High Voltage SEX, please help.

[pevelg]

Finally finished the unit after three days work.  My voltages are extremely off and extremely high.  I have not yet tried listening to anything as I am certain I messed up somewhere.  Any guidance would be appreciated.

Resistances:

All within limits except these:
Center of inputs:  @0 volume=~100K, @max ~100k   <-----this does not change as volume changed
19,39:  @0 volume =1.7ohms,1.9ohms, @max ~100K
A4,B4:  @0 volume =218ohms,224ohms, @max ~100K

Voltages:
--Unit powers on and tubes glow, fuse ok.
Voltages are within limit except the ones listed here:

1,21:  435,434
2,22:  444,443
4,24:  435,434
6,26:  913,911
11,31: 860,860
16,36: 833,831
A2,B2: 826,824
Power Transformer:
6: 444
7: 435
8: 442
9: 433
Plate Choke:
1,8: in 800's
4: in 800's
5: in 800's

Also, tubes get EXTREMELY HOT.

Where do I start trouble shooting?

[Paul Birkeland]

The resistance issues you have are an oversight in the manual, no worries there. 

Do you happen to live in a 220/240v country? 

I am slightly skeptical about those voltage readings.  900v in the power supply would blow up every capacitor and take the fuse out instantly!  Tell us about your meter/measuring techniques?

Do the tubes glow red if the SEX amp is on?

[grufti]

No matter what else you do: be careful!

If you really have 800V to 900V somewhere in your circuit then you are in real serious danger. Those are the kind of voltages that can hurt you very badly or even kill you.

[pevelg]

No, I am in the US, so 120v.

I attach the black lead to a ground wire (by the power cord) and then touch the various terminals with the red tip.

I just replaced batteries on the meter.

On my volt meter, I have the selection but on 200black.  When putting on terminals that are supposed to be around 300, I get a "1," so I put volt selector on 600red.  This is what showed be the volts in the 800 range.
Just remeasured all terminals that are supposed to be around ~300volts.  I still am getting these terminals in the 800's.
I also remeasured the power transformer terminals and I put selector back on 200black.  I am getting around 190 now.

update:  tubes are glowing yellow...  I am colorblind though, so that is subjective.

update 2:  I triple checked the wire colors, so I am sure those are correct.  My color blindness is more in differentiating shades of similar colors.

[Paul Birkeland]

Can you post a digital photo or a make/model of you meter?

It would take a miracle of impossibly random mistakes to have both channels making 900v, and you would have to have at least ten guardian angles keeping the fuse/caps from blowing if you really had that kind of high voltage in your amp.

Likely the meter just isn't properly set.  The yellow glow from the tops/bottoms of the tubes is normal.  When the black or grey plates inside the tube start glowing themselves, then you really need to worry.

[pevelg]

Sperry DM-210A
http://www.amazon.com/W-Sperry-DM210A-Function-Multimeter/dp/B000ET0UY8
Black cable is in center, red on right.

UPDATE:  Ok, looks like my volt meter is only rated 2/20/200 for DC power, so that must be why I am getting the "1" when testing things that are over 300 volts.  However, I am still getting around 190 volts on terminals 6, 7, 9, 10 on the power transformer.  7 and 10 should be "0"

What about the resistance on the input terminals?  According to the manual, it should change from about "0" ohms to 100k as volume is increased.  Mine is almost at 100k, regardless of volume setting.

UPDATE 2:

1,21:  ~190,~190
2,22:  ~190,~190
4,24:  ~190,~190
6,26:  1,1 <--------------indicates out of range of meter.
11,31: 1,1 <--------------indicates out of range of meter.
16,36: 1,1 <--------------indicates out of range of meter.
A2,B2: 1,1 <--------------indicates out of range of meter.
Power Transformer:
6: ~190
7: ~190
8: ~190
9: ~190
Plate Choke:
1,8: 1,1 <--------------indicates out of range of meter.
4: 1 <--------------indicates out of range of meter.
5: 1 <--------------indicates out of range of meter.

UDATE 3:  I guess I was getting the values in the 800's and above because I selected 600 AC instead of DC on the meter.

