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2235B Hum upstream of amp section
- Thread starter Lo-Fidelity
- Start date
Lo-Fidelity
Super Member
No haven’t ordered parts yet. Maybe get ordered this weekend. Thanks for checking. I wish we had somewhere in Houston that I could just pick these up. Last time I was in Fry’s they didn’t have much of anything.
Lo-Fidelity
Super Member
I am not sure I am up for replacing 15 capacitors. Is the there an 80/20 rule here that can be applied?
15 capacitors on the PE01 board doesn't take that long time.
At least not if you have a desoldering tool?
I think I did it leisurely in 1h.
At least not if you have a desoldering tool?
I think I did it leisurely in 1h.
Lo-Fidelity
Super Member
Lo-Fidelity
Super Member
Too funny.
Ok. I’ll figure it out. You have properly and politely shamed me into doing the right thing.
No you have to unscrew the tone controls and swing it out.
It's so easy to work on once you have done that.
This is what mine looked like before I started work on it.
Btw, if you need tips on how to remove the face plate etc let me know, it's pretty simple.
Lo-Fidelity
Super Member
Maybe you guys could take a quick look at my order before I hit the purchase button.
The recommended Nichicon UES CE23/24 is back ordered and an alternative is Nichicon UEP version. Is this ok or should I consider another alternative?
I don’t have a clue on the CE 07/08 C0G 100 pf. Is Kemer ok or should I look for another alternative.
Thanks in advance.
The recommended Nichicon UES CE23/24 is back ordered and an alternative is Nichicon UEP version. Is this ok or should I consider another alternative?
I don’t have a clue on the CE 07/08 C0G 100 pf. Is Kemer ok or should I look for another alternative.
Thanks in advance.
These should be fine for the CE07 and CE08:
https://www.mouser.com/ProductDetail/AVX/SR071A101JAATR1/?qs=UTEM2PllgJ8ZS01dy1YPWA==
UVP is a standard product but probably fine.
https://www.nichicon.co.jp/english/products/alm_mini/index_diagram.html
On the other hand you could go with WIMA MKS2, but maybe there's not enough space?
https://www.mouser.com/ProductDetail/WIMA/MKS2D041001K00JSSD/?qs=ISKKXg98%2B1nee2R%2BH1CXvg==
https://www.mouser.com/ProductDetail/AVX/SR071A101JAATR1/?qs=UTEM2PllgJ8ZS01dy1YPWA==
UVP is a standard product but probably fine.
https://www.nichicon.co.jp/english/products/alm_mini/index_diagram.html
On the other hand you could go with WIMA MKS2, but maybe there's not enough space?
https://www.mouser.com/ProductDetail/WIMA/MKS2D041001K00JSSD/?qs=ISKKXg98%2B1nee2R%2BH1CXvg==
Lo-Fidelity
Super Member
Found the UES version with a slightly different lead spacing.
Good to go.
Thanks for all the help.
Good to go.
Thanks for all the help.
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Lo-Fidelity
Super Member
My Digikey order arrived today.
CE25 tested high ESR just like the old capacitor. Could be the cheap little tester I am using as the other electrolytic capacitors showed 3-5 ESR.
I installed it and the hum is still there.
Hope to have some time tomorrow to do the rest of the board.
CE25 tested high ESR just like the old capacitor. Could be the cheap little tester I am using as the other electrolytic capacitors showed 3-5 ESR.
I installed it and the hum is still there.
Hope to have some time tomorrow to do the rest of the board.
That is indeed odd. We'll have to assume your tester is incorrect I think. A new capacitor won't be that bad.
"The hum is in both channels and present with the volume turned completely down and with all source inputs. With the volume down, the balance slider has not effect on the hum volume on either channel.
With the volume turned up some, the tone controls effect the pitch of the hum, and the balance slider effects channel hum volume but doesn’t reduce it lower than when volume is all the way down."
Reading this indicates to me it's after the volume control but before the tone controls. So on the input side of PE01.
The odd thing is that balance affects it since balance is before volume.
"The hum is in both channels and present with the volume turned completely down and with all source inputs. With the volume down, the balance slider has not effect on the hum volume on either channel.
With the volume turned up some, the tone controls effect the pitch of the hum, and the balance slider effects channel hum volume but doesn’t reduce it lower than when volume is all the way down."
Reading this indicates to me it's after the volume control but before the tone controls. So on the input side of PE01.
The odd thing is that balance affects it since balance is before volume.
Once it is in circuit and gets some electrons flowing through it, the ESR will drop. Usually within about 30 seconds.
tjasont
Member
Ill give u some advice that esr tester is worthless. Guess what a dead shorted electrolytic has super low esr. The best course of action is throw every single electrolytic in this thing in the trash and then burn the can to make sure they are dead unless u have a leakage tester your wasting your time all the lytic caps replace ever paper and foil cap replace only let the film caps live period or your just wasting time
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tjasont
Member
also the fact the esr drops after 30 is actually one of the scariest things i have heard today. diffently trash then burn then put a 5000 or 12000 hr rubycon in it for 3 bucks and let it live for another 50 to 80 years
I don't need that "advice", but thanks anyways.. One thing about the cheapo testers, is when a small cap takes a long time to charge up to get the results, it is a clear indicator it is fighting against the internal leakage. They are also very handy to identify transistor leads, and a quick way to see if one is shorted. Of course as with any low voltage "tester", take the results with a grain of salt.