Elekit TU8600S triggers current protection on one or the other channel at power on

[soi]

My board has the pads but there is no jumper. The traces in the manual show that the 5.1K resistor is in parallel with the 430 ohm resistor, which is equivalent to having the jumper permanently attached. My board is the same version as yours, so it should be the same.

 

[vkung]

here is using EH
Please call me.. I will tell you how to trace the issu
Are you sure your TP28 is 300V?
call (604) 788-8821
make sure you have a schematic in front of you

 

[CentralCoast]

We have already spoken on the phone. You told me it was soldering or parts placement.

I have checked both. The voltages that I included are with tubes. The voltage of TP28 is 22V without tubes installed and 300V with tubes installed.

 

[vkung]

i want to tell you how to trace from the schematic
i help so many people.. i do not know who i talked before.
it is your B+ issue.. I want to know how you measure your TP28.. where you get the 300V...

 

[vkung]

you must insert tube to test.
The voltage of TP28 is 22V without tubes installed and 300V with tubes installed.
did you swap the 300b to test the voltage again?

 

[CentralCoast]

Yes. I swapped 300B and get +300V.

I will call tomorrow or Saturday again.

In the mean time I would like to buy a pair of the black plate 300b to test. I sent you an email.

 

[vkung]

I offer you two options
1. help you via phone or email (free)
2. ship to me to fix for you
you need to take care both way shippings plus standard repair cost + parts

 

[vkung]

your problem is not tube set issue..

 

[soi]

You might want to make sure that you didn't mix up Q202 with U202. One is an SCR and the other is a voltage reference They look almost identical.

 

[Paul the painter]

Would the amp work with them mixed up?

 

[vkung]

No

I will check each soldering points on the problem side.
IMG_2146.HEIC - Google Drive

 

[soi]

I don't think so. Without analyzing the schematic in details, I think the voltage reference (U102/U202) is to set a threshold beyond which the 300B bias gets enabled. On the other hand, the SCR is to shut down B+ under fault conditions. Mixing up the two would cause B+ to shut down or B+ to never get enabled.

 

[vkung]

It is not mixing up..

 

[CentralCoast]

I spent all day working on the amp. The amp plays fine on both channels after I toggle power a few times.

It has power on issues. I will keep working on it. The 3 amp voltage regulator for the 300b heater filament is getting my attention now.

Several sources indicate that the 300b requires 3 amps or more during cold start. I will continue to work on it.

Since the amp works after finally getting it started, I am focused on turn on transients.

 

[EvanMcG]

Genelex Gold Lion for 300B and ECC83. RCA for ECC82

 

[tonystark]

Need help with channel not turning on

Hi Victor,
Would you mind if pm you? I have a similar problem to this thread.
Anyway I will pm you to save time. I can’t wait to listen to the TU-8600s again.
Thanks,
Tonystark

 

[tonystark]

Hi Victor as to VKung,
Would you mind if I pm you? I have a similar problem to this thread.
At the meantime I will pm you just to save time. I really miss listening to my TU-8600s.
Thanks,
Tonystark

 

[vkung]

please check your mail box..