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inherited some stuff.. please enlighten me


MainFrame

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If they are a four pin tube, any tube based ham operator will know a guru who will test them for a six pack of microbrew. Don't fall into the $50 a tube bs, testing all four takes under ten minutes.

 

besides, these tubes normally last about fifty years in a dedicated ham outfit. They aren't breaking a sweat in these amps. 

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1 hour ago, ricktate said:

From the looks of those tubes they look almost new I cant imagine anything being wrong with them. Even if there was wouldn't the amp just not work??? Why spend all that cash on testing the tubes??? Just wondering.

 

 

From what the guy at the shop told me I was under the impression that if a tube is bad it could potentially damage other components in the amp.. is this not the case??  If so then I might forego getting them tested at all.. or just test the $1 a piece ones.

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1 hour ago, sheltie dave said:

If they are a four pin tube, any tube based ham operator will know a guru who will test them for a six pack of microbrew. Don't fall into the $50 a tube bs, testing all four takes under ten minutes.

 

besides, these tubes normally last about fifty years in a dedicated ham outfit. They aren't breaking a sweat in these amps. 

 

 

Yep, four pin.. that's good info.  My options are expanding.

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On 5/12/2017 at 9:07 PM, robert_kc said:

IME, the minimum "bench fee" for a professional electronics technician is $70.  

I just had a Sherbourn AVR tested by our local tech for a $20 non-refundable fee.  That's what the market will bear in our area.

 

 

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Opened up the PAS-3 this afternoon.  Everything looks great for the most part.  There are a couple wires here and there with scorched insulation (looks to be from soldering), but not bad enough to expose the wire.  Caps look new, nothing charred/discolored.  No residual charge in the unit as I expected.  As far as I can tell the tubes are OEM, the caps look new.

I wiped down the tubes with an alcohol wipe, ran through the dials and everything with electronics cleaner and compressed air.. then I figured I might as well hook it up and see what happens.  It's plugged into a Bose setup I have for watching TV using my cell phone as a source, and I must say, it sounds fantastic!  At least as good as can be expected with these speakers..  Everything on it works as expected.


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1 hour ago, sheltie dave said:

Nice, clean unit!

Here are the Austin hams, they can help you without much bs.. http://austinhams.org/

 

 

Thanks!  I'll get in touch with them..




I may have discovered one issue with the preamp (or maybe this is how it's supposed to be).. I initially had the source on the "spare" channel and it seemed like the gain was a little on the low side.  When I put the case back on and set it up on my shelf I plugged into "special" and the gain is MUCH higher on this input channel.  Is that intentional?

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In my professional opinion "most likely" all that this gear will require.....

 

1) Test all tubes replace as needed

2) thorough electrical cleaning 10 years on storage creates lots of oxidization.

3) basic testing of any possible problems found during visual inspection.

4) slowly ramp gear up starting at 50 VAC with variac over several hours testing for problems like excessive current draw, heating up components, smoke or spark show) 

5) Once at full 120 VAC test for proper operation.

6) play some music!

 

With gear like this shipped in where I would have to unbox and re-box for return shipping I'd charge about $125 for each piece. If both pieces made it though the above process without needing repair I'd spend one bench day to complete 2 pieces of gear...

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6 hours ago, NOSValves said:

In my professional opinion "most likely" all that this gear will require.....

 

1) Test all tubes replace as needed

2) thorough electrical cleaning 10 years on storage creates lots of oxidization.

3) basic testing of any possible problems found during visual inspection.

4) slowly ramp gear up starting at 50 VAC with variac over several hours testing for problems like excessive current draw, heating up components, smoke or spark show) 

5) Once at full 120 VAC test for proper operation.

6) play some music!

 

With gear like this shipped in where I would have to unbox and re-box for return shipping I'd charge about $125 for each piece. If both pieces made it though the above process without needing repair I'd spend one bench day to complete 2 pieces of gear...



Perfect!  This is pretty much my exact plan.  I was thinking it might be a good idea to just go ahead and replace all the large capacitors at this point as well?  I ran some basic tests on the power supply caps in the PAS-3 and they seemed fine, so I went ahead and fired it up.  Now that I know it works I can do more thorough testing on them later on (I'll probably end up replacing them eventually anyways)..  All of the caps in the amps look brand new, and they've barely been used, but that doesn't change the fact that they're 15+ years old.  I know caps can test good, then fail under operating conditions, so if they're not too costly I might as well replace them.  I figured if all the tubes are good, the big power supply caps are good, everything is clean, and there aren't any signs of damage I would be ready to start slowly putting power to them.  I'm not going to go through the trouble of testing each and every little resistor/diode/cap individually when everything looks brand new.  Hopefully if something small has failed while in storage it will show itself at low voltage, then I can discharge the unit and replace as needed.

 


$125 a piece actually seems like a reasonable charge for this type of work.  I understand this stuff is vintage, and valuable, but when places are telling me they want a $600 deposit per amp just to look at them.. I might as well take the time to do it myself.  My DMM doesn't lie, and as far as electronics go these things are VERY basic.  I'm pretty familiar with all the components other than the tubes themselves.

