Search:

Type: Posts; User: Pedro Vecino; Keyword(s):

Page 1 of 18 1 2 3 4

Search: Search took 0.02 seconds; generated 22 minute(s) ago.

  1. The main feature of the EF86 Miniwatt Dario,...

    The main feature of the EF86 Miniwatt Dario, Valvo, TFK and other European Philips models is the treble dimension and its articulation capacity. It can be interpreted as brighter than a Svetlana or...
  2. Replies
    25
    Views
    212

    That effect of volume drop when activating the...

    That effect of volume drop when activating the tremolo I have only found it with very old defective/degraded or poor quality optocouplers. The volume drop is usually also associated with the low...
  3. The two connections that usually generate more...

    The two connections that usually generate more problems (feedback, bad sound...) in the 2204 circuit are the input (to V2A grid) and the output (from potentiometer to V2B grid). It īs advisable to...
  4. Replies
    126
    Views
    17,846

    A detail about these amplifiers is that...

    A detail about these amplifiers is that transistors 1 to 8 are not 2SK233 as indicated in the schematic, but 2SK223, already discontinued. Yesterday looking for a substitute for a defective one...
  5. Replies
    5
    Views
    185

    Clean channel does not have hum originally but it...

    Clean channel does not have hum originally but it does have more hiss than the lead channel with medium gain.
    Sometimes some Russian 12AX7 generate an abnormal hum. If you have equipped it with...
  6. Replies
    27
    Views
    765

    I have always wanted to know which brand sells...

    I have always wanted to know which brand sells that type of adhesive. Does anyone know the name they usually have (composition, tradename?).
    Thanks!
  7. The scheme you have put is that of the old model...

    The scheme you have put is that of the old model (not multi-watt).
    Sometimes the group of four power diodes for the switching circuit fails. At least in the old model, due to overheating /...
  8. I've seen it several times in old models. The...

    I've seen it several times in old models. The system I use to identify those amps susceptible to it (with the same origin as the bias drifting) is looking at the switches. Screen printing is also...
  9. Replies
    15
    Views
    384

    If you have known parameters for 6CA7 or EL34,...

    If you have known parameters for 6CA7 or EL34, use it. At least as a relatively close reference.
  10. Replies
    2
    Views
    302

    Remove the rear panel and the four upper screws...

    Remove the rear panel and the four upper screws that hold the chassis. I think there is no more.
  11. Replies
    17
    Views
    746

    Itīs an attempt to build a Princeton reverb in a...

    Itīs an attempt to build a Princeton reverb in a very small chassis while retaining a board of the same size as the original. A framing problem that started in minute 1.

    Approximately:

    55521
  12. Replies
    17
    Views
    425

    It has a somewhat complicated location and is...

    It has a somewhat complicated location and is fixed only at two points, but I would measure it to find a substitute.

    Like this for example:

    https://www.hammfg.com/files/parts/pdf/1750M.pdf
    ...
  13. What bias measurement system do you use? The...

    What bias measurement system do you use? The Blues junior is known for the tendency towards oscillation on one side when the connections of the plates are extended outwards.
    To avoid this, simply...
  14. For switching input signals, no problem. They are...

    For switching input signals, no problem. They are the ones that Engl uses, for example.

    But for speaker switching you need something stronger since itīs a critical function. As a reference, Mesa...
  15. The idea is a unit located above the amplifiers...

    The idea is a unit located above the amplifiers (like any attenuator) and make the change remotely with a footswitch.
    Grounding of the output on the inactive amplifier works as long as the amp input...
  16. Replies
    36
    Views
    1,362

    The loop circuit in that amplifier incorporates...

    The loop circuit in that amplifier incorporates two active elements (the two halves of a 4558 if I remember correctly). Apart from possible mechanical problems with some contacts in the jacks, the...
  17. I was referring to the common type of signal...

    I was referring to the common type of signal relay switching used in amps (Finder, Omron, etc.).
    This is the scheme:

    55434
  18. But the output of the inactive amplifier is not...

    But the output of the inactive amplifier is not open. Itīs also bridged through the relay. Nothing bad should happen.
    At least I have never seen a problem with that kind of protection.
  19. I would do it that way: a standard signal relay...

    I would do it that way: a standard signal relay for assignment to each amplifier and a powerful relay for switching amps to the speaker. Both synchronized.
    Muting the signal input in the inactive...
  20. Replies
    36
    Views
    1,362

    What happens if you insert a jack-jack cable into...

    What happens if you insert a jack-jack cable into the send/return? It could be a problem of the loop itself that goes unnoticed when you don't use it.
  21. Replies
    141
    Views
    3,804

    I've seen the video. That kind of sound artifacts...

    I've seen the video. That kind of sound artifacts (not a distortion in the usual sense) I associate them with a defective output transformer.
    The first thing I would do is measure the resistance...
  22. That amp looks like a copy of the Fender Blues...

    That amp looks like a copy of the Fender Blues Junior with 6L6.
  23. Replies
    141
    Views
    3,804

    I imagine you have both channels assigned to...

    I imagine you have both channels assigned to reverb and vibrato, right? It only has a 220K resistor connected at the PI input.
    Measure resistors around this circuit: 82K / 100K / 2 x 1M/ 470R / 22K...
  24. In my opinion the best packaging system is the...

    In my opinion the best packaging system is the one used by Hammond. I think itīs urethane foam. Volume is multiplied by approximately eight but the safety is complete.
    I always keep some boxes of...
  25. So is. The original reference is essential.

    So is. The original reference is essential.
  26. Iīve searched for videos of that model and the...

    Iīve searched for videos of that model and the first fifteen or twenty that I found on youtube were the modern version. This is the old version. In combos the dog bone shaped metal plates that hold...
  27. Here is the schematic: ...

    Here is the schematic:

    https://music-electronics-forum.com/attachment.php?attachmentid=47693&d=1521589896
  28. I hope this doesn't happen in the amp... ;) ...

    I hope this doesn't happen in the amp... ;)

    54972
Results 1 to 28 of 500
Page 1 of 18 1 2 3 4