• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

SA-7800, SA-8800, SA-9800 recap project

Backlight

Backlight

Active Member
Hi all,

I am about to start my recap project affecting my SA-7800, SA-8800 and SA-9800 amps.

To be honest I already recapped most of the PSU boards of my SA-7800 and SA-8800 with high quality replacements. The 4 power caps are still waiting.

I don't expect any big issues while recapping except that it needs a lot of patience and time, especially the SA-9800 which needs to be dissembled quite a bit. But I do have something that I do need some help with: finding the best replacement power caps: I know to look out for high quality ones (Panasonic, Nichicon, Elna) but I also need to have the correct pin-layout (including the dummie pin(s) for stability) and dimensions to fit the brackets in the SA-8800 and SA-9800.

I know xoaphexox has done some power cap recapping on one or two of these amp. Perhaps he could remember the brand, type and where to purchase them? Digikey and Farnell are online stores that could be potential sellers, but I can also try my local store here. If I specify the brand and type they can order them for me.

Any help is welcome and much appreciated!
 
Register to hide this ad
Thanks Mark,

These are very helpful! I only plan to replace the elco's, specifically the big power elco's, which are hard to get in the Netherlands in the right dimensions and pin layout. So if anybody has experience with these, tips are very welcome.

EDIT: Is it recommended to choose low ESR replacement caps for all caps on the PSU board, not just the NL types? I assume for the EQ and Power amp board I should use the audio grade caps according specs (as described in the Tuning Fork documents) to make sure the sound will stay the same, or at least not deviate into a completely different sounding sound.
 
Last edited:
I just found out that Mouser is also selling in Europe/The Netherlands! They have a broad range of Nichicon caps.

Some time ago they only sold in the US and Canada. This is good news for all electro and audio enthusiasts in Europe!
 
Low ESR caps are primarily meant for switching power supplies, in which they can experience significant internal heating in normal operation, and sometimes are NEEDED to heat up (the chemistry works better, as evidenced by a car battery in very cold weather).

The NL caps are LOW LEAKAGE and are put in sensitive (i.e. quiet) areas where the internally generated noise of more conventional caps would NOT be swamped out by other factors. It's the difference between 0.03CV and 0.002CV - which translates to the equivalent of a varying resistance of a vary high value ( megohms & microamps etc)
 
Thanks Mark,

I assumed Low ESR and Low Leakage meant the same. I now understand the difference. Anoth question about Nichicon caps: What is different between UPW types and UPM types? If I look at the specs they seem to have different sizes (UPW is smaller) and that the UPW is considered to have slightly lower ESR.

Since you recommend UPW's as replacements of most caps, does that mean you also recommend low ESR caps for the entire amp, not just the PSU boards?
 
There are other factors influencing upw and uhe cap selection - look at operating hours etc.... quality of the seals, more than the incidental low esr. There are more expensive ones, but the expense goes towards size reduction. There's enough competition out there so that you are getting what you pay for, and we're looking for long life because the capacitors retain vital moisture over the years, due to higher quality seal materials....

That's why the 105 degree c rating, vapor pressure is higher at 105 c and must be more effectively resisted.
 
Last edited:
I am working on a replacement cap list in Excel and came across a difference between the schematic in the SA-7800 service manual and the SA-7800 PSU board. See the attached picture where I circled a straight connection. On the PCB this is actually a low leakage 4.7uF/50V cap, basically in series with the one next to it of the same value and type.

What is the aim of this modification? Does it solve an issue that Pioneer's engineers found out later? Both caps are original Nichicon orange sleeved Low Leakage caps.

Any comments more than welcome.
 

Attachments

  • PSU SA-7800.jpg
    PSU SA-7800.jpg
    106.6 KB · Views: 111
Backlight said:
I am working on a replacement cap list in Excel and came across a difference between the schematic in the SA-7800 service manual and the SA-7800 PSU board. See the attached picture where I circled a straight connection. On the PCB this is actually a low leakage 4.7uF/50V cap, basically in series with the one next to it of the same value and type.

What is the aim of this modification? Does it solve an issue that Pioneer's engineers found out later? Both caps are original Nichicon orange sleeved Low Leakage caps.

Any comments more than welcome.
Click to expand...

Two electrolytic caps in series make a non-polarized capacitor, at half the capacitance value.

