Ask help on PASS X150 dc output differential settings

[gelly]

Zen,

there is no c5, c6. (capacitor)
maybe you mean header 5 and 6 ?

if you menth, header 5 and 6,
those are the measuring points for the IQ. (IQL1 and IQR1)
measuring not referenced to ground but between the 2 pins (1 header)

like you stated in your blog,
all measurements are made with inputs shorted (cinch and xlr). no speaker attached.
the absolute voltage is measured between ground and the (red or black) speaker terminal.

now, after 3,5 hours, playing very low volume, the temperature is risen to:
left 51.2 and right 50.3 degrees c. (ambient = 22)

 

[Zen Mod]

gimme full picture showing main board and I'll show which caps are C6 and C7 (there are four big horizontal electrolytics on pcb , near connection block)

if there is symmetrical voltage at them ( and it will hardly be anything other) , you'll need new UGS modules , as Wayne sez

 

[gelly]

ah, that one, not noticed, sry, here it is.

 

[Zen Mod]

yes , these two ......

and ?

 

[gelly]

unfortunately, about the new measurements, that would be possible at earliesest on saturdayevening or sunday.

 

[gelly]

Maybe a stupid question...
The measurements are made with inputs groundet.
Rca short, clear.
Xlr short,... the standard amp's u short between 1 and 3 ?
That is only grounding the negative input. ( is what i did).
Should i have shorted pins 2 and 3 maybe ? (Positive and negative pins)

 

[wayne]

The inputs are cap coupled so it shouldn’t really matter much for the measurements. They can be made with the inputs open. If the amp works and the sides are about the same temperature but the DC is off you may need new gain modules if they can’t be set to zero.

 

[gelly]

Are those gain modules still available and what is their pricetag ?

Is there a way to determine/measure on those gain modules to be shure to avoid the efforts and costs ?

 

[Nelson Pass]

The modules can be had from the factory. Kent would let you know what the
cost might be (his job description is Customer's Best Friend).

kente@passlabs.com

I would also ask him for referral to a good technician in Europe.

 

[gelly]

Hi,

An update.
Have received the needet info from Mr Kente (pass labs)
Great and fast response, very helpful informations.

Will be Continued...

Greetz from belgium.

 

[gelly]

Hi,
back with news.

the UGS4 module is not available anymore.
the UGS6 module is an alternative replacement but is not a 1:1 replacement and needs tweaking by a dealer ( in my case , the nearest is the netherlands )

about the question of the dc voltage on the C6 and C7, those are both 43.5 Vdc.
the C13 and C14 are both 46Vdc.

made some pictures...

all heat sink fets seams okay to me. even the resistors seames okay.

it is clear that the UGS4 module of the left channel (top pcb) has more heat dissipation on 1 transistor (or the resistors aside).
this is due to the close up pic and 2 cameras (flir) giving somewhat shifted pictures. (outlining of components vs IR view.)
pictures says more...

greetz from Belgium.

 

[coolnose]

Apologize the stupid question, but why not unsolder the active parts, check the passives for correct values and install NOS active parts, the Jfets are available (expensive though), I don't know what the big SMD are (Mosfets ?) ...

 

[gelly]

because i don't have the tools for desoldering smd's nor the schematic, nor the right spare fet's and i dont want to ruine those UGS4's.
the official repair is too expensive…
want to keep this amp because it sounds wonderful !
afraid to open up too much the trottle , avoiding eventual clipping and damaging my loudspeakers.
17 vdc left and 5 vdc right of absolute potential is too much...

 

[Nelson Pass]

the UGS4 module is not available anymore. the UGS6 module is an alternative replacement but is not a 1:1 replacement and needs tweaking by a dealer ( in my case , the nearest is the netherlands ).

It's my opinion that a new or repaired UGS would need some adjustment
in any case.

I would go with the UGS 6 (a pair) and have one of the qualified techs we
know in Europe adjust them.

Of course your fallback is sending it to California.

 

[wayne]

The UGS6 is the improved replacement for the UGS4. We send them out tested and adjusted and they should be close. All that is needed is a voltmeter and careful adjustment.

 

[gelly]

According to pass labs (mr Kent) , it is not a 1:1 drop in replacement and should be made by a recognized dealer.
So, placing and adjusting i would be able to do, but tweaking... no. I can't. (Ugs4 and ugs6 seam not drop in parts)

 

[indra1]

Gelly, perhaps it is not as impossible as it seems once you get a hold of proper instruction.

 

[gelly]

Indra1,

That i do not have.

 

[indra1]

Mighty ZM and Wayne are the ones to ask.

 

[Zen Mod]

Mighty ZM , even if in possession of few tiny papers , is not the one who can gave them freely

Wayne is da Man