[R-390] Too loud Amelco

[Craig]

Hi Larry,

 

Let’s see if this can be wrapped up quickly. In any manufacturing process there are rejects. Some pieces are not up to snuff. At times I’m believing a person gathered all the rejects that were not going to be reworked, put them all together for a complete R-390/A………….”Too Loud Amelco”.

 

Once again trust me: The help and suggestions here on this e-mail reflector are greatly appreciated, tried them all several times. In doing so, faults have been found. In some of the RF transformers, components were touching the metal can, think it was Z503 (IF area) a strand of Litz wire was touching the metal can, just about every resistor in the AF deck was way out of spec, the Local gain pot was marked 2.5K (inside was a 5K audio taper). All this and more besides the usual BBOD’s, etc. 

 

The AGC system, been there done that t-shirt is in the closet…………all caps replaced on the agc line. Local gain pot was a real eye opener????? R602……………..out of spec…………replaced with every resistor in the AF deck (AF deck was a real piece of junk). Swapping decks between other R-390/A’s: The decks from the Amelco now work as advertised in other R-390/A’s. Moving decks, parts & pieces from other R-390/A’s to the Amelco…….audio was loud until R104 & R105 were replaced with 5K audio taper pots. 

 

All fingers point to wiring harness. I’ve searched for opens, grounds, shorts, etc., ……………and don’t feel like dissecting the wiring harness. 

 

At this time with 5K audio taper pots for R104 & R105, life is good.  Signal/Noise ratio is near, at, or slightly above 20dB on all bands last time checked. Might add, it can hear every plasma TV in the neighborhood! 

 

Not wanting to discuss all of life’s issues, there is a doctor in town that wishes I don’t lift over 25lbs…………….

 

There is theory and there is real life. Sort of jokingly, Charles pointed out use the correct right parts……………I can’t find any new BBOD’s. Guilty for using orange drops, hope it isn’t a felony. In the end, my kids will look at the “man cave” upon my demise. Chances are the old man’s junk will end up in the land fill. After all the kids have smartphones.

 

Carry On,

Craig

 

From: Larry H [mailto:dinlarh at att.net] 
Sent: Friday, March 18, 2016 9:45 PM
To: Craig; '390 list'
Subject: Too loud Amelco

 

Hi Craig,  I've worked on a couple A's that were too loud - 1 was the agc system and 1 was the local gain pot not going close enough 0 ohms when set to 0.  Other possibilities are the audio gain is too high - maybe neg feedback R602 is in-op.

 

Regards, Larry

 

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