Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Please login or register.

Login with username, password and session length
Advanced search  

News:

SSGuitar has moved to PHP 7.1, enjoy the speed!

collapse
Pages: [1]   Go Down

Author Topic: Need Help Identifying a Diode.  (Read 442 times)

TK

  • SSGuitar Regular
  • ***
  • Chip Points: 0
  • Posts: 27
    • View Profile
Need Help Identifying a Diode.
« on: January 31, 2018, 11:12:23 AM »

Hi guys,, just wondering if anyone can help me Identify the Diode in the picture.. It's from my BassMate 25 repair.. It turns out to be blown and is part of the Baxendal compensation system. I've tried replacing the Diode with a standard low power diode and That dropped my overheating problem to almost half the temp it was but now I'm getting crossover distortion.. Going to try different diodes In34 Germanium and a 914 just to see,, but would be nice to try and replace the original Diode,, Thank you.
Logged

tonyharker

  • Elite SSGuitarist
  • *****
  • Chip Points: 17
  • Posts: 126
    • View Profile
Re: Need Help Identifying a Diode.
« Reply #1 on: January 31, 2018, 01:57:57 PM »

Looks like a thermistor to me not a diode.  Diodes are usually cylindrical.  :)
Logged

TK

  • SSGuitar Regular
  • ***
  • Chip Points: 0
  • Posts: 27
    • View Profile
Re: Need Help Identifying a Diode.
« Reply #2 on: January 31, 2018, 06:36:16 PM »

Hi Tony,, I'm really not sure what the heck it is,,, I thought it was a diode do to the placement,, I thought It might have been a zenor diode.. It's part of the Bax compensator,, so I'm thinking it's a Diode of some type,,, really strange looking for sure..
Logged

g1

  • Legendary
  • ******
  • Chip Points: 66
  • Posts: 508
    • View Profile
Re: Need Help Identifying a Diode.
« Reply #3 on: January 31, 2018, 08:37:55 PM »

Baxandall is a type of tone circuit.
Where is this part connected to if you follow the traces?
Is it between Q5 & Q6 where the YEV212 diode is shown?  Was it pressed up against the heatsink?
If so, I agree with tonyharker that it is a thermistor.  They may have altered the circuit from what the schematic shows.  Or it may be replacing the resistor and there still may be a diode in series with it.
If it's somewhere else, like a tone circuit, it could be a tantalum capacitor.
Measure it's resistance and see if it changes with some heat applied.
Logged

nosaj

  • Master SSGuitarist
  • ****
  • Chip Points: 5
  • Posts: 87
    • View Profile
Re: Need Help Identifying a Diode.
« Reply #4 on: January 31, 2018, 08:51:15 PM »

looks like a tatalum to me, http://www.antiqueradios.com/forums/viewtopic.php?f=4&t=263660
Here's a similar one.

nosaj
Logged

Enzo

  • Legendary
  • ******
  • Chip Points: 180
  • Posts: 1754
    • View Profile
Re: Need Help Identifying a Diode.
« Reply #5 on: January 31, 2018, 10:45:05 PM »

Schematic?
Logged

Jazz P Bass

  • Master SSGuitarist
  • ****
  • Chip Points: 9
  • Posts: 68
    • View Profile
Re: Need Help Identifying a Diode.
« Reply #6 on: February 01, 2018, 01:28:38 AM »

Traynor TBM25
Logged

Enzo

  • Legendary
  • ******
  • Chip Points: 180
  • Posts: 1754
    • View Profile
Re: Need Help Identifying a Diode.
« Reply #7 on: February 01, 2018, 04:24:23 AM »

I would vote tantalum cap.

If it is wired to a pin on the big IC, that doubles my vote.

If you are testing this part as a diode, then it will test bad.   Test it like a cap and see.
Logged

sortedaudio

  • Chipper
  • *
  • Chip Points: 0
  • Posts: 1
    • View Profile
Re: Need Help Identifying a Diode.
« Reply #8 on: February 12, 2018, 09:30:38 AM »

Looking at the schematic I think it's a dual diode. As the temperature of the output stage changes the voltage drop across the diode changes and alters the bias in the output stage, providing temperature compensation.  Two 1N4148 diodes in series may well do the trick. I must say the picture does look like a tantalum capacitor.

sortedaudio
Logged

TK

  • SSGuitar Regular
  • ***
  • Chip Points: 0
  • Posts: 27
    • View Profile
Re: Need Help Identifying a Diode.
« Reply #9 on: February 16, 2018, 08:11:33 PM »

Thanks guys,, It turned out to be a Dual Diode,,, I think it was still good but I replaced it with 2 diodes in series.. Yes Baxandall is a tone circuit but is also a Baxandall compensation system in SS amps,, I don't know much about it at this point but hopefully will be able to find more information on it.
That thing looks just like a Tantalum Cap for sure LOL,,, The first time I tested it I did a diode test and got over 1.1 volts.. I thought,, that's strange then I did do a cap test on it and got 60 some odd pf's,, really threw me for sure.
Logged
Pages: [1]   Go Up
 

* User Controls
 
 
Welcome, Guest. Please login or register.
Did you miss your activation email?
* Recent Posts
Cooked Super Amplifier by solidstate2199
[Today at 07:45:20 AM]


Marshall Code50 speaker by mensur
[May 19, 2018, 04:03:26 PM]


Fender Deluxe AB763... vibrato not working by Hawk
[May 18, 2018, 11:27:07 AM]


Hohner Pianet Amplifier Low Output by phatt
[May 18, 2018, 01:17:36 AM]


crate vtx 200s schematic by DrGonz78
[May 16, 2018, 04:06:24 PM]

* Sponsors