Technics-goy
Super Member
Technics SE-A7 discrete Amp
L : 0.2mV
R : 0.1mV
Temperature independent
L : 0.2mV
R : 0.1mV
Temperature independent
Amplifier Distortion, DC-Offset, and You!
- Thread starter EchoWars
- Start date
Sansui 9090
Took DC offset readings last spring 2018 left - 44.00 mv, Right 43.50 mv.
Adjusted today down to roughly to left 00.08mv, Right 00.05mv but it does move at over 01.00mv on both sides at times.
Funny I bought this last year off craigslist and just cleaned and oiled it. It was really dusty inside. Looks all original on inside and sounds great.
Took DC offset readings last spring 2018 left - 44.00 mv, Right 43.50 mv.
Adjusted today down to roughly to left 00.08mv, Right 00.05mv but it does move at over 01.00mv on both sides at times.
Funny I bought this last year off craigslist and just cleaned and oiled it. It was really dusty inside. Looks all original on inside and sounds great.
Attachments
Fisher RS-Z1.
Left terminal = 2.4mV
Right terminal= 2.6mV
That right? Meter set at 200mV, reading on meter 02.4. Is that 2.4mV or 24mV?
https://www.wikihow.com/Measure-DC-Offset
Left terminal = 2.4mV
Right terminal= 2.6mV
That right? Meter set at 200mV, reading on meter 02.4. Is that 2.4mV or 24mV?
https://www.wikihow.com/Measure-DC-Offset
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RTally
Speaker addict
Nope. Read the first post. You are golden. Leave well enough alone and enjoy the music.
cheapo_eddy
Active Member
Thanks for the refinement. I've always simply gone by the credo that "There Is No Such Thing As A Minor Driver Board Fire."
viapol
Member
Realistic 2000d.
Right .9 VOLTS...YES OVER 900 mv
Left only roughly 300 mv...I guess i should be happy about the 300?
Think I'm using the MM correctly because I have 5 other receivers I measured with the same MM. VDC.Right measured so high I had to set MM at 20 vdc. Left set at 300m on MM.
Right .9 VOLTS...YES OVER 900 mv
Left only roughly 300 mv...I guess i should be happy about the 300?
Think I'm using the MM correctly because I have 5 other receivers I measured with the same MM. VDC.Right measured so high I had to set MM at 20 vdc. Left set at 300m on MM.
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SeattleHiFi
Active Member
Yamaha A-S1100
Cold L channel 7mv R channel 8.5mv
Warm L channel -2.5mv R channel -2.5mv
Cold L channel 7mv R channel 8.5mv
Warm L channel -2.5mv R channel -2.5mv
cheapo_eddy
Active Member
12 kV.
Oh, wait a minute. This isn't a hi-fi amp, it's a neon sign transformer. Never mind.
Oh, wait a minute. This isn't a hi-fi amp, it's a neon sign transformer. Never mind.
RTally
Speaker addict
That sounds way too high. I would not hook up any speakers to that Realistic until you get it fixed. You may want to start a thread in this Solid State forum about fixing it.
viapol
Member
The strange part is I have Right channel and no left channel??
I would think it would be opposite according to the readings .
Also noticed the longer the receiver ran the vdc would just keep climbing until it basically bottomed out the MM reading. I shut it down once I seen that happening.
Pear52
New Member
Lafayette LR-9090 that I bought in 1978 as a Lafayette store manager before we closed our store in Wisconsin. They did go bankrupt.
Right +12 mv
Left +13.5 mv
All original except for power switch mod using a triac that K7sparky came up with back in 2013.
I'm happy with those numbers.
Edit. This was so interesting that I decided to try this little Realistic amp (SA-150, like 5 wpc) that I bought on fleabay to just transfer some records to digital through my computer. I had to chop up an RCA cable to connect to the spkr outputs, but I got VERY high readings. Had to change the scale to read them. 10 VOLTS on one channel, 1.5 VOLTS on the other...Yikes. I questioned my setup, but other than using an added length of cable for the connection, it is the same. If true, there is definitely an issue with this unit and I am thinking it might be a good learning project to try and repair. I never used it with speakers that I can recall, only headphones. Never was great sound, maybe I now know why! Is that possible? Did I miss something?
Right +12 mv
Left +13.5 mv
All original except for power switch mod using a triac that K7sparky came up with back in 2013.
I'm happy with those numbers.
Edit. This was so interesting that I decided to try this little Realistic amp (SA-150, like 5 wpc) that I bought on fleabay to just transfer some records to digital through my computer. I had to chop up an RCA cable to connect to the spkr outputs, but I got VERY high readings. Had to change the scale to read them. 10 VOLTS on one channel, 1.5 VOLTS on the other...Yikes. I questioned my setup, but other than using an added length of cable for the connection, it is the same. If true, there is definitely an issue with this unit and I am thinking it might be a good learning project to try and repair. I never used it with speakers that I can recall, only headphones. Never was great sound, maybe I now know why! Is that possible? Did I miss something?
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