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Trainor Bass Mate Solid State amp repair.

Started by TK, December 27, 2017, 09:04:15 PM

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TK

HI guys.. I'm trying to repair a Trainor Bass Mate 25 solid state Bass amp and I was wondering if anyone know's if there is a Schematic available for this amplifier.. The Model number is YS 1076 and it used 2 C 2233 Y NPN output transistors.

Jazz P Bass

#1
http://traynoramps.com/downloads/servman/sm_trayint.pdf

The full part number of the output transistor is '2SC2233'.
No need for the 'Y'.

TK

Hi J.P. I was posting what was stamped into the Chip,,, Not seeing anything too familiar in any of those Schematics,, Thanks for posting any way,, It's going to be another fly by the seat of my pants repair,,, Seems to be very hard to get schematics for Chinese made amplifiers,, even of bigger brand names.. This should be fun.
:dbtu:

Enzo

Traynor usually provides schematics if you ask.

g1

Quote from: TK on December 28, 2017, 05:49:47 PM
Hi J.P. I was posting what was stamped into the Chip,,, Not seeing anything too familiar in any of those Schematics,, Thanks for posting any way,, It's going to be another fly by the seat of my pants repair,,, Seems to be very hard to get schematics for Chinese made amplifiers,, even of bigger brand names.. This should be fun.
:dbtu:
Page 4 of the pdf posted by JPB shows the TBM25 schematic.  It uses 2233 output transistors like you mentioned. (Q7 & Q8).
What part is different?

Jazz P Bass

I was totally confused by that reply myself.

" Not seeing anything too familiar in any of those Schematics,, Thanks for posting any way,, It's going to be another fly by the seat of my pants repair,,, "

Oh, well.

TK

Thank you for the replies you guys.. So taking a closer look at things slowly finding similar things as I go... This is very interesting... Different part numbers for some things and same part number for others... I hope I can repair this Amplifier,, it is very interesting,, I really like that it is not a Pentawatt output design. Also very cool is the(never seen before Equalizer chip.. BA3812A in this case, On page 4 of the schematic it is a KA2235, which mixed me up a little for sure... output trans are 2233's,, Humblest apologies for the confusing statement,, Just me thinking out loud,, I do that sometimes... I will look into the other suggestions as well.. Thanks again you guys,, I really appreciate the help... Oh and of course,, Happy New Year and the Very Best to you..  :)


TK

Thank you for the Datasheet J.P. I'm Found at least one problem so far with this amplifier. well actually 2.. Who ever worked on it before,, ripped the wires out of the signal input header so I'll have to straighten that out. I usually check for power at the chips so I noticed that the power light did not come on when the on/off switch was activated.. I checked the Secondary windings and they were good,, but.. there was no continuity in the Primary winding so,, OUT came transformer and the tare down begain... I figured it had to be a burnt winding at first but noticed absolutely no smell or dis color .. After the plates were removed I separated the primary from the secondary(which was done quite easily because of the thought put into building this transformer(Thank you China)). Unwinding the Kaptan tape still no burnt wires,, I'm thinking cold solder joint,, then there it was!!!! Dun,,,dun duuuuuuun,,, The culprit.. A Chinese made wafer Fuse... Never ever seen one before.. Buuuuuuuuuuugger... so out it will come and I'll solder the wires together and install a fuse outside the transformer.. after I get it put back together,, Will be interesting to see what blew that fuse.. if anything,,,, Here's a picture. for the curious.

TK

I've rebuilt the Transfomer and installed it.. hooked everything back up and fired the amp up,,, So,, The fuse didn't blow..Good..It amplifies an input signal,,good,, but.. There is a wicked Hum coming out of the speaker.. Hmm,, The game is a foot.. If this was a tube amp I'd have a good idea,, but this being a Solid state amp mostly discrete, my first and only thought at this point is to check the 2 2200 35 volt power supply caps,,,,,

g1

 I hope it's not the same hum DC makes as it fries your speaker.
Did you check for DC at the amp output before connecting any load?

TK

HI g1,, I switched the amp off the second I heard the Hum. Thinking hearing that is never a good thing, I'm in the process of replacing the 2200uF caps,, 330 ohm resistors(replacing them with the proper wattage values),,and the 7.5 volt 1 watt zenors( increasing that to 5 watts) that were knackered. Not sure if i have to replace the rectifier yet but I'll build a discrete device if I have to,,Those rectifiers seem to be hard to find... I'll also check the speaker for a burnt and warped coil former as well,,, Thank for the suggestion...I have a sneaking suspicion that all this damage was caused by minimal parts values,, stemming from using 1/2 watt resistors instead of 2 watt resistors and using the old Trick from TV guys.. Mount the parts that will get hot off/away from the board surface... 

I have a silly question,, Why are the power supply caps such a high value 2200uf..? Thank you.

TK

Further update for my Bass Mate 25 repair,, I've rebuilt the power supply and everything there is great,, When I fired the amp back up,, and checked for DC on the speaker out put there was zero DC. But,,
The amp still buzzed and the transformer started to overheat.. Between turning the amp off and on for short periods of time I checked voltages at various points.. There seemed to be some type of voltage imbalance from the NPN side to the PNP side of components..
I thought I'd better start checking transistors,, I started with the output transistors first,, I checked the 1st c2233 NPN,, and it was Knackered,, I checked the second C2233 And it was hard to tell,, All the other transistors where ok.. So If I can find them I'll replace both 2SC2233 npn's and maybe even the drive transistors as well,,,