Echo North
Well-known member
ratty_7 said:Seems like bad solder joints on input pot on Unit B the readings are now....
20 = 381.9
12 = 189.1
8 = 128.3
4 = 66.8
So can you calibrate now? Is either unit working?
ratty_7 said:Seems like bad solder joints on input pot on Unit B the readings are now....
20 = 381.9
12 = 189.1
8 = 128.3
4 = 66.8
Hairball Audio said:Q13 is crazy off. You may want to replace it.
jdier said:Just ordered new 2N3708's. Will report back once i have one in.
Again, thanks for the support.
RspenceT said:Hi guys.
Just finished my second 1176 rev d rack build and I am glad to say the unit is working well with one small concern.
Compared to my other slightly older first gen build and to my vintage Urei unit, the input gain seems to be quite high. I have completed the calibration and the output seems to be all good. But i seem to need very little gain to reach the compression threshold compared to the other units. The input pot is right at the bottom of its travel and the output is high.
Could I have wired the input pot/pad wrong?
Seems to me that there is very little between the input and the q1 so perhaps I am not attenuating the input enough.
I have a very decent set of external meters for calibration and testing so I am certain that I am delivering +4dbm to the input.
As I say the unit otherwise is working perfectly. It is just that running the input down that low does not give me much flexibility of movement.
Normally I would run the input pot at around the 11 o'clock position. However on this unit it seems to want to run around the 7 o'clock position to produce the same gain reduction results.
Any insights would be much appreciated
Richard
ashtonv19 said:Got ahead of myself and started a new thread before reading this thread!! Sorry, I'll post my issue once again.
Just finished the build, cleaned up the wiring, calibrated, all is fine. As soon as I attempt to test with a real track, I find that engaging the attack DRAMATICALLY reduces the output. Also turning the output up past 24 results in a pop and nasty interference, pretty much with no output. Completely reset the trim pots and tried calibration again, voltages on the money. Same issue persists. With the attack off, signal is fine until the same output threshold is reached, then the pop and noise is there once again. Everything on the PCB looks fine, nothing is melting, no smoke.
Help?
tkobrick said:I got through 99% of the build this weekend on a pair of Rev. Ds. Amazing instructions, BTW. A couple of quick questions:
Question 1 - Build Guide says there will be a pair of 2n3707 transistors that are taped together because they have been matched, to use for Q12 and Q13. Neither of my kits had a pair taped together, so I avoided putting any 2n3707s in for now - do I need to try and match the transistors myself, or are they all close enough to use any 2?
Question 2 - I put in header pins for the match pair of FETs for Q1 and Q11. Instructions say to put the FETs in the header pins and solder. Is this correct? I should solder the FETs in the headers? Want to make sure this is not a typo.
Thanks! Can't wait to finish these puppies!
Hairball Audio said:Pretty stumped on this one.
If it calibrated normally, and the voltages are normal, it should work fine. However, what you are describing is not at all normal.
Check all the connector headers, especially the 6 pin, for shorts or bad joints. Make sure the pcb has been cleaned of flux.
Mike
ashtonv19 said:The only real struggle I had with a JST was CN10, I could barely get the leads halfway through the PCB. There was no kink in the outside leads as the build guide suggested. So perhaps that's the culprit. All the other headers dropped in nicely.
Hairball Audio said:So does the attack and release daughter board fit ok?
Do you get the weird noise with the unit in GR off mode?
Mike
ashtonv19 said:The attack/return board fits fine, nothing is being strained. CN10 is sitting 1 or 2mm off the PCB.
Yes, I get the noise in any configuration regardless of meter, ratio, or attack/release, even with no signal present. I can try to record a sample and send it later.
Hairball Audio said:Sounds like you have 2 issues.
Issue 1: Meter sits left in GR mode, is most likely an issue with your GR AMP section.
Issue 2: Rumble. No idea...are you passing signal? How did calibration go?
Mike
YoDudeRock said:Mike,
Thank you, you were right, it was two separate issues. And I got the meter working, I was a little sloppy with my solder and created a short. That's fixed.
I thought everything was fine and got it calibrated with no problem, but realized when I twisted the Output knob, while in +4 or +8 meter mode, the needle bounces. All with The rumble is still there.
BTW, I have another working unit, to compare readings.
So, I checked the resistance on the R23 output resistor and it shows odd readings
It reads maximum around 38K ohms, but my working unit reads 128K ohms.
Another anomaly is, the C7 Orange Drop capacitor reads 15VDC on one side and 2VDC on the other
My working unit reads 15VDC and 0VDC .
I was wondering if the Orange Drop is bad or the R23 potentiomenter is bad.
What do you think? I hope all that makes sense.
Thanks,
Chris
ilfungo said:Hi Mike
Just to understand the schematics
Where the last R59 pin go?
Thanks!
Jacob123588 said:Hello all,
So I finished the build and went to power up and it doesn't turn on. After building the power supply I tested it with my DMM following the build guide and the readings were accurate to what they should be. Now as I'm trying to trouble shoot they don't read the same, and I'm not sure why, nor do I really know where to begin, so what do I do? Thanks!