[R-390] fixer-upper/ More

[Bob Camp]

Hi

Well when you only have a hammer fix it with a hammer.

The Y2K manual has a bunch of good stuff in it. If you have not already 
downloaded it get one now.

One of the things in there is a list of voltages in chapter 5. They are 
a very good way to work though the radio. I suspect they will help 
track out the low B+ voltage. Just remember that the voltages in the 
manual are for a 110 volt line voltage and in some cases a high 
impedance meter.

The manual also has a set of  tables of resistances in it. I have not 
found them quite as useful as the voltages but they are something else 
to check out.

Based on what you have found so far I would bet on another loose wire. 
It sounds like somebody was having fun taking your radio apart ...

Of course if you have another radio handy you could do a couple of 
module swaps and figure it all out pretty fast. That would take all the 
fun out of it though ....

	Take Care!

		Bob Camp
		KB8TQ



On Feb 6, 2005, at 7:44 PM, Scott Bauer wrote:

> I forgot to mention that I did also check the 3TF7. Still
> no signals. B+ is 150.
>
> Scott
>
> ----- Original Message ----- From: "Scott Bauer" <odyslim at comcast.net>
> To: "R390 List" <r-390 at mailman.qth.net>
> Sent: Sunday, February 06, 2005 5:51 PM
> Subject: [R-390] fixer-upper
>
>
>> I decided to buy an old fixer upper to try and learn a little
>> by repairing it myself. I have a couple of manuals and know
>> how to solder and can follow a schematic just OK.
>>
>> Well, this is a little more of a hacked up, torn apart junker
>> than I thought. Guess where I found it :-)
>>
>> I first discovered somebody had unsoldered a couple of the
>> mechanical filters then stopped whatever they were doing for
>> some reason. I ohmed them out and then resoldered them, then
>> installed the IF into a working R390A. GREAT, the IF works!
>> I then installed a grounded power cord and installed a spare
>> PTO. This radio did not have one when it arrived. I know that I
>> am going to be off here but this is just for educational purposes.
>>
>> I then checked every tube. All were bad, most missing. Replaced them 
>> all
>> with good used ones. After checking under all of the other modules
>> for smoke leaks, I checked all of the fuses and moved the function
>> switch to standby for a few seconds and did not hear the antenna 
>> relay.
>> Then moved it over to AGC. Silence.... Nothing. Darn! I noticed the
>> OA2 was not burning so I shut it off. The fuse was blown. Geeze,
>> What have I gotten into. After taking a closer look at the AF module,
>> I noticed both caps were 45uf. I borrowed 2 known good caps from
>> another radio and looked around a little more. Ahh... A cut wire
>> in the harness. I don't know one was able to cut it without damaging
>> any others, fixed it. I then noticed the RF gain pot had wires 
>> falling from it.
>> After re-doing the whole pot, I installed another 1/4 amp fuse and
>> tried again. The antenna relay clicked in. Great so far!
>> Ahh, the OA2 is lit, and I am getting hiss in the speaker!!
>> No signals though, just hiss. No signal on any band. .
>> No difference in noise when I pull the antenna off except for one 
>> thing.
>> At around 140kc I hear a tone with the bfo on. I still have it on AGC
>> so I move the switch to calibrate. The tone remains constant whether
>> the switch is on AGC, MGC or Calibrate. Is the radio somehow
>> stuck in the calibrate mode?
>> I am now stuck. Any ideas? I have no test equiptment besides a volt
>> meter.
>>
>> Regards
>>
>>
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>
>
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