Jon Patton's (midwayfair) clipper ship: very low volume, funky dirt.

[ch1naski]

so, jon....

before i rip the board out of the box (yes, yes i know....i boxed it before i rocked it. i usually have pretty good luck. not this time...) i reflowed all the solder joints, swapped out the clipping diodes to 1n34a's that i know are good, triple checked the values of all parts, swapped out Q1 with a silicone tranny of roughly equal gain (hfe min:45).

I'm getting these voltages off a battery that is ~9v even:

q1: emitter     - 340 mv
      base       - 642 mv
      collector  - 8.86 volts

i know that is totally wrong.

before i go any further, i will tell you that i am getting almost equal voltage readings on either side of the D1 diode (1n5818) : 9volts on the anode, 8.9 on the cathode.

something don't seem right there.

i'm thinking the diode could be bad?

thoughts?

[midwayfair]

i know that is totally wrong.

That's not totally wrong. Those look about right except that the collector is a little high.

D1 is the polarity protection diode. All it does is block the wrong polarity voltage from passing. The 5817 has a very low forward voltage drop, so the readings will be almost identical. If the diode were bad, it would just pass voltage. You wouldn't get any polarity protection, but the circuit would work.

When you get a chance, post pictures, but I'm going to go ahead and suggest double checking R4 and R10, to make sure you used 270R and 560R, and not 270K and 560K.

Also, have you audio probed the circuit to see where your signal is dropping?

[midwayfair]

Also, what transistor ARE you using, and did you verify the pinout?

[ch1naski]

Thanks for the reply, Jon.

I will check those resistors again.  And also get the transistor number. (I'm at work now)

The Pinout of the silicone tranny that is currently installed is correct, verified from a data sheet. The MP 38a pinout was a little tricky to decipher, but at least I can read some Russian now

(I should make it a project to take all the Russian data sheets and transcribe them, for common transistors that we use. Maybe post a thread for them.)

I have not audio probed yet, but I have my probe ready for action after work.


I'll also get some detailed board photos.



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[midwayfair]

I should make it a project to take all the Russian data sheets and transcribe them, for common transistors that we use. Maybe post a thread for them.

I speak Russian; if people want to give me some datasheets I guess I could post partial translations (of the important parts).

[ch1naski]

So..
I've spent the last hour audio probing the circuit. It's odd.  Always below unity gain wherever I probe. And the volume control never works. Sometimes the tone control functions, depending on where I test, but I get the same funky dirty signal. I've swapped the transistor in Q1 with a higher gain device (2n2222a), and it's louder, but still below unity. And same weird distorted signal. Nowhere in the path do I get a normal, boosted signal.I can't pinpoint it. I've swapped diodes, FET's and the bjt.

Here are a couple of pics, hope these help.


Even after the first 1uF cap in the path, dirty funky low signal.  makes me think I should pull the jacks.

Transistor voltages to follow, but I need to go to bed....work at 4 in the morning.

Hope this helps a little. I am really looking forward to this circuit.

I may just pull the board completely and test it like that.

[midwayfair]

I really think you're going to have to pull this from the box to eliminate anything to do with the enclosure as part of the problem.

If the signal is clean at the input pad and dirty after the input cap, there's only a couple components at that point. Pull the germanium stabilization diode, see if that helps. You can also just pull Q1 and probe where the base would be and see if your signal is dirty there. I'm not sure exactly what it means if it IS dirty at that point, but we need to determine EXACTLY where signal is getting messed up at the start.

It's also weird that your volume pot is not working, but we'll cross that bridge when we have amplified signal at Q1 and Q2.

[ch1naski]

I really think you're going to have to pull this from the box to eliminate anything to do with the enclosure as part of the problem.

If the signal is clean at the input pad and dirty after the input cap, there's only a couple components at that point. Pull the germanium stabilization diode, see if that helps. You can also just pull Q1 and probe where the base would be and see if your signal is dirty there. I'm not sure exactly what it means if it IS dirty at that point, but we need to determine EXACTLY where signal is getting messed up at the start.

