SSA400 Driver module 2 problem

HA3KGX

Well-Known Member
Hi!

I have an SSA400 amplifier that I turned on yesterday. The drive is a TD90, perfect for communication with the amplifier.
I put a 50ohm dummy load on the amplifier, a TD90 got a A1 press CW and checked the instrument at the front of the amplifier.

On the UD1, the trimmers that controlled the drive were unwound, I started to rewind nicely during transmission.
The problem is:
Each module brings its described values, except for UD2, perhaps moving two divisions on the scale.
The output power according to the instrument is only 25--30 on the 100 scale.
The amplifier is intact, not mounted, could not use much, where do I look for the fault?

Voltages are fine
 

SM0AOM

Well-Known Member
Check fuse F2 underside the PA unit for continuity.

If you have low drive from UD2, check the bias circuit Y3,Y4 and Y5 for the BLX15s, so there is
standing current through both transistors which is present when the TD90 is keyed (=pin 6 of P1 is at ground potential).

There is one emitter ballasting resistor each about one ohm in total, for the BLX15.

1652442705971.png
 

HA3KGX

Well-Known Member
Hi! I measured all the parts on the PCB and found no faults. I will try to deduce the P1 6 point as shown in the drawing and measure what you wrote during operation.20220513_152621.jpg
 

HA3KGX

Well-Known Member
Check fuse F2 underside the PA unit for continuity.

If you have low drive from UD2, check the bias circuit Y3,Y4 and Y5 for the BLX15s, so there is
standing current through both transistors which is present when the TD90 is keyed (=pin 6 of P1 is at ground potential).

There is one emitter ballasting resistor each about one ohm in total, for the BLX15.

View attachment 7989
Point 4 of the drawing, which is connected to R11, I soldered a wire to it. I measured voltage, 45 was there constantly this normal?
 

SM0AOM

Well-Known Member
A constant +45V points in the direction that you do not have any keying
signal from the TD90. Keying of UD2 requires close to 0 V.

This signal goes through the Program Unit on the underside of the PA.
Pin 15 on the edge-connector goes to UD2 and pin 16 to TD90.

1652451437254.png

You must also press the "Tune" button on the TD90 after turn-on or frequency change so the flashing "Tune LED" goes dark. It is not possible to transmit if the LED is flashing.
 

HA3KGX

Well-Known Member
I did the following, a cable is soldered to point 4 above, I connected it to the ground through a potentiometer during operation. See the miracle the two modules come to life, all values are fine, the output power according to the instrument is 80. The lamp in the room flashes as I press the CW :) Do you suspect the program unit? Point 15 Y15 transistor? Or contact error
A constant +45V points in the direction that you do not have any keying
signal from the TD90. Keying of UD2 requires close to 0 V.

This signal goes through the Program Unit on the underside of the PA.
Pin 15 on the edge-connector goes to UD2 and pin 16 to TD90.

View attachment 7991

You must also press the "Tune" button on the TD90 after turn-on or frequency change so the flashing "Tune LED" goes dark. It is not possible to transmit if the LED is flashing.
 

SM0AOM

Well-Known Member
Hard to tell.

There is a sequential logic circuit on the Program Unit which controls the level setting in the TD90. If this circuit does not provide the UD2 keying signal there will be very little output.

You should be aware that each "band" has its own level control on the UD1 module.
Adjustment should be done so the tune sequence does not trip the overcurrent limit.
 

HA3KGX

Well-Known Member
Hard to tell.

There is a sequential logic circuit on the Program Unit which controls the level setting in the TD90. If this circuit does not provide the UD2 keying signal there will be very little output.

You should be aware that each "band" has its own level control on the UD1 module.
Adjustment should be done so the tune sequence does not trip the overcurrent limit.
The motherboard of this program is B10812 3650, I found an old patch on it. Isn't this a drawing of chance?
 

SM0AOM

Well-Known Member
I have the schematic for the previous version of Program Board B10812 3640, which is similar but not identical.

Check that the active low keying signal from the TD90 actually reaches the Program Board.
There may also be some problem at the interface for the optional antenna tuner.
 

HA3KGX

Well-Known Member
I have the schematic for the previous version of Program Board B10812 3640, which is similar but not identical.

