Recent content by pwauk12

  1. pwauk12

    NAD 2600 Power Envelope and 1300 Preamp. Speaker protection fuse

    It could be any number of things, however on the assumption(s) that the speakers where the same as usual, the volume was not ear bleeding, and that incoming signal did not have a large surge (pop/click etc), then it likely indicates that there is an underlying potential problem. If this...
  2. pwauk12

    NAD 2600 Power Envelope and 1300 Preamp. Speaker protection fuse

    The protection circuit kicks in when there is a problem, could it have been the soft clipping indicator?
  3. pwauk12

    Apt Holman Preamp Toggle Switch Pop Problem

    no problem, I am am wondering whether the problem my be (and forgive me for asking this- but I have also done this myself), self inflicted? I would suggest using a magnifier and bright light to look for track breaks, check the +/- on pins 4 and 8 of each IC, look for small solder links etc.
  4. pwauk12

    Apt Holman Preamp Toggle Switch Pop Problem

    the black transformer will support the OPA2134
  5. pwauk12

    Apt Holman Preamp Toggle Switch Pop Problem

    Is your transformer black or covered in a metal case? This would seem to suggest that the popping problem is in the mode stage, between the R>L switching and high filter. The rushing noise problem is likely correlated, and that implies as it rises with volume, that it is part of the gain stage...
  6. pwauk12

    Apt Holman Preamp Toggle Switch Pop Problem

    also does the tone defeat switch make any difference?
  7. pwauk12

    Apt Holman Preamp Toggle Switch Pop Problem

    so the problem is from volume control to the output-if you have extra IC's you might try swapping them to see if the noise/popping moves you might consider OPA2134- expensive but very good You mentioned you added some additional bypass caps (what are they?)- I would suggest removing them if...
  8. pwauk12

    Apt Holman Preamp Toggle Switch Pop Problem

    The rushing noise could be either transistor or IC- though if you have replaced them all that is unlikely. What IC did you use for the volume section? Does the pop occur on the tape outputs or external processor outputs?
  9. pwauk12

    NAD 1600 Monitor Series Tuner/Preamp... sonic upgrades?

    I use an RC206- which is 2A, not that the circuit will draw much current
  10. pwauk12

    Possible error on Kenwood ka701 schematic...

    Quite often the service manual says one thing (4.7uf) and what is installed is another thing (10uf). A safe choice is to replace like with like, that is 10uf. Kenwood may have changed the part because of an improvement or because that was what was available at the time and this is not an...
  11. pwauk12

    Kenwood KA 6000 Thumping Sound After Changing Our Amp Board Transistors

    I seem to remember in some Kenwood's, KSC458's should be replaced with KSC1815- there was a post here or on DIYAudio explaining why Did you replace all the caps?
  12. pwauk12

    JBL SA600 preamp transistor help.

    @johnhoef - good to know-enjoy...:)
  13. pwauk12

    NAD 2400 output transistors fried substitute recommendations???

    The 2SA1370/2SC3467 could be replaced with KSA1381/KSC3503 2SA970 = KSA992 and 2SC3423 = KSC2690 probably
  14. pwauk12

    JBL SA600 preamp transistor help.

    From some research of others who have replaced these transistors the following is suggested- NPN- 2N5827/PNP 2N6003/BC550 I have not tried these- but hope this helps,I think many low noise types could be suitable
  15. pwauk12

    Three Best Preamps from NAD: 1300, 1240 and 1130?

    I have just refurbished another 1130. The IC is used is am LM4562, however I added two 18v zeners to reduce the voltage to the IC to around 17.3v and paralleled them with tow film 0.01uf caps for power supply noise. The unit measured very well and sounds great. As with most of my work, I...
Back
Top Bottom