It's also weird that your volume pot is not working, but we'll cross that bridge when we have amplified signal at Q1 and Q2.

Yea, I have the feeling that I'm just not seeing the major screwup on my part. The board will come out tonight.
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[ch1naski]

I am just livid.

I lost my one and only MP38A.

[midwayfair]

I am just livid.

I lost my one and only MP38A.

"Lost" -- fried, or misplaced?

I can give you another after it's up and running if you fried it. In the meantime while troubleshooting, you can use a silicon or even a mosfet.

[ch1naski]

I am just livid.

I lost my one and only MP38A.

"Lost" -- fried, or misplaced?

I can give you another after it's up and running if you fried it. In the meantime while troubleshooting, you can use a silicon or even a mosfet.

I mean, I have no idea where it went. I'm usually anal about germanium, I can't find it anywhere.
I have a low gain silicon that I got from Joe Gagan I will use. I had planned to take the board out tonight, but I think I'm going to wait. Too disgusted with myself.

Going to apex Jr's warehouse tomorrow. I'm going to see if there's stuff we as a group might be interested in (besides vactrols).
Although since I missed out on the group buy, I'm going to grab 10 for myself. Planning on building a few tremolos for the kid and a friend (and myself).
Cardinal being one of them.
Any plans on a pcb layout that's printable? I thought I saw someone had done up a cad layout?
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[midwayfair]

Any plans on a pcb layout that's printable? I thought I saw someone had done up a cad layout?

You mean an etch? There's a single-sized layout in the build doc, page 4. https://docs.google.com/document/d/1dPlB8Lqn_a1A6Xpb3Lg-2cfTxGCLOkMfNUWALyGE3ZQ/edit

[ch1naski]

I mean, for the cardinal trem. ( sorry, it's a bit off topic.)

On topic, though....I found the mp38a last night. Around midnight. After a solid hour and a half tearing the place apart.
Of all places, it was in the ashtray. I almost threw it away.

That got me in a better mood (along with a little pinot noir), so I decided to start pulling the board and came across a couple of wires on the switch that literally snapped at the solder joints when I moved them (the wires were hidden by the switch board, only the solder side was visible). They just happen to go to the pcb In and Out pads from the switch. Hmm.

Thinking maybe that is the problem, I did a quick repair. But it was way too late to actually test it. I have not had the best results with the pre bond 26 wire from smallbear.

I'll know in an hour or so if that was the problem.

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[midwayfair]

I mean, for the cardinal trem. ( sorry, it's a bit off topic.)

Oh. I could give you the DIY Layout Creator file, and you could convert my perfboard layout to an etch. It won't be the tidiest etch build, and it requires some miniature parts (a couple tantalum caps and multilayer ceramic caps). You might want to wait for the PCB release (I'll let that get announced in its own time) -- probably a little over two months away. I've seen the proto layout and it's an excellent layout. Plus they'll be red. Based on the two-sided layouts I made for myself, I doubt there will be an "official" single-sided layout. It's surprisingly complicated routing because of the way the split trem stages are set up.

Er ... but, yeah, off topic.

Just a reminder: When you're working with the silicon transistor, I recommend pulling the temperature protection diode on Q1 regardless. There are times when it will make a silicon just stop working.

[ch1naski]

I mean, for the cardinal trem. ( sorry, it's a bit off topic.)

Oh. I could give you the DIY Layout Creator file, and you could convert my perfboard layout to an etch. It won't be the tidiest etch build, and it requires some miniature parts (a couple tantalum caps and multilayer ceramic caps). You might want to wait for the PCB release (I'll let that get announced in its own time) -- probably a little over two months away. I've seen the proto layout and it's an excellent layout. Plus they'll be red. Based on the two-sided layouts I made for myself, I doubt there will be an "official" single-sided layout. It's surprisingly complicated routing because of the way the split trem stages are set up.

Er ... but, yeah, off topic.

Just a reminder: When you're working with the silicon transistor, I recommend pulling the temperature protection diode on Q1 regardless. There are times when it will make a silicon just stop working.

I'll wait for your boards. I like to support the community.

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