I am placing this here since it seems like as good as place as any, especially since Mr. Pass designed it.
I was wondering if anyone has done a full cap replacement on this unit recently and if so would you have a copy of what the cap part numbers that were used are.
I have not had a chance to break open the unit since I picked it up. Not only that, but I purchased it from a gentleman who babied all of his gear but do to the age of the unit I would have to believe the caps could stand to be changed out.
I was also wondering if folks who would replace the caps if you would also replace some of the transistors, like the 2SC3298B (this would be discontinued, so I would need to find a suitable replacement).
Thanks in advance.
I was wondering if anyone has done a full cap replacement on this unit recently and if so would you have a copy of what the cap part numbers that were used are.
I have not had a chance to break open the unit since I picked it up. Not only that, but I purchased it from a gentleman who babied all of his gear but do to the age of the unit I would have to believe the caps could stand to be changed out.
I was also wondering if folks who would replace the caps if you would also replace some of the transistors, like the 2SC3298B (this would be discontinued, so I would need to find a suitable replacement).
Thanks in advance.
At this late date I have forgotten the dimensions of those cans.
I think you want to go to digikey or mouser and see what they have in those dimensions and pick something whose voltage is equal or greater than the original.
It'll work don't worry - it's not actually rocket science.
🙂
I think you want to go to digikey or mouser and see what they have in those dimensions and pick something whose voltage is equal or greater than the original.
It'll work don't worry - it's not actually rocket science.
🙂
Nelson,
Thank you very much for your reply.
I was just checking to see if any knew the footprint size so I could go ahead and order them without getting into the amp first (being a wee bit lazy there).
May I ask your thoughts about replacing those transistors like the one I mentioned above? Even if you think they should stay in I think I will clean up the thermal compound and put some new one them. When you do your company’s amp, do you just use a thermal compound or those little thermal pads that see out there (or possibly both).
One last question if I may. What thermal compound is used on the Pass Lab amplifiers?
Thanks in advance, James
Thank you very much for your reply.
I was just checking to see if any knew the footprint size so I could go ahead and order them without getting into the amp first (being a wee bit lazy there).
May I ask your thoughts about replacing those transistors like the one I mentioned above? Even if you think they should stay in I think I will clean up the thermal compound and put some new one them. When you do your company’s amp, do you just use a thermal compound or those little thermal pads that see out there (or possibly both).
One last question if I may. What thermal compound is used on the Pass Lab amplifiers?
Thanks in advance, James
no need to replace actives if operation parameters are OK
meaning output DC Offset (100mV bracket, +/-) and standing current
re-check screw torque on outputs
if in doubt, post pics
meaning output DC Offset (100mV bracket, +/-) and standing current
re-check screw torque on outputs
if in doubt, post pics
Zen,
Thank you for the reply and information.
I checked the service manual and there is no torque spec listed. Is there basically an industry standard for these type of amps when it comes to that spec, or is it just tightened but not just do not go crazy with it?
Thanks, James
Thank you for the reply and information.
I checked the service manual and there is no torque spec listed. Is there basically an industry standard for these type of amps when it comes to that spec, or is it just tightened but not just do not go crazy with it?
Thanks, James
if you have torque thingie, 0.9Nm for M3 screws (or US analog)
if you don't have it, use common sense ......... what is important - to check that there are no loose screws
if you don't have it, use common sense ......... what is important - to check that there are no loose screws
I just picked up a 5800. Has the right distortion light on for 1 min it warms up it goes off. Im assuming the caps need replaced. Also it works ok, but I seem to remember listening to one in the 90’s it sounded much like my 555 but with more power and bass. This one sounds fine as far as bass. But the treble is distorted, just doesn’t sound like what i remember. Perhaps the caps on the input are weak as well? Any kind of help would be appreciated. Also is there an easy way to adjust the the pots p1 seems simple enough but p2 seems it requires an oscilloscope. Or maybe the treble issue is me listening to my f5 turbo and not remembering exactly what the 5800 sounded like .
Why do you feel P2 needs a oscilloscope?
If it is for the bias offset, if so, you would need a signal generator for the 1KHZ input signal.
Do you have the service manual? If not, it may have been placed in this thread or another Adcom thread I may have started.
If it is for the bias offset, if so, you would need a signal generator for the 1KHZ input signal.
Do you have the service manual? If not, it may have been placed in this thread or another Adcom thread I may have started.
Another 5800 owner in need of a recap.
Is there a new/improved formula
For cost effective upgrades while replacing caps and transistors? For example, certain pot adjustments (thinking of the famous Bob Carver Challenge on stereophile years ago).
Lastly, any known amp repair experts near CT in case I chicken out on DIY?
Is there a new/improved formula
For cost effective upgrades while replacing caps and transistors? For example, certain pot adjustments (thinking of the famous Bob Carver Challenge on stereophile years ago).
Lastly, any known amp repair experts near CT in case I chicken out on DIY?
You may have inferred causality, which was not my intent.
I meant that while amp is on the bench and wide open, take the opportunity to adjust the pots.
I meant that while amp is on the bench and wide open, take the opportunity to adjust the pots.
Yes, but I do have the service manual for original spec parts; so my question is beyond restoration, but more about what “modifications” or “improvements” that can be made instead of re-capping to exact OE spec.
For instance, Mr Nelson Pass suggested replacing capacitors with those of slightly higher voltage….
What other sage advice might be beneficial whilst having the amp apart for re-capping?
Here is a list I made, feel free to shoot it full of holes : )
Sorry if my creativity is getting the best of me. I find this topic interesting and rewarding.
For instance, Mr Nelson Pass suggested replacing capacitors with those of slightly higher voltage….
What other sage advice might be beneficial whilst having the amp apart for re-capping?
Here is a list I made, feel free to shoot it full of holes : )
- Using higher quality/tolerance capacitors
- using higher quality transistors
- replacing with a larger/better power supply
- adjust pots to sound like higher end Pass design
Sorry if my creativity is getting the best of me. I find this topic interesting and rewarding.
Last edited:
For anyone needing bias setting it’s 800ma +- 50 ma let idle for 40 min then turn off , grab multi meter , remove positive from the board, use that wire install one lead into it and the other on the +tab you removed the red wire from. Turn on the amp Crank her up to 800 then hook back up let it cook for 10 or so min, re test , this is pot #2 . Mine was off by 400 ma on the right and 50 on the left. This definitely helped sound quality.
Pot 1 is for voltage make sure both sides are 1 Millivolt on speaker outs.
I replaced all the caps, none were leaking I just decided it was time. It doesn’t hurt to replace them with a little higher uF value. I still need to do the film caps. Just haven’t got around to it.
Fantastic Amp Nelson Pass.
Doesn’t have the soul sound of my f5 turbo. But I love it all the same sir
Pot 1 is for voltage make sure both sides are 1 Millivolt on speaker outs.
I replaced all the caps, none were leaking I just decided it was time. It doesn’t hurt to replace them with a little higher uF value. I still need to do the film caps. Just haven’t got around to it.
Fantastic Amp Nelson Pass.
Doesn’t have the soul sound of my f5 turbo. But I love it all the same sir
Last edited:
Joesch1999,
If I may ask, when did you do the cap replacement? The reason I ask is I was wondering if you had a spreadsheet or a page of notes with the part numbers for the corresponding cap that you ended up replacing.
Thank you very much, James
If I may ask, when did you do the cap replacement? The reason I ask is I was wondering if you had a spreadsheet or a page of notes with the part numbers for the corresponding cap that you ended up replacing.
Thank you very much, James
