I have some hand drawn schematics, some custom, some stock, but I created easier to read computer drawn schematics from them. PM me with your email and I'll be happy to give you what I have.
I've got my PSIV preamp almost fixed. I had noise in the Phono stage and the gain section. The gain section had a bad transistor but I still haven't found the culprit in the Phono stage. I'd be happy to swap notes!
I've got my PSIV preamp almost fixed. I had noise in the Phono stage and the gain section. The gain section had a bad transistor but I still haven't found the culprit in the Phono stage. I'd be happy to swap notes!
Passive has enough gain for me but I still haven't found the noise in the phono section, which sounds awesome BTW!
I have already re-cap'd mine and about half were bad or marginal, but it made little to no difference to the noise I'm getting.
The transistors used throughout the preamp are not both readily available. MPS8099(G) are still available at Newark.com but I couldn't find MPS8599. I got MPSA56RLRMG as a replacement which seems to work fine!
I have already re-cap'd mine and about half were bad or marginal, but it made little to no difference to the noise I'm getting.
The transistors used throughout the preamp are not both readily available. MPS8099(G) are still available at Newark.com but I couldn't find MPS8599. I got MPSA56RLRMG as a replacement which seems to work fine!
You could replace the front end transistors with types that are not equivalent.
Low gain types that are known to work properly will be nearly as low in low noise as good working high gain types. Most of the noise comes from the front end.
If after replacing you find no change in noise then you know it was not the old transistors. test them and put them back.
If the noise is much improved, then you know the old ones were damaged. Look for good replacement types.
Low gain types that are known to work properly will be nearly as low in low noise as good working high gain types. Most of the noise comes from the front end.
If after replacing you find no change in noise then you know it was not the old transistors. test them and put them back.
If the noise is much improved, then you know the old ones were damaged. Look for good replacement types.
Changing transistors one by one on this preamp is not practical since the solder side of the PCB is not accessible unless the whole thing is disassembled. Each board is soldered to another and all rear connectors and front controls and PCBs must be removed together. I found desoldering and re-soldering caused too much damage to the fragile traces than I'd care to deal with.
I have been cutting the transistor legs and replacing them one by one from the component side.
Thank you for your tip on noise usually coming from the front-end transistors. When I get back into this project I'll start there.
Do you have recommendations for different transistor replacements that would work properly? I find cross referencing very confusing!
I have been cutting the transistor legs and replacing them one by one from the component side.
Thank you for your tip on noise usually coming from the front-end transistors. When I get back into this project I'll start there.
Do you have recommendations for different transistor replacements that would work properly? I find cross referencing very confusing!
PS Audio IVH preamp
Let me apologize in advance for tagging onto this thread. I felt that doing so might allow me to reach folks who can really help me.
I pulled a PS Audio IVH preamp out of my closet recently. I am the original owner and I am guessing it is somewhere around 34 years old. It still works and I am using it with my original Amber 70 power amp (also pulled out of the same closet). Both still sound pretty good. My preamp has a small problem though and I am looking for advice on how to fix it. Often when I switch it on, only the right channel is working. All I have to do is give it a sharp rap on the cover and the left channel starts working. Sounds great, no hum, etc. Eventually the left channel drops out.
I have had the cover off and nothing looks amiss. I am wondering if the problem could be a poor ground on the central ground bolt. Does anyone have any other suggestions for me to follow up on? Warning, I am a mechanical engineer, not an electronics technician.
Currently I am using this equipment to replace an Altec-Lansing powered speaker system with my desktop computer. Listening to MP3 files, it sounds 100 times better than the Altec ever did, using an old pair of Mordaunt Short bookshelf speakers, also rescued from my closet.
Let me apologize in advance for tagging onto this thread. I felt that doing so might allow me to reach folks who can really help me.
I pulled a PS Audio IVH preamp out of my closet recently. I am the original owner and I am guessing it is somewhere around 34 years old. It still works and I am using it with my original Amber 70 power amp (also pulled out of the same closet). Both still sound pretty good. My preamp has a small problem though and I am looking for advice on how to fix it. Often when I switch it on, only the right channel is working. All I have to do is give it a sharp rap on the cover and the left channel starts working. Sounds great, no hum, etc. Eventually the left channel drops out.
I have had the cover off and nothing looks amiss. I am wondering if the problem could be a poor ground on the central ground bolt. Does anyone have any other suggestions for me to follow up on? Warning, I am a mechanical engineer, not an electronics technician.
