/diy/ - Do It Yourself

before the rebuild...

And everything running. I haven't done much to the preamp sitting on the floor yet but I have new power supply capacitors and am creating a list of internal caps I need to replace.

>>737779
That's some sexy point to point wiring anon.

They sure don't make them like that anymore, but i still do like my tripath amp and AD832AN NAD amp.

Would kill for a 240 though if i could afford the huge running costs and an air conditioner just for the room the amp is in.

Nice. I have a vt22 guitar amp that had been messed with some and could use some attention, and a pro jr that could probably benefit from some maintenance too. They've just not gotten close enough to the top of the money priorities.

so you dont know that foil/mylar caps never breakdown or drift? its only electrolytics that have a problem with age, those original caps in a mcintosh were fine and likly better then what you replaced them with,

>>737803
they do make them like that still, plenty of companies still make tube gear just like that amp in the picture

>>737893
>>737893
Actually that would be a negative. The stripped "bumblebee" caps actually fail quite frequently and do drift. I do not know if it is because of the amp design or if they just wear out but at least in McIntosh gear these are a frequent problem. I did replace a few that didn't necessarily need to be replaced (the larger non stripped ones commonly are left in) but I wanted a proper clean slate with all new caps. I tested the old caps and most were off spec.

As for those who like point to point wiring, here's what I get to work with on the preamp.

>>737895
>plenty of companies still make tube gear just like that amp in the picture

No, more like a few niche companies selling them at vastly inflated prices for "audiophile" use

>>737921
And even the new stuff generally does not use point to point much anymore. This is the interior of a new production McIntosh MC275 which had a virtually identical layout to my MC240 when they were produced in the 60s. Not saying it is bad, just not as cool looking.

>>737921
I can name 3 dozen makers of tube stereo gear of the top of my head, and there are many more out of asia, obviously is audiophile gear, who else is going to go through the trouble with tubes to listen to music

Hey anon, I'm doing a semi resto on this old Valve radio. so far all of the electrics look to be in great shape. other then a few wiring issues and two broken valves that I can see... I can post pics of the underside, but do you think I could just run the old caps.? its a 1940 model. tia.

>>737908
damnit I left the power supply capacitor cans at my place in Ohio so all I can do is basic cleanup and build a list of caps I still need to order. I guess I'll do all the cap swaps in a few weeks when I head back there.

>>737959
>70 years old electrolytics
Right. Even if they happen to be ok enough, do not apply the full mains voltage immediately. Ramp it slowly.

>>737959
uhhh well when was it last turned on? If that thing has sat for 50 years those caps might explode when turned on (literally). I own a variac which is useful to slowly bring up the voltage of an amp over a period of a few hours. That way you can check for overheating components before they get all explody. More than likely they are all out of spec and need replaced though. Mine seemed fine but after pulling them most had problems when tested.

The caps might just leak, or they could end up like the attached pic (and cause other problems)

>>737961
ok, well I have 3 other radios all around the same era, and they all work fantastic. all I did was blow out the dust and cobwebs. just wasn't sure

>>737963
ok, then anon. I will seriously consider this... next question. do I get the chassis acid dipped, stickers remade, paper diagrams replicated and try to make it back to original look.? or keep the internals rustic.?

pic of front

>>737974
I guess that is all personal preference there. What is your plan? In my case I removed a lot of rust from the chassis but I'm going to stick with the derusted chassis with the pitting. I haven't decided on if I want to use stickers to replace some of the worn off lettering or not.

Regarding rust removal, I use a paste made of Barkeepers Friend powder mixed with water. I then slather it on and cover with plastic. Usually after 30-60 minutes all my rust is gone. Some areas need 2-3 treatments if bad.

>>737980
nice. yeah it's a real toss up.

I just found the diagrams for mine. so I'll look into replacing the caps.

http://www.kevinchant.com/uploads/7/1/0/8/7108231/awa_models_84_193_194_501_and_310.pdf

>>737976
mirin