Spectra Problems

[mfn002]

I have an old VHF Spectra A7 (D43KMA7JA5BK) that has suddenly stopped receiving. There are no error messages on the screen and the antenna IS connected. I've tried turning the squelch all the way down, but no luck. It was receiving fine one moment, and nothing the next. It is pretty old (old enough that I had to replace a leaked capacitor). If it can be repaired, what do I need to replace?

 

[N4KVE]

It is pretty old (old enough that I had to replace a leaked capacitor). If it can be repaired, what do I need to replace?

If you had to replace 1 cap, you need to replace all the caps. GARY N4KVE

 

[mfn002]

If you had to replace 1 cap, you need to replace all the caps. GARY N4KVE

Wouldn't it give me an error if it was a cap though? As I said, everything looks normal, except that it doesn't receive anything.

 

[n5ims]

Depends on which cap failed. Several are in the audio section and they can easily cause sufficient damage to the board to prevent the audio from working properly. Often you'll hear popping or other noise, but this isn't 100% of the time. Generally when you replace one of the bad caps, you should replace them all since they either are leaking (even if you don't see it yet) or will leak soon. If you don't you'll nearly certainly end up with board damage.

 

[N4KVE]

Spectra's are well known for the "leaky cap"syndrome. After about 10 years they start to leak. Even if the radio has been sitting in the original box & never used. Many of the leaking caps don't show the leakage, & by the time the symptoms are noticed, serious board damage has already happened. This problem has been well documented on Batlabs. Even if you have an Astro Spectra, & it's getting close to 10 years old, the caps should be changed. In my case I had 2 Spectra's. The 1st started to have problems, & I sent it to Will to be fixed. While the 2nd radio still worked fine, I sent it to him to fix before the trouble started. Cheap insurance for a great radio. GARY N4KVE

 

[jhooten]

Antenna T/R switch stuck in transmit?

 

[mfn002]

Nah. I don't transmit with it and there are no transmit freq's programmed in it, i.e. all channels are receive-only. The audio isn't the problem, that works just fine (except for the fact that I have to use an amplified speaker). It's the receive part that isn't working. Right before all this happened, the radio would occassionally go into volume set mode all by itself. The volume wouldn't change, but it would show the volume level on the screen as if I pushed the volume button. There was even the key beep. Granted, this thing was old (20 years or so) and very well-used (it apparently belonged to the Phoenix Fire Department before being labeled "SURPLUS-FAIL 001"). It worked consistently for about two years after I replaced the leaked capacitor, and this is the first time it has given me any problems.

 

[FFPM571]

You shouldnt have to use an amplified speaker with a spectra. I bet the audio section was fubar and thats why it had a low audio. Now its just totally died.

Spectras are cheap these days..

 

[kb5udf]

Clean board

If you don't want to go through too much fuss (or like me lack much in the way
of soldering skills), I've brought back at least one spectra from the dead by
rubbing down the traces and in particular areas around leaky caps with alcohol
soaked cue-tips and cotton balls.

Radio has been working another 3 years. But from a cost standpoint other posters are right,
got my last spectra for $10 in Dayton.

JB

 

[jim202]

You shouldnt have to use an amplified speaker with a spectra. I bet the audio section was fubar and thats why it had a low audio. Now its just totally died.

Spectras are cheap these days..

You should be able to drive yourself out of the area with the normal speaker volume from the Spectra. Do yourself a favor and pop the top cover of the radio. You will need a T15 Torx driver to remove the 2 top cover screws.

You should see on the left a 15 pin IC that has a screw on the metal tab holding it down. This is the audio output IC. There are 4 caps around the pins. One will be larger than the other 3. These are the caps that go bad and start to leak. Many times when the audio is failing or has failed these caps are the cause.

If you look with a magnifying glass around these caps, you will probably see a discoloration on the circuit board. This is the goo leaking out of the caps and eating the circuit board up. You need to get this damage repaired before the board can not be repaired. In some extreme cases, the caps will fall off the board from the etching action of the leaking chemical from the caps.

Jim

 

[mfn002]

You should be able to drive yourself out of the area with the normal speaker volume from the Spectra. Do yourself a favor and pop the top cover of the radio. You will need a T15 Torx driver to remove the 2 top cover screws.
Jim

I just did that earlier this morning. I didn't see anything out of the ordinary, except for a slight brownish tint on the lower part of the pins on the IC where they connect to the board. It didn't seem all that bad and the tint appeared to be only on the surface, possibly from soldering. While looking in there, I did find something interesting tucked inside: the original channel list for the radio, showing the channel names, RX /TX frequencies, and squelch tones.

 

[cmdrwill]

From what you posted the audio IC may be already been fubarred by the leaking caps.

Do you get the BUSY indicator on the control head when receiving?

There are two simple tests if you have a voltmeter:
- lead to the radio chassis + to spkr pin

Measure the voltage on each speaker lead both in standby-no receive and in receive. 6 volts is normal when receiving. Little to no voltage squelched/no RX

Check again with the speaker disconnected. Each pin coming from the radio should be the same voltage when receiving.

Check the voltage across the speaker leads when receiving, with the speaker connected and disconnected should be zero volts.

 

[mfn002]

Do you get the BUSY indicator on the control head when receiving?

Yes. It always has. Again, the problem is NOT the audio. It is with the RX. The audio problem was just something I thought I would mention. It's no big deal now; I just won a replacement on eBay for $65 (Audio cable, mounting bracket and DTMF mic!).

As for the speaker test, remember that it won't receive anything, so I have no way of testing that.

 

[techman210]

The most common problem with this is that the area near the capacitor next to that LO injection pot - the only pot in the entire radio - leaked and destroyed the traces near the 82K (823) resistor nearest the pot.

Measure the side of that pot nearest the edge of the PCB. It should be somewhere near 8VDC. Also, measure that "through hole" near the pot - you should be able to adjust the pot to about 3.5 VDC.

If not, suspect the traces nearest the pot, and rebuild those. The components that supply the 8VDC are on the opposite side of the board, and you may need to check the traces between these, and rebuild, if necessary.

If you have 8V at the 82K resistor, but you cannot adjust the LO voltage at the point mentioned above, then suspect open traces between the 82K resistor and the potentiometer.

Also, check the integrity of the trace leading from the tiny transistor that goes between the nearby electrolytic capacitor, to a chip capacitor to the synthesizer chip. That opens ALL the time and will cause similar problems.

These particular failures will not give you the common "Fail 001" code. You will just stop receiving.

And, as a previous poster noted, you must replace ALL of the electrolytic capacitors, since they not only leak, but their leakage will eat away at traces within the radio over time.