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SX-1080 High End Muffled / Protection Circuit Comes On at High Volume

Sorry to hear about your loss. Congrats on the 2100 tho, good choice. What abut the 7080? That things a powerhouse too!!
 
Listening to the 7080 now

It's my spare. It sounds awesome.

It needs Deoxiting and the tape 1 inputs on the back have intermittant contact so it will need some minor work.

I'll do that another day.

I'm tired of soldering for now.

Cheers!
 
It is ALIIIIVE!!!

OK Folks,

Big lesson learned here.

If you followed this thread, Mark pulled his hair out trying to walk me through this repair and I chickened out after I re-did the amp board twice and so I brought it to a local technician to complete the repair.

When I walked in with it I showed him how I had the entire amp board redone again with all new parts. I told him every time I went to bring the receiver back to life, even with a dimbulb tester, I fried a couple of resistors.

Here is what I learned - these two steps are critical BEFORE plugging in even with the dimbulb tester:

1) The idle current pot VR1 100 ohms is set to zero ohms read in circuit.

2) The offset adjust pot VR2 150k is set to maximum, 150,000 ohms, read in circuit.

The tech said my soldering was perfect and because I had it all prepped for him all he had to do was adjust the two pots ( shown above ) and set the idle current and offset. He brought it up in stages ( I guess with a rheostat.)

He only charged me 40 bucks.

Mark tried so hard to figure out where the demon was in the circuit. I derailed and misunderstood him when he was showing me the steps. My lesson learned was to make sure I follow the steps to the letter.

Those pots are critical to be set at a safe range for powering up.

I have Dire Straits Love Over Gold ( vinyl ) cranked behind me. This receiver sounds brand new.
 
What he didn't mention is that he probably eyeballed each and every transistor on the board, and determined it was in correctly, and did a few other quick tests before ramping up the power.


That "home stretch ITCH " is a killer..... and it's hard to reach through the screen to "wooooaaaahhhhhh" somebody....
 
Yup

Yes absolutely he did say that and he did a bunch of measurements as he was applying power to check everything was in order.

You're right ... "Trigger" was smelling the home stable and was in a hurry to get home.
 
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I just read the entire thread and admire your courage to jump in. I was lost by the third post,,:drool: hell I was proud of myself for reading it!!! I'm definitely gonna take my amps to a tech to get re-worked..
 
I am impressed...just read the hole thread. That Mark is one of a kind...I am able to do the very same...but I would be crazy long before half way.
 
Yeah he was a lot of help. I learned a lot.

Now I'm listening to this receiver and wondering if I should re & re the other amp board the same way just because I'm thinking that I'm hearing the bass is stronger on one side than the other.

I think Mark said it wouldn't affect the sound at all if I left the other amp board stock.

I wonder if I'm getting a touch of OCD or if in fact there is a possible performance difference?
 
Grog said:
Yeah he was a lot of help. I learned a lot.

Now I'm listening to this receiver and wondering if I should re & re the other amp board the same way just because I'm thinking that I'm hearing the bass is stronger on one side than the other.

I think Mark said it wouldn't affect the sound at all if I left the other amp board stock.

I wonder if I'm getting a touch of OCD or if in fact there is a possible performance difference?
Click to expand...

There is only ONE cap that counts for / influences frequency response / sound : the input coupling cap... actually there are two that they put back to back to make them non-polar , HOW did you do that replacement on the first board? 1 uf stacked film across the outer connections?

The only other electrolytic cap IS the 0.22uf cap in the protect circuit's over current detector C11.

DON'T muck about with the transistors, THEY won't do this to you. Just the two (or three) caps.

A loss of input coupling capacitance WILL affect the bass , the LOW bass... the difference between 20hz and 40hz...

BUT, I remember this picture
so haven't you swapped out the caps on BOTH amp boards ALREADY???

attachment.php
 
Yes I did replace those two little caps C1 & C2 on the other amp board with the one which bridged over that little isolated foil. And I replaced C11 as well per your guidance. Both amp boards match in that regard.

All should be good then and I should stop listening for stuff that isn't there.

Perhaps it's because I have my right speaker in a corner and the other is not really in a corner ( room configuration ).

