Carver C1 going through rework
- Thread starter WOPL Sniffer
- Start date
so, 2 pre's doing the same thing after a Bill D upgrade that has been performed by hundreds of people before???? My direction of using the correct power up sequence sounds like the key..... Go ask the guys on Carver site.... I'm sure they will tell you to power up the pre first like most people do. Just saying. I don't power up my pre first to see if it will peg the meters, I leave that blunder to others.
They replace all the resistors with new 1% (waste of time), install some Brown Dog adapted OPA134's (no difference detected either) and some other stuff. Recap it etc... I take it a step further with a Power Supply Module, A Holography filter which fixes some problems), add an adjustable gain and the kit for putting in gold plated RCA's
Perry ,
I agree with you on the proper power up sequence ! Seriously I do !
I was just stating that the C1 passes the service manual tests but still thumps.....
Just trying to understand the circuit design and try to figure out why it does it now ?
It didn't "thump" before .....
I'm not sure what you are referring to in you first line
"so, 2 pre's doing the same thing after a Bill D upgrade that has been performed by hundreds of people before???? "
What 2 Pre's are doing the same thing ?
M
I agree with you on the proper power up sequence ! Seriously I do !
I was just stating that the C1 passes the service manual tests but still thumps.....
Just trying to understand the circuit design and try to figure out why it does it now ?
It didn't "thump" before .....
I'm not sure what you are referring to in you first line
"so, 2 pre's doing the same thing after a Bill D upgrade that has been performed by hundreds of people before???? "
What 2 Pre's are doing the same thing ?
M
Even the chumps on other sites know the correct sequence.
https://forum.audiogon.com/discussions/what-is-turn-on-off-sequence-of-amp-and-pre-amp
https://forums.stevehoffman.tv/threads/pre-amp-amp-turn-on-order.293117/
https://audiokarma.org/forums/index.php?threads/preamp-power-amp-on-off-sequence.680378/
https://forum.audiogon.com/discussions/what-is-turn-on-off-sequence-of-amp-and-pre-amp
https://forums.stevehoffman.tv/threads/pre-amp-amp-turn-on-order.293117/
https://audiokarma.org/forums/index.php?threads/preamp-power-amp-on-off-sequence.680378/
With the way i see it Perry; frankly you haven't answered Mohawk's original question at all lol. In other words you have basically said, just mask the issue. As such, i don't really understand why you are calling him a "hard head?" If you think about it, perhaps the reverse? 
I have been keeping tabs on this thread and the way i understand it is as follows...
1 - The BillD mod was completed on a stock and fully functional Carver C1; as such is my own. (thats why i am also trying to understand here...)
2 - A difference was noticed in its function after the mod was completed
3 - The functional difference was checked with the "service manual," and was noticed to coincide with an issue listed under section 4.6 of "General troubleshooting"
4 - As he said, the test of the FET drive circuitry was confirmed functional with the process laid out in sec. 4.6 (screenshot posted prev.)
If the test passes and the FET's are confirmed to be operationally stable, then why is this issue still happening? Do you not think what is happening to Mohawk's unit seems to be contradictory to the service manual provided by Carver?
Give me your expert opinion
Best,
I have been keeping tabs on this thread and the way i understand it is as follows...1 - The BillD mod was completed on a stock and fully functional Carver C1; as such is my own. (thats why i am also trying to understand here...)
2 - A difference was noticed in its function after the mod was completed
3 - The functional difference was checked with the "service manual," and was noticed to coincide with an issue listed under section 4.6 of "General troubleshooting"
4 - As he said, the test of the FET drive circuitry was confirmed functional with the process laid out in sec. 4.6 (screenshot posted prev.)
If the test passes and the FET's are confirmed to be operationally stable, then why is this issue still happening? Do you not think what is happening to Mohawk's unit seems to be contradictory to the service manual provided by Carver?
Give me your expert opinion
Best,
I didn't do the work so I have no idea as to what the workmanship looks like. I don't know how he checked the FET's (Changing them would have worked if they were suspect). Did the outputs attenuate by at least 20dB? What test equipment is he using? I change out all the opamps with NEW 4136's, maybe he has a noisy one since he didn't change any??? Did it happen at all Function Switch settings? What does the noise (pop, thump, whatever) look like on the scope, is the noise specific to +12Vdc??, or -12Vdc? I reflow most every connection on the board, does he have a bad/cold ground SOMEWHERE? That noise, or Thump, or POP during power up can come from any one component in the preamp including the Power Switch. Does it do it when listening through the headphones? It can be a 1000 different things and you need to get out the scope and get "Down and Dirty"... Change all the 40 year old op amps (New TI issue from DigiKey) and skip the Brown Dog OPA2134's and you changed 150 perfectly good resistors risking solder issues/damage/heat etc....