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thank you ! This tone board is loaded with 632As - thought those were on the bad transistor list ...

I'm curious on the DBT because prior, the light was going on and dimming to almost nothing. Now it dims, just now as much. Wondering if I am making progress of have a self-inflicted issue.

Question on the DBT - I've been changing out the transistors on F-1235 tone board - replacing them all with 1845s. When I turn on the receiver thru the DBT, the bulb goes bright and dims but still glows steady. Am I good here do you think or is there an issue? Also, I plug in music but get no...

Resurrecting this old thread as I am having the same issue with my Eight, except left channel. I'm going thru a complete overhaul anyhow, but I am finding the same issue - lots of crackling and popping from the left channel after the receiver has been on a minute or so. I swapped the driver...

Perfect-o - thank you again !

Hi Keith - I have the Bourns trimmers on order - thanks for the numbers. Would you by chance have the new part numbers for the transistors on the F-1278 boards? Per other threads I see folks used the following: TR801-802 - KSA992 TR803-804 - ZTX694B. no stock TR805-806 - B327/B337. incomplete...

Excellent - thanks Keith - this has been super helpful to confirm at least I'm not doing something stupid. I am going to go ahead and rebuild both driver boards - its the right thing to do and I think will clear up issues. I've already done the power supply so I am slowly working my way thru...

Interesting results: SM says to replace F001 before setting the right channel by measuring F003. In your last picture I do not see a fuse in F001. Without a fuse in F001 you won't get an accurate reading at F003. I did exactly that this time around. I see you have the original trimmers in...

Thanks Keith for the suggestions - please see replies. I see a few things. First, it looks like the right side of the fuse holder for both F001 and F003 are broken. I'm only seeing one side of the clip. Don't know if that is going to make a difference for electrical contact when a fuse is in...

so here is the set-up for the BIAS adjustmen - pretty straight forward. Again, the differential pair, current balance and speaker off-set all adjusted fine and are at the exact values they should be. I try to adjust the bias and TR803 has no effect - I can turn it full scale both directions and...

So I set-up everything exactly as in post #1. All voltages dialed in perfectly and balanced. Only issue is I cannot adjust the bias current. I removed the fuses #1 & #3 and measured 4.2mA for both left and right channels and TR803 does nothing - exactly as the SM states and comments here in...

thanks - I did the emitter resistor out of grin and giggles. Will set-up exact as in TRNSFRM's post #1. Need to go buy more multimeters. thanks!

Thanks Keith for this information. This has been very helpful and my first foray into adjusting these receivers. So I was pretty comfortable attempting this today but have missed something: Removed F1 & F3 (there being two fuses per channel, I only removed the top two F1 & F3, left presumably...

So stupid question - where are the hook-up points to measure the bias - I see the adjust os done on VR803 but am missing where to hook up the multi-meter. thanks in advance!

beautiful job - do you have a part number for the Bournes trimmers?

excellent - thank you for the clarification. that is what I figured.

So am I seeing it right that you are clipping off the center pin of those transistors? The collector?

this is what I thought. excellent feedback - thank you !

Hello - I am installing a new DL-110 cart into a JVC QL-A2 There is a mark on the plinth by the platter marked "overhang". The manual says to adjust tip of stylus directly over the mark - which I have done. It is exact. When I use my alignment protractor to double check, the cart aligns...

Thanks Whoaru - I didn't look very closely - will re-look.

All very helpful information and good link - thanks. So I'll use 1W on everything and can boost the sole 2W to 3 or 4. I'm leaning toward carbon film - good selection of all values. Metal film gets expensive. Is metal oxide a good option?

thanks. I measured the disc capacitors and they are still within +/- 10% so I'll leave those. That is what I thought on the resistors - no voltage specified in the selector tool - just resistance and wattage. For the 2w resistor looks like I need to go to a wire wound to get that wattage...

Hi - I have a couple Heathkit A-7 mono blocks I am restoring from the ground up. Resistors - I am going to stick with carbon resistors for replacements. I'm not seeing on the legend a voltage rating for these resistors. Do I need to get the voltage off the schematic? When I look up carbon...

got it - thanks for the great information.

so then is it safe to say it is generally ok to from metal to glass but not the other way around?