The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

Hello forum members.
I have a galaxy98vhp which was working fine untill now.
Now my problem is i can send it back for repair or try and get some advice to fix it.Now you will probably think why just no send it back....well it was a international buy and freight will be high.

So anyway this is the problem,the radio recieves like normal but the transmit has lost all its power,and will only draw 5-8 amps from my power supply.
So it does tx fine just at only 20 watts average on AM and SSB.

I know this doesnt tell you much but it might give me a idea what to do,or it could be something easy to fix.

Hmm, sounds like the amp board (with the 8 mosfets) isn't keying up when you TX on the radio.... maybe a relay is bad (not switching or stuck) or the switching circuit isn't functioning. Just my take on it.

Perhaps a tech could help you out in this matter, but that's what it sounds like to me.

Regards,
Rick (Triple 7)

Disconnect the radio from DC power and remove the bottom cover.

Once you have the bottom cover separated, remove the amp cover.

Using an ohm-meter, test the mosfet leads for shorts.

Most likely you'll fine one bank of 4 blown and other 4 good.

Unsolder the feedback pcb from on top of the bad bank of mosfets

Unsolder all 4 mosfets and check the white ceramic plates for cracks.

Replace any cracked ceramic plates and all 4 mosfets.

You will also need to replace the output toroid T6 and resistor R28 shown here, http://www.cbtricks.com/radios/galaxy/d ... layout.gif

The output toroid and resistor can be replaced with any combo small toroid from a Texas Star.

You can buy the mosfets and the small Texas Star toroid from RFParts.com

dave.c wrote:Hello forum members.
I have a galaxy98vhp which was working fine untill now.
Now my problem is i can send it back for repair or try and get some advice to fix it.Now you will probably think why just no send it back....well it was a international buy and freight will be high.

So anyway this is the problem,the radio recieves like normal but the transmit has lost all its power,and will only draw 5-8 amps from my power supply.
So it does tx fine just at only 20 watts average on AM and SSB.

I know this doesnt tell you much but it might give me a idea what to do,or it could be something easy to fix.

I was reading your post again and thinking it's possible that like Exit_Thirteen said, the relay may not be activating. Check the 2-pin connector on the amp board labeled J5 shown here, http://www.cbtricks.com/radios/galaxy/d ... layout.gif

Make sure it's plugged in and has 8 volts on the TX pin when you key the radio.

Thanks,for the help.There is 8volts at J5 so i looked at the mofsets and on the left bank there are 2 that are shorted out and T6 and r28 are burnt out as well.
Is there anything else i should check before i order these parts?

dave.c wrote:Thanks,for the help.There is 8volts at J5 so i looked at the mofsets and on the left bank there are 2 that are shorted out and T6 and r28 are burnt out as well.
Is there anything else i should check before i order these parts?

Before you order parts, remove all four mosfets on the bad bank and physically lift out the ceramic plates to see if any are cracked. If so you will need to order thee as well.

Be careful not to over heat the traces on the amp board. Doing so will require buying and replacing the amp board at the factory. It is not available to buy just yet.