Recent content by EmuMannen

Hi all, I am building a new input switching board for my DIY preamp (using a couple of CMOS and relays). I made it so that I could connect each input direct or through a voltage divider. I did it so that I could use it as a passive attenuator for too hot sources. The input board is going to be...

They sound great, not fabulous but great. What I like best is the look and the omnidirectional qualities.

I think I got it now. This thread and this page gave me what I needed to figure it out. And this thread is giving me what I need to move forward. Ps. Still interested to know how to interpret the markings on the coils though.

Ps. I have learnt that the tweeter is a piezo and that it would explain the lack of a cap but I still don't get the coil for the tweeter?

I got a pair of BIC SoundSpan TPR-600 that I got from a friend (who bought them new in the 70s). I was considering an XO upgrade or to go active, so I took a look at the original XO. But I can't wrap my head around it! Please take a look at the attached image. Red wire to woofer, green to mid...

Thanks everyone, you really kept me going. It is now calibrated (trimpots worked perfectly but a bit finicky) and I have made some initial testing through AUX-1 and the phone jack. Sounds perfect apart from a faint hum (earth related?) on max volume. Feels great to have it up and running again! :)

OK, found the "error"... Feels almost ashamed to tell you... I traced E IN to the back plane thanks to friendly forum users on the Swedish www.faktiskt.io board. This is where it got really weird, my board seemed to have the 9P CIS connector at the wrong place, in the middle instead of to the...

Power Circuit Board seems to contain more than power though, phone jack, speaker selector, speaker protection (is that what relay MX2PO does?) etc. Not the exact same problem but Power Circuit Board apparently could affect one of the main amp boards as in this post...

I swapped sides of main amp board and the problem did not follow. So I guess the root cause is not on the amp board but somewhere downstream. DC rails seems OK (equal in voltage). Next stop Power Circuit Board I guess...

It has been in the "off" position all the time. Could it be further downstream? I will swap position with the main amp boards just to see if the problem follows the whole boards or not...

R607 = 389Ω R605 = 149.9Ω

I got some new measurements. Initially measuring the zener-diodes I measured between E (OUT), when measuring between E (IN) I get 12V and 0V on D601 and D603. Some further measurements against E (IN): Left side Tr601 base = 0.631V and right side Tr602 base = 0.163V Left side R611 towards VR601...

I have now swapped TR601/603 and TR602/604, the problem did not follow, it persisted on the left side (same midpoint voltage as before on both sides, about 0.5V on left side, 4mV on right side). Any other ideas?

No still the same problem with the midpoint, will work on it this weekend...

Ps. I was initially planning to use a pair of UKW1J472MRD (4700µF, 63V, D22, L50, P10) instead of the two MAL205158472E3 (4700µF, 63V, D30, L40, P17.5) I had to make adapters for. UKW1J472MRD would also need some type of support I guess...