I have been very cautious about this. I have done countless searches and found many helpful threads. However, I have only been able to piece together info for the 5700 from related posts about the 6700 and 7700. I have done well and heeded all warnings and advice, thanks to all.

Now I have successfully adjusted the offset within the limits. It was painless and quite rewarding. I have tasted the water from the clear mountain stream(or something like that). I am now searching for more info on the Bias adjustment. This has been less straight forward. I have the brief instructions that someone attached to a post. The top view that was included was for the 6700/7700.

Question: Is this worth messing with?
If left unchecked/uncorrected, will it cause damage?
Is it possible to get a copy of the G5700 service manual from someone on this site? (I would rather send a donation to AK, than to an eBay-er.)

Other issue: After I adjusted the DC offset, everything seemed good. I waited a day and decided to take another measurement. I let the unit warm up for a good hour. Using my DMM, the measurements were about the same. I say "about" because while in mV setting the measurement really hunts and I just try to average. This time, I saw an occasional spike that was way outside the range. It was so fast, that I could not read it. I noticed that whenever one of these spikes occurred, that the light near the work area was dimming slightly. We live in an older home and I see this often. Is this ( the mV spike) just a reaction to line fluctuations caused by other appliances in the house? Is it normal? Can I buy something (cheaply) that will help with this?

Thanks for your interest.

Dan

Dan, It is a good idea to get the bias adjusted. If Bias current is too high, the outputs will overheat and burn up.

The fluctuations are most likely from AC line fluctuations. I wouldn't about it too much

I have been very cautious about this. I have done countless searches and found many helpful threads. However, I have only been able to piece together info for the 5700 from related posts about the 6700 and 7700. I have done well and heeded all warnings and advice, thanks to all.

Now I have successfully adjusted the offset within the limits. It was painless and quite rewarding. I have tasted the water from the clear mountain stream(or something like that). I am now searching for more info on the Bias adjustment. This has been less straight forward. I have the brief instructions that someone attached to a post. The top view that was included was for the 6700/7700.

Good work!

Question: Is this worth messing with?
If left unchecked/uncorrected, will it cause damage?

It can if the BIAS is way out of spec. Overheating and distortion soon follow.


Is it possible to get a copy of the G5700 service manual from someone on this site? (I would rather send a donation to AK, than to an eBay-er.)

Certainly! Your good work deserves a reward. You have a PM!

Other issue: After I adjusted the DC offset, everything seemed good. I waited a day and decided to take another measurement. I let the unit warm up for a good hour. Using my DMM, the measurements were about the same. I say "about" because while in mV setting the measurement really hunts and I just try to average. This time, I saw an occasional spike that was way outside the range. It was so fast, that I could not read it. I noticed that whenever one of these spikes occurred, that the light near the work area was dimming slightly. We live in an older home and I see this often. Is this ( the mV spike) just a reaction to line fluctuations caused by other appliances in the house? Is it normal? Can I buy something (cheaply) that will help with this?

Thanks for your interest.

Dan

Yes, DC offset is often erratic and can change with line voltage. If you find that the DC offset never seems to settle down but is quite jumpy when you're adjusting it, then those trim pots need cleaning or replacing.

Paul

PS: Don't forget to chek your PM :thmbsp: (well, give me 3 minutes to get it off :smoke: )

Good work!
Yes, DC offset is often erratic and can change with line voltage. If you find that the DC offset never seems to settle down but is quite jumpy when you're adjusting it, then those trim pots need cleaning or replacing.

Paul



Aha! That answers a question I forgot I had (about my G-5500) a couple months ago). I'll hit the bias and offset trim pots with Deoxit and readjust them. :thmbsp: