Hi, Now I have had a good night's sleep, I have found the info that I knew I had relating to Mesa/Boogie bias pot installation. I refer you to Aspen Pittman's excellent book "The Tube Amp Book -

Hi Colin, I've been trying to write this all day, but the family keep getting in the way. :) First of all my short reply has misled (my fault), I didn't mean to suggest that I replaced the resistors

In the manual, it states that if you put a scope probe on TP 1234, the output of the two switching transistors, and see a sine wave of line frequency with a high frequency low voltage pulse on the

Yup, I have those modules, that's why I didn't buy this plugin. I thought it would have gone at that reasonable price. Prices for 500-series plugins have been rising steadily.

The 2.3V isn't such a mystery, although I see it has baffled some owners. This is a Schhmitt phase splitter based on the Blumlein long-tailed pair. It uses a large cathode resistor, to act as a

One thing to consider is the reliability of these DIP switches. They only get switched once in the lifetime of the SA, and tend to get corrosion and hardened lubricant that prevents them from

Hi Goran : Thanks for you advice, I may build a dummy load for the test. Regard Tony 從我的 iPhone 傳送

Tony, it is the problem John had. The PS tries to start but shuts down at a rate of twice per second. on-and-off, tic-tic-tic... The problem is that the PS is overloaded in some way. Göran

Hi I know what tic ! Thanks Tony 從我的 iPhone 傳送

Hi What is tic ? Rd Tony 從我的 iPhone 傳送

You could use a Spice model and a tube curver tracer like the Tek 570 or Dennis's tester along with a 576 or 577 to investigate your circuit mod.  This would help you match tubes and tell you how

Tony, however, the power supply needs about 50W total load, if not it will go into tic mode again. Göran

Will try tomorrow ， it is midnight at Hong Kong already! It is most simple way to turn the power supply alone! Rd Tony Cheung Apr 16 2018 從我的 iPhone 傳送

Tony, yes you can. Göran

R882 is -10.2V Base of Q886B is -11.12V Base of Q886A is -9.1 V Collector of Q886B is 0.28V Emitter of Q886B is -9.72V The cathode of VR890 is 0V. (Isn't that supposed to be +9V ?) -Callie-

Tek 495P Memory Board DIP Switch S1050 Settings I have recently acquired a 495P as a parts unit along with a functioning 495P (both sn B03xxx). The seller reported that the parts unit has

Hi Goran : Is just connect +/- 15V with +/-15V sens ? can power on the PSU without any external load for PSU alone ? RegardTony CheungAPR 15 2018 To: TekScopes@groups.io Sent: Sunday, April 15,

Update? There are those of us who want to know. Leonard

Is R882 -11v or is the base of Q886B -11v or both?? The base of Q886B should also be the same as Q886A (-9v) +/- a few tens of mV. What are the collector and emitter voltages of Q886B? Dave

Hi Goran : I can ignore the connections of P1675 ( Green ) for H.V. CKT. and P1704 ( Yellow ) for CRT CKT. and Beam I sens. of P1483. if all of them disconnected will not shut down the PSU. Thanks