Currently I am using this equipment to replace an Altec-Lansing powered speaker system with my desktop computer. Listening to MP3 files, it sounds 100 times better than the Altec ever did, using an old pair of Mordaunt Short bookshelf speakers, also rescued from my closet.
PS Schematics
At the risk of sounding like a broken record, I too could use schematics to the PS 4.5 AND the PS 5.0. The 4.5 is working fine, but never hurts to have info on hand. The 5.0 I began working on 2 years ago but had to shelve the project due to life. My notes have since disappeared (two kids and 2 cats) and I don't remember where I was with it, so a schematic would be more than appreciated.
For those who do own one of these preamps, I can tell you that the switches and wafers are still available through Allied Electronics. If anyone needs part numbers, I'm sure I can dig those up.
Thank you in advance to anyone who wishes to send me a schematic. My email is jebsledge@gmail.com. Thank you again!!
At the risk of sounding like a broken record, I too could use schematics to the PS 4.5 AND the PS 5.0. The 4.5 is working fine, but never hurts to have info on hand. The 5.0 I began working on 2 years ago but had to shelve the project due to life. My notes have since disappeared (two kids and 2 cats) and I don't remember where I was with it, so a schematic would be more than appreciated.
For those who do own one of these preamps, I can tell you that the switches and wafers are still available through Allied Electronics. If anyone needs part numbers, I'm sure I can dig those up.
Thank you in advance to anyone who wishes to send me a schematic. My email is jebsledge@gmail.com. Thank you again!!
Count me as another broken record.
I have a PS IV + HCPS I bought new '82. It's given reliable service all these years until yesterday when I noticed a "burnt circuit" smell near the unit. It works & sounds fine but the LED never stops flashing.
Should be an easy fix if I had the schematic.
Please?
I have a PS IV + HCPS I bought new '82. It's given reliable service all these years until yesterday when I noticed a "burnt circuit" smell near the unit. It works & sounds fine but the LED never stops flashing.
Should be an easy fix if I had the schematic.
Please?
It's not hard to find schematics on forums that cater to older gear (and that have file hosting space) but for some reason I can't locate a complete schematic of this simple preamp. The original owners manual had a schematic of the phono stage but nothing else and I've found versions that include the line stage and power supply. None include the power-on timer/safety circuit or whatever it is.
Hi Greg,
I PM'ed you last night for the schematic as well. Thank you!
Anyone here has any other information, the timing/protection circuit, etc, for the PS preamp, please send it my way(soda_audio@yahoo.com). There will never be too much information on these good old gears.
Thanks in advance!
Stanley
I PM'ed you last night for the schematic as well. Thank you!
Anyone here has any other information, the timing/protection circuit, etc, for the PS preamp, please send it my way(soda_audio@yahoo.com). There will never be too much information on these good old gears.
Thanks in advance!
Stanley
I missed the notification that schematics had been added to this thread. Very helpful!
Oddly though mine is different from the 2 versions posted. HOW MANY were there? LOL
My power supply features neither numerous discrete transistors nor end-to-end diodes. I have 3-pin regulators and lots of open space on the PCB. I always assumed I had an early version of the PSIV since it came with cheap plastic knobs that I later swapped for the newer machined aluminum knobs.
Does that mean Paul & Stan found the handy 3-pin regulators were "less listenable" than a power supply made up of discrete components?
Oddly though mine is different from the 2 versions posted. HOW MANY were there? LOL
My power supply features neither numerous discrete transistors nor end-to-end diodes. I have 3-pin regulators and lots of open space on the PCB. I always assumed I had an early version of the PSIV since it came with cheap plastic knobs that I later swapped for the newer machined aluminum knobs.
Does that mean Paul & Stan found the handy 3-pin regulators were "less listenable" than a power supply made up of discrete components?
Oops forgot to include the link:
PS AUDIO Model IV preamp, Model Two power amp, and Elite schematics
This thread has more traffic than the one with the answers.
PS AUDIO Model IV preamp, Model Two power amp, and Elite schematics
This thread has more traffic than the one with the answers.
Hello. I am looking for the schematics for the PS Audio 4.5 preamp. I upgraded the entire PCB awhile ago. I noticed that PS Audio bypassed wires on the solder side by scratching out a trace then connecting a wire to another eyelet hole elsewhere on the board. Why was that?? Also one electrolytic I believe is 470uf has a eyelet solder which has no trace, just an isolated solder point. Is this possible. I don't recall it tracing to another point. The other end is solder across a bare wire bridge. Can anyone help??