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You are a lucky guy!

First, the PL400 VU meters are occasionally available, the PL700B meters are virtually impossible to find; those would have to be aftermarket. Then, you will need to find replacement Faceplates for your amplifiers because the meter dimensions are not the same. The replacements would have to...

Kyle, Use another pair of tie-wraps on the wires that connect to the Control Board. This will help to keep them out of your way and also prevent breakage. I find that tie-wraps about 1" from the wire ends works really well.

You have already started down the slippery slope.

I like Rod Elliott's projects. I have built several including an stand alone Headphone Amplifier - P113. https://sound-au.com/project113.htm I used the best OPAMP I could find at the time, a Texas Instruments LME49860. It does sound good. I get 250mW output with the 600 Ohm Headphones.

And that very nice Volume control!

Marco, Thank you for that explanation. The PL2000 does not have any output transistors. The Left and Right audio output comes directly from a Quad OPAMP (Z3). This was an RC4136 (14 pin DIP), now an SMD pair of Texas Instruments OPA2134 using a 060601 Brown Dog Adapter in a new gold-plated DIP...

Using Tape 1 or Tape 2 without an external headphone amp does not give me volume control. If I intercept the "Front" Left and Right signals before they get to the RCA Jacks on the back and route them to a Panel-mount Switched Stereo Headphone Jack and then back to the RCA Jacks on the back, I...

Let me ask the question a different way. If you decided to add a Headphone Jack to your PL2000 Preamplifier, how would you do that? Clearly, you would want a clean cut-off of the Output Jacks so that both the rear Outputs and the Headphone Jack were not active at the same time. I would probably...

George, have you ever considered installing a headphone jack in your PL2000? I think these preamplifiers could use a headphone jack... if done correctly.

"the wiper to ground sweep looks like." Sorry, I get carried away. With the amplifier off, set your meter to cover the value of the Treble potentiometer in Ohms. So for a 100K potentiometer, set your meter to 100K Ohms. Or, if your meter is auto-ranging, it will do this automatically...

Could be a bad pot, sending ground to the circuit. If someone turned the pot past the stops, it could be shorting to the case. Pots are pretty easy to check and change out. I would be curious what the wiper to ground sweep looks like.

1784 Incandescent Lamps https://normanlamps.com/1784.html

I would initially suspect noise from a open/broken trace on the PCB. You could try re-flowing the solder runs of the suspect channel in the area of concern and see if that helps. No parts expended in that exercise, and even if it does not cure the problem, it may prevent other problems in the...

Who is Kelly and how do we know he "Works"?

Those 6.3V bulbs should work. You need 8 bulbs to replace all the original bulbs. Or, you could order a new LED Meter Light Board from White Oak Audio in "Warm White" to match the original incandescent bulb color. Then you will not have a heat problem inside your meters and never worry about...

It could be the Bias Adjustment Potentiometer, or several other components on that 50 year old board. It is not advisable to run the amplifier with incorrect bias voltage. The sound will not be affected until it is; the bias is controlling the DC voltage supplied to the Output Transistors, it...

Translation: I am looking for a 400 phase linear VOLUME METER to buy as mine is broken, if you have one for sale let me know thank you

Don, I received them yesterday and installed one today. They are an exact fit (We Have A Winner!). Thank you for searching your parts bin. I you need something from me - it is yours. Sincerely, Mark

RCA 410 Driver Transistors are the consensus here for ruggedness and stability in the Phase Linear Power Amplifier driver position. They are slow, so oscillation is not an issue. The role of the RCA 410 is to set up the bias and drive parameters for the Output Transistors that actually do the...