Search:

Type: Posts; User: glebert; Keyword(s):

Page 1 of 18 1 2 3 4

Search: Search took 0.02 seconds.

  1. Replies
    4
    Views
    53

    This appears to be a pretty simple tube PT, no...

    This appears to be a pretty simple tube PT, no low voltage windings for op amps or anything, no tube rectifier heaters either.

    56712

    Maybe something like the Edcore XPWR002? ...
  2. I think Q6 needs to be scrutinized, based on the...

    I think Q6 needs to be scrutinized, based on the fact that current appears to be flowing into its base (because of voltage drop across R35) despite it being reversed biased. See discussion in #13-15...
  3. Replies
    8
    Views
    107

    You kind of lost me on this one. Using a model...

    You kind of lost me on this one. Using a model like this for the parasitics of the capacitor, an increase in the parallel resistance makes the capacitor more ideal. Did you mean an increase in...
  4. Replies
    8
    Views
    107

    Capacitors as diagnostic tools

    I've thought about this a few times and don't know that I have seen anyone say anything for or against the idea. The question is if you have a situation where you suspect a capacitor is bad, can you...
  5. Yes, I had mentioned this up in #6.

    Yes, I had mentioned this up in #6.
  6. There is current flowing through R35 (about...

    There is current flowing through R35 (about 0.3mA) to cause that 20V drop, so it is either going into the base of Q6 or C16 is leaking it to ground. Usually for reversed biased transistor I expect...
  7. I'm trying to figure out how the BE junction can...

    I'm trying to figure out how the BE junction can be reversed biased while current is flowing into the base.
  8. Thinking out loud, without the clearest head: ...

    Thinking out loud, without the clearest head:

    Going back to Q8, it is very strange that there is only a 0.1V drop across R39 (a 2 watt 180 ohm part), yet there is a 1.6V drop across R38a (220 ohm...
  9. Is the voltage at the collector of Q1 reading...

    Is the voltage at the collector of Q1 reading 0.014V? That seems pretty suspect to me. I don't know what Q1 and Q2 are supposed to be doing, but it looks like they are both shorted out. I don't know...
  10. Replies
    7
    Views
    173

    I do a little microbusiness buying (or trading...

    I do a little microbusiness buying (or trading for) broken gear, fixing it up, and then selling it. I tell anyone buying an amp from me if it has a problem within a week to contact me and I will fix...
  11. I think Q4 too. Also some of the transistor types...

    I think Q4 too. Also some of the transistor types are labeled wrong (NPN vs PNP), just don't want you to confuse yourself.
  12. Replies
    6
    Views
    190

    Here is a gutshot of a BV1001T. You say PSU is...

    Here is a gutshot of a BV1001T. You say PSU is OK, have you checked voltages at the tube sockets? Have you tried new tubes? Wiggling cables and connectors?

    56627
  13. So based on the Magnatone site it sounds like you...

    So based on the Magnatone site it sounds like you have the "second M15A" variant? Does it have the tone and echo controls? The schematic they have for the late 65 M15A has a part number that is...
  14. I remember going into Westwood Music in LA back...

    I remember going into Westwood Music in LA back in the early 00's and the owner Fred came up to us and asked "Have you played the $100 guitar?" At first I thought this was because he thought we...
  15. My son bought a Squier strat at a thrift store...

    My son bought a Squier strat at a thrift store for $20. It is a basic Bullet model, thin and light body with a hardtail. It has the absolute best "strat" pickups I've found. The other day I played a...
  16. Replies
    59
    Views
    968

    V2b is not used and is grounded out according to...

    V2b is not used and is grounded out according to schematic. https://www.thetubestore.com/lib/thetubestore/schematics/Fender/Fender-Blues-Deluxe-Reissue-2004-Schematic-Rev-A.pdf
    240V sounds right...
  17. Replies
    15
    Views
    299

    I wonder if Yamaha will be more friendly with...

    I wonder if Yamaha will be more friendly with sharing repair manuals than whoever owned Ampeg last. I was basically told to get lost when I asked about getting support for an SVT7 Pro a couple of...
  18. I find this kind of intermittent and short...

    I find this kind of intermittent and short duration problems to be some of the most frustrating to diagnose. It sound like it is somewhat repeatable, though, which is better than something completely...
  19. Replies
    15
    Views
    299

    By high voltage do you mean the +/-55V? Just want...

    By high voltage do you mean the +/-55V? Just want to differentiate from the initial rectified DC which should be something like 160V (I think). I am curious what U7 is doing. Some sort of power good...
  20. Replies
    15
    Views
    299

    What is the IN to the left side of T1? It looks...

    What is the IN to the left side of T1? It looks to me like on the right side the OUTs of U5 are driving in to T1, on the left side it is driving the gates of Q1 and Q2, which then chop (switch) the...
  21. Replies
    15
    Views
    299

    I believe the functionality of the KA3525a is the...

    I believe the functionality of the KA3525a is the same as the SG3525. This datasheet (https://www.onsemi.com/pub/Collateral/SG3525A-D.PDF) has a better description of the shutdown (pin 10) and soft...
  22. Replies
    15
    Views
    299

    Replacing the 2a165 with the 2a265 is the basic...

    Replacing the 2a165 with the 2a265 is the basic "Rev H" rework IIRC for a problem some had where the amp would go in and out of operation. Just google "SVT7 Pro cutting out." There are a couple other...
  23. Replies
    12
    Views
    241

    May not be functional if it is totally shorted...

    May not be functional if it is totally shorted out, but have you checked the over current and over temp signal pins?
  24. Replies
    12
    Views
    241

    Data sheets for ICE Power modules often have...

    Data sheets for ICE Power modules often have quite a bit of useful information. https://static.qobuz.com/info/IMG/pdf/icepower50asx2.pdf
  25. Replies
    15
    Views
    417

    The market has definitely gotten weird. I do the...

    The market has definitely gotten weird. I do the same sort of "fix and flip" as you do. Basically any PA gear that isn't powered speakers or digital mixers is almost not worth selling. For bass amps...
  26. Replies
    2
    Views
    157

    I am thinking that I want to do a side-by-side...

    I am thinking that I want to do a side-by-side comparison of the Yamaha SS bass amp vs. my Vibroverb clone (just as a pedal platform). Power is about the same and with a single 15" speaker.



    I...
  27. Replies
    2
    Views
    157

    Old bass amp as pedal platform

    I know the concept of using a bass amp for guitar isn't really new (Bassman, hello?), but I hadn't really tried it much. I got an old Yamaha Thirty 115b yesterday for next to nothing from a buddy,...
  28. Replies
    16
    Views
    452

    So where would one find examples of valuable old...

    So where would one find examples of valuable old semiconductors? There is a surplus electronics store near me, as well as a friend who fixes organs and hoards parts. Curious if it would be worth my...
Results 1 to 28 of 500
Page 1 of 18 1 2 3 4