Hey Guys
I thought id post this to keep a journal of my first Amplifier Upgrade / Repair, I have inherited my fathers HCA3500 and other audio equiptment a couple of years ago.
These mods have been on the mind for over 5 yrs and i always promised my dad i would attempt them for him, unfortunately he has passed and now found time to get started
More info has come available since i first looked into this many years ago, and noticed a few threads on here
The amplifier ran fine but started having trouble with the right channel, which would take about 10 mins to kick in, (possible faulty capacitor)
I have now spent the past week or so sourcing components and i will be following Sky audio mod list with a few tweaks
this how its going so far
I thought id post this to keep a journal of my first Amplifier Upgrade / Repair, I have inherited my fathers HCA3500 and other audio equiptment a couple of years ago.
These mods have been on the mind for over 5 yrs and i always promised my dad i would attempt them for him, unfortunately he has passed and now found time to get started
More info has come available since i first looked into this many years ago, and noticed a few threads on here
The amplifier ran fine but started having trouble with the right channel, which would take about 10 mins to kick in, (possible faulty capacitor)
I have now spent the past week or so sourcing components and i will be following Sky audio mod list with a few tweaks
this how its going so far
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Hi laup,
Why? Oh why?
Those amps are designed quite well. Upgrading it, very questionable.
Fix the fault first. I'm not sure what it does while powering up, buy "probably a cap" wouldn't be my first guess. Look at DC offset while it comes up. Do not start changing stuff before you get it running. Otherwise you just threw a bunch of variables into the mix and erased clues you needed.
Why? Oh why?
Those amps are designed quite well. Upgrading it, very questionable.
Fix the fault first. I'm not sure what it does while powering up, buy "probably a cap" wouldn't be my first guess. Look at DC offset while it comes up. Do not start changing stuff before you get it running. Otherwise you just threw a bunch of variables into the mix and erased clues you needed.
I hear you, but this amp hasnt had a good life, it has been in dire need of a service and upgrade, so I thought I would attempt the faulty channel first, I have a perfectly fine working left channel for reference.
I will be testing every component on this board once ive cleaned it up.
I have it on my shop bench, so will be back and forth to it between jobs
(in regards to the issue. when both channels are turned on at the same time, the right channel would literally take 5 minutes for any audio output compared to the left, but would sound absolutely fine once on)
I will be testing every component on this board once ive cleaned it up.
I have it on my shop bench, so will be back and forth to it between jobs
(in regards to the issue. when both channels are turned on at the same time, the right channel would literally take 5 minutes for any audio output compared to the left, but would sound absolutely fine once on)
Well, always get it running before changing anything.
I really am suspicious of "upgrades". There are times when engineered improvements make a difference. I've certainly done and seen many. I've seen more that cause problems or reduced performance. If you're lucky they don't change performance one bit, or negatively affect reliability. An upgrade is really re-engineering a circuit. Something not done lightly.
I really am suspicious of "upgrades". There are times when engineered improvements make a difference. I've certainly done and seen many. I've seen more that cause problems or reduced performance. If you're lucky they don't change performance one bit, or negatively affect reliability. An upgrade is really re-engineering a circuit. Something not done lightly.
I will be comparing to the original left side A/B and will deicide whether to proceed onto the other boards/channel. I have kept all the original components so, I can always revert back if needed and look at it as a learning curve....
Im using this opportunity to learn about the audio repair side, I fix laptops PC and consoles which dont rely to heavily on matched or quality of components,
So there is a finesse to all this... which i want to learn, ive already had a major headache trying to source certain resistors and bipolar capacitors and dealing with digikey and mouser shenanigans 🙂
Im using this opportunity to learn about the audio repair side, I fix laptops PC and consoles which dont rely to heavily on matched or quality of components,
So there is a finesse to all this... which i want to learn, ive already had a major headache trying to source certain resistors and bipolar capacitors and dealing with digikey and mouser shenanigans 🙂
For reference
https://www.mouser.co.uk/ProductDetail/Bourns/3296W-1-252LF?qs=VW5eOWd7Luy89Xw/Kwu/xg==
Trimmers
https://www.mouser.co.uk/ProductDetail/Bourns/3296W-1-252LF?qs=VW5eOWd7Luy89Xw/Kwu/xg==
Trimmers
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Just because a part is labeled "audio" doesn't mean it is well suited to the job.
Do not replace single turn controls with 10 turn types. Ever. If the originals were 10 turn, fine. I still question replacing them because now you've lost the running adjustment. Always, always, always use parts that fit the PCB, or are as close as can be had. If it doesn't mechanically fit, you can't use it. These are general comments as I won't research the unit and your parts. I order the correct parts if I don't have them on hand (and I have well over $10K new parts in drawers).
You're right. Analogue service and test equipment service is so different than computer and other kinds of service. You have got to know your parts and read those data sheets (not white papers). If you have a well engineered unit, such as Parasound, do not second guess the team of engineers that designed it. I'm just trying to keep you on the track for success and have a nice reliable amplifier when you are done.
Always remember. There is no one best type of capacitor or resistor. Each application may have a best type (and it has to fit). The application is what the part actually does in the circuit, not the circuit. Part types have characteristics that best fit a particular application. You have to know this stuff. Then, there are applications where the part type isn't that critical.
Do not replace single turn controls with 10 turn types. Ever. If the originals were 10 turn, fine. I still question replacing them because now you've lost the running adjustment. Always, always, always use parts that fit the PCB, or are as close as can be had. If it doesn't mechanically fit, you can't use it. These are general comments as I won't research the unit and your parts. I order the correct parts if I don't have them on hand (and I have well over $10K new parts in drawers).
You're right. Analogue service and test equipment service is so different than computer and other kinds of service. You have got to know your parts and read those data sheets (not white papers). If you have a well engineered unit, such as Parasound, do not second guess the team of engineers that designed it. I'm just trying to keep you on the track for success and have a nice reliable amplifier when you are done.
Always remember. There is no one best type of capacitor or resistor. Each application may have a best type (and it has to fit). The application is what the part actually does in the circuit, not the circuit. Part types have characteristics that best fit a particular application. You have to know this stuff. Then, there are applications where the part type isn't that critical.
My parts list for anyone
I have some 4.7k from Ukraine and some k71-4 from Russia here also
I have some 4.7k from Ukraine and some k71-4 from Russia here also
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Throw the Ebay parts in the garbage.
Don't mess around with odd parts. These were built with parts that did not hamper performance. You are now second guessing the engineering department. Not wise.
Don't mess around with odd parts. These were built with parts that did not hamper performance. You are now second guessing the engineering department. Not wise.
That is a beast of an amplifier - not sure I've seen close up shots of the PCB before.
Those are some unusual/interesting parts, But I give a nod to Rick at Bigskyaudio, I did two of his upgrades for ADCOM units and they both turned out very nice.
Good luck, tuning in to watch your progress and hear your thoughts on the audio when it's finished.
Don't forget, it's a DIY hobby, so take all the liberties you want to, experiment multiple different ways and as long as you don't mind redoing something more than once, it can almost always be fixed or tuned to your liking!!!
Those are some unusual/interesting parts, But I give a nod to Rick at Bigskyaudio, I did two of his upgrades for ADCOM units and they both turned out very nice.
Good luck, tuning in to watch your progress and hear your thoughts on the audio when it's finished.
Don't forget, it's a DIY hobby, so take all the liberties you want to, experiment multiple different ways and as long as you don't mind redoing something more than once, it can almost always be fixed or tuned to your liking!!!
There is a massive difference between an Adcom (did warranty for them also ) and a Parasound. The Parasound is far better engineered.
But, it is up to you what you do.
But, it is up to you what you do.
I don't disagree, there is a huge difference in ADCOM and Parasound, but it also sounds like the OP did his research, sought out parts/upgrades that he thinks will work and has the know-how ability to make a good repair/upgrade. We don't have to agree 100% on his choices and we can give our opinion, but in the end it sounds like the OP is doing this as much for the repair/upgrade, as he is a way to "remember" something he and father shared a love for. He also gets a chance to close an unfinished chapter in their lives they were trying to write together.
Even it doesn't turn out to be an upgrade, but functions as designed - the OP will remember his father every time he pushes the power button, or listens to music playing through it. I think that is one of the best reasons to do any DIY hobby, the memories.
Even it doesn't turn out to be an upgrade, but functions as designed - the OP will remember his father every time he pushes the power button, or listens to music playing through it. I think that is one of the best reasons to do any DIY hobby, the memories.
Hi bullittstang,
Sure, absolutely. However there are so many experts and upgrades out there, sorting out truth from wishful thinking is difficult, next to impossible for people not trained. Just trying to interject some sanity.
From some of the parts I saw, plus Ebay purchases, it's clear parts were bought from reputation instead of knowledge. If he was rebuilding a cheaper piece, sure. A Parasound is something different. I'd say the same if those parts were intended for a Marantz or other good product.
I'll just say this. Should a Parasound or Marantz (and a few others) hit my bench, those parts would be on the replacement list. I see it over and over again. What's the best part? Great, I'll use those in this piece. The best part depends on application, not reputation.
Sure, absolutely. However there are so many experts and upgrades out there, sorting out truth from wishful thinking is difficult, next to impossible for people not trained. Just trying to interject some sanity.
From some of the parts I saw, plus Ebay purchases, it's clear parts were bought from reputation instead of knowledge. If he was rebuilding a cheaper piece, sure. A Parasound is something different. I'd say the same if those parts were intended for a Marantz or other good product.
I'll just say this. Should a Parasound or Marantz (and a few others) hit my bench, those parts would be on the replacement list. I see it over and over again. What's the best part? Great, I'll use those in this piece. The best part depends on application, not reputation.
Tips: For Electrolytic Caps, get 105 degrees rated ones at least. This one above is not.
So I've done some recapping today and cleaning board up
I've tested each cap before installation
I've noticed there are scotch marks around diodes d9 through 12
Also behind r93 and c8 looks a bit dodgy along with r104, which I think has seen better days
I forgot to order 22uf replacement so I think I will reinstall the rubicon original as it tested fine
I've tested each cap before installation
I've noticed there are scotch marks around diodes d9 through 12
Also behind r93 and c8 looks a bit dodgy along with r104, which I think has seen better days
I forgot to order 22uf replacement so I think I will reinstall the rubicon original as it tested fine
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You're absolutely bang on there my man
Actually bought a tear to my eye
If it works out and sounds great it's a winner.
And I will do another if not
I've finally had a go at it. I will then go back to my 2x cinepro 3k6III
So fitted resistors and rectifier and the rest of the caps
I noticed a I made a mistake in previous pictures the k71s werent in parallel
Better with visuals so those can reference what's been changed and or removed
I noticed a I made a mistake in previous pictures the k71s werent in parallel
Better with visuals so those can reference what's been changed and or removed