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Make sure you check the operating points of the valves. Those black molded capacitors are most likely used for AC coupling stages and in my experience they are extremely prone to failure and leak passing DC on to the next stage messing up bias and shifting operating points. 

 

The wiring and layout around the full wave voltage doubler looks terrible. It shouldn't cost much money to have someone etch you a PCB to tidy things up. It would make things much more reliable and look much more professional.

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On 5/15/2017 at 11:30 AM, MainFrame said:



I totally agree (although I wouldn't really consider plugging a tube in and seeing if it works or not a lot of work).  That's precisely why it makes so much sense for me to do the vast majority of work needed (if any IS needed) myself at home.  A skilled tech will certainly have more experience, but not necessarily more skill, and likely no greater attention to detail.  The main difference I can see is that it will take me a good deal longer to get it all done (depending on said technician's work load.. the guy I took them to week before last said he was backed up for months).  I'm pretty busy myself, so I expect it to take some time to make sure everything is done 100% right.


 



How did you know?? lol

 

 



My wife said she remembers seeing at least two of the speakers that went with this setup in the storage container, so I've got my fingers crossed.. I feel like I saw the turntable somewhere as well.

 

 



Austin, TX..

I talked to a friend of mine in the recording business and he referred me to a guy who specializes in vintage guitars/amps, so hopefully he will be able to check the 811 output tubes.  If not I'll probably end up footing the bill to have them tested at the place that quoted me $50 over the phone.. although I'm not positive that the lady I talked to really knew what I was asking about.  I don't want to end up blowing a transformer or anything in the off chance that one of these tubes is bad.


As far as my wife goes, she is by far the most intelligent level headed woman I have ever known.  Not a day goes by that I don't feel grateful to have her in my life. ;)





I have set myself a goal to have the PAS-3 opened up, photographed, and tubes pulled by the end of the day today, have all the tubes from it tested, and barring any issues have it all back together and fired up by the end of the week.  Then I'm going to move my attention onto the home brew amp with the VT4C tubes.  If all goes as planned hopefully I'll have something hooked up to speakers and making noise within the next two weeks.

I'm in Austin.  We can get the tubes themselves tested for you.  I have a couple good testers. 

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19 minutes ago, alzinski said:

Make sure you check the operating points of the valves. Those black molded capacitors are most likely used for AC coupling stages and in my experience they are extremely prone to failure and leak passing DC on to the next stage messing up bias and shifting operating points. 

 

The wiring and layout around the full wave voltage doubler looks terrible. It shouldn't cost much money to have someone etch you a PCB to tidy things up. It would make things much more reliable and look much more professional.

 

 

Will do.. after putting it through its paces for a couple days I think I found an issue with one of those caps coming from the L bass control.  I'm gonna have to tear into it a little deeper and see what I can find.  Need to figure out why the gain is low on the spare channel as well.. plus there's a loose connection somewhere (I'm thinking around the "loudness" switch).  If I jostle the unit around just right it will kick the loudness on/off.  It definitely needs some TLC.. I wish I had just like, one whole day that I could work on it rather than 10-15 minutes every three or four days. :/


Agreed about the wiring at the voltage doubler, it's a mess, lol.  I probably won't get around to tidying that up until I've got everything up and running at 100%.

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On 6/21/2017 at 10:47 PM, Dr Morbius said:

Hey, any updates on how your amps are doing?  Just wondered....................................



Nothing yet.  They've just been sitting on my work bench since my last update.  I have so many other projects going on right now and these amps aren't time sensitive like a lot of the other things I'm working on.  Once I finish remodeling our bathroom, change the timing belt and everything on our Honda, clean up the garage and finish repairing all the drywall and paint it, then I can move the rest of my father in law's stuff in from storage.. after that I should have some time to chip away at getting the amps all fixed up and running.

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On 7/6/2017 at 7:09 PM, mike stehr said:

It's Summer. Amp projects are for the Winter. :emotion-46:

 

 

Word.. while I would love to fire this stuff up and see(hear) how they perform, I don't want to make a costly mistake and blow something up that was otherwise in good condition.  I've always been a big proponent of doing things right the first time.  Unfortunately in this situation that means putting it on hold until I have a decent block of time to go through testing everything and replacing components as needed before getting to experience what they have to offer.

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Glad to hear that the PAS3 worked and that you are getting it sorted out.

 

As has been previously stated, please do not poke around in the amps. This type of amp has LETHAL voltages. Touching the wrong thing can really ruin your day - forever.

 

@NOS Valves is correct: Get the amp into the hands of a qualified tech who is used to the protocols required to safely work on amps that use big transmitter tubes.

 

The reward for doing this the right way will be an amp that should satisfy your audio needs for many years to come - especially with efficient speakers like Klipsch.

 

I have 845 based amps and am amazed at how good they sound.

 

Good luck.

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