last step C84 voltage measurement... 295mv! Can't get to 0V.

Post questions or comments about the C84 here.

last step C84 voltage measurement... 295mv! Can't get to 0V.

Postby billkahler » Sun Jul 16, 2006 9:23 am

Step 43 of assembly - I've tried to adjust R33 so that voltage at Pins 2 and 3 shows 0v, but it will not go lower than 295mv. I'm sure I'm measuring the correct pins.

Everything else checks out fine. U1 is considerably warmer (hotter) than U2 if that means anything. I do have the correct R33 - it's labeled 202.

Sure am looking forward to recording some acoustic guitar with this pre. . . .

Thanks in advance for the help.
billkahler
 
Posts: 25
Joined: Tue Jul 11, 2006 7:59 pm

no luck yet

Postby billkahler » Tue Jul 18, 2006 8:33 am

After trying some other things, I replaced Q5 which I thought might be damaged.

I did some more adjusting. Voltages at Conn 2, pins 2 and 3, showed 280mv, and if I turned R33 clockwise, those voltages got up to around 350 mv. Then I realized R29 was fully clockwise, so I checked voltages with it fully counter clockwise and came up with the lowest voltage reading 120 mv. Maybe R33 is bad?

Should I plug in a mike and try it out or do I still have a major problem somwhere? Everything up to this point has checked out.

U1 is hot to the touch if that tells anything. U2 is pretty warm but not as warm as U1.

Any help would be greatly appreciated.
rootsy folky rock five buck cds at
cdbaby.com/all/billkahler and free downloads at billkahler.com
billkahler
 
Posts: 25
Joined: Tue Jul 11, 2006 7:59 pm

Postby tpryan » Wed Jul 19, 2006 12:47 pm

What's happening at step 40 and 41?
tpryan
Site Admin
 
Posts: 2078
Joined: Thu Dec 04, 2003 11:32 pm

step 40 and 41 check out fine

Postby billkahler » Wed Jul 19, 2006 7:20 pm

Step 40 and 41 check out fine - 0V, or very close considering the accuracy of the DMM.
rootsy folky rock five buck cds at
cdbaby.com/all/billkahler and free downloads at billkahler.com
billkahler
 
Posts: 25
Joined: Tue Jul 11, 2006 7:59 pm

Postby billkahler » Sat Jul 22, 2006 7:18 am

Still trying to figure out this voltage thing. Everything up to this point checks out fine but can't get the last voltage down to 0V. Anything else I can check?
rootsy folky rock five buck cds at
cdbaby.com/all/billkahler and free downloads at billkahler.com
billkahler
 
Posts: 25
Joined: Tue Jul 11, 2006 7:59 pm

Postby billkahler » Sun Jul 23, 2006 1:00 pm

Got the voltage all reading correctly and plan to try it out tomorrow!
rootsy folky rock five buck cds at
cdbaby.com/all/billkahler and free downloads at billkahler.com
billkahler
 
Posts: 25
Joined: Tue Jul 11, 2006 7:59 pm


Return to C84

Who is online

Users browsing this forum: No registered users and 6 guests

cron