Search results

  1. wattsabundant

    PL400 glad I found this forum.

    The original R/C networks are removed along with the original output binding posts. The relay board mounts on the new output binding posts. As Lee said the new R/C network is on the board. The resistor between binding post and input jacks is cut out, at the body of the resistor. This leaves...
  2. wattsabundant

    PL400 glad I found this forum.

    I don't see a fuse on the fan. Those heaters can get quite hot and possibly melt the the AC wiring. I don't think the box is big enough for extended testing. Attached are photos of a loadbank I built for testing inverters at the day job. The wiring is transformer magnet wire with high...
  3. wattsabundant

    Power switch mod?

    The thread is unobtanium power switch. I haven't looked at it in a few years. I just breceived an updated PCB that will allow multiple triac packages to be used. Stay tuned.
  4. wattsabundant

    Wood transistor

    Taking this sideways, does Nav have anything to say about wood?
  5. wattsabundant

    PL400 glad I found this forum.

    400 manual attached. If there is substantial DC on output and no failed drivers or outputs, check Q1-Q5 and associated diodes. If the leads of Q1-Q4 have turned black, change them out. See service bulletins for differences in transistor pinouts. Bias is last thing to check and only after...
  6. wattsabundant

    Audio Research sold by McIntosh Group to former sales director

    Wow, I've been out of the tube scene for 25 years. Didn't know ARC was still around.
  7. wattsabundant

    PL400 glad I found this forum.

    Attached is the 400 manual read it cover to cover. Re-read the troubleshooting sections and service bulletins. See the bulletin that suggests only certain transistors (RCA 410) for the drivers. The channel will oscillate at high frequency with with Motorola MJXXX and 2SD555 used as drivers...
  8. wattsabundant

    PL 3300 Series II rebuild/upgrade

    Whether the pot reads zero ohms or 10 ohms when at minimum position it doesn't matter. You would likely see about the same thing on every pot. For the regulators look at my post #55. On my 3300 I found that the raw voltage from the rectifier at 120 VAC input was 18 VDC. At 110VAC the...
  9. wattsabundant

    Motorola SJ5744-2 TO3 style transistor ID/Info

    They are showing 1985 date codes, if you believe that. I would say it's not very likely they are counterfeit. Probably an OEM's part number. I have a late 70's D.A.T.A. book for bipolar transistors I can check in a few days.
  10. wattsabundant

    PL 700 Series ii power switch

    Yes, I've sold a few here and there but haven't really pushed them. I have a new board being made that will accept 3 different cases. Attached are some photos. The triac mounts on the bottom of the board and connections on the top. The board uses standoffs and the lower screw that the...
  11. wattsabundant

    PL 700 Series ii power switch

    BTW, Mouser sells the mounting bracket. I did some testing a few years back. When the AC switch closed, I recorded inrush currents up to 145 amps. I developed a PCB and a solidstate switch (triac) to do the heavy lifting. The triac has a max input current rating much higher than anything...
  12. wattsabundant

    PL Similar to Dynaco - Is The Transformer The Real Basis For WOPL Rebuilds?

    This thread started out with a mention of Dynaco transformers which is my direction here. My first real job in 1978 was at Custom Coil in Zanesville, Ohio. I was more or less an engineering tech. I learned a lot about transformers that I never wanted to know. It was BORING. I did a lot of...
  13. wattsabundant

    Phase Linear 400 Series II Input Sensitivity Question

    It seems to me that Wombat is drawing a correlation between the maximum output level of the preamp and the maximum output power of the amplifier. According to his statement, the amp only needs 1 volt from the preamp to achieve maximum output, about 210 watts. Any further increase in the...
  14. wattsabundant

    Mark goes at it again... just bought a PL700/II!

    has anybody tried the generic stuff on Amazon? Since I bought a Hakko desolder gun I don't used much wick any more.
  15. wattsabundant

    To ground or not to ground?

    Does anybody know what the National Electric Code (NEC) says about a 3 wire receptacle that leaves the ground pin floating? Is it a code violation? One of the conclusions of the app note reads as folows: NEVER, NEVER DEFEAT THE SAFETY GROUNDING of any device having a 3-prong power cord. The...
  16. wattsabundant

    Power transistor help

    First you have to adapt the transformer to the chassis which likely means a pieced of sheet metal. It may not be relevant, but the C500 inverts one channel and then reverses the polarity of the binding posts. Using the Carver transformer in a 700 chassis will reduce transistor heat dissipation.
  17. wattsabundant

    PL400 Series 2 Build

    I've got an 87 (with no version number like this one). It's never been in for cal but still reads consistent with calibrated instruments.
  18. wattsabundant

    PL 2000 SII Preamp Issues

    Crowbar the output with a miniature relay powered off of the rectifier.
  19. wattsabundant

    Help Needed With Self Inflicted WOPL Build Wound....Above My Pay Grade

    Variacs do not limit current. A 100 watt incandescent bulb in a dim bnulb test set will limit current to less than 1 amp. Always use the dim bulb test set when powering up any project the first time. I use 25 to 40 watt for small receivers, preamps and signal processors. Loud hum suggests...
  20. wattsabundant

    You got lucky with the open 2.7k resistors. When they fail the amp usually dumps DC into the...

    You got lucky with the open 2.7k resistors. When they fail the amp usually dumps DC into the speakers. Also the feedback cap and several of the display caps are failure prone. I've got a drop in relay board to protect speakers against amplifier failure. It bolts on to the binding post so no...
Top