Thanks for your comments,

Cheers!
 
Thank you to the members for the capacitor list, i just finished my order at mouser for capacitors for the tuner assembly and power supply assembly, after i cap those two boards i'll see where the sx-1080 is in terms of sound, if i need to cap further i will, the cost for caps was $19.00 with shipping, wish me luck, bob
 
Tuner is the only thing to NOT recap by someone without the appropriate equipment.
 
I have a 1080 I just picked up. It works, but I was thinking of a recap or something.
After reading this thread I can honestly say, I am not going to touch it till my life gets organized.
Anyway Mine has a finicky tuner, but works fine. Was dusty and filled with cobwebs and similar stuff.

Cool.
Srinath.
 
finicky tuners are two things with the finned tuning cap -

1. grounding straps to the center shaft (rumbling on turning) - brass on brass corrosion/tarnish yields to wd40 (sorry, not deoxit usually - even though it's worth a try) dripped in on the contacts and then work it work it work it to get good contact through the entire range. keep it off the fins.

2. dust etc in the fins - zero residue cleaner and a FULL DAY (24 HOURS) of drying, fins fully unmeshed and then DRIPPING (thicker) oil into the tuner bearings keeping it OFF the plates - where even an oil film on part of the plates WILL change the tuning.
 
Oooo that I can actually handle ... yeaaaaay ... air compressor here I come - the thing was covered in 16 layers of ... lets just be kind and say "retirees".
Apparently it was sitting like on display but never used for years and years and years ... the TT I got with it was 1000 times cleaner ... I asked him why - he said that fit inside the cabinet ... this one did not, so it was on top.

Cool.
Srinath.
 
Grog said:
SX-1080 Recap List

Hi Mark!

Per our PM's and posts, here is the recap list for all electrolytic capacitors.

I have this in an Excel spreadsheet that is a lot easier to manage, but it I can't upload that and the Word.doc is still too big, so I had to convert it to a PDF to upload it. I can email you the Excel spreadsheet if you would rather work from that. Or I can send it in Word.

I was on Digi-key and Mousers' websites because I've noticed in other threads about recapping that people have ordered new caps from both companies. Note I have included columns for replacement model numbers, voltage and uF values, and quantities. I show the model number column as Digi-Key and Mouser because I don't know what company I'll be buying from?

I got a bit overwhelmed by their filters for selecting caps. Maybe I'm showing my noobieness here but from what I see it looks like I have to work with Aluminum Electrolytic Capacitors because that seems to be the class of cap that has the most choices? Some of the things they ask for are above my head but I think I only have the basics covered:

1) Capacitance - check.
2) Tolerance - I don't know what to select here.
3) Voltage Rating - check.
4) ESR - ??
5) Operating Temperature Range - ??
6) Termination - I believe I need to select "leads"?
7) Dimensions - ??
8) Product - Mouser's site asks for a selection with a range of options like: aluminum, bipolar/non-polar, computer grade, general purpose, high frequency, high temp, low esr, low impedance, low leakage etc. I'm not sure what to ask for.

I think you said you were going to send me a list of replacements? That would be awesome. Or if you could guide me in what to select in the options I show above that would be great too.

Pics attached are of the tone control assembly pulled out ready to go. I think when I get the caps I will do it first, then pull the next assembly and do it, and so on. The power amplifier assemblies ( AWH-071 ) look like a bear to get at. It would appear replacing the caps on them and getting those big ACH-085 by the power transformer look like major surgery. Am I wrong?

Speaking if the AWH-071 assemblies - it looks like there two of them. My manual shows a parts list for it but if there are two should I be doubling up on the caps they show?

Cheers!
Click to expand...
 
Mark
I am ready to order caps
For the eq board pre amp
Tone board Aug-056
Filter assembly awt-001
Speaker selector assembly gws-124
So not the fancy boutique, but
Nichicon fine gold, blue audio grade, epw nichicin,mylar and film.
Which flavor where would be nice to know when I order.
 
my choices of ("rules of thumb") Nichicon upw (or equivalent Panasonic) and low leakage Nichicon ukl are well documented, and film caps for what will fit at 2uf and below.
 
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