD1192 Darlington transistor
When i removed it, i could see the markings " X084 " or maybe "X094" on it.
The symbol on the board was that of a Zener diode, but i can't seem to identify what these numbers mean, except guessing that it might be an 8.4V or 9.4V zener,- however i see no listing for these values anywhere.
I don't have access to the schematic for this Radio, so can't determine what it is.
It's listed as D37 on the back of the board.
Does anyone have any idea what this means?
Hoping you can help.
Brian.

 

[sonoma]

see if this will have it.

http://www.cbtricks.com/radios/pearce_simpson/tomcat_23/graphics/pearce_simpson_tomcat_23_om_sch.jpg

 

[Yeti Communications Ltd]

super tomcat hes talking about i believe is the 40ch ssb version not the older am 23ch crystal synth radio

 

[sachabinky]

Thanks,- no luck there, but i found out that these names have the PLL in them.
LC7131 - Team, Kaiser, USW, and Courier Galaxy apparently.
Wondering if any use the same board?

 

[sonoma]

I looked around and never did find one for this radio.

 

[Yeti Communications Ltd]

try on the australian facebook cb groups..it was a popular radio over there ...i have worked on alot of them but generally i dont need diagrams to work on most of this stuff ..post a pic i am sure you are talking about the zener that supplys the pll but need to make sure(get it work and it will kill the pll )..if its that then it will be what ever the 7131 runs on

a pic of the radio front will help as there was 4 models of the ssb tomcat also

if it has a board number that will greatly help too

 

[sachabinky]

Thanks, here are a few pics
Serial number on the back is 00595
Sorry- i don't know why the pic of the front turned sideways.

 

[sachabinky]

Another thing i wanted to mention;;
This unit was working well in the first place, except ,the audio had a slight hum and i saw a leaking electrolytic cap, which led me to changing them.
Afterwards, when i started it up, the AM audio sounded really faint, instead of loud and vise versa for the sideband (louder than AM anyway).
It was as though it had bad receive.
Also, i was receiving on multiple channels, like i had killed the selectivity,..-I checked the board and found i had shorted a track under the solder lug of a tin plate shied on the back of the board, opposite side to the crystal filter- so fixed that, and , the wide-banding problem was gone, but the other issue remained.
It was then that i noticed the diode, which had gotten quite hot when i put a new capacitor in alongside and removed it to test on the multi-meter, getting open circuit readings either way.

 

[sachabinky]

OK- an update,- in which i am hoping someone here can help steer us in the right direction.
I sent the unit to a technician i found and this is what he said/did.

QUOTE:

"I noticed and fixed:
- Damaged PCB track directly under the VCO, where a hole has been made, this just fell off when I touched it
- Damaged track elsewhere was raised and cracked, jumpered this out
- Replaced the 5V Zener near the PLL that was open circuit, putting 9V on the PLL

After all this still did not TX at all and hardly RX at all ... did some more fault finding ....

- Found the crystal filter is not working, this is the device under the metal shield in the middle, very unusual for this to require replacing
and you cannot get the style used in this radio any more ... I tried replacing it with another type ... now transmits and receives but it
looks like there are still other issues as when it receives at normal levels you cannot understand any of the ssb audio anymore ...
I tested the filter itself yesterday, by comparing to a similar unit and it is definitely not working. I replaced it with another and the set starts to receive, but not properly because of the different characteristics of the filter that I am using. I scraped away the sealant at the bottom, to see if it was a simple problem, but the problem must be internal.

I have looked for this filter and cannot find any reference to it anywhere, so it seems not to be common, it is not the one normally used in
radios of this era. The best option would be to find someone that has one of these radios as a “parts” radio and take the filter from that.
The filter part number is MF10JC Type 2G"
I am hoping someone here has a lead on a parts Radio,- or that exact type of filter - by any chance?
Brian.

 

[sachabinky]

While looking for a parts Radio - A much nicer example of this model was found,- Which is running nicely in front of me right now;- So thanks for all your input everyone.
Thread can now be closed...