RIM Gigant/ Siemens EL34 GZ34/ help needed.

[Siemens EL34]

Hello !

Happy to be here. I am getting confused with this 25W little amplifier based on the RIM Gigant schematic. This had been built by someone back in the 60s or 70s.

I have here

V1 EF86
V2 ECC83
V3 ECC83

Two EL 34 power tube and a GZ34 rectifier.

Where I am getting lost is that the V2 ECC83. It seems that the previous owner left out the 1st Anode and seems that this tube is only a half ECC83.

Attached what I see so far on this amplifier. Could you please gude me if anything wrong here or this is correct, and the V2 only suppose to work as half and not full?

thank you

[sluckey]

Where I am getting lost is that the V2 ECC83. It seems that the previous owner left out the 1st Anode and seems that this tube is only a half ECC83.

I would guess that only half of V2 is needed. Post the entire schematic and we'll let you know for sure.

Does the amp work? If not, what are the symptoms?

[Siemens EL34]

Where I am getting lost is that the V2 ECC83. It seems that the previous owner left out the 1st Anode and seems that this tube is only a half ECC83.

I would guess that only half of V2 is needed. Post the entire schematic and we'll let you know for sure.

Does the amp work? If not, what are the symptoms?

Thanks! :)

I have just received the amp and not plugged it in yet as several issues visually were seen...leaking caps . loose wires..etc.. the schematic is this one (attached) BUT on there, the full tube is being used and on this unit there are no High and Low tone pots while on the schematic are. The rest seems to me the same so far more or less...

[shooter]

pleasant surprise it's self biased 
not sure the 12v o .1a note yet, still early

[sluckey]

Well, the preamp has been disabled. The redline drawing appears to be a direct input to the power amp, so apparently only the power amp was being used. You need to verify this. And if you want to return the amp to stock just follow the schematic and remove the redline stuff.

I stitched your schematics together to make it easier to follow.

[Siemens EL34]

Well, the preamp has been disabled. The redline drawing appears to be a direct input to the power amp, so apparently only the power amp was being used. You need to verify this. And if you want to return the amp to stock just follow the schematic and remove the redline stuff.

I stitched your schematics together to make it easier to follow.

Thanks... the schematic and the amp is from two separate source. Did not came with the amp. I just wanted to understand the hald tube usage and if the previous owner did this correctly as I am not familiar with this scenario..

Leaving anode     2 out
Grid 2                 1M to ground
Cathode 2           3,3k coupled with a 50uF cap
Both heaters       are soldered together (?)
Anode 1             3k, 30k, 16uF to ground and junction to other 50k / 8uF/ 50k to V3
Grid 1                10nf/ 18k to pot wiper (center) and a 1M to ground
Cathode 1           500 Ohms to ground (seems very low value?)
Heater CT           Soldered to ground

 

[sluckey]

Rather than saying anode 2, grid 2, cathode 2, etc., just use the pin number, ie, pin 1, 2, 3, etc. You have mixed up some of the stuff in your list.

I promise you that a 12AX7 with nothing connected to pin 1 is totally disabled, even though there is something connected to pins 2 and 3. Quit trying to understand why something was done. Just verify the actual amp follows the schematic and make notes of any differences.

[Siemens EL34]

Rather than saying anode 2, grid 2, cathode 2, etc., just use the pin number, ie, pin 1, 2, 3, etc. You have mixed up some of the stuff in your list.

I promise you that a 12AX7 with nothing connected to pin 1 is totally disabled, even though there is something connected to pins 2 and 3. Quit trying to understand why something was done. Just verify the actual amp follows the schematic and make notes of any differences.

Roger that and thank you. I need to wait to get a new tube socket as one pin broke off.. then would start everything from scratch...might some help from you guys here on this forum, please bear with me.. as I am not 100% with these old gears but I love them. The aim with this is to use it a mic pre... but to get to that point, the mentioned tube needs to be in action.


this is how it is with pin numbers:

Pin 1Leaving anode      out
Pin 2 Grid 2                 1M to ground
Pin 3 Cathode 2           3,3k coupled with a 50uF cap
Pin 4/5Both heaters       are soldered together (?)
Pin 6 Anode 1             3k, 30k, 16uF to ground and junction to other 50k / 8uF/ 50k to V3
Pin 7 Grid 1                10nf/ 18k to pot wiper (center) and a 1M to ground
Pin 8 Cathode 1           500 Ohms to ground (seems very low value?)
Pin 9 Heater CT           Soldered to ground


thanks once again and stay safe...

