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General Discussions => The Lab => Topic started by: drpat on June 29, 2009, 07:44:47 PM

Title: Federal AM-864
Post by: drpat on June 29, 2009, 07:44:47 PM
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Title: Re: What is this???
Post by: pucho812 on June 29, 2009, 07:53:57 PM
see if you can find info on what I have come to known as the "commerce compressor" It looks exactly  like that.

Edit: doh.... I had that wrong. Sorry for the misinformation.  Anyway looking  what appears to be

http://www.bunkerofdoom.com/federal/am864/ (http://www.bunkerofdoom.com/federal/am864/)
Title: Re: What is this???
Post by: MHanson on June 29, 2009, 08:09:24 PM
That looks like every Federal AM-864 compressor I've had or seen.  It been thoroughly discussed here.  If you don't see the info you need on here, let me know and I'll dig up a scheme.  But I'm pretty sure it's all up here.

Michael
Title: Re: What is this???
Post by: drpat on June 29, 2009, 08:29:46 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: mushy on June 29, 2009, 11:32:16 PM
If you haven't already found it:  http://www.waltzingbear.com/Schematics/Misc/AM-864.htm
Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on June 30, 2009, 04:58:02 AM
Hi drpat

i got one of these the other day but the caps are missing of the turret board wat are the values of  your caps and material made of micra so onon.


skaL1
Title: Re: What is this??? (Federal AM-864)
Post by: pucho812 on June 30, 2009, 01:15:52 PM
Pat those were military. I have heard that there were 2 versions. One was full frequency response, one was not.

Here is a link to the military manual. Note how it explains in detail everything from how to set it up, to how to destroy it so the enemy does not get their hands on it. Oh yeah it does have the schematic inside and a wiring diagram.

http://www.crossenstreams.com/federal_am864/Federal-AM-864-U-Manual.pdf (http://www.crossenstreams.com/federal_am864/Federal-AM-864-U-Manual.pdf)
Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on June 30, 2009, 02:32:00 PM
just dwl this , it has no reference to the voltage or either the the type of capacitors it uses  on the turret board , could some shed a light on this....


thanks


skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on June 30, 2009, 02:41:19 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: drpat on June 30, 2009, 02:43:40 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on June 30, 2009, 03:40:26 PM
Thanks drpat  ,wima cap should easily work their right ?  yours looks a bit different to mine ,i think some ones do a rewire on that .

skal1
Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on June 30, 2009, 03:47:57 PM
Hey drpat

have you come across those types caps before , would be nice if i could get the originals in their.


skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on June 30, 2009, 06:23:40 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on June 30, 2009, 07:05:20 PM
hey thanks for the link ,i need to pay more attention to things i thought that was a .1 uf also thanks for pointing that out . that c6 ,that one looks smaller than the rest hum...





skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 14, 2009, 05:38:03 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: EmRR on July 15, 2009, 03:18:27 AM
The only thing that I'm having a problem with right now is the meter. When in the ATT position, it displays 7db of gain reduction with no signal going to the unit. It deflects when I hear gain reduction happening, so I think it's just offset, as if -7 were "0". The OUT position may be off as well, but I haven't gotten too deep into checking that yet. I hope it's not a bad meter.

Since the meter reflects current draw in the input stage, it appears your current draw is low, or R2 is off in value.  Or R2 needs a new value.  Do you have known well performing 6SK7's?  If they are weak/dying, current through meter will be off. 
Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 15, 2009, 05:10:03 AM
Hey  drpat glad to  here your unit is working fine , i am still have a hum issue here is a link to my probelm , have you got any tips  on solving  the issue..


http://www.groupdiy.com/index.php?topic=34210.msg420931#msg420931


skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 15, 2009, 09:36:30 AM
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Title: Re: What is this??? (Federal AM-864)
Post by: EmRR on July 15, 2009, 11:58:44 AM
I'd try some other tubes anyway.   I have seen several Gates SA-39's that would not adjust to 0 without a change in the parallel resistor, with all other possibilities eliminated first (voltages and current confirmed, resistances confirmed, various tubes tried).    -7 is probably too far down to apply to this idea, but is it possible to get inside the meter and zero the  mechanical trim?  Strange that they all have the mechanical zero posts, but no external access. 

