[Grandlizzard]

Hi good people of TT- Forum!

Its possible that this question has already been disgussed, but im afraid im not familiar with German, and google translate did not do a good job for me. So I hope its OK, if I post in English ( or rather Norglish, as my English is not fluent either)

I have a couple of issues, that I hoped I could share with you.

1 - On the 12AX7 tube - the schematics tells me that im supposed to have 170V on Pin 6, and 1,3V on pin 8. My readings are 270V on Pin 6, and 5,4V on pin 8. Any suggestions welcome

2- I,m able to play through the reverb unit, but im not getting any Reverb at all. Get an increasing hum from the unit as I turn up the MIX.  I do not remember the values, but there is resistance when I check the RCA terminals on the Accutronic tank. Any suggestions welcome

The Mini PSU is putting out 272 V on B3, not 260 as stated in the Schematics, but not shure if this has anything to say at all.

Best Regards.

Grandlizzard

[guanre]

Hello Grandlizzard,

are your shure you have the right resistor on Pin 8? 10K instead 100k? And the same for the other Pins!!

Please check it again:

guanre

[Grandlizzard]

Hi Guanre!

Not shure if i understand you, according to schematicsen, Pin 8 is supposed to have a 1k5 resistor, or maby im missing something here.

Brg.

Grandlizzard.

[Athlord]

Hi,
did you now this site:
https://www.tube-town.net/cms/?DIY/LoW-Projekte/Reverb_%28engl%29

Please check the value of R3 and R4...

Regards
Jürgen

[guanre]

Hi,

sorry I mixed pin 8 with 6.

V21 and V22 P6/1 should have 100K. V12 P6 100k.

For P8 you're right, 1K5.

I would suggest to check all resistors, capacitors again.

Heater voltage right?

By the way, measure the Anode is between Anode and Chatode. For example, andode voltage V22 is between P 6 and 8

guanre

[Grandlizzard]

Hi again!

Found the problem with the higher voltage on Pin 6 and 8 on the 12ax7. R15 was not grounded good enough. Down to 178 volt now. Same for pin6 to Pin 8

Athlord, thank you. But that is the one im using.


Guanre, i had not checker the heater voltage before, but it is actually only 3,5 vac

[Dirk]

Guanre, i had not checker the heater voltage before, but it is actually only 3,5 vac

Make sure the the leads are blank. Remove all of the insulating varnish.


Best regards, Dirk

[Grandlizzard]

Hi Dirk!

Thanks for the advice, had them off, and scraped them, but still measures 3,5vac.

Any ideas for what i can have missed conserning the missing reverb?
There is conductivity in the reverb tank.

Brg.

Grandlizzard.

[Dirk]

Are you sure hat the DMM works correctly ?

Regards, Dirk

[RoehrenJeans]

Hi,

...but still measures 3,5vac.

Where have you measured these 3,5vac ? Directly at the transformer or between "somewhere" and ground ?
Cheers
Stoffel

[Grandlizzard]

Hi again Gurus!

Im sorry to have wasted some Of your time, but i was messuring Pin to ground, Pin to Pin gave me a better reading. 7volts.

So, now all my messurepoints are correkt.

But i still have no reverb, only clean sound coming from the whole reverb unit. Any ideas to where i can start looking for errors?

[Athlord]

Hi,
Is the Reverbtank correct connected?
Grounding of the Reverbtank?
Did you hear some noise when you knock at the Reverbtank?
Regards
Jürgen

[RoehrenJeans]

Good morning,

Im sorry to have wasted some Of your time, but i was messuring Pin to ground, Pin to Pin gave me a better reading. 7volts.

ha ha ... don't worry
Here in Germany every "electrician" learns the phrase "Wer misst misst Mist" (Mist = rubbish) ;-)

So, now all my messurepoints are correkt.

fine ...

But i still have no reverb, only clean sound coming from the whole reverb unit. Any ideas to where i can start looking for errors?

Now you should check the signal path...Do you have an oscilloscope ?
If not, post a good photo of your "building" ...
Try to connect a little 8 Ohm speaker instead of the reverb tank and check if there is a signal.

Good luck
Stoffel

[Grandlizzard]

Athlord - It should be correctly connected according to input/output, and I have also tried to switch the RCA cords. Its grounded through the RCA connectors, and I have checked for conductivity. there is no sound when I tap the reverb tank itselves.

RoehrenJeans -  I do not have any oscilloscope training, but we have a Rigol DS1102E at work 2 chanel 100 MHz that I can borrow. As stated I have no training with this, and im not shure how to set it up. The guy who used to use this is not working here aymoore, so I can not ask him either :-)

I really appreciate you all for taking the time to help me out.

Brg.

Grandlizzard

[RoehrenJeans]

Hi,

there is no sound when I tap the reverb tank itselves.

OK, then there is something wrong in the return path  (see attached screen shot).

I would recommend, go for the scope, ...
There are some good tutorials in the web and your present problem is a good starting point to get familiar in working with a scope.

Cheers
Stoffel