2230 recap

[Dearslayer]

Just started the recap on my 2230. This unit sounds pretty good already, and is very clean on the internals but it’s one of few units I have that was in the que to be recapped to hand down to my kids someday. Is it the opinion of most that it’s better to remove Printed Circuit Boards completely for recapping or is it ok to remove as little as possible and just enough to gain the necessary access as long as there is no strain put on the remaining wires left connected? I would think that complete removal has the most advantages for ease of recapping and cleaning etc but if things aren’t really dirty is it the norm to recap in place? So now on to the recapping questions. I finished the Power supply without much issues and I’m in the process of the 750 amp boards. I’m following a BOM list ( thanks to Mburas ) and the old cap at C757 was a 50V 22uF ( as seen in the picture below ) however the list I’m following has the new cap at 50V 33uF. The Service manual has it at 35V 22uF, so not sure if there is an error in the SM or if the cap had already been replace at some point before my pocession. Is it ok to increase the value on both the Voltage and uF on this cap? Next question…. When I do finish this board and reassemble ,do I apply Thermal compound to the thick plastic gasket ( doesn’t look as though there was ever any there ) on the underside of the output Transistor ( is that the proper name ) or just on the Mica gasket where it contacts the heat sink and transistor on the outside of the Heatsink as shown in the pictures below. I can see where the old paste has dried on both sides of the Mica gasket so I know that it has to be done again but the other thick plastic gasket where the wires attach I’m not sure about.

 

[MBuras]

That's a whole lotta questions in one paragraph but I'll see what I can do to answer.

I would never completely remove a circuit board unless there's a specific advantage to be gained, like access to other boards, etc. Desolder pins as needed but the idea is to disturb as little as possible.

The 50v/33uf should work fine. That said this is the reason I don't follow lists and rarely publish them. Some of these receivers were made for years and multiple versions of boards existed. Or work was done over the years like you suggested. Best practice is to document the boards in the unit noting exactly what you have in your specific unit and buy to that list. Or at least verify the list you're using before purchase. This is all learned over time.

Do not apply thermal paste to the inner plastic connections. Only apply to the flat face of the TO-3 output transistor, then apply mica insulator, then apply paste again and install.

From the pics I'm guessing you have a Euro or International model. That fuse panel by the power board isn't on the US version.

 

[Dearslayer]

That's a whole lotta questions in one paragraph but I'll see what I can do to answer.

I would never completely remove a circuit board unless there's a specific advantage to be gained, like access to other boards, etc. Desolder pins as needed but the idea is to disturb as little as possible.

The 50v/33uf should work fine. That said this is the reason I don't follow lists and rarely publish them. Some of these receivers were made for years and multiple versions of boards existed. Or work was done over the years like you suggested. Best practice is to document the boards in the unit noting exactly what you have in your specific unit and buy to that list. Or at least verify the list you're using before purchase. This is all learned over time.

Do not apply thermal paste to the inner plastic connections. Only apply to the flat face of the TO-3 output transistor, then apply mica insulator, then apply paste again and install.

From the pics I'm guessing you have a Euro or International model. That fuse panel by the power board isn't on the US version.

Sorry for all the questions Mike but thanks for taking the time to answer them. I appreciate it.

 

[MBuras]

No worries. Happy to answer what I can. That's why it's audio karma. Paying it back.

 

[rBuckner]

Great advice there mB! It is the euro version to have the fuses internally. A couple hints on the thermal compound: don't get the Arctic silver as it's conductive, get the plain white stuff and also smear it on in a very thin coat. Any more than that can actually make it work less well by spacing the transistor away from the heatsink. It's there to just take up any gaps, pits and uneven surface mating.

 

[Dearslayer]

Great advice there mB! It is the euro version to have the fuses internally. A couple hints on the thermal compound: don't get the Arctic silver as it's conductive, get the plain white stuff and also smear it on in a very thin coat. Any more than that can actually make it work less well by spacing the transistor away from the heatsink. It's there to just take up any gaps, pits and uneven surface mating.

Great, will follow the advise to a T gentleman. I'm sure I will have many more questions on this 2230 recap quest.

 

[Dearslayer]

Got the first 750 Amp board completed last night. Does the part ( not sure if this is a transistor?) in the pict below require Thermal paste on both sides. There was some remnant of paste on the small metal clamp side so I applied some on that side but the side against the Heat Sink was void of any paste at all.

