Pioneer SA-7800 with burnt out resistors
- Thread starter leesonic
- Start date
I used a blue LED Mouser part number 749-R7BWD. It wasn't an exact fit, I had to file down the edges and keep trying it through the hole in the front panel. I think I remember choosing this LED because it had a diffused case and a wide viewing angle. Some blue LEDs have a really narrow viewing angle, they blind you when you look right at them, and are relatively dim off-axis.
I powered this LED from the heater winding for the FL display, it's only 4vac or something like that. I made a small board with a couple of diodes, a smoothing cap, and a dropper resistor (can't remember the value though).
Lee.
I powered this LED from the heater winding for the FL display, it's only 4vac or something like that. I made a small board with a couple of diodes, a smoothing cap, and a dropper resistor (can't remember the value though).
Lee.
MrAndyPantz
New Member
Hi Leesonic,
Firstly, Thanks for posting up all your hard work for us forum creepers to use.
I'm using your recap list to recap my SA-7800. And I'm 3 caps into replacing everything, and I've noticed a mistake! On the power supply board, C34 and C35 are listed as 47uF and have an associated part number for purchase which is different from what's in the board (4.7uF).
Unfortunately I've already purchased the caps on the list so I'll have to put together another order. I thought I double checked everything, but obviously missed that.
Just figured I'd put this out there for the people who are planning on using your list. Perhaps I can save someone a little trouble.
The list covers everything else just fine as far as I can tell.
Cheers,
Andy
Firstly, Thanks for posting up all your hard work for us forum creepers to use.
I'm using your recap list to recap my SA-7800. And I'm 3 caps into replacing everything, and I've noticed a mistake! On the power supply board, C34 and C35 are listed as 47uF and have an associated part number for purchase which is different from what's in the board (4.7uF).
Unfortunately I've already purchased the caps on the list so I'll have to put together another order. I thought I double checked everything, but obviously missed that.
Just figured I'd put this out there for the people who are planning on using your list. Perhaps I can save someone a little trouble.
The list covers everything else just fine as far as I can tell.
Cheers,
Andy
hoggwild89
Active Member
OK, gotta ask...
The audio grades you have listed are 85deg caps. Mouser has audio 105's in these values. Why? or perhaps the reason is this list is 7 years old?
The audio grades you have listed are 85deg caps. Mouser has audio 105's in these values. Why? or perhaps the reason is this list is 7 years old?
Without looking inside one of these amps, as I don't have one at the moment, I can't tell you what they originally had inside them. The KW series caps are indeed 85C caps, but they are also towards the top end of "audio grade" caps, which is why I use them. Where there are caps that are near hot running transistors (like in the power supply), it might be prudent to use something that is rated for 105C.
Think about it though, 85C is very hot, and 105C is above the boiling point of water. If you have a cap that's running that hot, maybe there are other issues? The only time I've ever found a cap running that hot, or with evidence of running hot (like with a shrunken jacket), there have been other issues going on inside.
That's just my thoughts though...
Lee.
The 85 vs 105 is a difference in the seals of the caps, the 105 is more robust (and expensive).
The seal slows the loss of water and the drying out of the cap.
Longevity...
Yes, Mouser only recently listed those 105 degree caps. Whenever possible I specify 105 degree e-caps.
The seal slows the loss of water and the drying out of the cap.
Longevity...
Yes, Mouser only recently listed those 105 degree caps. Whenever possible I specify 105 degree e-caps.
What series caps are we talking about here?
I thought you specified PW series in your recap lists? These are 105C right?
Lee.
UPW and UHE from Nichicon is the general purpose e-cap series I usually recommend. Yes, they are 105 degree c caps.
There are Panasonic caps EchoWars recommends as well, they are fine.
THEN there are the low leakage caps, which is some circuit locations DO make a difference. They ARE literally QUIETER.
They are the unique Nichicon UKL series, which was originally just an 85 degree c cap line.
Now there are UKL's that are 105 degrees c rating.
When examining the recap lists (especially the ones I personally did) You will find MANY UKL caps in them.
My "rules of thumb" for caps:
It didn't cover non-polarized (or "bi-polar") caps, there are a few, but I can't look up that answer now at this computer about which Nichicon series to use.
The "stacked film" caps are being discontinued in some convenient voltages, but regular ecq's will do.
There are Panasonic caps EchoWars recommends as well, they are fine.
THEN there are the low leakage caps, which is some circuit locations DO make a difference. They ARE literally QUIETER.
They are the unique Nichicon UKL series, which was originally just an 85 degree c cap line.
Now there are UKL's that are 105 degrees c rating.
When examining the recap lists (especially the ones I personally did) You will find MANY UKL caps in them.
My "rules of thumb" for caps:
It didn't cover non-polarized (or "bi-polar") caps, there are a few, but I can't look up that answer now at this computer about which Nichicon series to use.
