Galaxy SSB Echo Base - no modulation

[Hawkeye351]

Got a Galaxy SSB Echo Base on the desk today.

Issues:
No modulation on any mode, good carrier.
Weak receive, low volume.

Strange mods, 2 look like some sort of clarifier mod (1 on bottom of LSB sensitivity adjustment L13, 1 on bottom of LSB PLL Offset Osc. L21). The other mod looks like some sort of swing mod (small black glass diode across legs of large disc cap c189 right behind the AF regulator). They also lifted the outer leg of the limiter transistor and inserted a 1.2k resistor in its place and tied the other end to the lifted leg of the limiter trans TR32.

I fixed the low receive, low volume issue. It was the 455khz FL1. I yanked one out of an old dx 33hml and now the receive is up and volume.

Still no modulation on any mode.
I did remove c128, c129, limiter trans TR32 and checked them. They all test as good.

Yanked out the AF regulator (tr50), passthrough regulator (tr51) and modulation trans (tr49 I think), checked them and they all show good. Shaking wires does no good, changing mics does no good, both SSB and AM Modulation VRs work smoothly and tested around the correct values, checked mic socket on radio, all wires firm, no audio heard on monitor radio. No PA neither. Roger beep sound works fine.

If I put radio in PA mode and then turn it on, there's a loud beep in the PA speaker, but no audio if I key up in PA mode. No echo either.

Stumped guys...

 

[Hawkeye351]

Here is the voltages for IC8: Receive
1 - 13.75 (closest to passthrough reg).
2 - 7.11
3 - 0
4 - 1.83
5 - 1.83
6 - 0
7 - 0
8 - 0
9 - 3.03
10 - 14.39 (closest to 8v reg).

Xmit:
1 - 11.86 (closest to passthrough reg).
2 - 0
3 - 0
4 - 2.46
5 - 2.45
6 - 0.29
7 - 0
8 - 0
9 - 2.99
10 - 14.12 (closest to 8v reg).

Anything seem odd to you all?

 

[Hawkeye351]

Mic OP Amp (IC4) Voltages: xmit
1 - 4.50
2 - 4.59
3 - 4.59
4 - 0
5 - 2.23
6 - 3.34
7 - 2.51
8 - 8.41

Receive:
1 - 4.60
2 - 4.62
3 - 4.62
4 - 0
5 - 4.53
6 - 3.37
7 - 7.78
8 - 8.48

Anything seem off?

(Edit: I listed the pin numbers backwards, corrected.) Thank you nomad...

 

[nomadradio]

Anything seem off?

Sure. Pin 9 of IC8 should read roughly half the supply voltage at pin 1. 3 Volts is way too low. The TA7222P chip may be bad. If you unsolder pin 9 from the edge of the pc board and probe the pin, see if the voltage comes up to 6 Volts or more.

I think you're counting the pin numbers of IC4 the wrong way around. Pin 1 is to the left of the notch or dimple at one end, as seen from the top. The numbers go up in a counterclockwise circle from there. Pin 4 is ground. Should be the one that reads zero.

I would unsolder the center pin of TR32, and isolate it from the foil pad. If this restores the missing transmit audio, you have a fault that's tripping the modulation limiter and killing the mike audio.

Might not reveal the problem, but it's a quick and easy way to cross one possible cause off the list.

The radio is old enough that failed electrolytic capacitors can cause quirky faults. Don't know when they quit making that model. Late 80's, pretty sure.

73

 

[Hawkeye351]

Audio IC does get scorching hot within 20 seconds of holding a key down.

Will do that when I get back to the house. Let you know shortly.

A bad audio IC would also exhibit no PA audio too right? Cause I have no PA audio neither.

 

[nomadradio]

The speaker amp TA7222P has no transmit function. It is used for receiver audio only. Are you sure the heat isn't coming from the modulator transistor bolted to the heat sink just to the rear of the 7222?

73

 

[Hawkeye351]

You mean the passthrough reg (2sb754)?
Yes, it gets hot also, but I figured the heat was from that audio IC.

When I checked the voltages on the passthrough (754), they checked out right.

Collector had around 5.4v and would change with power adjustment VR. Base and emitter voltages showed about right also. I just yanked it out to upgrade it to an 817, along with the AF reg to a 1012.

I talked to the owner about this no modulation issue and he said he could fiddle with the echo board and get it to modulate (you gotta love those that withhold information til later down the road, lol...).

I'm still at family's house for get together, once I get back home then I'll check out pin 9 and then try the TR32 trick.

While with my family, my nephew finally located a specific radio I've been looking for for a while. Went and checked it out, made the trade, she's now mine. Guy didn't know what he had.

It's a very hard to find, rare chassis. It's the Dirland Superstar 3000HP with dual audio chips. Known to be the loudest radio on the market. It's in excellent physical and visual condition. No service info on it anywhere, but with you guys assistance I'm sure I'll get it aligned with no issue and top shelf.