 

[catrafter]

That is a bias temperature compensation diode. I would apply a little thermal compound to both sides

Tom

 

[Dearslayer]

That is a bias temperature compensation diode. I would apply a little thermal compound to both sides

Tom

I just started the other 750 board on the opposite side. First thing I noticed was a little paste on both sides of that diode so I removed the first one and applied a little compound to the other side as well and left it unfastened while I waited for a reply to this post. Thanks so much Tom. I will fasten it now.

 

[bryans12v]

I'll just add to be very careful with that diode as they're known to have fragile leads that break right where they come out.

 

[Dearslayer]

Good to know. I will extra careful with the one I'm doing now then. I try to move things as little as possible especially the things I'm not replacing.

 

[Dearslayer]

While waiting for a couple of parts for the 2nd 750 amp board that I forgot to order ( they arrived today ) I moved on to the 150 Am Tuner board and the 300 MPX decoder board, this last board was a bit more challenging as others have already stated. I didn't really want to go any further until I had the 2nd 750 amp board done and reinstalled so I could DBT it, but patience has never been my strong point and I moved forward anyway ,and I hope I don't regret it. I will find out tonight after I install the 2 small 50V/50pf caps at C758/9 and re install it. I wanted to avoid dropping the tuner string but trying to remove the one light brown wire on the left side of the 300 board ( noted in the pict below with an arrow ) left me worried about hitting the string with the hot iron so best to be safe than sorry, so I dropped the string to be sure it wasn't in harms way. From there I took lots of picts and even drew a small diagram of where the wires went so I would get it right when reassembling. I certainly hope it goes well after the DBT later tonight after work and I don't dim the house lights or see smoke. If it does go ok, are there some voltage/Bias adjustments I should do before proceeding any further or wait till completed? I may need some direction at this point.

 

[Steven Tate]

When I did the 300 board on my 2230's, the brown wire was connected by wire wrap and I didn't want to disturb the connection, so I just clipped it in the middle of the visible wire and then soldered the ends together and shrink wrapped. On the 2245 and 2270, those wires were soldered to the jumper pin, so I unsoldered them. I certainly couldn't find a way to get to the bottom of the board with that brown wire attached. Looks like great work. I'm with you in that I hate to do those boards before testing left 750, but access is so much better, I always do. As soon as you get the left power amp installed and pass the DBT test, I would set the power supply voltage and idle current on each channel to keep all of the boards happy. Then readjust them when finished. Keep up the good work!

 

[Dearslayer]

Thanks Steven.. none of these were wire wrapped...maybe because of an earlier statement of it being a euro version?? The SM states Connect the VM to J08 and adjust Trimmer R810 to 35.6 V. Is this just one single adjustment? Also diagram for the 750 board in the SM is mostly blacked out. Would you remember the pin numbers to connect to for the trimmer adjustments for Idle Current of 5mV? I'm guessing the clipping level has to be done with the stated oscilloscope? Sorry for all the questions and being so unsure when it comes to these adjustments.

 

[Steven Tate]

On the 800 board, test with VM between chassis and J808. Adjust the only trimmer on the board, R810, to 35.6 VDC. To set the idle current on each power amp, measure across R747 which happens to be J757 and 758, located at the bottom of the board - opposite from the trimmers. Adjust the trimmer R765, which is the one nearest the top corner of the board, to 5 mV DC. Normally clipping level is adjusted with a scope, but there is a thread going just today with an alternative. I haven't adjusted clipping on mine, so I haven't done it yet. Good luck!

 

[Dearslayer]

great thanks so much appreciate it

 

[Dearslayer]

Well good news is no dimming of the house lights and no smoke. DBT went fine so set the Voltage as suggested. It seems it's harder to set the idle at 5mV. I can set it no prob but it will fluctuate a little and climb to 5.4 the longer it's left to sit. Not sure if that's something to be concerned about or maybe the final adjustments can be done at the end when the unit has been powered up and stabilized and the setting will remain at 5mV. Onward through the fog.

 

[rBuckner]

Nah, don't worry about the small fluctuation. You did get it off of the DBT to set them though I hope?

 

[Dearslayer]

OK cool. Yes set plugged in as normal and off the DBT. Don't remember though if I had the volume knob turned all the way down but I think so.

 

[Steven Tate]

I haven't figured out yet how long it takes that idle current reading to stabilize. In the ones I have done, after ten minutes, it is still slowly rising, but the rate is slowing down. It looks like about 20 minutes is what it may take to completely stabilize. I don't know if that's the experience of others, but I don't stop watching it for at least 15 minutes and it still may go up a tenth or two. I would like to hear from the more experience guys how long they let it run before calling quits on the idle current adjustment.