President Ronald - Lo Bands Problem

[Phuture]

Hi Sammy,

Thank you for your advice - it helped me get on the right track!

I checked the voltages on all of the local oscillator variable inductors and found them to be between 6.8V and 8.5V depending on the selected mode. I tested the radio from cold to get the "working readings" before switching the mode switch to USB, LSB or keying up in any mode, which all trigger the fault. I'm not sure exactly why these states trigger the fault but presumably more current is drawn via the inductors(?). Anyway, I noticed L20 failing to deliver any voltage on the opposite side of it to the diode. Looking at the trackside solder pads of the inductor with a 14X eye-piece magnifier it looked like one of the two-pin side pins might have a dry joint, but it was completely invisible without the magnifier. Anyway, re-soldered the pad and fault seemingly repaired! Changing the mode switch to USB, LSB or keying up work faultlessly and I've had it on for about half an hour and trying from time to time. It has never lasted more than a handful of attempts before so I'm hoping this is it. Okay so of course I also checked the frequency readings for the erroneous readings on inductors A, B and C and they are all correct and stabilised now. Fantastic!

I'm going to carry out a full alignment shortly but I notice the S-meter is awfully lazy in FM and AM even with VR1 fully clockwise, which just makes S9 with a 100uV/40dB signal. I've seen a mod to replace D12 (1N4148) with an 1N60P or similar germanium. Have you had to do this for any of your S3900s?

Thanks!

[cb4ever104]

Good news !

There's no-one on here to check my S meter

I have done that germanium mod before . Think I did it on my 2000 GTL. You could try it anyway. Nothing to lose.

Cheers

[Phuture]

Cheers Sammy.

One other question, is the frequency counter can secured to the chassis with a metal or nylon screw? I ask as mine was just floating around inside my radio when I got it and I noticed there is a cardboard insulator stuck tot he side of the chassis. Of course this could be to prevent electrical noise occurring through vibration even with a metal screw but I want to be certain.

Thanks!

[14CS06]

Hello

Only nylon screw

@+
Claude

[cb4ever104]

Hi.

Yeah. You must insulate the counter with the cardboard. If not then you'll short the negative line to chassis. And use the nylon screw as well, as this will do the same if you use a metal one.

S

[Phuture]

Ah okay - glad I asked! Thank you Claude and Sammy. Sorry to add another question but is it normal for the LM7808 and the two nearest (green) caps inside the frequency counter can to get very hot? The LM7808 and aluminium cap tops are too hot to even touch. My infrared thermometer shows they're around 55-60C.

[cb4ever104]

I don't remember any of mine getting that hot. You might have a short somewhere. I presume the counter works ?

[Phuture]

Yep, the counter works. I do some searching - perhaps there's a solder bead or splash somewhere in the can.

[cb4ever104]

Ok. To be honest i never really remove the counter cover, so it might run hot. The only time I've been inside it was to fix the whine that it gives out.

[Phuture]

Oh I noticed that whine through the speaker. Is there a mod to fix it somewhere?

[14CS06]

Hello

Please look at this post from Sammy

viewtopic.php?f=29&t=49692&p=442646&hilit=whine#p442646

solder a .01uf capacitor from pin 8 of the TC5032 IC to the nearest ground point. "

@+
Claude

[Phuture]

Ah great - thanks Claude. I'll give that a go. I'll need to check the PCB version but hopefully I have the version that's compatible with this modification.

As I'm now able to make progress with the alignment procedure, I've picked up one or two differences between the French service manual alignment advice and that provided in the Secret CB alignment. Specifically, setting the correct amperage for the driver/final bias with VR12 (step 1 in both Tx alignment procedures). In the French service manual it advises setting 6-band sets to 25mA and 5-band sets to 20mA but in the secret CB procedure it just advises 10mA. As I have an EPT360011Z board and 6-band radio I guess I am tending towards the French (presumably official) version of the service manual. What do you guys have yours set to for any 6-band 11Z sets in your collections, assuming you've carried out Tx alignments on your radios? I checked what amperage is currently set on the radio and it's 16.2mA, which is sort of in the middle of both settings so not very helpful.

French Service Manual: http://www.cbradio.nl/president/Service ... ald_FR.pdf

Secret CB Tx Alignment for SS3900s:

P29.jpg

Cheers,
Tony

[cb4ever104]

A few of the manuals are different. You can do it voltagewise as well . Set each base for 0.7v ssb . Mic gain minimum on TX. That'll do it.

[14CS06]

Hello

I've not carried my Tx alignments on my radios

French Service Manual: http://www.cbradio.nl/president/Service ... ald_FR.pdf

Notes :
R I is for Ronald I EPT360011Z
R II is for Ronald II EPT360010A

@+
Claude

[Phuture]

Thanks Sammy. That's seems to concur with the French version of the service manual as I checked using both methods, i.e. amp settings and using 0.7V voltage for both. The amp settings provide a slightly higher voltage, but only by about 0.2V and 0.6V respectively.

Thanks for the notes, Claude. Yep, I generalised with 6-band (R1) and 5-band (R2) President Ronald radios but specifying the exact board version is probably more helpful.