Recent content by punchback

Sorry... I posted before I noticed another page of posts.

It's probably the same as mine was. It also had 3 adjustment pots per channel.

Your PL400 is probably a 4 fin heatsink unit. I have a similar PL400 and ended up going the WOPL route. Here is the link to my upgrade. https://forums.phxaudiotape.com/threads/my-new-early-model-pl400-w-4-fin-heat-sink.8581/

BTW - What is the max size for picture uploads?

Hi everyone it’s been a while. This project has been on the backburner for some time. I’ve been following the DChristie's PL 2000 thread and will use the knowledge gained to make my final assembly better. I was also wondering why there was the break in the ground plane back near the RCA’s. I...

I'm getting some 2.2K 50V caps tomorrow. I'm also going to try +/-15 volt regulators sine I've apparently got enough bulk DC to power them. Per the service manual the 2000 is supposed to have +/- 17 VDC. I'm not sure how they were getting the with a 117/24V CT transformer. Correct me if I'm...

I'm assuming you're talking about the 18.85 VDC I measured initially.

It seems odd that I'm getting +/- 23.5 volts out of essentially the same circuit. When the 2000 was fully assembled I got 18.85 volts. The 23.5 come from an unloaded circuit and my PS has 1k uF filters as opposed to 470uF. Would the unloaded circuit or higher filter capacitance explain the...

I measured the unloaded output of the transformer and it's 17.8 VAC. I think the capacitors being just 25 volts may be a bit on the low side seeing that I'm getting 23.5 volts. Maybe new 2.2k uF 50 volt capacitors are in order?? The schematic I mentioned was based on a 15 vac transformer.

After getting some parts, I'm getting started on the +/- 12 Volt Power Supply that will power the new op-amps. I found a schematic on the internet and ordered parts accordingly. I ordered ST Micro L7812CV and 7912 for the regulators. After ordering the parts based on the schematic I found...

Watts, I hear you about the +/-12. About the TO92 package, on Mouser it looks like they can only supply 100mA. I may be reading datasheet wrong but assuming I'm not, is 100mA enough?

Anyone have any experience with LDO Voltage Regulators? They only need 1.75 volts headroom. I bought a power supply kit but it's going to be a pain to fit in. The more I think about it some perf board and a couple of components would convert the 18 volts into regulated 15 or 12. I guess I'll...

All of the amplification than happens in the 2000 is by either the RC4136 or the RC4739. I know just enough to be dangerous but I believe opamps are limited by the power supply rails. In my case the 2000 with its unregulated supply is making +/- 18.85 volts which is more than the RC4136 and...

I will be doing one thing at a time. Probably start with the Electrolytics. I'm glad to hear someone say that 1/4 watt is fine. I didn't think there would be a need for 1/2 watt resistors. I had already ordered the 1/4 watters by the time I noticed the service manual also said that the...

I’ve recently acquired the subject PL2000 preamp. I’m going to go through it and rebuild it as follows: Replace Electrolytics. Replace CF resistors with 1% Metal Film. Replace op-amps with modern op-amps. Install regulated +/- 15 power supply. For the Electrolytics it will be the standard...