PL 700 II Clair Bros Rising from the Ashes

[Peter S]

Hi Joe, they are 3 contact, Tip, Ring, Sleeve (TRS). All 3 contacts are insulated from the mounting hole.

 

[Gepetto]

Hi Peter
You should have success wiring as you propose as long as the sleeve is left floating although I would be inclined to leave the sleeve inside the 700S2 unconnected. The reason is that the minus of the differential signal will end up going to single point ground in the 700S2 through the control board.

 

[VSAT88]

Hi Folks; It's been a little while! I've taken Perry's advice and replaced all AGX fuse holders with new AGC holders. Yes, I could only find AGC 5 Amp fuses locally. I'm glad I did---found a second broken holder. I'm still far from bringing up even the back-planes but Joe mentions "bring up on DBT and Variac" several times...What is a DBT?
That was my daily dumb question.

DBT = Dim Bulb Tester. I use one regularly. If you would like you can google "Dim Bulb Tester" and get a whole load of ideas to build one.

 

[Peter S]

I have built a Variac box with Volt and AC Amp meter and fuse. It has a switched shunt to increase the Ammeter FSD from 1 Amp, to approximately 3 Amps. I watch the current when powering up. I am inclined to believe that this is (an even better?) substitute for a DBT.

 

[Peter S]

Sexy sexy! Look at those input jacks!.... Keeping it simple; the phone jack ring and sleeve connections have been connected together, but floating from the chassis.
Why is it necessary to connect the input grounds together at the jacks? Is this not a potential ground loop? Depending on the source equipment, wouldn't the ground be common in that unit?
Thanks for any opinions, I always seem to be rocking the boat.

PS: the amp with back-planes and bottom row of outputs (drivers) has been powered up. So far so good. WO rev G board to be installed next!

 

[Gepetto]

Sexy sexy! Look at those input jacks!.... Keeping it simple; the phone jack ring and sleeve connections have been connected together, but floating from the chassis.
Why is it necessary to connect the input grounds together at the jacks? Is this not a potential ground loop? Depending on the source equipment, wouldn't the ground be common in that unit?
Thanks for any opinions, I always seem to be rocking the boat.

PS: the amp with back-planes and bottom row of outputs (drivers) has been powered up. So far so good. WO rev G board to be installed next!

Keep them separated if you have RevG1 and Backplanes installed.

 

[VSAT88]

I have built a Variac box with Volt and AC Amp meter and fuse. It has a switched shunt to increase the Ammeter FSD from 1 Amp, to approximately 3 Amps. I watch the current when powering up. I am inclined to believe that this is (an even better?) substitute for a DBT.

Super nice. I use all three. Ammeter, DBT and Veriac. I like the fact that the DBT is a good visual indicator as well as good at current limiting. Each to their own though. I watch mine like a hawk.

 

[WOPL Sniffer]

I'm just using the Variac now. As you turn it up, I just watch the current (my Variac has voltage and an ammeter) as I turn the voltage up. Best thing I ever did was restoring that Variac I bought.

 

[VSAT88]

They are very nice to have. I think Perry built or rebuilt one in another thread. Seems I remember it was a huge one. Mine is like a 1950 model. Works perfectly.

 

[WOPL Sniffer]

Yeah, I rebuilt one, and restored the one I kept. I haven't needed the DBT for quite some time. As you turn the voltage up, you just watch the current. If the current starts to rise, turn it off and search for your short.

https://forums.phxaudiotape.com/threads/fresh-10-amp-variac-fs-or-trade.8558/

 

[VSAT88]

Perry, do you use an isolation transformer ?

 

[WOPL Sniffer]

Perry, do you use an isolation transformer ?

Thats what a variac is..... It's a transformer

 

[VSAT88]

My Veriac is so old it has no isolation built in. It adjusts voltage only that is why I asked.

 

[WOPL Sniffer]

Perry, do you use an isolation transformer ?

After reading your question again, it's not an ISOLATION transformer. No need for it.

 

[WOPL Sniffer]

Mine is old too. It just looks new.

 

[FredR]

Mine is old too. It just looks new.

Seeing those I'm embarrassed for my poor Variac.

 

[WOPL Sniffer]

Seeing those I'm embarrassed for my poor Variac.

You want your variac restored Fred? It took me a while but I found a NOS Transformer, then I found the meters..... Took it all apart and had the case powder coated, installed a new outlet and switches, and had a new applique for the face made etc etc etc.....

 

[WOPL Sniffer]

My Veriac is so old it has no isolation built in. It adjusts voltage only that is why I asked.

Using it to find faults is no problem. When you have Zero Volts, you have Zero current. As you turn it up off zero volts, you just monitor the current meter... If the current keeps creeping up, stop and turn it back down and troubleshoot your short... It doesn't get much simpler than that. Some of the guys here say you need a DBT AND a Variac.... Bullshit.... You can do it all with a Variac.... I know since I use it every day with the broke dick shit coming in the door.

 

[WOPL Sniffer]

Best part is, if I get up to operating voltage and the current is in the normal range, I don't have to stop and disconnect the DBT and go back to setting the Bias, Idle, or whatever. I just leave it plugged in to the Variac and keep on trucking.

 

[VSAT88]

Using it to find faults is no problem. When you have Zero Volts, you have Zero current. As you turn it up off zero volts, you just monitor the current meter... If the current keeps creeping up, stop and turn it back down and troubleshoot your short... It doesn't get much simpler than that. Some of the guys here say you need a DBT AND a Variac.... Bullshit.... You can do it all with a Variac.... I know since I use it every day with the broke dick shit coming in the door.

LOL. That is how mine is set up. A really old veriac that I attached a modern digital volt/ammeter to. I have the DBT set up where I can use it in circuit or out. I just wondered if you were using an isolation transformer ahead of those.