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Syntor X control head jumpers

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Syntor X control head jumpers

Postby HA5BRG » Fri Jun 29, 2018 12:27 am

Hi Guys,

I am trying to revive an old Syntor X radio with using old factory cables and control head. I have bought these stuff on Ebay a few years ago. All of these came from different sources, so I had to reconfigure the pins in the control head cable.

The control head now acts as a basic Systems 90 cable for 8 channels, with no scanning (

The radio itself is a VHF high-band type, Model number is: T74VXJ7D04BK.

The control head housing is HLN4008, inside there are two boards: TRN4344A and a TR4395B. It is a non-scanning, basic 8 channel Systems 90 head.

When I connect all these stuff together, the control head lights up, I am able to change channels, I can control the volume and the squelch. The radio can TX and RX, everything seems fine, except one thing:

On some channels I can hear a loud buzzing from the speaker. The buzzing quits only when I unplug the purple connector (this has the channel selector wires). At this state the radio selects Mode 1 by default. The radio can TX and RX on Mode 1 and there is no buzzing from the speaker.

With the purple connector still unplugged: when I manually short the Mode pins on the J1 connector manually, the radio switches channels and receives/transmits on those without any issue and withput buzzing.

I assume that the TRN4344A board's jumpers are not configurated properly, and this is why the head acts strange.

Unfortunately I didn't find any information regarding the so-called clamshell type or the Systems 90 type heads' jumper settings.

Can comeone point me to the right direction or send the manuals needed?

Thank you in advance.

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Re: Syntor X control head jumpers

Postby WB6NVH » Mon Jul 02, 2018 10:21 am

I presume you found the Syntor X pages on the web which show the cable and colored plug pinouts. And I assume you have that part correct.
Moving on, you need the manual for the 8 mode circuit board, which is 68P81110E87 . But since you are in Budapest that seems unlikely to happen.


The head section you have is called a Systems 90*S. The T74VXJ is not a VHF high band radio, it us a UHF radio (probably 450-470 Mhz). If it is a 470-512 MHz "T-Band" UHF radio then it is more or less useless and there will be tears before bedtime.

The jumper ID's should be printed on the circuit board of the TRN4344 8 mode pushbutton module. It would seem strange that any would need to be changed, but here they are at their normal settings:

JU1,2,3 - Ignore
JU4 - OUT "Encoder input disable"
JU5 - OUT " " "
JU6 - OUT " " "
JU7- OUT " " "
JU8- Pos. A when used with TCN1352A, TCN1350A(16 modes or less)
Pos. B when used with HLN1065A, HLN1066A(32 modes)
JU9- Pos. A when used with TCN1352A, TCN1350A, HLN1065A(16 modes or less)
Pos. B when used with HLN1066A (32 modes)
JU10- Point A "Special customer application"
JU11- Point A " " "
JU12- IN "M8 Data Line buffer input"
Ju13- Point A "Special customer application"
JU14- Ignore
JU15- IN "Switch enable signal"
JU16- IN " " "
JU17- IN " Encoder U3 input enable
JU18- IN "Data lines M4 through M8 buffer input"
JU19- IN "Special customer application"
JU20 -OUT "Special customer application"
JU21, 22 Ignore
Ju23- IN "Module troubleshooting aid."

If your jumpers are correct then you have a wiring error or a faulty pushbutton mode board. I can't remember for sure but there are also a bunch of jumpers all over the personality board inside the Syntor X radio which have to match the cable and head in use. Some radio drawers were for a handheld control head and have an additional "HHCH" board for that purpose which must be removed and a ton of jumpers replaced. But most drawers should have come from either clamshell or Systems 90*S accessory group use and need few if any changes.

Note also that a 150-174 MHz Range Syntor X or X9000 will not function properly on the 144-148 MHz amateur band without tuning the front end of the receiver slightly, at the two resonators closest to the mixer, and do not use the ham version (5.00?) RSS to program a VHF radio. See previous messages on this board about getting a VHF radio to work on 2 Meters. If your model number is correct, you have a UHF radio anyway, but same comment applies.

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Re: Syntor X control head jumpers

Postby HA5BRG » Sat Jul 14, 2018 12:11 pm

Thank you very much for your help and the information. I think I can start troubleshooting with this :)

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