Galaxy DX2517 issues

[liquidh8]

Good morning all. I have a Galaxy DX2517 I picked up a few months ago. It was a tech special. It would power up and work in PA mode, but I got no receive, no TX, no lights nothing in any other mode. I changed the Regulators, RX/TX transistors in the front, checked the finals and driver. The power supply is good. And even after all that, I wasn’t getting the 8vdc out of the regulator, ever after putting in new, and known good parts.
Fast forward to last night. While talked to a friend on the air, I plug it in, turn it on, still nothing in SSB/CW/AM. I turn the mode swith to PA, get lights, turn it back to AM, and I get the freq display, channel display, and I am receiving! So, I turn it to side band, I can kinda hear myself while transmitting in another radio right next to it, but the volume is all the way up and I have to have my ear right next to the speaker. Tried an external speaker and it is the same, low receive audio only in SSB. The S-meter really moves though.
So, I put a mic on it, go to transmit in SSB, I get a dead key, 10w+. USB and LSB. AM it seems to have worked.
To sum it up.
• To get the radio to power on, I have to turn on the power switch, switch to PA, THEN to another mode.
• Receives fine on AM
• Hardly any receive audio on SSB
• Dead key on SSB
I didn’t look any further last night. These were my initial observations. Anyone have any insight or tips?

231 PA

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Wed May 01, 2013 11:12 am

I checked and cleaned the mode switch. Took it of the chassis, took it apart. (these are modular, two little rotary switches riveted together) Took it apart, cleaned it all up, same symptoms. Then it went back to what is was doing before. No 8 vdc feeding anything.

The power supply is working, I am getting the 13.8-14.1 volts, the rx/tx led is lit in PA, but half as bright. I have already changed the regulators, twice. One with new ones, and again with working ones pulled strait from another radio.

It appears something is keeping the 8 v regulator circuit from doing its job, ughh.

[TheCBDoctor]

Good morning all. I have a Galaxy DX2517 I picked up a few months ago. It was a tech special. It would power up and work in PA mode, but I got no receive, no TX, no lights nothing in any other mode. I changed the Regulators, RX/TX transistors in the front, checked the finals and driver. The power supply is good. And even after all that, I wasn’t getting the 8vdc out of the regulator, ever after putting in new, and known good parts.
Fast forward to last night. While talked to a friend on the air, I plug it in, turn it on, still nothing in SSB/CW/AM. I turn the mode swith to PA, get lights, turn it back to AM, and I get the freq display, channel display, and I am receiving! So, I turn it to side band, I can kinda hear myself while transmitting in another radio right next to it, but the volume is all the way up and I have to have my ear right next to the speaker. Tried an external speaker and it is the same, low receive audio only in SSB. The S-meter really moves though.
So, I put a mic on it, go to transmit in SSB, I get a dead key, 10w+. USB and LSB. AM it seems to have worked.
To sum it up.
• To get the radio to power on, I have to turn on the power switch, switch to PA, THEN to another mode.
• Receives fine on AM
• Hardly any receive audio on SSB
• Dead key on SSB
I didn’t look any further last night. These were my initial observations. Anyone have any insight or tips?

231 PA

---

Wed May 01, 2013 11:12 am

I checked and cleaned the mode switch. Took it of the chassis, took it apart. (these are modular, two little rotary switches riveted together) Took it apart, cleaned it all up, same symptoms. Then it went back to what is was doing before. No 8 vdc feeding anything.

The power supply is working, I am getting the 13.8-14.1 volts, the rx/tx led is lit in PA, but half as bright. I have already changed the regulators, twice. One with new ones, and again with working ones pulled strait from another radio.

It appears something is keeping the 8 v regulator circuit from doing its job, ughh.

Hi liquidh8,

It is possible that a component is drawing down the 8 volt supply. You first must determine if you are missing the 8 volts due to an open or a short. My instructor in electronics school taught me something that has help me many times. He said, "Voltage measurements can be deceiving; always follow the current."

If you are missing 8 volts due to an open circuit there will be no current flow. If you are missing 8 volts due to a short, then you will have a large current flow with the voltage being dropped across a resistor after the 8 volt supply. If you don't have 8 volts measured directly at the output of the 8 volt regulator, then put a current meter (Ampere Meter) in line with the 8 volt supply and the point on the board where it feeds the circuit. If you are reading 1 to 2 amps, then you have a short somewhere on the board. If you lift the output of the regulator and measure 8 volts, but when you solder it back down you lose the 8 volts, then you definitely have a short.

The fact that you have dimly lit lights or LEDs tells me that the 8 volt circuit is where you have the problem. The sideband is created at the balance modulator circuit. There is a carrier null adjustment that is supposed to remove the carrier for operation on SSB. Without a good schematic you will just be spinning your wheels. A good troubleshooting technique is to start at the 8 volt regulator output and unsolder all the components that are at the next solder point. You do not have to remove the legs of the components, just make sure they are not touching the board. Using a metal jeweler's screwdriver, touch each component to the solder point while monitoring the 8 volts at the regulator. The first component that drops the 8 volts down to near zero is the path that has the short.

