TA-500 Left Channel blown- AN7070 bad?
- Thread starter jd3rdcoast
- Start date
Yea I am spoiled with the one day delivery. I do also usually buy at least 10ea for the price breaks. Typically buying for one unit at a time, but was unable to test the PHONO board properly because unit was non functioning until I got the output transistors and the AN7070 that were all toast.
I know I should get more efficient and buy for more than one device at a time. I have several I picked up over past 6 months that need attention. Then I got sidetracked rebuilding couple of my own pieces and a keeper 2270. Time to get busy and sell some items. So I can buy something else
. This is a fun hobby for me for past 10 years. But was laid off last year after 25+ years successful med-device sales career and now at 58 dealing with definite age discrimination trying to get back in the game. Frustrating. At least the small wins doing these repairs helps my attitude and keeps me busy.
Our design lab was sold twice and I have been laid off twice, now hung it up. I see in my area they are looking for mushroom pickers. I wonder if they drug test there 
Good luck getting your TA-500 going. I looked at the design, looks to be a nice unit.
I see ceitron selling those part, people say you can trust them
https://www.ebay.com/p/AN7070-original-Panasonic-matsushita-18p-DIP-IC-2-Pcs/1241887853
that and some 150-200W bjts from Onsemi and you should be good hpefully
Good luck getting your TA-500 going. I looked at the design, looks to be a nice unit.
I see ceitron selling those part, people say you can trust them
https://www.ebay.com/p/AN7070-original-Panasonic-matsushita-18p-DIP-IC-2-Pcs/1241887853
that and some 150-200W bjts from Onsemi and you should be good hpefully
Last edited:
kevzep
Its all about the Music
Well thats what I am not looking forward to, looking for a job in my 50's, but I have an unusual skill set and I will always be able to get work, this thing is a side line for me although after taking on two more jobs today, a JVC and a Yamaha, its starting to feel more like full time!! Two full time jobs....
That’s where I got my AN7070, It was in new condition, looked like never installed so I was happy to see that. I already got the unit operational (Post #8) then found the fusing resistors on Phono amp board were bad. I also ordered set of main filter caps 6800uf 50V Nichicon (647-UVZ1H682MRD) drop in replacements plus bi-polar 3.3uf ES Nichicon to replace the orange Nichicons at the input.
All is well that ends well. Installed the new metal film resistors x4 on the phono board and two new 6800uF UVZ Nichicon main filter caps. Powered up on DBT, check. Then tested the phono stage and got no right side output. Went back with a 1kz 100uV signalt and scope saw the signal at collector of TR02 which feeds base of TR04 was much higher than Left side so just replaced all four BJT's. TR01, TR02 (PNP, 2SA906) = KSA992FBU and TR03, TR04 (NPN, 2SC1845) = KSC1845FTA. (DBT-check) Tested with a Sansui SR-333 TT and getting real nice clean, defined sound from both channels into set SP-200 (recapped) speakers.
Now just need to decide on green or light blue lights courtesy of DWOJO.
Now just need to decide on green or light blue lights courtesy of DWOJO.
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