As far as the galaxy ssb audio IC not having any affect on xmit, I may replace it anyway because the radios receive volume still isn't up to par like other Saturn's and such that I do. With dummy load hooked up, and volume all the way up on AM I still have to put my ear down to speaker to hear the static, but if I key up my monitor radio then it feedsback loud. It has been replaced before, sloppy though. They got a heat sink compound imprint of the IC on the side wall in an angle, plus compound all around that area. I did notice some of that dried up brown stuff around 3 electrolytic caps in that same area. The brown stuff looks thick and is wrapped around 3 legs of a nearby transistor, both ends of a nearby resistor, both ends of a nearby diode, etc... Is that electrolytic seepage conductive or corrosive? Obviously gonna change out those caps but should I also be concerned about the nearby components conducting with each other? I'll clean it all up, just curious if that leakage could cause other nearby components to be affected.

 

[Hawkeye351]

I was just looking over the inside of this 3000hp and noticed both the audio ICs are directly attached to the aluminum heat shield. No insulator (has grease but no insulator) and no ferrel around the screw at the tab. Screw is directly contacting the tab. Wouldn't this cause heat issues, shorts, etc...?

 

[Hawkeye351]

And obviously someone screwed around with the high power adjustment VR once too much and messed it up.

Got some more golden screwdriver mess to fix when I get home. Oh well, at least that's all that I see wrong with it. I did hook it up in his truck, talked to several people and got great reports.

 

[TM86]

I did notice some of that dried up brown stuff around 3 electrolytic caps in that same area. The brown stuff looks thick and is wrapped around 3 legs of a nearby transistor, both ends of a nearby resistor, both ends of a nearby diode, etc... Is that electrolytic seepage conductive or corrosive?

That brown stuff may be glue to hold the caps in place. You'll probably want to get that out as the glue used in most radios tends to become both corrosive and conductive over time. I've seen it eat the legs off components, discolor the circuit board, and eat traces.

 

[Hawkeye351]

Yea, I've seen glue eat through legs of PLL's, VCO blocks, crystals and such. Wasn't sure if this was that glue or electrolytic cap seepage.

Was gonna get that stuff out anyway, just curious about seepage. As thick as it is, it might be that glue. Coming out anyway...

 

[Hawkeye351]

Well,
Got home, hooked the 3000 up to my equipment, took a jab at the test points and alignment points, BINGO....

The test points are the resistors with no coating on the leads, kinda in same general areas. VCO adjustment was easy to spot, got it adjusted to 3.20v on ch 1 AM. Both VCO buffer adjustment spots were in the general area, maxed both out on scope. PLL Offset oscillator was in the same general area, and the test point was in the same general area, got the frequency set at 16.2700mhz on ch 1 AM receive, was off just a bit (16.2707mhz). Took me a bit to find the xmit freq adjustment but I found it, it's a variable capacitor (vc). Xmit freq was off a tad at 26.9671mhz, adjusted it back to frequency. Figured out which were the xmit mixers, found them and readjusted for max power with minimal emissions/harmonics/spurries. Fixed hi power adjustment (VR) back to 7w. Set low power to 3w. Swings 32w peak (2w average) in hi, and 20w peak (3w average) in lo.

Now to get back on the galaxy ssb echo.

 

[nomadradio]

Pretty sure the tab on the audio chip is ground. Only has to be insulated if the radio is set up for a positive-ground vehicle.

Just be nice to it. This is the meanest single-final radio you'll see. But there is no service data, no schematic out there. Tried like the devil to turn it up when they were being sold new 20-plus years ago. Never did.

Watch your antenna system's SWR and it should do a heck of a job. I seldom use the phrase "monster audio", but it fits for the 3000.

73

 

[Hawkeye351]

Galaxy SSB Echo Base:

Ok, I lifted pin 9 of the audio IC (8).
Checked voltage on lifted pin 9, shows 3.03v.

Soldered pin 9 of IC 8 back in place.
Completely removed TR32.

Still no modulation.

I did go ahead and replaced TR51 with an 817, TR50 with a 1012, TR49 with a new 945. I also removed that disc cap (c189 I think) from in between the AF reg and passthrough reg that had a glass diode strapped across the bottom legs, it was a 473, replaced with just a 473 disc cap.

Still no modulation.

I was looking over a schematic and it shows the mic gain center pad and the echo board both are tied into the IC8, but that was on a 99v, so may be different on this one.

Roger beep does work. Long beep but it works.

 

[Hawkeye351]

Replacing IC 8 due to extreme heating. Plus still low on receive volume.

Someone replaced it once before, sloppy work. They used a Toshiba TA7222P, all I have in stock is Toshiba TA7222AP. Any difference in the 2? The schematic calls for a TA7222AP, not TA7222P.