Is it ever "just" the Relay? Troubleshoot STA-2000 help please...
- Thread starter polypetalous
- Start date
polypetalous
Super Member
So as to not leave everyone hangin'...
After some sleep and reflection, I have decided that IF the replacement fuse gets me back to my original problem (post #1 - speaker relay non-responsive) that I am going to go for a DIY recap... Figure I'll start with the Power Supply PCB and Protection Boards one at a time first.
Been talking about doing this for years, time to just do it, not like I have too much to lose.
So couple of questions as I gather parts:
And apologies, know these have probably been covered ad nauseam...
1) I had started a recap parts list year or so ago and had the following notes:
a) Use Nichicon caps - typically audio grade (FG) for values 47uf and below and power supply (VR) for values above.
b) Replace all of the tantalums with electrolytics (over 1uf) or poly films (under 1uf)
Are these true/accurate statements?
2) One piece of equipment I will need is a better/decent soldering iron than I typically have owned..
Any suggestions on a reasonably priced (cost effective) iron that's suitable for this work?
3) This will stand to take me a while to do and I have GOTTA be able to play records in the meantime:
I have a stand alone phono preamp but no amp to work with.
Will one of the little class D "chip amps" (TPA3116 or similar Fosi/Breeze/nobsound 50W or 100W) with my phono pre be enough to drive my Nova 7b speakers reliably at typical listening levels? Will it sound at least half-decent?
Thanks again and as always open to any and all opinions, advice, etc.
Ben
After some sleep and reflection, I have decided that IF the replacement fuse gets me back to my original problem (post #1 - speaker relay non-responsive) that I am going to go for a DIY recap... Figure I'll start with the Power Supply PCB and Protection Boards one at a time first.
Been talking about doing this for years, time to just do it, not like I have too much to lose.
So couple of questions as I gather parts:
And apologies, know these have probably been covered ad nauseam...
1) I had started a recap parts list year or so ago and had the following notes:
a) Use Nichicon caps - typically audio grade (FG) for values 47uf and below and power supply (VR) for values above.
b) Replace all of the tantalums with electrolytics (over 1uf) or poly films (under 1uf)
Are these true/accurate statements?
2) One piece of equipment I will need is a better/decent soldering iron than I typically have owned..
Any suggestions on a reasonably priced (cost effective) iron that's suitable for this work?
3) This will stand to take me a while to do and I have GOTTA be able to play records in the meantime:
I have a stand alone phono preamp but no amp to work with.
Will one of the little class D "chip amps" (TPA3116 or similar Fosi/Breeze/nobsound 50W or 100W) with my phono pre be enough to drive my Nova 7b speakers reliably at typical listening levels? Will it sound at least half-decent?
Thanks again and as always open to any and all opinions, advice, etc.
Ben
Last edited:
petehall347
the brandy coffee man
check the output transistors for shorts
ttbccw
Active Member
Yes, I usually do the Power supply and protect boards first. Good stable power section is very important. Especially if you need to trouble shoot another section.
1) a: I have used Nichicon/Panasonic caps in my restorations. I have used FG in the power amp, phono amp, Tone board, and other audio path places. I love them. I also use stacked film WIMA caps in certain places when they will fit. Depends on the volts and uf, but always in the tone section. I have also used the Nichicon ES Bi-Polar green caps in audio input places to replace tantalum or ceramics. These are places where you have very low uf and v ratings in the circuit. And I use a "standard" or "High Reliability" type Nichicon for the power and protect boards.
https://www.nichicon.co.jp/english/products/alm_mini/index.html
b: Yes. If they fit I would change them out with film or new electrolytic...they are smaller now than they were in the 70's so new electrolytic should fit. It's all about physically fitting the new component in, especially if your changing the cap type (Electrolytic, film)
2) I bought a soldering station from Radio Shack a few years back when the store closed. I don't know what a good, reasonably priced one would be. You should also consider a solder sucker remover too. Makes taking the old caps out much easier. For $20 I got a soldering iron/sucker combo pen from Amazon. Works great on the PCB's in 70's units.
3) I have no experience with class D amps. Sorry.
I agree that you should also check the output transistors...and probably any transistor directly connected to the circuit that was shorted. And diodes too...
1) a: I have used Nichicon/Panasonic caps in my restorations. I have used FG in the power amp, phono amp, Tone board, and other audio path places. I love them. I also use stacked film WIMA caps in certain places when they will fit. Depends on the volts and uf, but always in the tone section. I have also used the Nichicon ES Bi-Polar green caps in audio input places to replace tantalum or ceramics. These are places where you have very low uf and v ratings in the circuit. And I use a "standard" or "High Reliability" type Nichicon for the power and protect boards.
https://www.nichicon.co.jp/english/products/alm_mini/index.html
b: Yes. If they fit I would change them out with film or new electrolytic...they are smaller now than they were in the 70's so new electrolytic should fit. It's all about physically fitting the new component in, especially if your changing the cap type (Electrolytic, film)
2) I bought a soldering station from Radio Shack a few years back when the store closed. I don't know what a good, reasonably priced one would be. You should also consider a solder sucker remover too. Makes taking the old caps out much easier. For $20 I got a soldering iron/sucker combo pen from Amazon. Works great on the PCB's in 70's units.