[sluckey]

There is no mystery about the heater connections. This is a common connection to operate a 12AX7 tube from a 6.3v source.

[Siemens EL34]

There is no mystery about the heater connections. This is a common connection to operate a 12AX7 tube from a 6.3v source.

Yes that is OK but why both heaters if the half of the tubes were used..was my questionmark for :) ..... to me the confusion came from looking at the values of the parts...and the placement of the parts...and the whole "half tube in operation"

[sluckey]

It doesn't matter! Quit wondering why. The other half tube works just fine.

[Siemens EL34]

It doesn't matter! Quit wondering why. The other half tube works just fine.

I know... i know.. sorry. Thank you for your help so far. :)

stay safe and healthy!

[PRR]

> why both heaters if the half of the tubes were used..

I see no proof of deliberate plan to "use a half tube". Clearly both halves were used when new. Later hacks may be incorrect.

There is no strong reason to use "half the heater". Do we even know which half? And what do we save, less than a Watt? On a chassis which must suck over 100 Watts?

[Siemens EL34]

Okay... i did solder back everything how I received it with just to see how it is.

There were a couple of lose connections. With the new filter cap the amp turning on nicely, rectifier good, the two EL34 good and here are at the ECC83s... 

That particular one the V2 in this post discussed, have a pin 4+5 exact 6.4V AC , and pin 6 have exactly 168V DC. This tube does not lit up at all.

I am having difficulties to understand what parts I should remove from the schematic shared before in order to make this right. The schematic has two extra pots while I do not have the extra pots.

Could you please advise what components I should leave out in order to make this work...? I am lost a bit on that... the V3 ECC83 looks OK by the look of it, nothing sparky or out of ordinary (visually)

Thanks again...and again attached the schematic.

[shooter]

This tube does not lit up at all.

work the problems you find, this is a problem.
without the tube in, your meter set for VAC, put one probe in pin 9, the other in pin4/5, you should have ~ 6VAC

[sluckey]

This tube does not lit up at all.

Nothing else matters until you get the tube filaments to glow. The tube will not work without the filaments being hot. Kinda like driving a car. It the engine does not work you ain't going on a joy ride.

The correct way to accurately measure heater voltage is to put one probe on pins 4/5 and put the other probe on pin 9. If you have 6.3vac then either the socket is bad or the tube is bad. If you don't have 6.3vac then check the wiring between the PT and that tube.

[Siemens EL34]

Thanks guys... so without the tube in I do measure 6.4VAC on pins 4/5 not to pin 9 but to chassis ( the pin 9 is soldered onto a rail which is connected to chassis)

I did swap the two tubes around, both tube works in the V3 socket, lits up.

None of the tube is working on the (brand new) V2 socket but as above, I do measure 6,4VAC there... how is that possible?

Thanks you so much for guiding me through this.

[sluckey]

Thanks guys... so without the tube in I do measure 6.4VAC on pins 4/5 not to pin 9 but to chassis ( the pin 9 is soldered onto a rail which is connected to chassis)

THIS IS VIP! READ CLOSELY...

The correct way to accurately measure heater voltage is to put one probe on pins 4/5 and put the other probe on pin 9.

[Siemens EL34]

Thanks guys... so without the tube in I do measure 6.4VAC on pins 4/5 not to pin 9 but to chassis ( the pin 9 is soldered onto a rail which is connected to chassis)

THIS IS VIP! READ CLOSELY...

The correct way to accurately measure heater voltage is to put one probe on pins 4/5 and put the other probe on pin 9.

Understood... sorry. I thought as it was connected to chassis it doesn't matter. Clearly I was wrong. Thank you .

[PRR]

> I thought as it was connected to chassis it doesn't matter.

New amps, old amps; even if it looks like it is connected, check carefully. Bad joints are everywhere. Especially in gear that has not worked in a while (or ever).

What can be fun is a socket so tarnished that the socket is live but the tube pin is dead. This can be hard to find.

[Siemens EL34]

Thanks guys for the help..

I did measure the voltages between pin 9 and 4/5 on the socket (new one, ceramic base) and measuring 6.3V with no tubes in.

I did re checked the soldering, seems fine.

