Studiomaster Powerhouse Vision 8 , 700W mixer amp,1996

A group slider may refer to the aux buss group. Don't know how the fan is governed but I'll assume it has infinite control like my Studiomaster 700D amp. That probably gets its feedback from a sink monted sensor, unknown where it is driven from.

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I've never seen that before, a TO220 device trackside under each pa pcb, thermally touching the heatsink. Only 2 pins used, the B-E junction, with 2 isolated traces to the umbilical ribbon the carries the low voltage rails and signal i/p. I wonder what is special in the 2SD1763A used for that purpose.

On our Mackie aux buss is referred to as 'group',

As far as the 220 devices go the BE junction resistance probably has the desirable thermo electronic properties the engineers were after. I've seen it in many other amps using different package devices including TO-18 and TO-92 eitther fitted into a hole in the sink, clamped, or just touched with a blob of thermal paste. However these were used for PA bias but also are temp sensing like the fan driver.

Same goes for my SCS 700 watt MOSFET amp. Infinite control fan and temp sensored driven. Good for bass guitar final since the fan noise is controlled. I used a Crown Microtech 1000 but band members complained its one speed fan sounded like a microwave oven running. And my BGW 700w was much the same. Guess both were designed to be off stage unlike the SCS and Studio.

We have a few Wharfedale PAs that the fan always idles at a noticeable RPM but increases with demand. And a 2008 Behringer powered 12ch mixer where the fan acts the same as your Studio.

You need to be talking to Graham Stevenson (Eeyore) I think he designed it.

Ron

Yeah don't talk to us lowly nincompoops about something someone else designed.

Where's Graham gone lately ? Used to enjoy some of his design insights, and also his tendency to suddenly fly off the handle occasionally !! :-)

C'mon Graham - bet you're still lurking - we all luv ya really ...

Arfa

Haven't seen him since for a month or so. I think he gets dragged into here via xpost more often than not.

Come to think of it, I havent seen him online lately (we sometimes have a yatter in MSN) or in the pro.live-sound group. Hope he`s ok.

Ron

He was posting in sci.e.d on the 7th.

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Geo

Perhaps he's just got tired of talking to us lowly menders ... You know what these design boys are like ... :-) Come to think of it though, I'm sure I saw a reply from him in one of the threads on here a coupla weeks back.

Arfa

You talking about Eye-Snore?

I think he was just in a couple of days ago.

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glad to see we are not alone got similar problem,have run studiomaster vision 8 for 12months no prob but have suspected fan not doing its stuff. summertime is hot here so used external fan just to be sure,However--- big prob occured running just one guitar in practice session, unit suddenly lost digital display, developed loud squeal from both speakers, master straight to off, peak red lights showing max!! then nothing. tried powering up again same result. have carried out detailed inspection, all pcb's ok visually.ribbon cables and pins good,transformer seems ok but I'm not sure what value outputs I should be measuring at each pin?? would really appreiciate any help

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glad to see we are not alone got similar problem,have run studiomaster vision 8 for 12months no prob but have suspected fan not doing its stuff. summertime is hot here so used external fan just to be sure,However--- big prob occured running just one guitar in practice session, unit suddenly lost digital display, developed loud squeal from both speakers, master straight to off, peak red lights showing max!! then nothing. tried powering up again same result. have carried out detailed inspection, all pcb's ok visually.ribbon cables and pins good,transformer seems ok but I'm not sure what value outputs I should be measuring at each pin?? would really appreiciate any help

I've not got the schematic but I've found you can run it stripped down. Disconnect the 2 pa and all the ribbon cables except the one between the ps one, via small rear panel and up to the mixer. To check for any mixer problems, removing display and memory stuff, monitor output by phones. It looks, not done so yet, that you can then plug in one amp at a time , or swap around , to localise single channel problem to one ch or the other in pa or mixer section. There seems to be odd power rails , +/65V main power rails and a pair of

+/79V. I have some monitored voltages at the pa headers, will get back to it today

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

With pa's and mixer removed and Conn3 and conn4 ribbons removed, so just the main combined ps and thermal board in place, DC voltages on con3

80,0.2(£),15,0,0

-80,16.6($),0,0,0 (*)

• has 0.6V ac, and £ has 0.2Vac on it with 400Hz input and 0db bar registered on the meter $, 16.6V via 100R to base of thermal monitor TO220 ,to test point T12 , obviously drops down to Vbe , with pa in place

T10 for the other amp TP

The 0.6V ac also on that pin of conn4, clear and balanced , unlike originally with all connected, very marked signal imbalance. There was a problem with the "group" slider , but maybe not the cause of original problem. I will next try with swapped pas in place, then display board if all seems well.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Previous 2x5 header volts viewed/monitored at pins , starting from main caps end

At 75 percent or less of mains voltage both red LED "fault" lights light, gives some sort of check of functioning. I don't know what temperature is required to activate the yellow LEDs and channel/channels ? shutdown, but presumably greater than 90 deg c

With PAs loose(on nylon standoff only, not nutted down) in the amp , make sure there is insulation between both sets of live heatsinks. You can monitor signal in of the PA at R11 , R9 end. Monitoring output and T12 TP, increasing the heatsink temp with hot air gun and fan off. No change in output level up to 90 deg C. With fan connected , fan comes on (at T12) with Vbe between 0.61 and 0.62 and temp between about 45 and 55 degree C (the "thermal" Tr is underneath), dropping to 0.52 or so at 90 deg C. Both channels checked like this

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Hello to everybody! I need the user manual for stidomaster powerhouse vision 8 , anybody can help me!? THANKS!

Hi there,

I have a copy! I?m packing up to move house and just found it! snipped-for-privacy@yahoo.co.uk

I thought I?d lost it, just emailed you the front cover. Mine is a photocopier version from the previous owner

snipped-for-privacy@yahoo.co.uk