Pro-2006: Unknown Problem

[dem1]

If within your technical abilities, check the internal power supply voltages with a meter. You should be able to find a PRO-2006 service manual online to assist if you don't have one.

The PRO-2006 converts 120VAC to 12VDC (unless operating directly from an external 12VDC source, as others have recommended), and then converts the 12VDC to 5 VDC and 8.3 VDC via a pair of voltage regulators (IC8 and Q32 respectively) to feed its circuits. It subsequently converts the 5VDC to 30VDC via an inverter circuit (T9, Q24, Q25) for the PLL board.

Basic tests:

• The audio amplifier is fed directly by 12VDC. You should hear a pop from the speaker when the radio is turned on and a very slight hiss while powered up, but a loud hum could indicate failure of the main AC filtering capacitor.
• The display illumination is fed by 5VDC. Since yours works, it would suggest that the 5VDC regulator is healthy
• If the LED above your Sound Squelch button works, it would suggest that your 8.3VDC regulator is healthy.

Even If your radio passes these tests, proper voltages can be verified more definitively using a voltmeter at various test points internally.

There is one additional CMOS 5VDC regulator (IC9) which provides memory backup power on the CPU5V line even when the scanner is turned off (or unplugged, assuming the battery is installed). It is reportedly susceptible to failure, but I'm not sure whether or not that would cause the entire scanner to stop working. If verifying this voltage, take anti-static precautions, use a high impedance voltmeter, and be careful to avoid short circuits to prevent component damage.

As a hail Mary, you can allow the radio to sit overnight with power and battery removed, then reconnect both and turn the radio back on while holding down the reset button for several seconds.

The three components in your photo (C152, C151, L56) appear to be in the IF section and not likely related to your problem. They are connected to Q14, which is identified in the block diagram as a noise amplifier.

Good luck. I still use my PRO-2006 and hope you can revive yours.

 

[tvengr]

I have come across some old electrolytic capacitors that don't function until they heat up. Just for laughs, try heating the circuit board with a hair drier. The expansion and stress caused by the heat can cause bad solder connections to reduce resistance. Also, check for an open fuse and any sign of overheated resistors or a discolored circuit board. You can also check for corrosion on the circuit board. The leakage current can cause computer circuits to quit functioning.

 

[bob550]

Have you tried powering the scanner using the 12 volt power input jack on the back rather than plugging it into the wall?

Yes. No luck.

 

[bob550]

• The audio amplifier is fed directly by 12VDC. You should hear a pop from the speaker when the radio is turned on and a very slight hiss while powered up, but a loud hum could indicate failure of the main AC filtering capacitor.
• The display illumination is fed by 5VDC. Since yours works, it would suggest that the 5VDC regulator is healthy
• If the LED above your Sound Squelch button works, it would suggest that your 8.3VDC regulator is healthy.

There is no pop, hiss, or any other audible noise when powering up the scanner. The LED above the Sound Squelch button does illuminate. I've disconnected from power and removed the battery. We'll see what happens tomorrow.

 

[fxdscon]

We'll see what happens tomorrow.

Sent you a PM.

.

 

[trentbob]

I had two of them, made for Radio Shack by GRE and I'm guessing they're about 30 years old, beautiful machines for the day. One died a natural death and the other is in the scanner Museum in the garage with the other few hundred scanners and receivers I've had in the last 50 plus years.

As far as what you should be looking for? I would say a large caliber handgun, take it out behind the shed and put it out of its misery. LOL.

 

[Ubbe]

The photo of the choke and two capacitors show a connector to the right of it. That are probably the CN3 connector where you can measure the different voltages.

/Ubbe

 

[dem1]

The photo of the choke and two capacitors show a connector to the right of it. That are probably the CN3 connector where you can measure the different voltages.

That particular connector is CN1 to the logic board, but you are correct about measuring voltages on CN3 (which contains 8.3V, 5V, and CPU5V) or CN2 (which contains 8.3V, 5V, and 30V). You can also unplug and inspect CN1 for any sign of corrosion, contamination, etc., especially if the nearby parts look dirty.

