Phoenix Gold XS2300

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The amp had one channel blown(output transistors Q114,115) and Q113(A06) which I believe drives the gate. I have replaced what I know was bad, but I this channel will startup fine then drop out, startup then dropout. I would believe it has something to do with a protection circuit.

Any thoughts?

Cory
 
Humm... Hi guys,
This amp has very little protection circuitry on it. It does have one 2.2k @25C thermal sensor that can shut down the amp for heat issues. Other then that it has no DC offset sensing and shutdown. One LM339 device is used for thermal.
It uses one of the other LM339 devices for the bias reference. It has a 5.1 volt reference supply on the power supply side that feeds the bias circuitry. Please remember from other posts these XS and Tantrums amps are cousins of each other and both share a common design issue of this unique bias voltage supply from the 12 volt side.
The other two LM339 devices are used for over-voltage at 16.0 Volt threshold, and low turn on threshold of 9.0 and 9.5 volt. All on the 12 volt side of the supply.

Ummm. have you checked for any DC output from each channels speaker terminals with no RCAs and no speakers connected. I like to see less the 0.010 MVDC or 10 milli-volts DC or LESS on each channels speaker terminals, if not in this range you most likely have issues within the channel somewhere.

Also what size power supply are you using to test it with or is it connected to a car battery for this test ? Factory says 30 amp fuse so it looks like this little amp can draw some juice when it wants to.

Misc. other numbers are a +33.5 volt supply to the input diff pair and bias circuitry only. And a +&- 27.5 volt set of rails to the rest of the main amp stages. And of course a lower bipolar supply of +&- 15 VDC

XS and Tantrum series amps all share some design commonalities. The bias supply for the amp is one and the other is when they blow output and drivers they can and do feedback damage further back in the channel. Luckily the parts to rebuild a entire channel rarely run more the 5 or 6 bucks, and a little extra time and effort...Hope this helps some....;)
 
Ummm. have you checked for any DC output from each channels speaker terminals with no RCAs and no speakers connected. I like to see less the 0.010 MVDC or 10 milli-volts DC or LESS on each channels speaker terminals, if not in this range you most likely have issues within the channel somewhere.

The good channel has 18mV and the bad is all over the place when it stops working, otherwise it would read about 30mV

Also what size power supply are you using to test it with or is it connected to a car battery for this test ? Factory says 30 amp fuse so it looks like this little amp can draw some juice when it wants to.

My supply is 25amp capicitive coupled DC supply, not the issue. One channel works fine while the other starts out fine then drops out.
Misc. other numbers are a +33.5 volt supply to the input diff pair and bias circuitry only. And a +&- 27.5 volt set of rails to the rest of the main amp stages. And of course a lower bipolar supply of +&- 15 VDC

The rails read +-~27Vdc and the +-15 read -16Vdc, 20Vdc

)
 
Ok the 20 volts is no good so i would say check R127 it should be 240 ohm 1 watt, and the zener D29 its a 15 volt 1N4744A. These are the most likely trouble spots for the 15 rail. I would try to get this first then go back the unstable channel. 20 Volts to any of the Op-amps could have been deadly to them. I would check voltages on all of the NE5532P and even the LM13600 remote bass gain control chip. Pin 6 is -15 and pin 11 is +15 on the LM13600.

18 MVDC is liveable but well used IMHO, The other channel with it all over the place and then settling at 30MVDC is the source of trouble as the amp channel is most likely oscillating which gives you the all over the place ready, and the 30MVDC is a sure sign of weakened components before those you replace already.

As I said in the earlier post I like to see these amps below 10 MVDC for like new operation. Check the 200 ohm 2 watt resistor, and the 4.7 ohm 1 watt resistor. These like to open up on blown channels. Also read test points 15 & 16 and then 17 & 18 these should give you the bias voltage readings in Milli-volts. Replacing outputs usually requires realignment of bias. Please read across the test points with your meter one probe to TP15 and the other probe to TP16, and the same for TP 17 & 18.

