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Good luck with the EQ board. Desolder the flat wires, unscrew the line input and copy shafts from the front panel (face plate needs to come off). Pull the shafts. Unscrew the EQ board, disconnect the three power cables, LED cables to the face plate (mark the positions) and it should come out as...

Blue man noticed on the tone amp board you have installed two BP caps in C27,C28,C29,C30. Only one 47uF 16V/25V BP cap is needed with the other position shorted with a jumper wire (trimmed cap lead). Please check and confirm what value you have installed as it will affect the sound.

Great progress @dolamike. Recommended to put the amp back on the DBT before powering up. Bias and offset will need to checked on full power. Excellent you also got the distortion issue figured out with a full restoration of the preamp board. Above all - how does it sound? Blue man looks perked...

Looks like the blue man is ready for a walk!! I am assuming 1. You have swapped the scope probe/channels to rule the test equipment out. 2. Input thru aux is exactly the same signal from signal generator 3. From the pic I see tone is engaged. Toggle to tone defeat and check the waveform I...

OK - while you are waiting, please READ this thread carefully by @Hyperion I still believe its a grounding issue. Please follow the steps outlined in the first post and see if the voltages are back.

No worries.. happy to help. Something is not correct. Please leave DBT connected. We have continuity from Pin 21 to Chassis ground. Please validate. 1. From service manual - validate you have around +/- 51V at R05/R06/R15 and R16 - Be careful use mini grabbers. 2. Check R17/R18/R23/R24...

What changed between post 67 and 73? Disconnect preamp board. Leave the phono board connected. Check voltages and report back. Meter black to chassis ground - measure at the emitter of TR01 through TR04 on the PSU board. Assuming you have mini grabbers (be careful).

Hmmm... Let's try this. Power down the amp. Meter in continuity mode. 1. One probe to pin 21 and the other probe to body of RCA connector (outside) of Phono-1/Phono-2. You should have continuity. 2. Next check continuity from RCA connector to chassis ground (any non painted surface). 3...

Yes - the delta 56-19 = Approx 35V. Please go ahead and connect the power cable to preamp and all three power cables to phono board. Power up with DBT and check voltages with meter to chassis ground. Ler's see. I recommend that we leave the driver boards off the equation for now. You can check...

Please try meter black probe as shown in the pic - "Square red markup". Marked at two points. You can use either one.

Brilliant John (@skippy124 ), I missed the 11v offset part. The voltages are correct :banana:

Move the meter black lead to board ground (try pin 21/22) or main filter MINUS to PLUS wire connector. Measure again. Looks like Chassis ground is unreliable with all the other boards disconnected (I am assuming they are) The regulated voltages are incorrect due to improper ground I think. You...

Here is what I did. On initial power up the following was connected/disconnected 1. PSU board installed - all wires soldered to the board 2. New filter caps installed 3. AMP modules - DISCONNECTED/NOT installed 4. Power cable from Preamp/Tone board removed 5. Power cable from Equalizer board...

Yes - required for proper heat dissipation. Looks like Mr. Blue is tired watching you work. Good progress.

I would try warm soap water and a toothbrush on the board to lift the blue stuff off. IF that does not work try Acetone soaked cotton swab. I would not spray it as there are plastic parts on the board. I would try 99% IPA on the volume pot (completely soak it in IPA for a few hours) to loosen...

Received 2SA1209S/2SC2911S from @TupolevFan today. Super fast shipping. 2 days from East to the West coast!! Did the swap of TR05,TR11 --> 2SA1209S and TR07,TR08 --> 2SC2911S. If you recall, I had TR05, TR11 --> TTA004B and TR05, TR11 --> TTC004B after restoration. Factory used: TR05, TR11...

At the risk of hijacking this thread (but relevant to issues OP may be having), I followed @MIJ_Pioneer thread in my restoration with the exception of the TR05,TR11/TR07/TR08. I am having NO such issues including engaging Loudness for overcoming "dullness". Note: I did not replace the drivers or...

TR01-TR02 – Original 2SC1400 ECB / Now KSC1845F (HFE Matched) - OK TR03-TR04 – Original 2SA750 (PNP) ECB / Now KSA992FB - OK TR05 ; TR11 – Original 2SA899 / Now KSA1381 -OK (See below) TR06; TR09 – Original 2SC945 / Now KSC945CY - OK TR07-TR08 – Original 2SC1904 / Now KSC2690AYS - NOT OK (see...

The output looks suspicious - please use THIS post by @avionic and check again.

Correct. However @Hyperion suggests 27.4K HERE. May be I am not reading his post correctly? Anyway I have used 27.4K in my restoration and seems to be fine.

I started using the Toshibas as KSA1220AYS is NLA (KSC2690 is still available). The improvement was pretty evident to my ears. HERE is the comparison between TTA004B and KSA1220AYS. HERE is another example Many Sansui examples in AK where the Toshiba's are widely recommended. Hope this helps

Looks good. 1. For the Zeners you can switch to 2% tolerance (Like this one 6.2v 1/2W). 2. For D608 you can switch to MUR220RLG Rest looks good. Enjoy the walk with the Blue man!!

About the relay, there is some noise in AK about the reliability of the OMRON. The relay I chose has 12A current rating and is not tall, will clear the frame when you reinstall the board in the chassis. I have switched to TE relays for all my restorations. This board is a bear to work on as you...

I agree, don't like mass replacement of films in tone boards. I try to use UKL instead (especially for the orange caps and feedback) and to my ears sounds great. Not had any issues upping the filter cap in PSU and local decoupling caps in the driver, tone and EQ amp boards which I generally do.

I had a similar experience after restoring the PSU and driver boards. Sounded good but lacked punch. Then I decided to replace 2SA899/2SC1904 with TTA004B/TTC004B. Now I just love the way it sounds. All new transistors except the drivers and the final outputs. Absolutely rocks. Give it a shot...