The fact that you have absolutely NO sound whatsoever from the speaker is interesting. It suggest that either the audio amplifier chip has no +12V power at pin 2 (which seems unlikely if the +5V and +8.3V regulators are both receiving power), or the audio output at pin 1 is somehow disconnected from the speaker (have you tried plugging a monaural earphone into the front panel headphone jack?), or the chip is blown. And if the chip is blown, it suggests a possible voltage surge or spike which could have damaged other components as well. Indeed, the lack of sound and lack of display could have two separate causes. And the audio stage may be easier to diagnose. But checking voltages is a good place to start.

 

[bob550]

@dem1 and @Ubbe, that's great information! As time permits this weekend, I'll test what I can to verify the correct voltages. One correction to one of my earlier posts is that the speaker does, in fact, make a popping sound upon powering up the scanner. That wasn't obvious at first because the top was inverted on my desk. Unfortunately, removing the battery and unplugging overnight did not resolve the problem.

 

[bob550]

As far as what you should be looking for? I would say a large caliber handgun, take it out behind the shed and put it out of its misery. LOL.

That thought occurred to me too, LOL. In reality, this scanner was given to me at no cost several years ago. Aside from that, resurrecting the PRO-2006 may be the equivalent of repairing a 35 year-old IBM Selectric typewriter. But, I'm gonna try anyway.

 

[trentbob]

You know I was kidding but... In today's world you are kind of limited in what you can get with the radio anyway. I remember getting that radio when it was brand new and it was a sweet quality machine but even the best equipment succumbs to old age, even us.

You have a lot of very good suggestions from people who know here and it would be very satisfying for you to actually revive the unit.

Good luck with that and keep us posted on this thread... Bob.

 

[bob550]

You have a lot of very good suggestions from people who know here and it would be very satisfying for you to actually revive the unit.

Yes, and I appreciate all the contributions! I am locating as many test points as possible to verify correct voltages. I'm also going to disassemble the front panel and check my previous work done when the EL panel was replaced. Perhaps there's a bad solder joint or connection somewhere there. I'll post back with the results of my work.

 

[RogerH11]

Try an external AC Adapter but that's grasping for straws.

 

[bob550]

Try an external AC Adapter but that's grasping for straws.

I did that but there was no change. I have disassembled the front panel and checked and verified connections. I have performed some voltage checks at different points and have verified both 8 and 5 volt readings where they should be. I think the failure is significant, as I get nothing showing on the LCD (except the backlight), and hear no audio when the squelch is turned off or keys are pressed even though the speaker does seem to work.

 

[mancow]

Well that might account for the lack of any audio. But what would account for a blank display?

I would be looking at a main CPU crystal oscillator failure, up there in the image above on the left side.

 

[Ubbe]

CPU crystals rarely fails but I have seen several times that the reset pin of a CPU are constantly in reset due to a faulty discrete component. I would check the voltage at both ends of the D501 diod and I'm very suspicous about the delay reset capacitor C508 being leaky or R517 100k resistor gone open.

/Ubbe

 

[moonbounce]

I had the same problem and I had posted it on this thread, https://forums.radioreference.com/threads/pro-2006-parts.378249/ hope this helps. My Pro 2006 is now running like new.

My display also came up blank and I had no sound, it all came back to the squelch and volume controls with bad connections to the wires and very dirty volume control. Also one of the wire harness wires was loose causing the display to be blank. You could gently wiggle the wires around , I am sure it will be something simple as a bad connection.


MB

 

[bob550]

So, I swear I have not touched the 2006 since my last post. Yesterday, I powered it up and ....... the LCD display works again! Everything with the display appears as normal after a reset, scanning all empty channels and banks. However, I programmed in my local NOAA frequency and hear nothing unless I break squelch, and then all I get is static. The static noise seems like electrical interference with random rapid popping. It's more than simply background noise and I get the same identical noise when the squelch is broken on any unprogrammed channel. I switched power source from AC to DC and note the same conditions. Using an outdoor antenna is of no help and the static is present to the same degree without an antenna. Maybe I should just let it sit for another two weeks and see if it totally fixes itself.

 

[Ubbe]

Let the scanner sit on the NOAA channel with squelch open and turn down the volume. Check every day if it starts to receive something. That crackling noise could be a leaky capacitor in either the power to the PLL/VCO part or a capacitor in the PLL/VCO. Maybe it will go away when the power have been on for a longer period.

/Ubbe

 

[tvengr]

I don't think that a PLL/VCO problem would cause the display trouble. Sounds like he may have 2 separate problems. I would check the connections to the display. The power supply is common to both the oscillator and display. I would check voltages with the display working and not working.