Search found 9 matches

by amplifiersurgery
Fri Oct 31, 2014 12:05 pm
Forum: Preamps
Topic: Conrad Johnson PV-5 Preamp
Replies: 20
Views: 34480

Re: Conrad Johnson PV-5 Preamp

Here is the unit playing post-restoration. Sounds incredibly detailed and has a fantastic bass definition too. Should be good for another lifetime.
http://youtu.be/51KLffksIx0
by amplifiersurgery
Tue Oct 14, 2014 10:40 pm
Forum: Preamps
Topic: Conrad Johnson PV-5 Preamp
Replies: 20
Views: 34480

Re: Conrad Johnson PV-5 Preamp

I am currently restoring a PV5. This particular PV5 has Amperex tubes. The unit has a very well built layout and a very clean signal path. Here is a picture of the unit under work. Note the Mundorf EVO Silver-Gold-Oil capacitors in the signal path (these are the ultimate Mundorf signal path caps for...
by amplifiersurgery
Tue Oct 14, 2014 10:24 pm
Forum: Preamps
Topic: Capacitors in a PV7
Replies: 2
Views: 1377

Re: Capacitors in a PV7

Hi Mike, We have used Mundorf MCAP capacitors for dozens of CJ restorations in the past and these have worked very well. They have a very long life (over 10,000 hours) and have the same temperature tolerance as the original CJD capacitors. You can easily purchase these from our website (www.amplifie...
by amplifiersurgery
Tue Oct 14, 2014 10:11 pm
Forum: Preamps
Topic: PV-12AL hum issue due to shorted transistors
Replies: 9
Views: 2576

Re: PV-12AL hum issue due to shorted transistors

Folks at CJ told me that their international distributors may have an old schematic that perhaps they could share.
So I am hoping that this forum has some international CJ enthusiasts that can perhaps get a copy of the PV-12AL schematics.
by amplifiersurgery
Mon Oct 13, 2014 4:20 pm
Forum: Preamps
Topic: Any PV7 Experts Out There?
Replies: 8
Views: 4239

Re: Any PV7 Experts Out There?

We restored this particular unit.
The caps on the underside were installed there to further avoid the heat from the tubes. You can see a video of the unit running here:
https://www.youtube.com/watch?v=PUQ7pVuUPPg
by amplifiersurgery
Mon Oct 13, 2014 4:15 pm
Forum: Preamps
Topic: PV-12AL hum issue due to shorted transistors
Replies: 9
Views: 2576

Re: PV-12AL hum issue due to shorted transistors

No worries, thanks for responding and for taking a look. I am sure someone else out there will have the same model too. The only way to access the part is by removing the top plate (just like you would if you were changing the tubes).
by amplifiersurgery
Mon Oct 13, 2014 2:23 pm
Forum: Preamps
Topic: PV-12AL hum issue due to shorted transistors
Replies: 9
Views: 2576

Re: PV-12AL hum issue due to shorted transistors

The pair of transistors are to the right of the tubes. I think one can make out the part numbers on the front transistor and that should be all that's needed. The one on mine shows IRF710 (which is a MOSFET transistor). I want to confirm that it is the original part. I have attached a picture showin...
by amplifiersurgery
Mon Oct 13, 2014 2:02 pm
Forum: Preamps
Topic: PV-12AL hum issue due to shorted transistors
Replies: 9
Views: 2576

Re: PV-12AL hum issue due to shorted transistors

Thanks for the warm welcome. I had a look at the PV-12 schematic and it is quite different. The PV-12AL has many modifications and I am not even sure if this shorted transistor pair should be a bipolar transistor or a MOSFET. I called CJ today and they mentioned that they did not have any schematics...
by amplifiersurgery
Mon Oct 13, 2014 1:46 pm
Forum: Preamps
Topic: PV-12AL hum issue due to shorted transistors
Replies: 9
Views: 2576

PV-12AL hum issue due to shorted transistors

Hi Folks, I am restoring a PV-12AL and found a pair of shorted mosfet transistors near the front right side that are mounted together to the same heat sink. The previous owner had put in incorrect transistors that also burnt many zeners down the line. I am unable to find the schematics for a PV-12AL...