View Full Version : sansui 881


maclvrbr
04-19-2013, 05:03 PM
I recently acquired one. The owner admitted it to have a hum and had replaced the large caps next to the transformer. I have a variety of questions for those who have this model and would appreciate your assistance. I will provide a few pics. The caps that were replaced are smaller in diameter and were not stabilized to the board just hanging from the solder connections. I removed the bottom cover and realized I will need an experienced sansui guy to decipher this. The caps replaced have some component between the positive and negative poles on each cap. Can I find different larger caps to fit and be stabilizer to the chassis?Is there a better way to wire them in than what I see? The tuning knob is not smooth period, any ideas? Is there a recent BOM list, caps? One of the meter lamps is out, is this any easy fix? thanks guys, I like the quality build, the rugged aluminum face and glass display lens as well as the solid aluminum beauty ring around the display lens. The boards seem to be user friendly a lot of plug ins easy to access areas of the receiver.

Hyperion
04-19-2013, 05:31 PM
Your pictures show some really poor soldering IMO, (not clear pics). The XX1 series often get reports of hum in one or both channels - usually caused by poor ground connections in the amplifier section.

However the 881 is the TOTL in this series and very well worth getting fixed up properly.

Robisme
04-19-2013, 08:29 PM
Should be pretty easy to find a cap that will fit those clamps.

Take a measurement, then go to the Mouser site and search the cap value. Go to caps, and select the diameter filter and pick the size. Make sure the voltage is high enough.

Or, find something the wrap around the caps so they fit the clamps.

Rob

bd1886
04-19-2013, 09:50 PM
Lot of people love that receiver.

stereofun
04-19-2013, 09:53 PM
Best way is to get caps that fit in diameter or close enough for a band of weather strip to make up the difference for a secure grip within the bracket. A backup plan is to buy a dirt cheap glue gun and put a ring og glue around the perimeter of the cap on either side of the plate. Not the prettiest.... but if you already got new caps in place.

dr*audio
04-19-2013, 10:14 PM
The technology for making caps has improved since the 881 was built and new caps are smaller. It is difficult to find caps with larger diameters and they are more expensive. Wrap a piece of corrugated cardboard around each cap and tighten the clamp to secure it. If you are dead set on finding the proper size caps, go to Michael Percy Audio website. Look at the Nichicon caps in his catalog. You may have to get a higher value of capacitance to get the right diameter.

bktheking
04-19-2013, 10:34 PM
Do it correctly, Panasonic caps from Mouser should work, i've had good luck with my rebuilds by using them. The soldering job is HORRIBLE, solder some ring connectors to the snap in leads and solder to the rings, much cleaner and easier than soldering to the snap in leads which are made for circuit boards.

pete_mac
04-19-2013, 10:44 PM
Horrible, horrible workmanship! :(

The 881 is definitely worth hanging onto. One of my favourite Sansuis.

maclvrbr
04-19-2013, 11:40 PM
thanks for the replys . I would like to find a cap that will fit the brackets better, will check with mouser and the other supplier mentioned, the caps are 10000uf 50volts. I am very concerned about what is soldered in between the cap terminals. Do I need this? Does anyone have a stock photo I can see? Also any ideas about lubricating the tuning mechanism? Is this a typical issue with this model? thanks

skippy124
04-20-2013, 03:18 AM
The component soldered in between the Capacitor terminals is meant to be there, they are bleeder resistors that will discharge the caps when the unit is turned off (they are 3.3K ohm 2W and the schematic reference is R701 and R702).