I don't think that trick will work with solid aluminum or tantalum caps.

Thus low leakage and non-polarity were important ion that location, (I haven't delved deeper) and it is possible, if it will fit, to use a single stacked film metalized poly capacitor instead, a 2.2uf 50v like:
5989-100V2.2-F 2.2 100 $0.97
5989-250V2.2-F 2.2 250 $1.16

or the digikey number EchoWars uses.
 
Hi, I have ordered all replacement electrolytic caps for the SA-7800 and SA-8800. I will recap the SA-9800 at a later stage because it looks quite a challenge to get to all the caps.

I didn't order the big power elco's yet because I have trouble finding the best match in both capacity, characteristics, dimensions and pin leads and distance. I started this thread hoping that someone recapped one or all of these SA-x800 units recently (inclusing the power caps) and could recommend me a brand and type to choose for these. Available in the Netherlands off course. Any help on this on is highly appreciated!
 
Backlight said:
Hi, I have ordered all replacement electrolytic caps for the SA-7800 and SA-8800. I will recap the SA-9800 at a later stage because it looks quite a challenge to get to all the caps.

I didn't order the big power elco's yet because I have trouble finding the best match in both capacity, characteristics, dimensions and pin leads and distance. I started this thread hoping that someone recapped one or all of these SA-x800 units recently (inclusing the power caps) and could recommend me a brand and type to choose for these. Available in the Netherlands off course. Any help on this on is highly appreciated!
Click to expand...

IN the USA, there's a company called JEA capacitors, and the sell as capacitor12 on ebay, that have many applicable caps. Then there's a lot of research back to the manufacturers, and the search won't be fun - but know your dimensions (max and the old caps) capacitance and voltage, all can be increased, major increases should be checked here for ramifications.

You are looking for "computer grade" which use screw terminals or "snap in" which have solderable posts.

It would HELP, if you would post the micofarads, volts and dimensions of the present caps in each model.
 
Last edited:
I will measure the caps' dimensions and pin configurations after Christmas. The values are 8000uF/50V x4 for the SA-7800, 12000uF/63V x4 for the SA-8800 and 15000uF/71V x 4 for the SA-9800.

The caps in the SA-7800 have some room for replacements to be a bit higher and thicker. The caps in the SA-8800 and SA-9800 are clamped to the board by metal brackets around them, leaving not much room for different diameter replacements. For the SA-9800 the caps also have only little room between the top and casing.

After Christmas I will post the measurements. Thanks Mark and others for helping and thinking along with me.

Merry Christmas to all!
 
I hope you all have had a happy Christmas.

I have now completely recapped the SA-8800 (except the power caps) and started on the SA-7800. I must say I am surprised by the significant improvement of the dynamics of the SA-8800. I hear a lot more "air" in the sound and the clarity has improved significantly as well, with extremely well well "rounded" highs. This was well worth the time spent!

I found another deviation on the SA-7800 from the service manual schematics on the Tone Control board: two of the 22uF/16 NP caps were actually 10uF/10V NP caps and the two 4.7uF/25V NP were actually 1uF/50V NP caps. I decided to leave them in and replace them with the same values and not the values specified in the service manual. But I have to order them...

About the sizes of the power caps:

SA-7800: 8000uF/50V, 30mm diameter, 65mm high and pins are 15mm apart, 1 dummy pin 10mm from each real pin. There is enough room around them so the replacements can be wider and/or higher
SA-8800: 12000uF/63V, 40mm diameter, 70mm high and pins are 25mm apart, 3 dummy pins. The diameter is fixed but the height can be increased if necessary.

I have not yet had the time to open the SA-9800. But I hope this helps a bit giving me some advise on possible replacements.
 
Hi all,

A little update. I finished recapping my SA-7800 too (except the power caps) and I could not withstand a 1 on 1 comparison to the recapped SA-8800.
I was surprised by the difference in depth and dynamics between the amps on the same speakers with the same music. The SA-7800 is way behind in bass and "openness" in the mid and highs. It goes loud, but stays more or less "flat" (compared to the SA-8800) all the way.

I compared the SA-8800 and SA-9800 with original caps some time ago and they sounded very similar.

