Pass Nation, I have some XA100 amps which I really enjoy and cannot part with even for a repair. The issue I have is the meters have quit working properly. The amps are working perfectly and sound fantastic. I have talked to Kent at the Pass Lab site about what to do. Clean out any spider webs and de static the meters etc. This has not worked. Has anyone ever repaired these meters? What did you do? I can easily get them out to clean them more but before I do that has anyone else had this problem? I will not ship the amps to the factory do to the cost and not being able to use them. The problem seems to be that the indicator wand gets stuck halfway up the meter. It should stop at the half way point 12 pm but stops at about 9 am on the meter. I also have a pass x350.5 that has the same problem. I don't want to spray and oil etc into the wand. Kent did send me some voltage readings to take but I haven't done that yet. I think it is a mechanical issue. Please advise if you can and thanks, dave
first make measurement
in case of mechanical cause (if , then temperature cycling only can be possible culprit) , you'll not need any sort of oiling
just partial disassemble and some dusting , eventually slight tweaking of pivot setting screw
in case of mechanical cause (if , then temperature cycling only can be possible culprit) , you'll not need any sort of oiling
just partial disassemble and some dusting , eventually slight tweaking of pivot setting screw
Ok-I will try this, Once I start up the amps I hate to turn them off. I built the Pass 1.2 amps many years ago and have built the Pass A-75 and they are all still working. My meters for them were voltage meters reading the power supply. Thanks again-dave
meters in PL amps are usually placed across part of power rail (conductor), measuring tiny voltage sag
whatever , as with any Weston
all you need to know is there voltage at connectors
that , and simple probe with ohmmeter ( it must jump , more or less - depending which range on DVM you chose ) will tell where is culprit - even without opening it
if needed , you can bring it to diode DVM test , where you usually push 1mA through DUT
whatever , as with any Weston
all you need to know is there voltage at connectors that , and simple probe with ohmmeter ( it must jump , more or less - depending which range on DVM you chose ) will tell where is culprit - even without opening it
if needed , you can bring it to diode DVM test , where you usually push 1mA through DUT
Very interesting, ZM. I've never experienced a "real" Pass amp in person, and I assumed the meters measured output watts, or MOSFET currents.
So what you're saying--they effectively are "millivolt meters" tied to two points on one of the voltage rails, and thereby measure the voltage drop caused by the PSU current flowing through the (very small) resistance of a length of the V+ or V- rail itself?
Again, interesting....... would this not indirectly then be a measure of the MOSFET current? Thanks--just curious.......
The meter problem is probably mechanical, and if so is likely the wand rubbing
against the front or rear surface. The mechanism is barrel shaped and it is
possible to very gently adjust it forward or backward so as to clear these
surfaces.
I don't need to mention that the amp must be disconnected from the AC
power line when the top is off.
Lacking that, they will have to some back.
😎
against the front or rear surface. The mechanism is barrel shaped and it is
possible to very gently adjust it forward or backward so as to clear these
surfaces.
I don't need to mention that the amp must be disconnected from the AC
power line when the top is off.
Lacking that, they will have to some back.
😎
Do I need to remove the meter from the chassis to clear any rubbing of the wand? I don't see how I can get at the meter to adjust it any other way but maybe I am missing something? Thanks to all for the help. Again these amps sound terrific. By the way Kent told me to check the meter terminal connections to make sure they were ok. I did this but I didn't measure the across the meter. The connections were tight and I didn't see any corrosion.
at least try to measure voltage at meter terminals , for start - then compare with normal value , got from PL boys
you're arriving on point of too much contemplating , zero work
you're arriving on point of too much contemplating , zero work
Zen Mod--this issue is due to recently retiring. Things that used to take 15 minutes to do now take 4 days. When listening to music with a glass of wine kind of dulls my perfectionist instincts. I depend on NP to be the perfectionist now. Thanks for your help and yes I will absolutely take your advice about the zero work. Now where did I leave my glass of wine? dave
No, you only need to remove the top (AFTER the power cord). If you look
very carefully you may be able to discern where the wand is hitting the
surface. The front to back positioning of the meter is adjustable by gently
moving the "barrel" which is the center.
😎
Pass Nation-I have adjusted the meter on my XA100.5's following NP's suggestion. I removed the meter and cleaned in gently with some air and noticed that the wand was ok and not hitting the meter. However by gently readjusting the barrel I got it to work.
Kent told me that the ma across the meter should be about .5ma. I did not want to desolder anything so I took a millivolt measurement and got about 8+mv and divided that by the resistance I measured of 1.4ohms to get approx 5ma. Being retired this is about my max stress for the day. I will do the others tomorrow. Be carefull with the wand as it bends easily. Don't do this with coffee nerves. Time for some wine. Hope all is well in the nation. dave
Kent told me that the ma across the meter should be about .5ma. I did not want to desolder anything so I took a millivolt measurement and got about 8+mv and divided that by the resistance I measured of 1.4ohms to get approx 5ma. Being retired this is about my max stress for the day. I will do the others tomorrow. Be carefull with the wand as it bends easily. Don't do this with coffee nerves. Time for some wine. Hope all is well in the nation. dave
Does anybody knows if the .5 are possibility to adjust the wand on the meters at the front like on the .8 series at the back L and M holes?
I`wll have on end of december Pass Labs XA 160.5
I`wll have on end of december Pass Labs XA 160.5
In general it would be an internal pot. If you know the specific #'s on the
pc boards, specific information can be had.
😎
pc boards, specific information can be had.
😎
most probably P1 (regarding pcb issue), which I labeled with two red dots
check temperature on all 4 heatsinks (I mean on big ones , amp sides) , they need to be app. the same
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