The "stacked film" caps are being discontinued in some convenient voltages, but regular ecq's will do.
I was actually trying to get an answer from hoggwild89 as to what series caps he was referring to.
Mark, I have already followed your excellent recap advice for Pioneer units, and all the other brands I work on. Using KL low leakage in the signal path of the NAD amps I seem to work on a lot makes them sound a lot better. Bypassing these with WIMA films, or even using a WIMA film for values up to 10uF improves the sound even more. The PW series are branded as "low impedance", could or would that cause a problem in certain locations?
Comparing the PW, FW and KW series, using a 10uf 50v cap just as an example, they are have a life of 2000 hours, the FG series only 1000 hours. Looking at Nichicon's own data sheet for the FW series, it shows the KW is a step up in "higher sound quality", and the FG series as a step up in "higher grade". Which is better, "higher sound quality" or "higher grade"? In the case of the FG series, "higher grade" equals half the lifespan of the FW or KW series.
Lee.
Mark, I have already followed your excellent recap advice for Pioneer units, and all the other brands I work on. Using KL low leakage in the signal path of the NAD amps I seem to work on a lot makes them sound a lot better. Bypassing these with WIMA films, or even using a WIMA film for values up to 10uF improves the sound even more. The PW series are branded as "low impedance", could or would that cause a problem in certain locations?
Comparing the PW, FW and KW series, using a 10uf 50v cap just as an example, they are have a life of 2000 hours, the FG series only 1000 hours. Looking at Nichicon's own data sheet for the FW series, it shows the KW is a step up in "higher sound quality", and the FG series as a step up in "higher grade". Which is better, "higher sound quality" or "higher grade"? In the case of the FG series, "higher grade" equals half the lifespan of the FW or KW series.
Lee.
hoggwild89
Active Member
Series? Now I dont remember off hand. I uploaded the posted cap list to mouser when I noticed the 85's and started looking for 105's. The low noise caps listed, i believe, were 105's
I have a 7800 in my "to do when I get around to it" list of my personal collection of amps.
I ran the spec test, pre-recap, for thd on a leader thd meter using an ultra low noise sig source and I got .02% (@35w) which honestly is not shabby but not near its ratings of a spectacular .007 (as though MY ears could hear the difference, LOL)
I would really like to see what it's thd is after a recap, de-oxing and bias alignment.
I have a 7800 in my "to do when I get around to it" list of my personal collection of amps.
I ran the spec test, pre-recap, for thd on a leader thd meter using an ultra low noise sig source and I got .02% (@35w) which honestly is not shabby but not near its ratings of a spectacular .007 (as though MY ears could hear the difference, LOL)
I would really like to see what it's thd is after a recap, de-oxing and bias alignment.
USMC Spike
Well-Known Member
Thank you my brother with soldering iron and pics of broken amp.
May the Kharma gods bless you for the good deeds.
May the Kharma gods bless you for the good deeds.
USMC Spike
Well-Known Member
Don't mind the emoticon's folks. When my little girl sees these thing
dancing on line, she starts yelling and screaming Daddy Daddy look at that.
She has the biggest smile on her face and for that it is so worth while.
-- spike
dancing on line, she starts yelling and screaming Daddy Daddy look at that.
She has the biggest smile on her face and for that it is so worth while.
-- spike
Timothy Flath
Active Member
Can't seem to find a service manual and am looking to substitute the power light that burned out in my TX-7800 with an equivalent LED. Any recommendations for a newbie that I can straight up plop in its place?
Thanks
Thanks
Timothy Flath
Active Member
Fair - do you have the part number for an amber or yellow light that might work? Not sure what voltage and mA to use? I think 8V 50 mA but can't find anything on mouser for that in an LED - I could also be reading the schematic wrong....
If the same as the SA-7800 I would want two to make sure the lights match.
Quite comfortable with mod to make it work...
This was the brother amp I just re-capped:
If the same as the SA-7800 I would want two to make sure the lights match.
Quite comfortable with mod to make it work...
This was the brother amp I just re-capped:
BargainBrad
Member
Sorry to bring back an old thread, but can anyone tell the model of the Omron relay used on the board to replace the original?
TalYWaun
Active Member
Sorry, can’t help with the relay unless it’s the same one as the SA-9800.
Re leesonic’s posts on LED’s. Here is a Mouser part that is an exact fit for the existing diffuser 2mm X 5mm.
696-SSL-LX2573USBD
It’s a blue one and whilst that is what I wanted seeing the blue next to the cyan display doesn’t quite work. It’s a 20mA part running at 5-7mA but is still too bright for my liking.
Re leesonic’s posts on LED’s. Here is a Mouser part that is an exact fit for the existing diffuser 2mm X 5mm.
696-SSL-LX2573USBD
It’s a blue one and whilst that is what I wanted seeing the blue next to the cyan display doesn’t quite work. It’s a 20mA part running at 5-7mA but is still too bright for my liking.
