KENWOOD KA-701 POWERS ON, NO RELAY CLICK

[CapLeaker]

I did understand exactly what you mean. A 1/4w resistor has a physical smaller size than a 1/2w resistor. There is a wattage rating. So if you put for example a 1/4w resistor in a circuit designed for a 1/2w resistor, it will run hot and blow at some point. What did you replace the original resistors with? Did you go from carbon to metal film or something? As long as the new ones are rated for a 1/4w that's all that matters. Old carbon resistors are usually brown and huge compared to their modern equivalents.
I wasn't aware that your 2 amps actually had different version boards.

[rccrasher65]

I did understand exactly what you mean. A 1/4w resistor has a physical smaller size than a 1/2w resistor. There is a wattage rating. So if you put for example a 1/4w resistor in a circuit designed for a 1/2w resistor, it will run hot and blow at some point. What did you replace the original resistors with? Did you go from carbon to metal film or something? As long as the new ones are rated for a 1/4w that's all that matters. Old carbon resistors are usually brown and huge compared to their modern equivalents.
I wasn't aware that your 2 amps actually had different version boards.

I matched all resistors, as per parts list if it's 1/4 w the new is 1/4w, no resistor is lower in wattage. I actually want to place some metal film in around those transistors. They are 1/2 w, and 1W mostly. The physical size in old resistors are a little bigger than the new resistors of the same value, that was my question, does that matter? Yes, same amp KA-701 INTEGRATED, has two different boards, I was actually surprised myself. The one we are working on has more caps (6 ). My amp has only one. Same with resistors, and Transistors. Are there a different set of schematics, I never found anything other than what we have. Will resume with component replacement. Starting with Q11, Q10, Q9, ect. Then the caps. I will then, replace those bad resistors.

[CapLeaker]

Newer components are usually smaller than their old versions. Same with capacitors.

[petehall347]

i would replace all those fusible resistors with metal film .

[rccrasher65]

Newer components are usually smaller than their old versions. Same with capacitors.

Yes, I knew about the caps, I thought the resistors would be close to old size, but not so, as I'm seeing.

[rccrasher65]

i would replace all those fusible resistors with metal film .

I plan on it, going to place order on Friday, will continue, with the caps and transistors. Thanks

[rccrasher65]

Well didn't get much done this weekend, but ordering some new metal film resistors. Resistors should arrive on Thursday. I'm going to replace some caps, till those new parts come in. Hope all had a great Mother's day, this past weekend.

[rccrasher65]

Replaced the caps C-1, C-6, all 10uf 16V, replaced with 10uf 35V. C-6 was bad, tested at 4.3uf, very high ESR. The rest tested between 10uf- 14uf. On to the Q11, Q10, Q9 ect.

[CapLeaker]

Not too bad then. Could have been way worse!

[rccrasher65]

Not too bad then. Could have been way worse!

Yes , I thought I would have a disaster on my hands, seems to be working out better than I thought. New metal film resistors arrive Wed, so I'll replace those around, the 4 transistors, Q11, Q10, Q9 ect. I think most of the damage was on the Q11, side. That's where I found those burnt resistors.

[CapLeaker]

Sounds promising!

[rccrasher65]

Sounds promising!

Well some test results for Q11, hfe 60, IE 512ua, ube, 527mv. Q9, hfe. 66. IE. 627ua. Ube 520mv. Q10, hfe 102 IE. 966ua ube. 520mv. Q12. hfe. 148 Ie. 1.37ma ube. 556mv. I don't believe any are bad. Q11, Q9 seem weaker than rest. All were replaced with new originals. On to the resistors around these 4 transistors, there are 3 for each one. I found 2 bad. Some are dark, so those will be replaced also. I post results thurs. Looking good so far for damage.

[rccrasher65]

Well some test results for Q11, hfe 60, IE 512ua, ube, 527mv. Q9, hfe. 66. IE. 627ua. Ube 520mv. Q10, hfe 102 IE. 966ua ube. 520mv. Q12. hfe. 148 Ie. 1.37ma ube. 556mv. I don't believe any are bad. Q11, Q9 seem weaker than rest. All were replaced with new originals. On to the resistors around these 4 transistors, there are 3 for each one. I found 2 bad. Some are dark, so those will be replaced also. I post results thurs. Looking good so far for damage.

I checked the data sheet for Q11, it is working , but considered bad. hfe should be a minimum of 65, so that explains why It worked when it wanted too. Q9 is also bare minimum, but works.

[rccrasher65]

I changed the dark resistors around Q11, R-23 was smoked, replaced. R-3. Fell apart, but was ok, replaced. R-21. Fell apart, replaced. Q9, R-1 smoked, open. Replaced. As far as damage found.I think I have cleared all so far. Not seeing or testing any bad components. I will test each one, section by section of the board.

[CapLeaker]

I checked the data sheet for Q11, it is working , but considered bad. hfe should be a minimum of 65, so that explains why It worked when it wanted too. Q9 is also bare minimum, but works.

I don’t think that is the case. Way too little Hfe difference. Now, there are NPN and PNP transistors that look good measure good with your DMM, but do not work correctly. Usually the hfe is then very low. Now these transistors aren’t there at all yet.

[rccrasher65]

I don’t think that is the case. Way too little Hfe difference. Now, there are NPN and PNP transistors that look good measure good with your DMM, but do not work correctly. Usually the hfe is then very low. Now these transistors aren’t there at all yet.

They have all been replaced regardless. I'm now working my way across the board, replacing resistors that are dark, there are only about 3 that I see. They have all tested ok so far. Diodes are testing ok in circuit so far, just have the small transistors to check, I can get about 7 components in a day, before eyes get tired. Once I've gone through all the components, I think I will try a test on the Dimbulb, praying for no short.

[CapLeaker]

Good idea.

[petehall347]

where are the original replacement transistors coming from ?

[rccrasher65]

where are the original replacement transistors coming from ?

Mostly old stock, from reliable sources, others from Digikey , and mouser. I tested all before installing. It's hard finding original output transistors. Unit is over 50 yrs old. The originals have dried up. Found a pair of 2sc2525 in Japan. Had to choose the best replacements, I could finded. I've seen alot of your posts on other audio sites. Thanks for your input, valuable, and much appreciated.

[rccrasher65]

They have all been replaced regardless. I'm now working my way across the board, replacing resistors that are dark, there are only about 3 that I see. They have all tested ok so far. Diodes are testing ok in circuit so far, just have the small transistors to check, I can get about 7 components in a day, before eyes get tired. Once I've gone through all the components, I think I will try a test on the Dimbulb, praying for no short.

I have 4 resistors, I can't identify, they are not on the parts list. I found on the board, R7, R10, the other 2 are under the resistor itself.I think the color bands are white, violet, violet, gold, not sure. I'll attach a photograph, see what you guys come up with. I think it's a 970 M ohm. Resistor. They are ok but look a little brittle.