In both amps I replaced all caps with Nichicon's UPW, UKL, UVP and UES. In both amps I could not prevent a UVP cap (instead of a UES type which were not available at the time of the order) in the audio signal path in the pre-amp, so both have this disadvantage. And both amps has been adjusted for idle current etc according the instructions, so should work according to or close to specs.

I know the SA-7800 only has only two power transistors per channel in the power stage, where the SA-8800 has four per channel and they are of different type (same as the SA-9800), but the specs on paper are quite close.

Why am I telling this? I was surprised by the huge difference in sound quality (or character) and I am curious if this is normal or there's something not normal in my SA-7800?

About the power caps: I found a Panasonic cap on Digikey that I think could be a good choice for the SA-8800. Is this decent for this purpose? It should fit the bracket and PCB holes, at least the + and - holes.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P10034-ND

Thanks again for any advize.
 
Last edited:
Any replacement transistors in the 7800 (or others) amplifier sections?

The 7800 is rated at 0.009 % distortion
while the 8800 and 9800 are rated at 0.005 % distortion...

The NSA amp (in all three) is rather sensitive to transistor speeds in the power amps' outputs(60mhz originally) and drivers (200mhz originally).

If the drivers are 4 mhz instead of 200, the distortion goes from 0.006 to 0.06 %.

There are very few suitable TO-220 200mhz transistors transistors out there anymore, so I am investigating some TO-123's that should have enough oomph and speed.
 
Help me out a bit. I am not familiar with amplifier circuits, let alone the NSA circuit. Is the driver the transistor driving the base of the output transistor?
 
Checked the drivers. They are original: two times 2SA913 and two time 2SC1913. The power transistors are original as well.

Replacements could be 2SC2591 and its counterpart 2SA1111, if I'm correct. They are TO220, 200MHz and can deliver quite some power. Some guy sells "new old stock" on ebay: http://stores.ebay.com/audio-doctors

Any other ideas why my SA-7800 doesn't "sparkle" as expected? Two things I would like to check:

1. I temporarily installed two standard ESR 220uF/100V of Chinese make in the PSU board since the leads of the Nichicon replacement were to thick for the holes. I assume they should filter and flatten the DC supply to some parts of the amp, such as the pre-amp and perhaps parts of the power stage. Could this be the cause? I thought of drilling the holes to 1 mm, which should be enough for the Nichicons.

2. The inside of the amp is not really clean. It seems as it has been in a dirty environment for some time, perhaps a smokers house. I tried to clean as much as possible but on the PCB between the components cleaning is quite difficult, so did not do that thouroughly. Could this film of dirt affect the sound much?

Any suggestion or thought is appreciated!
 
Last edited:
Magic has happened! :)

I did three things to the SA-7800 and the sound now has solid bass and the mids and highs opened up! This is what I did:

1. I drilled holes in the PCB to fit the Nichicon 220uF/100V caps on the PSU board to replace the cheap Chinese standard ones
2. I changed the two coupling caps on the TC board back to the original ones (ELNA). I will replace them again when I receive the proper Nichicon parts (UES instead of UVP)
3. I re-adjusted the idle current which for some reason (replaced caps?) was quite a bit off spec

I don't know what did the trick, but it worked! The amp is delivering the power and depth that one expect from it again!

Still any suggestions or comments on the power caps are welcome! (where are you all?)
 
Hi all,

I found replacements for the SA-7800 power caps on mouser: 647-LKG1H822MESCBK which are Nichicon 8200uF/50V caps designed for audio equipment. The lead spacing is only 10 mm so I will need to drill to make them fit the PCB.

But I am having trouble finding replacements for the SA-8800 and SA-9800.

For the SA-8800 I need 12000uF/63V caps, ideally 40mm diameter to fit the clamp. I do find some on Mouser of 35mm but these are general purpose caps. Is that good enough for a high end amplifier?

For the SA-9800 I need 15000uF/71V caps which translate into 80V since 71V is nowhere to be found... Again ideally 40mm diameter to fit the clamps and not higher than 80mm to have enough clearance to the casing. I have not found any decent replacement yet that is on stock in any online store (mouser, digikey, farnell etc). Also locally I did not find any.

If I look for replacements, what is most important for replacements? Low ESR, high ripple current, long life? I want high quality replacements that provides the best and cleanest power to the power stage of the SA-8800 and SA-9800.
 
You must log in or register to reply here.
Back
Top Bottom