3) I have no experience with class D amps. Sorry.
I agree that you should also check the output transistors...and probably any transistor directly connected to the circuit that was shorted. And diodes too...
century tek
Addicted Member
You accidentally shorted something so a new fuse is just going to blow again. You can know this by the fuse being blackened. You can certainly try a new fuse but in my experience, 99 times out of 100, an output transistor is usually what shorts when when a slip up happens.
polypetalous
Super Member
I'm trying to be "optimistic" but I fear (and half-assume) you all are correct that I did indeed make matters worse.
I haven't even looked up "output transistor testing" yet... Can you test/check them in place?
Ben
petehall347
the brandy coffee man
you can test for shorts then if any appear shorted will need removing and testing again .
polypetalous
Super Member
Did some quick checks and not that I 100% understand the numbers or am I saying I did it 100% correctly, but there is a clear difference form LH to RH channels.
Both Output Transistors on the LEFT are showing 001 on a leg each and I am seeing continuity between legs that isnt there on the RIGHT.
So my "guess" is that the LH Outputs are toasted (by my own idiocy)
IF they are gone:
1) Is it ok to only replace output transistors on one channel and not the other or just best to do both channels?
2) Looks like each Channel has one each NEC D287A and NEC B539B
Quick search shows these arent available anymore.... of course
Are MJ21193G and MJ21194G suitable replacements?
3) Am I in over my head?
Ben
Yes..
Might be..
petehall347
the brandy coffee man
you need to remove the suspects and test again . there is a good chance with those readings the driver transistors are shorted
polypetalous
Super Member
Upon even more reflection and a lil more sleep...
I am thinking I am "in over my head here."
Not that I think it would be "impossible" for me to take this on, but I know the reality is that the "time needed" is what I probably can't afford or do not have.
After the lack of time there is also, lack of experience, skills, equipment etc.
Soooooo...
Thinking I am down to either a new receiver/integrated etc.
or
Have this unit rebuilt/repaired professionally.
To make this more complicated, I HAVE to be cost conscious here yet make sure I end up with something I can live with (enjoy) for the long haul.
I have been on the hunt for a local tech and "may have found one."
I spilled my guts to him about ALL I have done to this poor poor receiver and his response was:
Hi Ben,
We appreciate you contacting us, especially for the opportunity to work on circa 77's receiver with enduring appeal.
Restoration of your vintage Realistic STA-2000 Receiver (non-Dolby model):
Keeping all the components of the same / from the same manufacture build is critical for match balance bias between the L/R channels.
They along with the new CAPs will all settle (burn in) in really nice together.
Consider after the refurbishment, that you are in effect purchasing both a NEW and VINTAGE unit.
My work flow plan / cost mitigation recommendation,
Ken
A) I don't know this guy at all and have NO recommendations to go on..
B) It "sounds" (to me) like he knows what he is talking about and has a good "plan of attack."
But just curious, if anything in what he said would be problematic or a red flag for other more experienced people?
Not so much asking about his quoted price, as I figure I would be nearly a third of his cost to just get output transistors and a decent soldering station.
Any thoughts, opinions?
Ben
I am thinking I am "in over my head here."
Not that I think it would be "impossible" for me to take this on, but I know the reality is that the "time needed" is what I probably can't afford or do not have.
After the lack of time there is also, lack of experience, skills, equipment etc.
Soooooo...
Thinking I am down to either a new receiver/integrated etc.
or
Have this unit rebuilt/repaired professionally.
To make this more complicated, I HAVE to be cost conscious here yet make sure I end up with something I can live with (enjoy) for the long haul.
I have been on the hunt for a local tech and "may have found one."
I spilled my guts to him about ALL I have done to this poor poor receiver and his response was:
Hi Ben,
We appreciate you contacting us, especially for the opportunity to work on circa 77's receiver with enduring appeal.
Restoration of your vintage Realistic STA-2000 Receiver (non-Dolby model):
- All new parts, full CAP replacement, both sets of output transistors and relay, Parts only $230.
- Other parts electrical damaged (if any) from pins #4 & #5 short event, will need to advise.
- Work is slow at this time, a full refurb of this order typically runs, Labor only $200.
- Your receiver design is least labor intensive as the circuit boards are each easy access.
- With that said, the labor for this specific time frame and receiver is, Labor only $100 total.
Keeping all the components of the same / from the same manufacture build is critical for match balance bias between the L/R channels.
They along with the new CAPs will all settle (burn in) in really nice together.
Consider after the refurbishment, that you are in effect purchasing both a NEW and VINTAGE unit.
My work flow plan / cost mitigation recommendation,
- 1st stage, order minimal parts, replace both transistor sets, parts $25 and labor $25.
- Test unit to exclude any pin #4 & #5 short event damage.