In listening, be sure to do a full polarity swap on the unit for comparison, since the side chain detection is just a single side of the PP total.
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 15, 2009, 06:48:49 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: mOBiTh on July 15, 2009, 07:39:56 PM

Note how it explains in detail everything from how to set it up, to how to destroy it so the enemy does not get their hands on it. O

Quote
g. Destroy Destroy everything

Hahaha!
Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 16, 2009, 11:34:31 AM


In listening, be sure to do a full polarity swap on the unit for comparison, since the side chain detection is just a single side of the PP total.

Good point, don't know how I missed that, but I'll try it.

What s meant by the full polarity swap ?


skLa1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 16, 2009, 04:23:33 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 16, 2009, 07:48:44 PM
hey thanks again drpat .

i was just wonder about the threshold and limiter pots, have you experience  any oscillation when both pots are turn to the max ?

skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 16, 2009, 08:21:32 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 16, 2009, 09:16:51 PM
This thing is hurting my head  drapt ,would it be possible to take some voltage reading off your unit , i do not know where you you measure from ,but i thing you have more knowledge than i  on this.

do you know what would cause this effect ?


thanks

skal1
Title: Re: What is this??? (Federal AM-864)
Post by: pucho812 on July 16, 2009, 09:55:49 PM
hey Pat, You should drop an e-mail to walter sear at sear sound, He modded his units. IIRC he added attack and release times.  He is quite the friendly fellow and I am sure he would offer some suggestions.
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 17, 2009, 01:39:09 AM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 17, 2009, 07:25:48 AM
now i am going man  >:(  i have check the voltages and have found that their is 200 volts at pin 8 of v1 and v2 , the manual say that it should be around 155volts .


what would  cause this 50v difference The heater voltage  is not that bad it   is 7.01volts  , i should be able to use a rsistor to drop that .7volts .


skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 17, 2009, 08:19:04 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: CJ on July 17, 2009, 11:18:15 PM
dude, whats that tent city like?
are there cattle roaming the streets?

Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 18, 2009, 10:28:37 AM
hey drapt plate resistors 12k



dude, whats that tent city like?
are there cattle roaming the streets?



cj what are you talking about ?

skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 18, 2009, 06:20:16 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 18, 2009, 06:23:10 PM
CJ,

The only people not living in tents around here are the legislature who just rewarded their inability to pass a budget with a 20% pay raise! And yes, this place has turned into a meat market.
Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 19, 2009, 08:56:44 AM
 ??? changed the plate resistors for 24k seems a little better , but still getting oscillation.what can cause this.

i also checked the output tx ct connection to ground i read a voltage of 1.20volts is this right , i thought should not see any dc through the secondary of the tx.


skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 19, 2009, 05:57:06 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 19, 2009, 07:54:14 PM
drapt i did change the caps in filter section , 22uf for two 12uf and 10uf for the 12uf that should be ok yes {IMP) it has not changed the hum factor.

yes this looks like an original


C2, C3 and C5 look new  markings on caps 104k


i changed the c6  for 0.01 600vac  Polypropolene Capacitors with Metal Foil ,is this ok ?

i have checked all resistors by lifting one leg from circuit and value are within  5%


skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 19, 2009, 11:29:56 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 20, 2009, 12:22:13 PM
Ok did what you suggested ,here we go


V4
pin 4 to ground ,1.4 meg 

pin 8 to R11 , 1.4 meg 


V1

pin 4 to ground ,2.67 meg 
pin 7 to C2 ,27.4 meg 
pin 8 to R2 ,12K

V2

pin 4 to ground ,2.67 meg 
pin 7 to R1 ,1.4 meg 
pin 8 to C5 ,0 OHM



skal1

 
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 20, 2009, 06:54:40 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 20, 2009, 07:46:48 PM
drpat


i have already check R1 measures 2.25 Meg

as a side note i did find that if i removed R1 the oscillation stopped. if the c1 was bad would you see the effect in att mode, when in att mode their was know release is this due to r1 not being in Parallel with C1.

I will recheck with R5 full clockwise , and take reading ref to ground ..

