Man O' War DX - Calibration

[benny_profane]

These voltages look pretty good to me. There some variation but that's not unexpected.

What about your MN3101? Where did those come from?
Do you have a frequency measurement option on your multimeter? It might help if we can verify the range of you clock frequencies across the min and max delay times.

It's not that unusual to hear a bit of clock frequency in the BBD depending on where the clock trimmers are set, but given that there is no delay output at all the problem must reside in either the BBDs or the MN3101.

Thanks for taking a look at this, Brian. I appreciate it.

Good to know that the voltages look alright. None of the variances seem to indicate anything incorrect with the passives? I've gone over everything multiple times, but I'm not seeing anything wrong there.

I got the MN3101s from Paul at diyguitarpedals.com.au and the BBDs from cabintech.

I don't have a frequency option on my DMM, unfortunately.

There is delay when I probe the BBDs, however, it swells to runaway oscillation and is in no way under control—biasing to a 'clean' delay while probing is not possible. I bought four 3101s, so I can try the others. I don't have backup BBDs..

Should I start swapping the clocks and go from there?

[benny_profane]

I'm getting the same response with the other MN3101 clocks from the previous order lot. I now have replacements coming in from SBE. I've never had an issue with MN3101 clocks from them before. If that's the issue, I'm hoping the replacements will be the solution.

[danfrank]

I bought 10 MN3101 from diyguitarpedals.au around 6 months ago and at least 3 were bad. I feel I still came out ahead because he was selling them so cheap so I didn't complain to him. But a percentage of the MN3101s he's selling are bad.
All the BBDs from Cabintech I have bought have been good ICs.
As a side note, all these ICs are very static sensitive. I hope you're using safe handling techniques with these ICs because they are very easily zapped.
Good luck with your troubleshooting.

[benny_profane]

I bought 10 MN3101 from diyguitarpedals.au around 6 months ago and at least 3 were bad. I feel I still came out ahead because he was selling them so cheap so I didn't complain to him. But a percentage of the MN3101s he's selling are bad.
All the BBDs from Cabintech I have bought have been good ICs.
As a side note, all these ICs are very static sensitive. I hope you're using safe handling techniques with these ICs because they are very easily zapped.
Good luck with your troubleshooting.

Cheers. I've got some new devices on the way. I've never had an issue with cabintech either and Paul has been very courteous and more than accommodating when I contacted him—even though I'm not sure it's the clocks at this point.

However, I'm hoping that's the issue because I've gone over this to the point that I've either hypnotized myself into missing something very obvious, or it's a bad IC. On my end, I've been particularly careful—but it's been cold and static electricity certainly becomes more of an issue when the RH drops. I'll report back when I've auditioned the other devices, but I'm taking a break from it for now.

(Seriously though: if anyone has run out of Where's Waldo books, please tell me I've done something boneheaded with population!

[Scruffie]

I'm going to complicate matters and say I don't think it's the MN3101, clocks either work or don't and your voltages seem fine and you are getting some delay so they must work, same goes for BBD's they either work, are extremely noisy when damaged or are dead. I think it's your compander output bias, I don't know why but for some people the low bias is fine and for others it causes issues, this isn't the first time that issues come up in a delay debugging thread. So I would adjust the two biasing resistors (can't bring up the schematic right now to get the designations, the two with an electro to ground in the middle) equally. IIRC @ 12v 36k should bias to half supply (33k would be fine if you don't have that value).

[benny_profane]

I'm going to complicate matters and say I don't think it's the MN3101, clocks either work or don't and your voltages seem fine and you are getting some delay so they must work, same goes for BBD's they either work, are extremely noisy when damaged or are dead. I think it's your compander output bias, I don't know why but for some people the low bias is fine and for others it causes issues, this isn't the first time that issues come up in a delay debugging thread. So I would adjust the two biasing resistors (can't bring up the schematic right now to get the designations, the two with an electro to ground in the middle) equally. IIRC @ 12v 36k should bias to half supply (33k would be fine if you don't have that value).

Cheers. Thanks for the suggestion here. I'm more than happy to try this out; though, I'm a little unsure of where exactly you're referring. Would you mind updating this when you're able to reference the schematic? (I'd attach the compander section of the schematic, but attachments are still disabled.)

[Scruffie]

Between pins 5 & 7 if that helps

[benny_profane]

Between pins 5 & 7 if that helps

Okay, right now pins 5 & 7 both connect to 10k resistors (R17 and R18) to a 10uF cap (C14) to ground. I'll try increasing both of those to 36k and see what happens. Cheers!

[Scruffie]

Them's the ones! It should raise the voltage on pin 7 so check it's close to 6v after the adjustment.

[benny_profane]

Them's the ones! It should raise the voltage on pin 7 so check it's close to 6v after the adjustment.

Great, good deal. I'm pretty sure I only have 33k and 39k in both 1/8w and 1/4w—so I'll give the 33k a shot and see what happens. Cheers! I appreciate the suggestion.

[benny_profane]

Them's the ones! It should raise the voltage on pin 7 so check it's close to 6v after the adjustment.

By the way, this is a significant increase in voltage on that pin—will BBD biasing also need to be compensated? It seems that a big aspect of this circuit is the low voltage leaving the compander.

[Scruffie]

BBD bias should be totally separate, although the input may be hotter. See if it works first
before looking at any adjustments but a BBD bias is specific to the chip, not what's surrounding it.

[benny_profane]

BBD bias should be totally separate, although the input may be hotter. See if it works first
before looking at any adjustments but a BBD bias is specific to the chip, not what's surrounding it.

Okay, the build doc mentions that BBD biasing might need to change if those resistor values are altered so I wanted to see if there might be an issue there. Regardless, I'm going to socket those parts and use that as a start.

[benny_profane]

Three updates:
1) I socketed the replacement clock devices: no change.
2) I removed R17 and R18, installed sockets, and tried 33k resistors instead of 10k. The voltage at pin 7 of the compander increased to ~5.5v, but the same noise occurred when probing pin 7 of the compander as well as pins 3 and 4 of the first BBD.
3) I replaced the MN3005 with a new device: no change.

I think it's safe to rule out the compander, clocks, and BBDs at this point since they've all been replaced with devices from reputable sellers with the same behavior. Any other thoughts on what could be happening here?

[Scruffie]

Damn... well my final idea without a scope is that I see some 'nichion' caps by the compander, are they from Tayda? Not unheard of to get bad caps from them.