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2230 recap

catrafter said:
I like to set the bias then come back a few hours later and touch it up.

Tom
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That sounds like what is needed. It's amazing how you can set it at, say, 10mV after 15 minutes of running and come back five minutes later and it's 11 or more. I guess it just needs LOTS of time to stabilize. Thanks!
 
Please check this fuse, it may be just on the picture, but it looks tilted dangerously close to the other one!!! :yikes:
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Dearslayer said:
Thanks I will check that later tonight after work.
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Checked the fuse spacing as soon as I got in tonight from work and it's all good. Just that angle of the picture. Also completed the 500 board tonight and it went well. Polished up the chrome covers some and I think they came up ok.
 

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Looking good. Looks like you still have the big caps to do. It's always a chore getting them out and the new ones wired back in. But not as bad as that 300 board. Once you get that done, it's all downhill. :thumbsup:
 
Yea still 2 boards to do plus the large caps. Do you remember if you had to cut any wires on the 700 board? Looks like I may have to at first glance this morning. Will look closer when I have time to get to it. The large orange and green wires are really tight at the top and behind that board. I may either have to unsolder some at the bottom to flip it up or remove a small bracket at the bottom of the board that's screwed to the chassis.
 

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I don't think I had to cut any wires on 700. I'm beginning to get my models mixed up, but I thought once that ground strap was unscrewed that the board would flip right to left. Or was the ground strap on 400? Grrrrr. If I don't have it sitting in front of me I can't remember what goes with what model. :mad:
 
You don't want to disconnect the orange and green wire if there is any way around it. Those are the shielded cables from the RCA inputs. They have four things to solder -- two shield connections and two signal connections. I fought those things for a long time when I changed the 700 board twice on my 2245. If something has to come off, I would remove every other wire and leave those connected if possible.
 
Thanks for the advance warning and saving me a whole lot of curse words ( alternative to smacking my forehead ). I will try everything to avoid them.
 
I'm a little confused now on the 700 board. I just found some time today to get back at it for an hour or so. All I have left on this board is H709 and C011. Following the MBuras parts list. It says that H709 should have (2) 512-1N4148's in series but I currently see only 1 old one on that location so do I actually join 2 together as a replacement for the same footprint?

Also C011 currently has a large axial 50V 220 uF cap. The new replacement cap has a negative stripe down the side with arrows indicating the direction of polarity positive on the right running negative to the left as indicated in the posted pict????Would this be correct or am I way of base on this one as well?

And lastly, when I replaced the caps at C703/4 the old caps had the orange insulator on the leads but I'm also assuming the new electrolic caps do not require the orange insulator and can just be installed as per normal?

Sorry for all the questions but I'd rather not to have to take it all apart again later if I made a mistake if I can avoid it now.

GT.
 

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You do replace a single diode with a pair at H709. I take the anode from one and just twist it to the cathode of the other, fairly close to the diode body. Then I solder them together and clip it about 3/8" from the diodes. This leaves the soldered pair sticking up in the air, so I put shrink wrap on it, heat it up, press the shrink wrap together above the clipped wire to seal it, and then clip it off past the seal. Both black stripes should be pointing the same way, so you orient as usual to solder it to the board. As for the axial cap, you have it right. The old one marks the positive end and the new one marks the negative end. You only need the wire insulators if the new cap won't fit against the board without exposing a lot of wire. But if the lead spacing doesn't allow a close fit, just take the old insulator and slide it on the new cap.

Here is a pic of the diode pair. Maybe not the neatest system, but it works. I just bend the insulated pair parallel to the board.
IMG_1578_zpstclqim43.jpg
 
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Perfect thanks Steven that helps big time. Now I can proceed to finish this board. How are you enjoying the new Oscope and signal generator?
 
Well all went well on that board ( thanks Steven ). Buttoned it up and DBT went fine so on to the 400 board. Not sure if it's the home stretch or not as that board looks like it may present its own challenges. Any advise before starting on it?
 
Lots of WIMA films on this one. It gets a little dicey back around C411/412 where they share some PCB holes with other films. Also, some holes in the area don't get used, so get some good pics. I solder some lengthening leads onto the films that share holes with C411/412 (413/414?) because the short leads won't reach. Lengthen them to about 1/2" or so, and put shrink wrap on them. You can see a little bit of it in the top center of the pic. Ignore the white Mundorfs. You won't need them. I was just experimenting.

I've only used the scope once for power output testing. Got my new 200W dummy loads in the mail today, so anxious to see how hot they get compared to the little 100's I had.
Steve

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