Should the federal be on while taken the resistive readings.

I will post 2morrow

thanks again drpat

skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 20, 2009, 09:33:37 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 21, 2009, 07:56:58 PM
Hey me again here are the new values follow your set up  method.

V4

pin 1:0 ohms

pin 2: 300k

pin 3 : 1.5 ohms

pin 4+5 : 2.37meg

pin 6: 45k

V1

pin 1to5: 0 ohms

pin 4 :2.30meg

pin 6: 1.032

pin 8:27.6k



V2

pin 1to5: 0 ohms

pin 4 :2.30meg

pin 6: 1.032

pin 8:27.6k




I also replaced c1 , it had no effect on the oscillation with threshold and current at max. so what i did next was to parallel the two 1uf capacitors  to make 2uf and the oscillation  was gone  ???.

does this rule out the c1 as the suspect component i think so what , do you think?

skla1


 
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 22, 2009, 09:19:55 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 22, 2009, 09:58:46 PM

These are the readings that are off:
V4 pin3: your current control is probably mis-set. Re-align your current control and lock it down for now.

manual says set to 2.5 vdc correct?

V4 pin4&5: This reading points to R11 being high... my guess is that it reads in the neighborhood of about 120K, which would be waaaaaay out of spec. Can you verify that R11 is within tolerence? If it really is out that far... replace it.


Will check and replace 2morrow

V1&2 pin4: a tad high. replace R1 with something that's in tolerance to bring this within specs.


Will check and replace 2morrow

V1&2 pin8: Did you change your plate resistors BACK to 12K?

I did replace plate resistors back too 12K , so that  is ok.
Another thing that you can try is croc-ing another 22µF cap in parallel with the single 22µF cap AFTER L1 to give you 44µF total. Or just put one in permanently and leave it there.

Will try that 2morrow

and thanks again, i think where really close to finding the problem

skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 22, 2009, 10:36:55 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 23, 2009, 08:59:01 PM
OK did those exchanges

R11{46.7k

R1  {2.08 meg

V4 pin 4+5 : 2.07meg
     pin 3 : 167 ohms

V1 pin 4 :reads 2.01meg

V2 pin 4 :reads 2.01meg

still oscillates though. ???

skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 23, 2009, 10:13:19 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 23, 2009, 11:36:03 PM

What resistance readings are you getting from V3 pin1 to ground, and V3 pin4 to ground?

V3 pin1 to ground, 470 ohms

V3 pin4 to ground ,471 ohms


Did you add the extra capacitance after L1? You could just use a single 47µF cap to replace both of the 12µF caps like I did.

yes ,just put a 25uf across the one that was their.


You might need to match V1 & V2 better. You tested all of your tubes, right?
i have no tube tester.how can you match the tubes , can they be matched in circuit ? what should i be looking for in a good match... current /voltage...


skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 24, 2009, 04:55:15 AM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 24, 2009, 10:03:24 AM
V3 pin1 and V3 pin4 should be 470K!!! Holy smokes! Change R13 and R14, quick!

sorry my mistake

V3 pin1 and V3 pin4  do read  470K.


skal1
Title: Re: What is this??? (Federal AM-864)
Post by: EmRR on July 24, 2009, 12:48:51 PM
The addition of a balancing circuit on the plate side would be simple and useful.  I believe several people have presented one here before.  Won't solve a drastic mismatch, but lets you fine tune one that's already reasonably close.   Some limiters come with this already (BA-6A), Gates used shorting jacks in the path to insert current meters for in circuit measurements. 
Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 24, 2009, 02:29:40 PM
here´s a plan... don´t mess with the cathode:

(http://img.photobucket.com/albums/v172/rafafreddy/balance_mod2.gif)

sorry for the mess, but it should be readable.

so something like this should work..

skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 24, 2009, 06:11:43 PM
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Title: Re: What is this??? (Federal AM-864)
Post by: skal1 on July 24, 2009, 06:19:36 PM
Hey drpat  i have no means of testing c1  is their a test you can do with ddm.


skal1
Title: Re: What is this??? (Federal AM-864)
Post by: drpat on July 25, 2009, 12:47:20 AM
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