As I said before this amp has no shutdown from DC output or the like so the channel that is muting is because something in that channel is breaking down and shorting in the channel as their is no mute circuitry like you would normally see in other amps. Any turn on muting must be controlled by the bias circuitry and its reference signal to each channel. There are no J-fets and No mute drive indicated anywhere, so this leaves the bias circuitry from the 12 volt side to control any muting on turn on and off.

I have seen the 1/8 watt resistors in defective channel change value BOM says 1/8 watt 1% metal film unless visibly otherwise. Those and the 4 zener diodes 2 are 15 volt 1N5245B and 2 are 6.0 volt 1N5233B these like to go south also on channel failure.
If none of this checks out then most likely several of the MPSA06 and MPSA56 devices are leaking. Input pair is 2SC2389 times 2 and I have seen them cause excessive DC offset as they get beat up by the activity that killed the amp in the first place.

Sorry so much info but your on top of your game with this so long list should not deter you too much IMO....;)
 
This amp was beat and beat some more, poor thing. It was bridged for sub use and probably driven into a clipped state for years. Not my amp so I don't know the complete history!

I was mistaken with the 20Vdc level, +-15V supplies read fine(15.3Vdc, -16.2Vdc).

Where are these TP's? I see nothing marked on the board indicating test points. ie TP15

1moreamp you seemed to be well versed in the phoenix gold, since most of the CD's are screened under the part, do you have a schematic that is close to this amp? I doubt PG will send me one, they are not RF when it comes to giving out the schematics.

I haven't checked the zeners yet, next on the list. I will most likely replace all transistors in this section to be safe at some point.


Thanks,
Cory
 
Any idea what resistor value should be placed just in front of Q115 marking. It was burnt and from what I could tell on the other channel it was 120 ohms. Not having much for leaded parts I dropped a couple 60 ohms SM parts in the place.

Here is a pic
 

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Any idea what resistor value should be placed just in front of Q115 marking. It was burnt and from what I could tell on the other channel it was 120 ohms. Not having much for leaded parts I dropped a couple 60 ohms SM parts in the place.

Here is a pic


Oh please check the red coil to see if it is broken one of its leads to the board I have seen this on several occasions and it will cause the floating /oscillating issues you mentioned earlier. If broken re-attach and then apply liberal amounts of RTV to keep it from breaking again.
As for schematics I most likely have any PG amp posted here already here on my bench or with in reach. In this case of 2300's and 2500's I turn these quickly and return them to owners because for 4 to 6 bucks the channel can be completely rebuilt like new. So those get this routine and go back quickly to owners.

In your picture it would appear that someone tried to use a couple SMD resistors to make one of the 1/8 watt thru hole resistors that most likely fried. NickParr is correct about it being a 324 ohm resistor IF it is connected across the Gate to Source leads of the fet. It also is 1% tolerance metal film. As posted before all resistors in the channel will most likely need to be checked for integrity, and 1% is the max out of spec you should find anywhere except for the larger 5% resistors.

With your description of the amps abuse level IMHO may I suggest that you consider GUTTING the amp channel to insure a fast and complete repair. I have had to do this myself on many many occasions. It costs no more the $10.00 US to replace everything silicon and be done with it. Trying to find each little out of spec device could take you hours , while clearing the slate and making it all new will take way less time. Time being money in the repair business I hope all of you see why I do this.
 
PG SCHEMATICS:
To my limited knowledge nothing has ever been publicly released on the net or elsewhere that may be deemed open to the public. This means that it is all still copyrighted private Intellectual property.
The DMCA prevents me from even posting hand drawn interpretations of other peoples intellectual property in this country. Since even the hand drawn stuff is still someone's property. Sorry I want to help anyone, and everyone, but I don't want to go to jail being helpful. Hope everyone understands this. It takes written permission to post other folks intellectual property, and I don't have this. If it was my property I would most likely feel the same way about it. So its just the way things are:eek: What hard info I may or may not have is copyright stamped and marked do not distribute plainly, and came with a warning not to openly post on the net or distribute in any way. So I gladly try to do the best I can with out making the powers to be upset with me.....:)

I even don't feel comfortable elaborating in detail about this on open forum. I will continue to try and be as helpful to all as much as possible, while trying to staying off the radar screen. If AAMP/Stinger decides to openly post anything like this I will start linking to it immediately.
None of this is up to me folks. I'm just living with things the way they are, and trying my best to be helpful while not getting buried by my own kindness to others.:soapbox:

P.S. brandes.cm Perhaps if you PM NickParr maybe he can help in a way I can not since he is not a resident/citizen of the US his nationality grants him some latitude from US DMCA copyright law somewhat.;)
 
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So basically just replace all diodes and transistors in the channel? I still need to know what value resistor should be in place of my SM mess.