[pevelg]

Ok, I decided to try and see if the amp actually makes sound...  Hooked up my iPod and a cheap pair of in ear headphones....

I hear music!!!!!!

I went and put in my Ultrasone Pro's and the music sounds great thus far, even from the iPod.  Volume is great, only on 9' o'clock and listen levels are good.  Is everything good to go then?

UPDATE 2:  Just plugged in a cheap pair of speakers and that works also!!!!  Volume sounds the same on each channel.

[Paul Birkeland]

Plugging her in was going to be my next suggestion.  The input resistances in the manual are an error, they will not change as the volume pot is moved.

It looks like that meter says it is good for 600V AC or DC, try measuring those DC voltages with the knob on the black 200 and the probes plugged in as you describe (red right, black center).  It is possible that it only goes up to 300v.

Also, don't worry about the power transformer terminal measurements, they are wildly different depending on the meter.

[pevelg]

It looks like that meter says it is good for 600V AC or DC, try measuring those DC voltages with the knob on the black 200 and the probes plugged in as you describe (red right, black center).  It is possible that it only goes up to 300v.

With the meter on black 200, I get the "1" indicating voltage is higher than meter range (look at update #2 of post #6).  I won't have my car for about a week, so I won't be able to get a new meter.  Am I safe using the amp with my better speakers?

BTW, the Grado + Seduction + SEX sound great with my Ultrasones.  The seduction is a little noisy, but that is because cart is 1.5mv I guess.

[Grainger49]

The meter is insufficient for measuring the voltages on the SEX amp.  Sorry!  I don't think I remember anyone warning about a meter not having enough range for the kits.

I hadn't even thought of this till you posted the link to the meter and Amazon kindly had a picture large enough to read the meter ranges.

Paul, I will edit my post about tools for kits with the maximum voltage needed.  Can you tell me what the highest AC and DC voltages there are in Bottlehead kits? 

[Doc B.]

600V and 1000V are common top DC ranges for meters, 600V would be adequate for most measurements on most of our kits, 1000V would generally be more safe. There are also meter safety category ratings, CAT I, CAT II, CAT III and CAT IV that are related to the ability to withstand transients. Those ratings aren't quite as important for what we are doing, they are more for consideration when working with AC mains and high current DC motors and such.

[Grainger49]

As industry has almost converted to VFAC drives, I can see that transient spikes could wreak havoc with meters.  Even with the new transistors (IGBTs) that are being used there is a lot of noise and high frequency noise that creeps through.  

Sadly, I haven't seen many of these, I'd love to.

Great comment.

[Paul Birkeland]

I would say a meter that goes to 600V dc is a good idea. AC voltages are generally not super high, as we like using voltage doublers. I'd say 350v AC would be enough 99 percent of the time.

Yes, 1.5 mV is probably too low for the Seduction, and about as low as you'd want to go on the Eros. A 1:5 step up would probably help your cause. (Search for 15095 SUT)

-Paul

[pevelg]

Yes, 1.5 mV is probably too low for the Seduction, and about as low as you'd want to go on the Eros. A 1:5 step up would probably help your cause. (Search for 15095 SUT)

-Paul

Ya, my Eros kit just shipped yesterday so hopefully I will be able to get that up and running in a few weeks.  I will be posting the Seduction here when I can get some pictures.  I'll make sure and get a new meter prior to starting building the Eros and will double check my voltages on the SEX.  For now, I will just enjoy the music.

[Paul Birkeland]

If you're a comfy solder slinger and there's a Radio Shack near by, you could build yourself some new meter probes to solve your problem.  Grab a pair of banana plugs for your new probes to plug into your meter, some wire for the leads, maybe an alligator clip for the black lead, and a probe for the read lead. 

What you would want to do is to connect a 2.25M resistor an a 250k resistor in series, with the 250k resistor connected to the black plug and the 2.25M resistor connected to the red plug (close to where they plug into the meter preferably).  At the junction of these resistors, run your read lead with probe.  If you do this, be sure to heat shrink over all these exposed joints.

If you do this, any DC voltage you measure will be reduced by a factor of ten.  Measuring a 400v terminal in the SEX amp will now appear to be 40 volts on your meter.

-Paul