New Tubes for a MKI Herbert and banana plugs infos

[diezel&gas]

You would read leaking current in a few mA range

thanx Olaf!

 

[diezel&gas]

thanx everyone yes the procedure is ok, i read some articles and saw many videos of technicians doing it, my only concern was about the connection of the leads to the bias points, so ok i'll try it without the banana plugs


another thing... Should this happen the same on Diezel amps? https://www.youtube.com/watch?v=l2GGggx ... NQ&index=3

 

[diezel&gas]

If you haven't tried it, you have no reason to think it won't work. That's what most people use on their amps. No issues.

Try it. You'll see that it works just fine.

HELLO!

Master volume @ 0, cook the amp with load for ~5 minutes, DMM in hand (red probe - mA, black probe - COM), probe amp ground 1st, probe 1st amp bias test point 2nd, 200m (ampere) setting on DMM, then flip run "on" adjust bias test point to ~ (65-70)mA pairwise (clockwise colder, counter clockwise hotter) = Rock TF out while the pizza's on its way!

(clockwise colder, counter clockwise hotter)
it's the oppostite clockwise hotter, counter clockwise colder.
i know you know it


edit : i was trying my DMM and it read 0 !! .... lead test probes are 1.5 cm long... could the reason be they are too short? i tried also placing them a little sideway in order to touch the side of the internal jack but i got 0 response as well....

 

[diezel&gas]

( I mean the tip of the lead probe)

 

[docben]

Same experience here ( O on my DMM with the little needles probe).

So I used BiasMaster Probes.

 

[FourT6and2]

Probes could be too short. 1.5cm is very short. The probes I have are much longer.

 

[Black Sabbath]

(clockwise colder, counter clockwise hotter)
it's the oppostite clockwise hotter, counter clockwise colder.
i know you know it

Maybe your hot is my cold and vice versa. I'm far from an IEEE but on my Herby with my DMM adjusting it clockwise will decrease the mA reading, adjusting it counter clockwise will increase the mA reading. Furthermore I'm not 420 friendly so that's not an issue.

Also my probes are exactly 3/4" long. All they need to do is touch the outer rim of the insert to the bias test point for conductance.

However you get there, (70 mA each pair).

Works for me and sounds even better.

 

[diezel&gas]

Thank you!At this point I really can't understand why the reading was 0... Even @docben have had the same result...
I'll go to search different lead tests... Banana or longer ones ( longer tester tip )....

 

[Peter Diezel]

There is a fuse inside the DMM. It´s often broken by a short

 

[diezel&gas]

hi Peter! i just came from my electronic shop with longer test pins, let's see what will happen now, i'll also check that fuse !
if you guys notice a mushroom cloud.... it's me

 

[Black Sabbath]

if you guys notice a mushroom cloud.... it's me

Hey, not so fast now. Maybe your Herbie is a fixed bias? Just play it and let your ears be the judge.

j/k - I wish you luck my friend. Peter did really make this aspect of bias adjustment quite straight forward.

 

[diezel&gas]

Yes the procedure is really clear and simple to follow...
By the way still nothing... Even with longer test leads
the DMM fuse is ok and it works on other applications...
Getting angry

 

[FourT6and2]

Yes the procedure is really clear and simple to follow...
By the way still nothing... Even with longer test leads
Getting angry

Either your meter's fuse is blown or you don't know how to operate the meter correctly. Black probe should plug into the COMM jack. Depending on your meter, red should plug into the correct corresponding jack. Post a photo of your meter and we can tell you which one to use.

Also, make sure your amp is out of standby. If it's in standby, you will read zero.

 

[diezel&gas]

connections on the DMM are ok, i also asked that in a old post in this forum, tha's my DMM there viewtopic.php?f=14&t=25626
even the fuse is ok, the dmm works in other operations.

i followed an old page it was available on the old Diezel tech page as well.

the amp of course is running, not in stand by

 

[diezel&gas]

wait wait wait..... i've eventually taken the DMM fuse off, it was blown !!!!!!!

i'll fly to the electric shop!!! bb later.


edit:
Petes was right!!!! Peter for president!

problem solved!!!! it was really the DMM fuse blown! thanx! the internal filament of the fuse is very thin so it wasn't noticeable without removing it from the DMM.
Amp with stock tubes re-biased now, just before to buy a new fresh set. bias was at 52mA per pair before my bias regulation, i raised it a little to 62.7 mA on both 3 the pairs.

 

[Black Sabbath]

Getting angry

Calm down. Do you have a copy of Moving Pictures handy? If so then throw that on to release some stress.

Not to be too fussy, but you say "it" works on other applications. You are in fact referring to the DMM itself working and not just the fuse?

Do you have a standard AA 1.5 V battery lying around that you could test on?

 

[FourT6and2]

wait wait wait..... i've eventually taken the DMM fuse off, it was blown !!!!!!!

i'll fly to the electric shop!!! bb later.


edit:
Petes was right!!!! Peter for president!

problem solved!!!! it was really the DMM fuse blown! thanx! the internal filament of the fuse is very thin so it wasn't noticeable without removing it from the DMM.
Amp with stock tubes re-biased now, just before to buy a new fresh set. bias was at 52mA per pair before my bias regulation, i raised it a little to 62.7 mA on both 3 the pairs.

There ya go.

 

[diezel&gas]

Getting angry

Calm down. Do you have a copy of Moving Pictures handy? If so then throw that on to release some stress.

Not to be too fussy, but you say "it" works on other applications. You are in fact referring to the DMM itself working and not just the fuse?

Do you have a standard AA 1.5 V battery lying around that you could test on?

lol yes the dmm was working, i.e. : Testing a 9 V battery, it worked... Only the Current reading was dead because of the fuse fault.
Now I solved everything, experience done! Now I have a little knowledge more

 

[diezel&gas]

Other questions: which exact size should the screwdriver to set the bias on the trimmer be?
Is the black plastic guide that helps the screwdriver get into the trimmer removable pulling it upwards? Has it the function of a insulation too?
Thanx!

 

[FourT6and2]

Other questions: which exact size should the screwdriver to set the bias on the trimmer be?
Is the black plastic guide that helps the screwdriver get into the trimmer removable pulling it upwards? Has it the function of a insulation too?
Thanx!

A flathead that's relatively small. Just stick one in there and and if it's able to turn the bias pot, then it fits. This isn't rocket science. Not sure if the rubber grommet on the chassis goes all the way to the trimmer or not. Doesn't really matter, though. Just use a screwdriver that's insulated.