• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Pioneer Spec 1 Pre-Amp Sound Issue

xXColdShotXx said:
Just hooked the spec 2 up and let it play for around 10 minutes, then all the sudden I hear a small pop and smell something get hot, then I noticed the right meter was almost on 500 and the protection light was on. I had a yamaha cx-600/u pre-amp hooked up to it and it was playing just fine on both channels until that happened.
Click to expand...
Should have t-shot this first before a mass swappnig of parts.
Are you/we/us chasing the original problem ? Or perhaps something that was inflicted while working on the unit ?
 
Last edited:
I just noticed when I tried it again the bulb barely lit up and went right back so dim you can't tell it's on. I am recapping the spec 1 at the moment. The spec 2 may be next depending on how the spec 1 goes.
 
The Spec-1 only consumes 17W according to the specs so it will only draw enough current through a 75W bulb to get a momentary flicker upon turn on. You would need to use a much smaller bulb in order to see a brighter flash before going dim. The dim bulb is indicating that there isn't excessive current flowing which is a good thing.
 
You appear to be fine. You want to see the bulb go bright briefly upon power on as the PS caps charge up and then go dim.
 
That's exactly what it is doing. I guess time to take the front metal plate back off to change the power light indicator bulb. The original bulb didn't work before the recap.
 
Hooked the spec 1 up without the DBT and so far so good. Just gotta run some sound through it to see if both channels work.
 
Got a new problem, the right channel is working now and before it wasn't, the left channel used to work and now it doesn't. The left channel is acting worse than the right used to. It's making a really low sound barely there kinda sizzly sounding.
 
Got an even bigger problem, now the damn thing pops through my yamaha amp and speakers right after turning it on and makes the yamaha amp go into protection mode. It used to only play on right channel. I did some touching up on solder joints to make them clean as possible and after that it started popping through the speaker. I found a few leads that were loose also after soldering them this issue started. It is still passing the DBT test for some reason.
 
Last edited:
I've tested around half of the AWM-082 filter amp board and found some resistors not up to par. So far here is a list of those resistors.
R8 - 220k - getting 200.3k
R7 - 220k - getting 170k
R90 - 22k - getting 3k
R88 - 180k - getting 40k
R47 - 220k - getting 114k very slow climbing
R45 - 220k - getting 114k very slow climbing
R53 - 47k - getting 25k very slow climbing
R54 - 47k - getting 25k very slow climbing

Could these resistors be the issue with the popping as soon as the spec 1 is turned on and causing my amp to go into protection mode?

I have quite a few more to test. If anyone can share a mouser list for resistors I'd appreciate it.
 
I've replaced most caps and transistors. Got a few resistors out of spec, still need to test more on the filter board. I tested the resistors in circuit with the unit's power unplugged.
 
Does anyone have some high definition pics of the spec 1 AWM-082 board (foil side) with good copper traces?
 
Last edited:
@xXColdShotXx In answer to your PM, please post any questions you have in this thread so anybody reading it can benefit from the answer.

The 1000uF cap is a factory addition, on the later versions it's mounted on the board in front of the muting relay (chrome case) on the AWM-082 board. Also, those pots on the power supply do need adjusted when you redo the board, they control the +48v and -48v rails. Put the black lead of your meter to ground and measure pin 1 for the +48v measurement and pin 12 for the -48v measurement. Set the pots so the pins read +48v and -48v respectively on line power, do not set them on the DBT.
 
Ok, my bad. I will do that. Remember when I said speaker B relay wasn't working? I found a broke wire that went to the relay and soldered it back and not it works. I just wish I could figure out why it went from playing on the right side to kicking my amp into protection mode all the sudden.
 
You must log in or register to reply here.
Back
Top Bottom