I will order up some parts shortly.

You wouldn't happen to have a parts list of what you normally replace?

Thanks again

The SMD repair looks to be 324 ohms like Nick Parr said, but to double check please make sure it connects to the gate lead and the source lead of the fet. if it does it can only be 324 ohms like Nick said. This I am 100% sure of. If it does not connect as above please tell me how it connects on each end and I will give you any real 100% confirmed parts value.

I need to know if your bad channel is the right or the left, please?? There is one single difference on the right channel and this difference is a single 6.0 volt zener D19, one 1 ufd cap C18, and one single 100k resistor R139. ...thanks:)
 
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2 each 2SC2389 input diff pair
3 each MPSA06
5 each MPSA56
2 each 1N5245B 15.0 volt zener diodes
2 or 3 each 1N5233B 6.0 volt zener diodes< right channel has one extra >
10 each 1N4148 silicon small signal diodes
2 each IRF540 mosfet output
2 each MPSA56 as Q32 and Q4 in the power supply used to feed bias drive to both channels from the 12 volt side 5.1 volt reference. If one channel is OK then this section is most likely 100% functional, so no needed parts.

Please read across both 0.1 ohm resistor in the good channel to get a idea on where the proper bias level should be on your repaired channel and use the 12.0 volt idle current draw spec from PG docs for the whole amp to set both channels bias equally but not exceeding typical bias idle current draw spec's. I also check this at 14.4 levels and idle soak the amp to make sure the bias tracks and does not thermal runaway.
As you can see above the parts list is not very expensive total to just overhaul the entire channel. Like most mosfet amp designs it uses jelly bean driver transistors due to extremely low drive current requirements for mosfet gates. Thus making complete rebuilds very affordable, along with the fact the amp will run and play like new for cheap.;)

Hope this helps, any questions please ask away.....C:)
 
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Very cool, this will help a bunch. I have most of these components at my place of work so I can get them for pennies.

The left channel is bad.

I usually set the bias and do a thermal cycle with the amp prior to letting it go. This is with RF amps anyway. I haven't seen much of PG.

Again thanks for the help, I will post the outcome when it is complete.

Cory
 
you might post this on phoenixphorum, theres a guy there valeks1 whos all about pg amps. he helped me fix my xs4600. i wound up having to replace all the mpsa06 and mpsa56 transistors on one channel as one was leaking, and rebias'ing the whole amp to fix mine. works like a charm now!
 
Is there a cross for the 2SC2389? Digikey, mouser and Octopart show no stock or availability.
The gain for this part is huge.

I got mine from MCM recently <2 weeks ago>and for fairly cheap prices also. My stock ran low so I ordered 36 pieces and it was very affordable. They have two case style versions a TO-92 and a very small style case, either works fine, although they will ship you what they pull and not what you asked for sometimes. They did this to me, but case style really does not matter IMO.:)
 
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you might post this on phoenixphorum, theres a guy there valeks1 whos all about pg amps. he helped me fix my xs4600. i wound up having to replace all the mpsa06 and mpsa56 transistors on one channel as one was leaking, and rebias'ing the whole amp to fix mine. works like a charm now!


He is a laid off PG employee not sure what position or how long he was with them, but he does offer repair services thru Alt-srv LLC his newly formed LLC company. I only dealt with product design engineers, so I don't believe I know this fella..Plus if you read the post carefully you will see Cory is doing about the same with his amp already. Valek1 not being employed by PG any longer has stepped in to replace what I did over there for many years. But thanks for plugging My old forum that I was a moderator and founding member of. :eek:
 
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