Check that the active low keying signal from the TD90 actually reaches the Program Board.
There may also be some problem at the interface for the optional antenna tuner.
I found an old repair to the very transistor that the pin leads to, unfortunately good by measurement. In the drawing, which pin is where the signal comes from if there is a TX?
 

HA3KGX

Well-Known Member
Hi!

I took out the TD90 book, do I understand that the driver also gives a transmit signal to the amplifier? The RF LED on the connection cable on the front panel also flashes, showing the output power level. Is it possible that the connecting cable is damaged?


c1.jpgc2.jpg
 

HA3KGX

Well-Known Member
I have the schematic for the previous version of Program Board B10812 3640, which is similar but not identical.

Check that the active low keying signal from the TD90 actually reaches the Program Board.
There may also be some problem at the interface for the optional antenna tuner.
Hi!

Today I disassembled the unit I wrote in the picture is correct, at point 24 it was +4.4 if I press CW it drops to 0v. I measured the entire connecting cable all the way through, everything is faultless.
But I don't have a tuner, did I hear you have to tie something up like that?
I noticed the input of the program module where the transmit signal is coming out, it is routed to the antenna tuner connector, and the incoming CW signal is also routed there.
I bridged with a wire, the amplifier goes, but the UD2 keeps going and heats up quite a bit.

I measure +14.4 volts at the input of the program unit, +4.4 volts comes from the TD90, which drops to 0v when switching. Should the module only go on TX?
 

SM0AOM

Well-Known Member
If you enable UD2 at all times it runs quite hot, as it operates in Class A, but it will not be damaged as long as the fans are working OK.

The RF out indication is a transistor closure which is derived from the SWR detector module.

Proper operation of the Program board is when the TD90 Tune LED immediately starts flashing after turn-on or frequency change. It should then stop flashing after pressing the Tune button and the PA should be briefly keyed and then return to the unkeyed state after either the TD90 output level has reached maximum or the RF power has reached 400 W.

There are several conditions that may prevent the Tune sequence to start or be completed.
 

HA3KGX

Well-Known Member
Thanks! If I have to disassemble it again for exercise .... :) It's huge, it's not easy to assemble on its own, it would be good if it works fine because the UD2 is warming up enough. I have noticed that the input of the prorgam module is routed to the tuner connector, if I pull it to the ground the UD2 module will start.

Td90 works as described, it is exactly what you write
 

SM0AOM

Well-Known Member
You should check if the bridging between pin 1 and 8 on the P 59 (antenna tuner) connector in the back of the SSA400 is present. Some editions of the SSA400 require this connection.

1652603877781.png
 

HA3KGX

Well-Known Member
You should check if the bridging between pin 1 and 8 on the P 59 (antenna tuner) connector in the back of the SSA400 is present. Some editions of the SSA400 require this connection.

View attachment 7994
Hi, the problem with me is the foot layout is different, it's marked with letters, not numbers. Here is a picture of my motherboard, you can switch whether this tuner is present or not. And some delay, regardless, can be connected to the tuner connector ....


20220514_113109.jpg
Tuner connector:

20220514_111905.jpg
 

HA3KGX

Well-Known Member
You should check if the bridging between pin 1 and 8 on the P 59 (antenna tuner) connector in the back of the SSA400 is present. Some editions of the SSA400 require this connection.

View attachment 7994
Unfortunately, my B10812 3110 motherboard doesn't match either, according to the drawing, the sign comes at point 43, there is nothing connected to me in the picture.

20220515_124023.jpg
 

HA3KGX

Well-Known Member
Hi!

I measured all the points, and by the end it turned out that the connector was numbered inside ....... :oops:
I connected the two points you suggested, but unfortunately nothing has changed, I'm starting to give up .... I could use it so that UD2 keeps going, but it's not intended to be used ...
I don't know what to do, I really like the amplifier, but it's very rare with us, I can't even ask for advice.
 

HA3KGX

Well-Known Member
Hi!

I made a drawing so it's simpler, unfortunately the compiler is quite interesting. I just want to ask, do I understand the drawing well?

Thanks!


SIGNAL.jpg
 
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