Bottlehead Forum

Bottlehead Kits => Eros Tape => Topic started by: mkontor on August 17, 2013, 05:25:40 AM

Title: eros tape shunt regulator voltage test
Post by: mkontor on August 17, 2013, 05:25:40 AM

I am up to this part of the build.
On the B side of the board the 2 LED's do not light and I get 300VDC; the A side is fine (225VDC) and LED's glow.
I have double checked all the connections etc.
Any ideas anyone?
Cheers,
mike

Title: Re: eros tape shunt regulator voltage test
Post by: mkontor on August 17, 2013, 05:36:15 AM

i removed the 12BH7 and both sides of the board measure 350VDC, which is correct as there's no draw from a tube.So I guess I have a faulty 12BH7...will have to dig up another one

Title: Re: eros tape shunt regulator voltage test
Post by: Grainger49 on August 17, 2013, 06:58:40 AM

Without the 12BH7 the circuit doesn't regulate, it will be high.

You are lucky, you have a working side to compare the non-working side with.  First just check that the components are the same.  I think this board is kind of Mirror Imaged so be careful.  If the components are good you need to check the solder joints.  The ones that are most problematic are the ones on the transistors.  Just reheat them touching the solder and the transistor lead.  Both get heated till it is liquid and let it cool again. 

Because these are so close together I'm not suggesting that you not add solder right now.

Check this and post back.

Title: Re: eros tape shunt regulator voltage test
Post by: Paul Birkeland on August 17, 2013, 06:36:52 PM

What are the Kreg voltages on each side of the PC board? 

No LED's lighting can mean a lot of things, I'd triple check that you have the 2N2907 transisors on that board, and not he 2N2222A.

-PB

Title: Re: eros tape shunt regulator voltage test
Post by: mkontor on August 18, 2013, 04:08:07 AM

t's all good, resoldered the board