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Babelfish M25, SissySIT - general building tips and tricks
Babelfish M25, SissySIT - general building tips and tricks
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Old 11th September 2019, 02:46 PM   #1001
Ylab is offline Ylab
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Originally Posted by rhthatcher View Post
Amp 1 fixed with 2 x 102R 1% from my stash in R1 and R3 position.

I checked amp kit #2. It seems 2 impostors are hidden in the mix.

Measure all the 100Rs!
Those brown stripes almost seem black when you look at them under a cool white light !!
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Old 11th September 2019, 11:42 PM   #1002
cal3713 is offline cal3713
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Is it normal to not be able to measure the trimpot settings at r6 and r7? I couldn't, just got .23 ohms, and became convinced I'd ruined them by bending pins. When I pulled them, however, they measured fine (but now are running because I cut them out).

The other two trimpots measure in circuit fine.
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Old 11th September 2019, 11:53 PM   #1003
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Babelfish M25, SissySIT - general building tips and tricks
that's practically across R4 and R5?

what's measurement across them , without trimpots in place ?

and - is it one channel , or both?
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Old 12th September 2019, 12:18 AM   #1004
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Both channels. One is on a heat sink, after I tried and failed to start it (over 1v at output and then pulled the plug). Haven't done anything but go to bed on it.

The other isn't installed yet. Also couldn't measure r6/r7 on it. Pulled them and both measured normally, but one was at the wrong value ($!?!$!!). Without any pots installed, both r4/r5 measure appropriately (39 ohms).
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Old 12th September 2019, 12:39 AM   #1005
cal3713 is offline cal3713
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I guess this is not normal. Dammit. Really hoping I'd gained enough skill not to go through the tech support process.

Here are my boards:
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Old 12th September 2019, 12:40 AM   #1006
ItsAllInMyHead is offline ItsAllInMyHead  United States
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Thank you all for the tips for tapping. I should have backed them out more often, I think. I did use lube. Tapping jokes never get old... I agree.

ZM, I like the idea to just drill between the fins. Much easier! I'll do that next time.

I've made some progress. I thought I'd have the bias process started tonight, but getting the power supplies built and getting the chassis configured took me all day. It's a lot more snug than I thought. I was originally going to mount the donuts vertically, but ... the mounts I ordered are too wide. I may re-visit that later. It's starting to look like an amp.

I got both new PSUs run through the dim-bulb tester separately and then together. +- 26.4V for both unloaded.

Tomorrow, I'll try to get the I/Os and V+ V- to the amp boards, get the CL-60 run to the safety ground, and get it tested and biased. Then I'll clean up all the wiring and button up the chassis.

SISSY MUSIC SOON!
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Old 12th September 2019, 01:44 AM   #1007
Ylab is offline Ylab
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Quote:
Originally Posted by cal3713 View Post
Is it normal to not be able to measure the trimpot settings at r6 and r7? I couldn't, just got .23 ohms, and became convinced I'd ruined them by bending pins. When I pulled them, however, they measured fine (but now are running because I cut them out).

The other two trimpots measure in circuit fine.

First setting for R7 as per schematic is 0R. 0.23R is pretty close to 0. Not sure if itís relevant. Mine goes to 0

First setting for R6 is max. So if you got a 100R trimpot in parallel with R4 (39R) you should read something like 28R on the board. 1/39+1/100=1/28
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Old 12th September 2019, 07:34 AM   #1008
Zen Mod is offline Zen Mod  Serbia
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Babelfish M25, SissySIT - general building tips and tricks
yup ........

naive question - is there really something wrong with boards (both channels !! so veeery small probability for being that) ......... or you didn't set these trimpots in a way it is needed ?

Gremlin , must be , we just need to sort which one ....
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Old 12th September 2019, 08:41 AM   #1009
dewdrop is offline dewdrop
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Babelfish M25, SissySIT - general building tips and tricks
I have the 2KR and 100R trim pots whose legs are staggered, were these sent wrongly as the PCB calls for the straight line ones?

I wanna make sure before I either bend them to fit or to buy the right ones20190912_163850.jpg
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Old 12th September 2019, 08:53 AM   #1010
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Babelfish M25, SissySIT - general building tips and tricks
bend them

that's ZM's lazy approach , stopped worrying when I order ones and get the other ones ...... so in last decade or so I'm just taking care where screw is , pins are long enough to make them behave
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