TG1 - advice from any one who has built it...

[Bonsaimaster]

I am not sure why this is a complicated question. I know measuring is the way to go but personal experience would help.

Bonsaimaster

 

[duantro]

I got my point to point power supply buttoned up and working. A few more switches to wire up and almost ready to test if it will hold the magic black smoke. These molex connectors take a while to connect!
Hey Bonsaimaster, how did you end up with the vu lamp connection? Are you using the Sifam 2.4 mA meters also?  Do you still have extra HS2051's? If so, shoot me a pm and Let me know what you have, and how much you'd like for them.

 

[duantro]

Got everything wired up. Upon power up my r77 gets very hot. I've got a short or bad wiring somewhere. I'll keep looking to see if I can find it.
Edit: ok, I think I've found it. The unmarked cap on pcb (c3), I had mistakenly put in a resistor!   Must have gotten it confused with the unmarked resistor in the same area. Looks like that solves it.

 

[duantro]

PSU putting out 27.7v. Main Board 20v test points are looking good with 1 jumper. However, I'm not getting signal out of it. It's dead Silent. Meters move when I boost the test signal So it is getting signal to some parts of it.. Opa604 voltages are only 21v. It looks like I have a 3k05 instead of a 3k5 in r91 and r92! I'll switch those tomorrow and see if it helps any. 24v on Relays drop down to 18.4v when energized. Is this too low? I tapped into my VU LED+ for my festoon bulbs and sent the ground of the bulbs to case. This wouldn't be causing any issues , would it?

Edit: after putting in 3k5's, I've got 24 V on relays. Still measures 18.4v at relay side of r110 when switch is in iron.

Edit: I figured I would check the output transistors, since I had wrong component in c3 and likely messed something up here.
vdc measurements
The 2n4898 =  B 20.42 (r75), E 19.72 (r74), C 0(t_op).
voltage drop  diode test =  B to E .268    B to C .531

The 2n4910 = B .648 E 0 C 0
voltage drop diode test  B to E .516    B to C .516

The transistor tests were done in circuit. Does it look like I need a new 2n4898?

Back to tracing signal...
I'm sending  a  .775vac at 1khz.
While using a home made  audio signal tracing pen (one that connects injected signal to a speaker), I'm getting signal at the "in" connector on relay pcb that heads to the main board with opamps and iron settings.  It progressively drops down as I continue on in the circuit.
I am getting a faint (.084vac) audio signal at r100. after that it disappears. Not sure where to look here. Can anyone suggest things to check?

 

[Spencerleehorton]

Then 0.6v emitter/base rule of thumb on transistors looks like your 2N4898 is faulty.
Other than that I haven't looked any further.

Spence.

 

[duantro]

Then 0.6v emitter/base rule of thumb on transistors looks like your 2N4898 is faulty.
Other than that I haven't looked any further.

Spence.

Thanks Spence,
That's what I thought. I'll get some more and see what that does.
Edit: just noticed that this is reply 666. This beast is sure to sound evol once I get it working!!

 

[duantro]

Well crap, I pulled the 2n4898 and it measures good voltage drop out of circuit. Must be something in line that was altering the reading. I was really hoping it was faulty so my bad trouble shooting skills could be put to an end.  Is the 2n4910 base voltage not quite high enough to cause conductance thru the collector the issue?  Can anyone suggest where to check that would be causing the transistors to read 0v on the collectors? I've triple checked all of the values/ polarity of components and voltage drop/ orientation of transistors in this area. I'm about to lose my mind!
Edit: How high of an ac audio signal should I be seeing at these base junctions?  ...or anywhere prior to here, so I can find where I'm dropping signal.

 

[duantro]

Another day after I've came back in from the ledge, contemplating whether  to throw this thing off, jump off, or both.  I've checked ALL of the resistor values once again. No mysteries here. Ac audio Signal seems to oscillates after vt1 (32vac-0)
Here is a voltage chart I put together to see if it makes any sense.

 

[Bonsaimaster]

Do you have the schematic? I had an oscillation problem and traced it to a blown VT28. Included it here. Sometimes time away from a project brings clarity. Don't give up!

 

[duantro]

While going over the "sharpened" (but still blurry)  original schematic I think I  realize that I have my bcy34 in the wrong spots. I have them in vt 26 in stead of vt 27! Man trying to keep all of the cross referenced and original transistors straight has been a task. Hopefully this will sort out my problem.

Edit: oh hell yes, it is working now!! This thing sounds freaking awesome! Time to calibrate!
Looks like  everything is pretty close with the standard AOT values, besides not looking at distortion calibration yet. Also I am getting .395vac on output,  with a .775 vac input signal. I think others had this also and opted for a 1:2 output transformer and output amp options  to compensate.  I used 1k resistors on a 11 position lorlin switch for the hold, and am going to change them out for the values listed on festers schematic. As is, not much  happens until the last few positions.

 

[duantro]

I have Marinair T1448's on the input, wired 10k:9k6. I'm going to try these as 9k6: 2k5 and see how it sounds.
Here are the spec's that  I've found for them:

Marinair T1448
This is a line bridging transformer. Designed specifically to isolate equipment with previously unbalanced input arrangment, this transformer may be inserted without serious loss of level.
10k/2k5 : 9k6/2k4 ( 2 x 5k : 2 x 4k8 windings )
Secondary load: 9k6 (rated)
Input impedance: 10k
voltage ratio-insertion loss:1dB
Frequency response (600ohms source, 9k6 load): +/-0,3dB (20Hz-15kHz and -0,5dB at 20kHz
Distortion: <0,1% (above 40Hz) and < 0,01% (500Hz-10kHz)
Squarewaves: No overshoot, no ringing,

 

[Ilya]

Has anybody of you guys got an original PDF from Winston? Any chance I can get a copy?

 

[chefducuisine]

I have the documentation of Igor's version if that helps.
You can see mine here: http://groupdiy.com/index.php?topic=63350.0 (Scroll down a bit).

 

[skeeler87]

Does anyone know where I can get boards for this? Would love to give this one a shot!

 

[chefducuisine]

Boards are not available at the moment but member electrochromic is planning to do some in the future:
https://sites.google.com/site/diypartsstore/catalog/pcb-transistors-op-amps-pots

 

[Spencerleehorton]

Anyone know where I can get hold of these pcbs?

Regards

Spence.

 

[desol]

These boards are long gone.  Unavailable for over a year.

 

[Spencerleehorton]

Isn't it time for someone to make some more then?
I only have the facility to make single sided boards, is there any printouts or anything layout wise?

Regards

Spence.

 

[mrclunk]

There isn't any layouts avaliable.
Igor was smart making black PCBs, you can't scan them to make copies I tried before stuffing mine.

 

[bruno2000]

There isn't any layouts avaliable.
Igor was smart making black PCBs, you can't scan them to make copies I tried before stuffing mine.

Don't be so sure..........
Best,
Bruno2000