[R-390] R390A not working at all Head Phones on

[Flowertime01 at wmconnect.com]

Kurt,

Head phones on 

Line meter switch to -10
Band pass switch too wide.
Line gain knob to max.
Local gain to max.
Switch the limiter switch off
BFO band width to 16
BFO switch on
BFO pitch to + or - 1 but not at zero.
Dial lock free
Zero adjust off
MC above 8
KC to 400 500 or 600
Function switch to mgc
RF gain max
Break-in off 


Run line gain up and down and see if line meter wiggles
If that meter needle gets off the peg V603 is OK.
Leave the local line gain at max

On with the headsets.
Run the local gain up and down.
At max gain you should have some power hum in the headsets.
Leave the local gain at max.

Flip the wide sharp switch
If the noise changes then V602 and V604 are good.
Leave the switch in wide setting

If the local gain changes the noise level the V601 is good.

Power supply is good you have V605 lit from visual inspection
So you have 150 volts.
You checked the B+ fuses so you think you have B+.
You have some noise in the audio tubes so you think you have some B+
You eyeballed the filaments so you think you have 6.3
You eyeballed the connectors so you think the wire harness connectors are 
seated.
You eyeballed the BFO tube in the IF deck (V505) so you think the ballast 
tube RT510 is good.

The Audio deck is good you have noise from all the audio deck tubes.

Switch the limiter switch on and off.
You should hear a pop in the headsets and the line meter should twitch with 
the noise. As you turn the limiter up the noise should decrease. V507 is OK
Leave the limiter switch off.

Set the function switch to AGC
Play with the AGC fast slow and medium.
Changing the switch causes the caps to discharge and pegs the carrier meter.

If the audio noise dies when the meter pegs, you are good to back some where 
in the IF chain. V506 is OK

Short the diode load to ground. This is like -7 volts DC on a good day.
You should hear the pop of the DC circuit making and breaking as you short 
the back panel jumper to ground.

With the jumper shorted you should have a drop in noise.
No pop is a problem between the diode load and the ears.
No noise drop is a problem before the diode load not passing noise to get 
shorted to ground.

Hand a DC meter on the diode load.
Turn the BFO off. Load should be less than -10 volts.
Turn the BFO on. The Diode Load should go over -20 volts.
No increase in negative voltage from the BFO on the diode load is a BFO 
problem.

The BFO should be on.
Swing the BFO pitch from end to end. Do not force it.
The shaft clamp comes loose. The shaft turns the inductor one way but not the 
other way. Over time this winds the inductor over to one end or the other. 
This is another problem. Just do not break some thing else trying to fix the 
first problem.

You should hear a change in noise as you change the BFO pitch.
No change in noise. See V506, V504, V505 and RT510.

Turn the BFO off, Noise should drop.
No change in noise level is likely no BFO operating. (V505)

If the diode load changes voltage with the BFO switch on and off and you do 
not hear it in the headphones the problem is between the diode load and the 
headphones.

Play with the bandwidth switch the noise should change as the bandwidth 
changes.

Open P218 and P213 on the IF deck.
You should get a drop in noise. As you just unhooked the RF deck.
No change in noise leaves you working in the IF deck.

History tells us once you have all the tubes lit and just plain no signal 
from the receiver that 8 of 10 will be the IF deck. 1 will be the RF deck and 1 
will be in the function switch antenna relay.

If the noise dropped off then its over to the RF deck.

Set the dial to 7 +000 and look at the mechanical cam alignment.
Read the Y2K to see if your mechanical alignment is good.
Once you know you remember.

Next check the band switch operation.

This is under the Rf deck it switched the six racks of RF transformers. I 
call then octaves. One slug rack and three slugs in three cans per octave.


The bands switch at .5 - 1.0 band switch at
2.-3,  4-7, 8-15, 16, 32

As you change the MC knob you should see the band switch gears change.
Both going up the dial and down the dial.

Often a clamp will get loose, crack on a gear and drop 

If the RF deck mechanical is working OK and you can not get a CAL tone on any 
100 KHz any where in the receiver its time to get out the signal generator 
and volt meter.

Wait until you have read the Y2K manual until you get into this level of 
trouble shooting.

These two passes through the eyeball and hearing test should fix most 
problems where it worked yesterday and now I have nothing type problems.

Once you get back to a working receiver you then begin to work on having a 
very good receiver by doing alignment and replacing bad tubes. Alone with that 
work you get to replace some old resistors and capacitors that have reached the 
end of their useful life. For your lifetime these are a do once project. The 
caps you place in a receiver today are likely to last another 50 years. Most 
of the ones in the receiver today have lasted that long. Resistors have been 
fried out of range by tubes being left in the receiver until the tube failed. 
The bad tube chars the resistor and its value changes (high). The tube got 
replaced and the resistor never was checked. They look OK to the eye. The receiver 
will meet signal to noise specification with several of these bad resistors 
and several bad caps in the receiver. Fixing these gets a signal to noise ratio 
in the receiver that exceeds specification. You do this stuff, as you want. 
You get motive by listening to noise in your receiver and know there are signals 
there you want to hear.

The real key is to read the Y2K manual and get to know your receiver from end 
to end. Once you get it working, keeping it working is much easier.

Do the two series of checks eyeball and hearing. When you get to a point that 
fails post a message to the reflector. Tell us all about the test you did and 
what you see of hear. We can then help you narrow it down one test at a time. 

Tell us about your signal generator. Name will do nicely. You need a 455KC 
out put from it. If you do not have a signal generator FEAR NOT. That can be 
faked if you need to.

It's a Mc Giver thing. Do it easy if you have one. If not we can help you 
deal with it. 
We just have to DC test until we get a cal tone through the receiver. Then we 
use that with a DC meter on the Diode load for alignment and calibration. If 
you have a scope and frequency counter you are in real good shape. Again not 
needed but use what you got. If you just have a tuna tin transmitter and a 
voltmeter you can bring a R390 back to life and better its alignment.

It sould take longer to read this mail than to have performed all the checks 
detailed in this mail.

Looking to read what you find.

Roger AI4NI