Solder the other components back into place after checking them as describe above and follow where the short goes to next point and repeat the procedure. Eventually you will get to the troublesome circuit. Every decoupling capacitor has a resistor in series with it. The purpose of an electrolytic decoupling capacitor is to remove any RF voltage (AC) from the DC voltage supply. The voltage supply is dropped across the resistor if the capacitor is shorted to protect the voltage regulator. Most of the time the capacitors to check are rated for 10 volts in an 8 volt circuit.

Whatever it is that is wrong must be intermittent or the radio would not work sometimes or partially. At some point you will get the display to light up as you remove the shorted circuit going through the radio as I described. The 8 volt supply is used for the channel display, frequency synthesizer, and parts of the radio's circuitry. At some point the 5 volt circuit is tapped off of the 8 volt supply. They usually will use 6.3 volt caps to filter out RF in the 5 volt circuits.

Put the volt meter on the output of the 8 volt regulator by soldering a wire to the output and put your meter there. Ground the other side of the meter to any of the I.F cans on the radio's circuit board. By using the technique I laid out you will be following the current. Remember that voltage readings can be deceiving, but the current measurements never lie.

I hope this helps. It has help me on more than one occasion when I did not have a schematic. Even if you have a schematic I would use this method to find a short. I doubt that you have an open circuit. Using this method will determine what condition you have at the very start. I will place my money on a short and very likely an electrolytic capacitor.

Respectfully,

[liquidh8]

Ok, after looking through the schematic, doing something similar to what you had suggested there CBDocter, I did get it fixed.

I replaced both zeners, the 5.1V d70, and the 7.5V, d73. The ma diodes, and the regulator produced 8volts, and the radio came alive. Looks like the MA were fault, and the 7.1 zener was faulty as it smoked a resister.

I then changed q30, 31 and 33 just for haha's, it tx's in all modes, good power and modulation. rx was a different story. On am, I got a great signal and great audio volume. On ssb, I also got a great signal, but hardly any audio volume. I had to put my ear to the speaker to hear people. But it was pulling in the signal as I compared the same two friends on my Washington right before switching the coax over.

So, I had to figure out what was with the SSB audio volume.

The RF meter is messed up, it is sticky. but everything else is working.

After pocknig through the schematic and block diagrams some more, I Found D36 bad right by TP1, replaced that and the SSB audio came back. Seems to receive good compared to the Washington. (858 Washington has the scottky diodes and 2sc2999).

Still an issue or two. VR13 (SSB ALC) and VR16 (AM AMC) do nothing. I replaced both of them with new units since these looked all funky. I have what seems to be full modulation. I have to dig out the scope and check it out. Q39 is in place and wasn't clipped. I would like to get this fixed. My Ol Dosy may be messed up.

I went through and set the driver and finals bias', they were all cranked up. Swapped out Q54 for a 2sc817 unit. Changed the modulation transitor to the heavy duty one also. I went through the TX chain and tuned it for max power, about 32-39 watts depending on the band. (2312 finals). I put the freq counter on it and aligned it, was pretty close from go, the course clarifier was off a hair, but it could be the temps here.

L11 and L12 for the SSB IF sensitivity, L11 is cranked way down, and L12 is sticking out of the can a bit to get the max sensitivity (receive) on SSB. Don't know what the deal with that is either, but it is working just fine. I tested all the rx chain amps and they are all getting the right voltages, diodes all good too.

The RF meter never goes to zero, looks like it is sticky. No biggie.

And finally, the echo does not work at all! I don't use it much, but it doesn't at all work. I have a TRB-x2 I'll throw in, just gotta get a schematic or something to get it to work.

I have to throw the scope on it and align the s-meter yet. But all seems good at this point. Thanks for all the inputs on this issue.

I have been getting audio reports of it being "bassey", but sounding great. Wonder if there are some bad caps in the audio circuit? I am using the same mic I usually talk on to the same guys I usually talk to.

Thoughts?

[TheCBDoctor]

Hi liquidh8 ,

If you found bad components due to a high current draw, then it is possible to have something that still needs to be replaced. It is always a good idea to replace any cap that is rated at 10 volts. You may have one that is leaky. The resistance across an electrolytic cap should be more than 100K ohms. A radio will work with a leaky cap. Usually they will have a resistance of 10K ohms or less and still work. When they are bad they will read 1K or less. If they are shorted then the radio will not work.

Dig deeper into the capacitors and replace any cap that is rated for 10 volts and replace it with one rated for 16 volts. If a zenier diode was bad that means it drew more current than it was designed to do. Check the circuit that had the Zenier in it and I will bet you have a cap that is close to being shorted or has a low resistance.

Good job on the repair.

Respectfully,

[liquidh8]

Rick, I have been doing just that. I have a stock of 25v caps, and all those small caps I usually go through and replace. There are only a handful of the electrolytics on the EPT69xx board here. I have been talking on it, and it tx's and rx's great. Good power and modulation. Broke out the scope and the freq counter, ran through the alignment. Other than the RF meter not settling on 0 (it rests on 2 watts), the radio is all working now.

I had a TR B-x2 echo board laying around, I don't use echo, but I want it to work for the next guy.