2275 rebuild project

See....I DID stump all of you! Actually, the bleeding of the signal was a result of putting too much voltage into the Aux input via my 1/8" to RCA adapter cable from the iPhone headphone jack. I hooked up a normal CD player to Aux In and it all went back to normal.
 
Working on the phono board this weekend so more pix coming. I also wanted to extend the offer I made to Steven re: the insulating fiberglass material. If anybody would like to try a chunk, just PM me and I'll mail you a length of it (approx. 24"). I have WAY more of it than I"ll need in one lifetime!
 
Finally got a chance to do the large caps last night and was following Steve's progress with his 2275 caps. I first built the "bridge" replacement using a brass rod. Leestereo/ObiWan told me that brass isn't a good choice as it has lower conductivity than copper so I remade it using some solid core copper grounding wire (#8 or #10 gauge...not sure) that I had on hand for an outdoor FM antenna upgrade project I'm working on. Solder technique not the cleanest but all the connections seem to be solid:
_DSC3003.jpg

I took all 6 of the ground wires and bundled them into 3 pairs to do the "star ground" that Leestereo had mentioned. I used a hammer to flatten and widen the copper wire to give me a wider solder contact area for the drop lead to the chassis. I had to buy a longer screw (M4-0.7 x 8mm) to allow for the stack of ring terminals:

_DSC3010.jpg

Here's the view of both caps from the bottom:

_DSC3009.jpg

.....and from the top:

_DSC2991.jpg

I was constantly wondering how much tension to apply to the screw terminals of these caps. They seem to be big, beefy connections but I didn't want to risk twisting the mounting post and damaging the caps internally. So, I made them WAY more than finger-tight but didn't torque them down excessively. Any guidance on that part of the build?

C006 & C007
Originally 13000uF 55v ---> Now 18000uF 75v (Mouser # E36D750MLN183TC79M)

On to the tone board!
 
Last edited:
....one more thing....
Haven't powered it up yet so will put the DBT on it but was wondering how it will look when first charging up these new caps. Will the glow be brighter and longer than the previous power-ups?
 
I didn't see much difference with the DBT -- maybe a second or two longer. The main thing I noticed was after passing the DBT, I plugged it in and fired it up in FM mode. The sound was very distorted for a few seconds and I thought Uh-Oh - big problem. But over 20-30 seconds the distortion went away and never came back. I have no idea if it had anything to do with the new filter caps, but the timing made me think it did. Very nice job on the bridge, and I much prefer your ring terminal solution over the solder solution I used. I will do that next time. Good luck with the power up! :thumbsup:
 
I will use your copper wire with ring terminals when I swap out the filter capacitors on the 2275 I am working on now. Great style.
 
Hoping to fire it up (figuratively speaking) when I get home tonight. The ring terminal solution was fairly easy to do but I had to leave the caps loose in their clamps so I could rotate both of them a tiny bit to get ALL 3 the holes to align.
 
Hoping to fire it up (figuratively speaking) when I get home tonight. The ring terminal solution was fairly easy to do but I had to leave the caps loose in their clamps so I could rotate both of them a tiny bit to get ALL 3 the holes to align.
Hmmm. Seems like it would be impossible to tighten the clamps with the caps installed. Maybe mark the caps and clamps for position, remove caps, tighten clamps and reinstall? :dunno:
 
I only had to loosen the clamps for the initial alignment of all 3 screws. Once all the connections were made, I tightened the clamps again so nothing is going to move now.
 
The main capacitors' installation looks very nice, good job Dave.

Hey Lee, YOU kept me from doing something that would have caused the magic smoke to escape the chassis. Many thanks for all your guidance and patience.
 
PE01 Tone Board
I finally got back to the rebuild so thought that this board would be easy. You'd think that a board that is so easily removable and totally accessible would be easy to work on, wouldn't you? ;-) This board really kicked my newbie butt!!

Lots of blue blobs to change on this one:

_DSC3042.jpg


Here's the "before" of the PE01 board:

_DSC3041.jpg



.....and here's the "after":

_DSC3064.jpg

The biggest issue I ran into (as a complete newbie at this) was the way this board was put together. The power supply, phono and power amp boards were pretty easy to rebuild with most all of the parts inserted with the component legs hanging straight down prior to soldering. Almost every component on THIS board was inserted and then bent at a right angle to hold the part in place. So, every part had to be desoldered enough to bend the legs straight before they would come out. This became such a PITA that I damaged a couple of the solder pads. This is the worst one. I had to use one of the snipped parts legs to bridge across the bad hole over to the other part that shared this pad:

_DSC3065.jpg


My best guess is that I was too aggressive with the solder braid OR I managed to snag the trace with the bent end of those blue blobs as I tried to straighten them. Any tips on how to attack these bent leads in case any of my remaining boards were put together this way?

My first test with the DBT was not a good one. The tester did it's usual bright glow and then dimmed but as soon as the relay kicked in, I had problems. I heard hiss coming out of the right channel and then some nasty crackles and pops. I double-checked all my solder points and found a bad one....problem solved. I've been running the 2275 for several hours this evening and the first thing I noticed was a pronounced brightening of the sound. I'll try to give some more feedback on the sound changes after I live with this update for a few days.

Here's the parts list for the PE01 board with original and replacement values and Mouser part numbers:

CE05 - 1uF / 250v ---> 1uF / 450v (ECW-FD2W105J)
CE06 - same as CE05
CE09 - 100uF / 10v ---> 220uF / 25v (UPM1E221MPD1TA)
CE10 - same as CE09
CE11 - 10uF / 35v ---> 22uF / 25v (UES1E220MEM)
CE12 - same as CE11
CE13 - 3.3uF / 35v ---> 3.3uF / 50v (MKS2B043301H00JSSD)
CE14 - same as CE13
CE33 - 1uF / 25v ---> 1uF 50v (MKS2B041001C00KSSD)
CE34 - same as CE33
CE35 - 3.3uF / 35v ---> 3.3uF 50v (MKS2B043301H00JSSD)
CE36 - same as CE35
CE37 - 4.7uF / 16v ---> 4.7uF 50v (MKS2B044701K00JSSD)
CE38 - same as CE37
CE39 - 220uF / 35v ---> 470uF / 35v (UPW1V471MPD)
 
Last edited:
I did have to use my side cutters (like yours) on the parts that were reachable. I darn near stopped halfway though to order a desoldering gun!! Haven't pulled the trigger on that one yet. (sorry for the pun)
 
I did have to use my side cutters (like yours) on the parts that were reachable. I darn near stopped halfway though to order a desoldering gun!! Haven't pulled the trigger on that one yet. (sorry for the pun)
oh, I'll get one ASAP.
 
The desoldering gun makes this fairly easy. Slightly wiggle the part as you suck out the solder, and the wire will (usually) be free from the board where you can then straighten it with a hemostat or small pliers.
 
Back
Top Bottom