Tested all the tubes I have in the socket V1 where I have the heather lightly glowing. All the tubes I have in V1 socket glowing.

The V2 socket is brand new...just purchased it no long ago. What could be the issue? I dont understand. 

 

[shooter]

(new one, ceramic base)

fwiw;
I quit using the ceramic's a few years back, they were impossible to tension pins, tubes were almost impossible to seat/unseat properly so the pin contact was real sketchy.  I bent pins, I broke a tube, just getting them in n out

[Siemens EL34]

(new one, ceramic base)

fwiw;
I quit using the ceramic's a few years back, they were impossible to tension pins, tubes were almost impossible to seat/unseat properly so the pin contact was real sketchy.  I bent pins, I broke a tube, just getting them in n out

Thank you.. sadly locally was only ceramic based was available...I did re check and it was a loos soldering as mentioned by PRR.

Now I have a heater on V2 and V3.

Moving on the EF86 V1... already noticed a completely broken flat capacitor and something not quiet right here either...\i dod not notice any glowing on this tube either, only at the base of the tube I see something glow-ish thing...  Will replace that cap and see what will happen.

Thanks guys for the guide... i hope I am nearly there :)

[Siemens EL34]

OK..I did connect a speaker to this amp and switched it on.

Huge amount of hum coming through the speaker with both pot's down.

Interesting that the two pots are together in a way...these are not two channels with individual pots...does not work separately..both pots needs to be turned up in order to respond...there is a nice "hiss" when the pots are turned up but the hum is so loud ! Need to find out what sort of hum is this but its a massive AC hum... sounds like the transformer hum amplified massively...

I would really be thankful if you would have any suggestion... :)

[Siemens EL34]

guys

could you please help me.... is this resistor burned? This resistor is the R32 on the schematic..measured 160 Ohms , no markings on it. Schematic calls for 130 Ohm...i do not know the wattage of this...could you please please advise me? Thank you

[sluckey]

It's been hot. Replace with a 10 watt.

[Siemens EL34]

It's been hot. Replace with a 10 watt.

Thank you !

[shooter]

I would also replace the 100uf cap, just because.

[Siemens EL34]

I would also replace the 100uf cap, just because.

Yes, will definitely do that...also those 16 and ufs 450V to ground at the V1+V2+V3 ... spent my whole afternoon figure it out what that person whoever built this amp did.. he merged two electrolytic s into one..so one 16Uf's is taking care of the 8+8Ufs...  its a lot to go with this i think but I will not give up..

[sluckey]

I think the schematic you posted has very little to do with the few amp pics you posted.

[Siemens EL34]

I would also replace the 100uf cap, just because.

...quick question on this...would you go for higher value or lower value? i have several large caps from 20uFs to 200uFs or 500uFs...might be a good place to use them?

I could not find a 130R 10W resistor...i went for 150R instead...?

Thanks for your advise.

thanks

[Williamblake]

"TB Aufn." is short for tape record. Maybe the red part is completely external. It is in a very similar amp i recently aquired but i couldnt find out the manufacturer until now.

And they also build a poweramp without preamp. http://www.jogis-roehrenbude.de/Rim/Titan.htm

But you seem to have a stripped down version of the Gigant or Gigant S, as it normally seems to have two mic inputs and a tone control.

http://www.jogis-roehrenbude.de/Rim/Gigant-S.htm

Appearantly they designed the kit with and without the HT switch and also went ultralinear the same time. Your schematic seems to be the only one around with the HT switch still present? Were did you get it from?

What they did stick to though all the time is the paraphase, cathode bias, GZ34, EL34 power- and EF86 input-tubes.

If it helps, i can post pictures of the amp i got but someone did a very tight job in a big chassis.

Maybe this could be a decent little backline, but it has some very usable iron for guitar, too ...

On a sidenote i learned from the start the OP gave, this amp and its successors which offered more channels, was the go to diy backline for Krauts who couldn't afford Dynacord and the company offering this kit did go solid state, too, but was later on aquired by Conrad which is similar to Radioshack but was mostly mail order back then.

[sluckey]

"TB Aufn." is short for tape record.

You may be talking to the trees. This thread is over 1-1/2 years old and Siemens EL34 was last on the forum 8 months ago.

[Williamblake]

Maybe the trees are talking to me? Wasn't sure if i googled this or someone got what i couldn't figure out. Always thankfull for a heads up, though.