- Conditional no other issue then we advance to 2nd stage of refurbishment, ordering the CAPs & Relay.
- Finishing with full cap and relay replacement balance $280.
- Total part $230 + Total Labor $100, refurbished total $330.
Ken
A) I don't know this guy at all and have NO recommendations to go on..
B) It "sounds" (to me) like he knows what he is talking about and has a good "plan of attack."
But just curious, if anything in what he said would be problematic or a red flag for other more experienced people?
Not so much asking about his quoted price, as I figure I would be nearly a third of his cost to just get output transistors and a decent soldering station.
Any thoughts, opinions?
Ben
polypetalous
Super Member
To add some levity to this, thought y’all would appreciate my “temporary fix” to keep me spinning records:
That’s right 1976 Magnavox console pull. Had the console set aside slated to get recycled...
Can at least play some records...
Sure is a damn ugly sight.
And here’s where I’d say “how surprisingly good” it sounds.... but no... I have heard far worse, but it it ain’t great.
Using some small Monkey-ward Airline speakers to not blow up my Novas.
thank you all for at the very least putting up with me.
Appreciate it.
Happy Friday.
Ben
That’s right 1976 Magnavox console pull. Had the console set aside slated to get recycled...
Can at least play some records...
Sure is a damn ugly sight.
And here’s where I’d say “how surprisingly good” it sounds.... but no... I have heard far worse, but it it ain’t great.
Using some small Monkey-ward Airline speakers to not blow up my Novas.
thank you all for at the very least putting up with me.
Appreciate it.
Happy Friday.
Ben
polypetalous
Super Member
Well the STA-2000 has been with a a local tech for nearly a week now.
Majority of the troubleshooting is complete and I believe I can report that my dummy move of shorting pins #4 & #5 on the protection board ONLY damaged the Left Output transistors (and main fuse), outputs were goners.
So waiting for new outputs and the unit is going to get a full re-cap and already has a new Speaker Protection Relay installed. The relay most likely wasn't causing the original issue (relay wouldn't engage at start-up) but the contacts were pretty bad. As well, I had been into the relay a few times and quite frankly my "repair mantra" for this unit is "If I've touched it, its suspect."
I also suspect this repair/bill is going to get a bit "out of hand," but you know I guess this STA-2000 is now that air-cooled Porsche I always wanted ...
But really I have nearly nothing invested in my stereo, and have probably been too proud of that alone for too long. I have spent so much time putting my money into records its probably about time I put some into the system as well.
And it will be nice to be able to turn on my receiver without having to cross-fingers first and hopefully so for the remainder of my days.
Ben
Majority of the troubleshooting is complete and I believe I can report that my dummy move of shorting pins #4 & #5 on the protection board ONLY damaged the Left Output transistors (and main fuse), outputs were goners.
So waiting for new outputs and the unit is going to get a full re-cap and already has a new Speaker Protection Relay installed. The relay most likely wasn't causing the original issue (relay wouldn't engage at start-up) but the contacts were pretty bad. As well, I had been into the relay a few times and quite frankly my "repair mantra" for this unit is "If I've touched it, its suspect."
I also suspect this repair/bill is going to get a bit "out of hand," but you know I guess this STA-2000 is now that air-cooled Porsche I always wanted ...
But really I have nearly nothing invested in my stereo, and have probably been too proud of that alone for too long. I have spent so much time putting my money into records its probably about time I put some into the system as well.
And it will be nice to be able to turn on my receiver without having to cross-fingers first and hopefully so for the remainder of my days.
Ben
polypetalous
Super Member
To close this one out...
the STA-2000 has returned!
Repaired, refreshed and sounding great.
Re-capped, except tuner (which is problem free), new speaker protect relay and new outputs for both channels.
As well as full adjustment and dialing in of unit.
Ken (local tech) did a fantastic job, to say above and beyond is putting it lightly.
Without my asking or requesting, Ken went so far as to hollow out the old filter cap cans and use the empty cases as a covers on the new, smaller filter caps.
And, this one blows my mind... Ken took the time to wax-string, lace the wire bundles through out the unit. No zip ties here, just nicely done lacing.
couple of pics:
I’ll be putting her through the paces over the next couple days.
So all in all, hate that I caused so much damage, but now the units in a way better place than before and I can run her confidently.
Ben
the STA-2000 has returned!
Repaired, refreshed and sounding great.
Re-capped, except tuner (which is problem free), new speaker protect relay and new outputs for both channels.
As well as full adjustment and dialing in of unit.
Ken (local tech) did a fantastic job, to say above and beyond is putting it lightly.
Without my asking or requesting, Ken went so far as to hollow out the old filter cap cans and use the empty cases as a covers on the new, smaller filter caps.
And, this one blows my mind... Ken took the time to wax-string, lace the wire bundles through out the unit. No zip ties here, just nicely done lacing.
couple of pics:
I’ll be putting her through the paces over the next couple days.
So all in all, hate that I caused so much damage, but now the units in a way better place than before and I can run her confidently.
Ben