If the diameter of the original is 40mm then you would be best to look for 63V caps, for example

http://www.newark.com/vishay-bc-components/mal205018103e3/capacitor-10000uf-63v/dp/25M1839?in_merch=Popular%20Products

maclvrbr
04-21-2013, 10:43 PM
Thanks for the advice. I have decided to keep the new caps and install weather stripping 3/16 between cap and cap holder , it works very well and I have cleaned up all of the extra solder . A few things, Has anyone used any type of lubrication to help the tuning dial spin smoother? It seems quit restricted. Maybe that's the way it is? Also 1 of the meter light is out the fuse(bulb) is good, what can I check? thanks

dr*audio
04-22-2013, 07:50 AM
Thanks for the advice. I have decided to keep the new caps and install weather stripping 3/16 between cap and cap holder , it works very well and I have cleaned up all of the extra solder . A few things, Has anyone used any type of lubrication to help the tuning dial spin smoother? It seems quit restricted. Maybe that's the way it is? Also 1 of the meter light is out the fuse(bulb) is good, what can I check? thanks

Apply a couple of drops of light weight machine oil to the pulleys for the dial cord at their pivot points, to the flywheel bearings (both the sleeve bearing for the shaft and the rear bearing if there is one) and to the bearing where the shaft goes into the tuning cap. That should free up the dial.
For the meter bulb, measure the voltage across the bulb socket, in AC Volts. Should be 8V. Check the solder joints on the socket. If the dial lamps work, it has to be either a bad solder joint on the socket or the lamp is bad.

DCinDC
04-22-2013, 05:46 PM
Read the good Dr's sticky in the tuner section about cleaning the tuning capacitor. It's likely needed and will probably bring the FM performance back to factory fresh.

Glad you decided to forego replacing the caps. It's not needed.

What IS needed is to replace the braided ground straps from the caps to the chassis. I recapped my 881 and it still hummed. I replaced those braids and it was stone cold dead silent after. They tend to corrode.

The dial lamps are available from partsexpress or AK member dwojo 8v festoon lamps. DON'T break the plastic!

pete_mac
04-22-2013, 05:50 PM
What IS needed is to replace the braided ground straps from the caps to the chassis. I recapped my 881 and it still hummed. I replaced those braids and it was stone cold dead silent after. They tend to corrode.


Great piece of info that! Thanks. :thmbsp:

maclvrbr
04-23-2013, 12:14 AM
I will replace the ground braid to large caps. Has anyone ever used solder wick to do this? Ideas thanks for all the advice guys. Also I did diagnose the lamp for the meter was blown. Got any good tips for removing the cover to the tuning capacitor? The way I see requires desoldering it from the bottom of the receiver.

dr*audio
04-23-2013, 08:06 AM
I will replace the ground braid to large caps. Has anyone ever used solder wick to do this? Ideas thanks for all the advice guys. Also I did diagnose the lamp for the meter was blown. Got any good tips for removing the cover to the tuning capacitor? The way I see requires desoldering it from the bottom of the receiver.

Yes, I use Solder Wick for braid all the time. It's just copper braid with flux added to it. Some of the tuning caps have to be removed and the dial cord restrung in order to take them apart. It sounds like this is one of them, don't do it. Instead, spray non - residue cleaner into the cap through the holes in the shield. Try to look through the holes and see where the shaft goes and spray along the shaft. Then run the tuner back and forth across the dial 30 times. This works very well.

maclvrbr
04-23-2013, 02:41 PM
Thanks for the advice, instead I used a piece of 16 gauge wire to replace the stainless steel braid ground wires to the 10000uf 50v caps. Unfortunately the hum is louder thanks before. I will spray through hole in capacitor cover, thanks. Any ideas about possibly other ground issues?

maclvrbr
04-24-2013, 03:46 PM
Hi guys I would appreciate any other ideas to help me with this hum issue. Anyone have any suggestions.

bktheking
04-24-2013, 05:35 PM
Have you got a scope?

maclvrbr
04-24-2013, 06:06 PM
No, I have no test equipment. Keep the ideas coming, Thanks for responding

bktheking
04-24-2013, 06:11 PM
Have you tried grounding the chassis to see is it disappears?

maclvrbr
04-24-2013, 06:50 PM
Can you give me an idea of how to do this? Any examples. The grounds are going from the caps to the PCB boards. Can I ground to the receiver chassis?The receiver plug is 2 prong instead of 3. THanks

dr*audio
04-25-2013, 08:17 AM
Thanks for the advice, instead I used a piece of 16 gauge wire to replace the stainless steel braid ground wires to the 10000uf 50v caps. Unfortunately the hum is louder thanks before. I will spray through hole in capacitor cover, thanks. Any ideas about possibly other ground issues?

