Klemt Echolette E-51 trim pots and tubes location

[Mickey]

TO AlbanLG
A photo of the capacitors you will need to source and fit. These were on an NG51 which I repaired a while ago, tight fit but it works. Mickey

[alq]

Hi, you have checked that there is a ECC81/12AU7 used as a bias oscillator (Ro 5) , now check that you have about 300volts at the bias oscillator transformer also on pins 1 & 6 of the oscillator valve. If this all appears as it should then I think you will have to buy,beg or steal an oscilloscope to measure the voltages going to the heads, where you will be looking for 60V,90V & 120V on heads 1,2 & 3 respectively.
Before attempting the above you could check the voltages on the playback valves, pins 1 & 6 of Ro3 & Ro4. Approximately 90-100Vs on Ro3 & LHS section of Ro4 and approximately 200V on RHS of Ro4.
Let us know what you find.
Cheers, Mickey

Hello there Mickey, you seem to know your stuff around this wonderful machine. Im having a non erasing eraser head problem, also echo repeats seem muffled (like low passed), and i think the source of the problem is the same. So i went on to test the bias oscillator voltages and found only 130V on pin 6 (with tube put on), pin 1 also reads 130V (tube on). Used oscilloscope to read the bias osc at eraser head and found the wave to be distorted at the bottom. What was strange is that i swapped the 5814 for a 12AX7, and the oscillation became lowered in amplitude in the oscilloscope by half, and the repeats lost gain, but they became a lot clearer and detailed in sound, with proper high freq content, non muffled at all. The wave seemed more symmetrical than with the 5814.

What would the problem be here, the osc transformer? Power transformer seems to be outputting the expected 300V, so its not that the voltages are lowered at the source, also the audio line is perfectly fine. Thank you.

[Wagemaker]

Hi everyone.

........
Another thing that bothers me is the way my record head number 1 pot behaves, if i go CCW all the way the unit starts to self oscillate really fast instead of shuting off the echoes. I see in the schematic that this pot is different than the others and that it is somehow connected to the regeneration circuit. What was the point of this? I solved this annoying problem (or not) by unsoldering one of the pot lugs. But i wonder what was the purpose of this in the first place.

.......

nisios, did you figered this out. Did you solve it? because I have the same problem. And it is not clear to me which pot lugs you unsoldered, as a modification than to the standard schematics?
Any one encoutered this phenomenon?
greetings Matthe

[Chuck H]

Matthe, I admire your thoroughness. But this is a ten year old thread. In fact nisios has had no activity on the forum since this thread. The probability of getting a response to this here is is lower than if you keep with the thread you started. Any probability of nisios responding is a lot lower than that. We call these old threads that get "resurrected" necro threads. It's nearly alwyas better to link this thread and reference any important post numbers in the thread that you started. This way others that are still posting here are most likely to read what you did in this thread and possibly offer their evaluation.

I'm sorry to keep making suggestions about your forum activities. I'm honestly trying to keep things as efficient as possible for you.

EDIT: Okay, I just read the thread and it seems like tacking onto this old thread is popular with people that own these machines But as you can see, the last poster before you to tack onto it got no response. There is some really good info here about these units. But as far as the modification made by nisios by unsoldering one lug of the head 1 pot is not recommended. For one thing theirs was not the ng51 but the e51 so there's no guarantee the circuit would be affected the same. For another there was no follow up discussion about what OTHER affect lifting that pot leg may have had on other functions. And for yet another thing, why would they have made the unit with that pot lug connected if it worked better without it? I would consider this an untrustworthy modification.