realblues
Member
I am pretty new to servicing and diagnosing vintage components.
HELP ME SAVE THIS BEAUTIFUL 400!!! If you have an attention span and don't mind my long-windedness read below and PLEASE ADVISE
To be up front, I didn't compare apples to apples here so this isn't the best way to ask for qualitative advice but here goes: my dad asked me to pull a nice, clean 400 apart and part it out because: 1) it broke up at about 5 set flat - this was on a pair of 2-way bookshelf advents (8ohm) with 6" woofer(sorry no model #) and 2) output transformers are reading about 100ohms apart. Changing a transformer to try to match the "good" one at approx 98ohms is a possibility but my dad says that will only uncover more problems down the line.
I replaced most caps and resistors on this unit + Rectifier. It sounds close to a 500c until I get it loud with the Advents. Unfortunately I am stuck testing it on those advents..
Here's the kicker - I tried the same music on the 500c (fully rebuilt) in to Altec (again no model #) but they are huge - over 2' wide and almost 3' high (16ohm). They are 2-way with honeycomb grills... anyway sound was similar (trying to set aside the difference in tone of the speakers) but I can go almost full volume with no problems.
******* I think I am overdriving the Advents with the 400 but the numbers and the scope tell me a different story. All signs point to ONE funky output transformer. BUT, I am pretty new to this. My dad knows his stuff but I am doubting him on this.... but he has a much better understanding (he rebuilds and calibrates tube testers like the triplett 3444 & hickock 539c & Western Electric card-o-matic as well as it's hickock counterpart)
I WANT to save this unit from death and have a transformer on eBay I'm watching (if only I could get a matched pair??).
QUESTION: should I try to save this beautiful piece of equipment or scrap it out? Is the difference in my transformers OK (I can play for over an hour with no problems). With a transformer (assuming no other problems) my investment will exceed the value of a refurbished, trouble-free unit. This receiver will not be a keeper for me but I hate scrapping. I've seen my dad send so much awesome stuff to the recycler years ago because he didn't know the value or how it could be used - example hundreds and hundreds of transformers just tossed away...
If you read the entire post, thank you. And if you have advice to help me from sending one more unit to die I appreciate that even more!
HELP ME SAVE THIS BEAUTIFUL 400!!! If you have an attention span and don't mind my long-windedness read below and PLEASE ADVISE
To be up front, I didn't compare apples to apples here so this isn't the best way to ask for qualitative advice but here goes: my dad asked me to pull a nice, clean 400 apart and part it out because: 1) it broke up at about 5 set flat - this was on a pair of 2-way bookshelf advents (8ohm) with 6" woofer(sorry no model #) and 2) output transformers are reading about 100ohms apart. Changing a transformer to try to match the "good" one at approx 98ohms is a possibility but my dad says that will only uncover more problems down the line.
I replaced most caps and resistors on this unit + Rectifier. It sounds close to a 500c until I get it loud with the Advents. Unfortunately I am stuck testing it on those advents..
Here's the kicker - I tried the same music on the 500c (fully rebuilt) in to Altec (again no model #) but they are huge - over 2' wide and almost 3' high (16ohm). They are 2-way with honeycomb grills... anyway sound was similar (trying to set aside the difference in tone of the speakers) but I can go almost full volume with no problems.
******* I think I am overdriving the Advents with the 400 but the numbers and the scope tell me a different story. All signs point to ONE funky output transformer. BUT, I am pretty new to this. My dad knows his stuff but I am doubting him on this.... but he has a much better understanding (he rebuilds and calibrates tube testers like the triplett 3444 & hickock 539c & Western Electric card-o-matic as well as it's hickock counterpart)
I WANT to save this unit from death and have a transformer on eBay I'm watching (if only I could get a matched pair??).
QUESTION: should I try to save this beautiful piece of equipment or scrap it out? Is the difference in my transformers OK (I can play for over an hour with no problems). With a transformer (assuming no other problems) my investment will exceed the value of a refurbished, trouble-free unit. This receiver will not be a keeper for me but I hate scrapping. I've seen my dad send so much awesome stuff to the recycler years ago because he didn't know the value or how it could be used - example hundreds and hundreds of transformers just tossed away...
If you read the entire post, thank you. And if you have advice to help me from sending one more unit to die I appreciate that even more!
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