Well, that should tell you that 16 AWG wire isn't good enough. The original design used braid, so use braid. Also, there is a screw on the pc board next to where the braid attaches. Tighten that screw, it provides connection to the chassis. Also the original braid was not stainless steel. You can't solder to stainless steel. It was copper, probably plated with tin.

maclvrbr
04-25-2013, 10:46 PM
thanks for the reply, I will try copper solder braid and will check the screw you mentioned.

maclvrbr
05-05-2013, 10:33 PM
thanks for the suggestion. After soldering in solder wick to the large caps to ground the hum is not there. I trust it will stay away but for now its great. Thanks to all for your suggestions. Althoug I have tried lubricant at all areas where tuning string pulleys through I am unhappy with the difficulty of rotating the tuning wheel. Should it rotate smoothly or is this normal operation?

DCinDC
05-05-2013, 10:59 PM
get rosin for a violin bow or rosin liquid for solder

dr*audio
05-06-2013, 07:42 AM
thanks for the suggestion. After soldering in solder wick to the large caps to ground the hum is not there. I trust it will stay away but for now its great. Thanks to all for your suggestions. Althoug I have tried lubricant at all areas where tuning string pulleys through I am unhappy with the difficulty of rotating the tuning wheel. Should it rotate smoothly or is this normal operation?

It should rotate smoothly. Did you oil the bearing on the shaft that the tuning knob is on? Also carefully oil the bearings in the tuning capacitors but don't get any oil on the fins.

maclvrbr
05-06-2013, 02:18 PM
I'd like to get to the tuning capacitor but it appears getting the cover off of it would require a lot of work desoldering multiple placed on the bottom of the receiver where the cover is soldered to the pcb board. Do you have any other ideas to access the capacitor shaft? thanks again

DCinDC
05-06-2013, 02:20 PM
For now back off the tuning cap. The problem is likely not there. I would remove the tuning shaft from the front panel, and remove the inner shaft from the bushing. It should rotate smoothly in there. You may need to apply heat to it after removing from the front panel and chassis

dr*audio
05-06-2013, 10:23 PM
For now back off the tuning cap. The problem is likely not there. I would remove the tuning shaft from the front panel, and remove the inner shaft from the bushing. It should rotate smoothly in there. You may need to apply heat to it after removing from the front panel and chassis

Take lots of pictures of the dial cord so you know how to re-string it, and turn the dial all the way to one end before you start.

maclvrbr
05-06-2013, 10:33 PM
That was going to be my next question as to the best way to remove the string. Do you have any approaches that may be best? Aside from mentioning turning knob all the way to one end. Also I was inspecting the tuning shaft and weight . Are there areas of lubrication that cannot be accessed without removing this shaft? It appears that I could get oil in all areas. Certainly don't want to remove it unless absolutely sure this is necessary . Thanks for the suggestions guys.

dr*audio
05-07-2013, 07:54 AM
That was going to be my next question as to the best way to remove the string. Do you have any approaches that may be best? Aside from mentioning turning knob all the way to one end. Also I was inspecting the tuning shaft and weight . Are there areas of lubrication that cannot be accessed without removing this shaft? It appears that I could get oil in all areas. Certainly don't want to remove it unless absolutely sure this is necessary . Thanks for the suggestions guys.

Usually you don't have to remove the shaft, you just inject oil into the bearing. If the grease in the bearing is gummed up, then you have to remove the shaft and clean the bearing with alcohol, then oil it.