DChristie's PL 2000

[laatsch55]

Dean sent his 2000 about a year ago to be recapped, 4136 refreshed and the 4739 checked. And anything else Sir Joe and the rest of us can think to improve it. It is a museum quality unit ..

 

[laatsch55]

Pics...

 

[laatsch55]

It came without a 4739...

 

[laatsch55]

The 4739 was in a bag of components that was already replaced...we'll put it in and see if it tests..

 

[laatsch55]

Pretty sick in the gain department. With a 250 mv input we are only getting 1 volt out...in the aux and tuner input...

 

[mlucitt]

Power supply voltage?

 

[laatsch55]

Haven't checked yet Mark...

 

[laatsch55]

We're getting +,- 18 volts to the IC's....

 

[mlucitt]

Plenty of horsepower there. The PL2000 Service Manual says +,- 17 volts, so you are tracking.

 

[laatsch55]

It also says 15 db gain out of the high level inputs of 250 mv....
i'm getting 11.97 and 12.5 db with 250 mv input...

 

[laatsch55]

The phono section gain is wayyyyyy down too....30 db compared top spec of 41 db..

 

[laatsch55]

Got some Brown Dog adapters coming with some OPA 2134's mounted, got some new RC 4136 by TI coming and some NOS 4739's....something is going to work...

 

[Gepetto]

Anybody mess with the resistor values in the gain circuits? You said there were a lot of parts in a bag.

 

[laatsch55]

No resistor changeouts Joe. It looks like it has been altered sometime in the past to a service bulletin that addressed a "fast" 4739, consisting of an RC network added. Apparently there could be some oscillations at 50K if it wasn't followed.

 

[laatsch55]

Some electro caps, some 1N4004's and a 4739 was all that was in the bag..

 

[Gepetto]

How does it A/B compare on gain to one of your other PL2000s Lee? Same for yours?

 

[laatsch55]

Joe I dont have one at this time. It should have 2 volts out with 250mv in on the tuner and aux inputs.
Phono is way down too. Book says 41 db gain at 10mv input. I'm getting 30 db or 300mv out.

 

[wattsabundant]

Look for cracked solder joints on I/O jacks. Low gain at all frequencies? Tone in/out? Coupling caps caps C21, C22, C47-50, C42,43

 

[laatsch55]

Yep, low gain through out, tone out, I'll check the caps..

 

[wattsabundant]

The only problem I had with my 2000 was the volume control didn't go to zero. Sound could be easily heard on any source that was operating. Didn't even try to find a new pot. Gave it to my brother with a 400.