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  1. d3imlay

    Marantz 105 bulb replacement

    The back to back/reverse parallel idea works most of the time. In this case the LED had to fit in a small cartridge and there wasn't space for 2 LEDs.
  2. d3imlay

    Marantz 105 bulb replacement

    I installed yellow/white LEDs for the indicators. Buy them direct from Parts Express. For the dial light I had a white LED in the drawer that fit perfectly. I used a series 1N4148 diode and a current limiting resistor. I don't remember the value.
  3. d3imlay

    Marantz 105 bulb replacement

    I have a Marantz 105 tuner that needs the lamps replaced. I saw one Youtube video for a Marantz receiver where they went in from the front. It looks very difficult to try accessing the bulbs from inside? Suggestions?
  4. d3imlay

    How does a protection circuit actually work?

    If I recall right, the 2245 and the 2270 are earlier versions that were replaced with the 2250 and 2275. The 2275 has the same shorting connection between pre out and main in found on the 2325.
  5. d3imlay

    How does a protection circuit actually work?

    I have a 2245 and associated service manual. The headphone jack signal goes through a voltage divider resistor network to reduce the level. The signal is taken, schematically, from the input side of the speaker switches. These inputs are protected by the output relay. Consequently, so is the...
  6. d3imlay

    Central Ohio, specifically Columbus anyone.

    Anything happening anytime soon?
  7. d3imlay

    Phase Linear Model 200 II Blown

    I was a part of the industry to keep the rockers rocking. Today I still do a few repairs here and there. I designed drop in relay boards for the 400 & 700. https://www.wattsabundant.com/
  8. d3imlay

    Phase Linear...good looking, impressive specs, POOR quality?

    The 200 had reliability issues. The 200II was an improvement. Surprised to find your still works. I have the manual but it's too large to attach here.
  9. d3imlay

    Phase Linear Model 200 II Blown

    Many found their way in rock and roll systems for which they were not intended. Properly supported in a rack with fans they would hold up.
  10. d3imlay

    Phase Linear Model 200 II Blown

    The 200 was a disaster. The 200II was an improvement. Both versions had an output relay. Problem is the contacts could weld. A replacement relay needs to be a form C which has a normally open and normally closed (NC) contact. The NC contact shorts out the binding posts when it disengages and...
  11. d3imlay

    Any Phase Linear Experts out there?

    The caps are slow down caps from base to collector to stop oscillations. The driver board is the full comp (latest) version. Latest = 1981
  12. d3imlay

    Phase Linear 4000 Preamp Euro 220v model

    The only difference is the input transformer to accommodate the line voltage.
  13. d3imlay

    Carver C-500, in trouble now.

    Contact me for info on protection relay
  14. d3imlay

    Quencharc question

    The data sheet for Paktron quencharcs has scope photos of arcing switches with and without a quencharc. .1uf/100 ohm is a default value. They do the job. However the inrush current at turn on is still going to be hard on the switch.
  15. d3imlay

    Dyna MK3 blown fuse

    I did not run the amp continuous with a load on it. I did do load testing for THD, frequency response etc. The fact that I could consistently see the bias current run away on one tube, and replacing that tube stabilized the bias current, seemed conclusive that the tube was at fault.
  16. d3imlay

    Dyna MK3 blown fuse

    The resistance on the output transformer was 68 ohms on the blue tap and the blue /white tap was 79 ohms. I set up 2 Fluke 87's on the bias pin (pin 8 on the preamp socket) to confirm they both read the same. Then I moved one to the blue tap and one to the blue/white tap.. With a third meter I...
  17. d3imlay

    Dyna MK3 blown fuse

    Would have to modify the amp to check bias individually. Don't want to build a test set. I would expect a bad cap to show up instantly. Can cap has been replaced. Didn't check date code but believe it is OK.
  18. d3imlay

    Dyna MK3 blown fuse

    It's been about 20 years since I've worked on tubes and I'm a little rusty. I have a Dyna MK3 on the bench. It was brought to me with a blown fuse. It has a relatively new driver board and Gold Lion KT88's. I installed the 3 amp fuse and walked it up with a variac/light bulb and all was good...
  19. d3imlay

    Knight KG-600B Tube Tester

    I have some KT88's to test. I have a Sencore TC162 tester that I haven't used in 25 years. I recently had a Knight KG-600 tester given to me that's in pretty good condition. I could not specifically find the KT88 in the roll chart. There is a KT8. Thus far I haven't figured out how to set...
  20. d3imlay

    How to tell if Phase Linear 700ii has upgrades

    I fail to understand why a quasi comp amp would run hotter than a full comp. The bias determines the heat dissipation and the current path is between V+ and V-. Furthermore upgraded transistors may be slightly more reliable, but do not increase output power. Ouptut is a function of the power...
  21. d3imlay

    Marantz 250 Output Transistor Replacement Question

    If the amp has a failure that dumps DC on the output, the relay attempts to disconnect to protect the speakers. If you look at the contact rating, you'll likely see that the contacts are rated for 250 VAC and 32 VDC. The reason for the low DC rating is that when the relay opens arcing occurs...
  22. d3imlay

    Protection in firing up an old amp

    Variacs don't limit damaging currents. DBT does. Been using it for 40 years, never fails to protect. 100W bulb on 200W/C amp. 25W bulb for preamps etc.
  23. d3imlay

    Phase Linear 2000 RCA jacks..... ( ! )

    Any substitutes should not be mounted/grounded to the rear panel. The original jacks are floating and grounded to the board. Otherwise hum and buzz is likely.
  24. d3imlay

    Building a poor mans variac

    Here is a version of DBT that mounts in a 4" box
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